Anesthetic Complications in Urologic Surgery




Abstract


This chapter contains a comprehensive elaboration of significant anesthesia complications in genitourinary (GU) surgery, with intensive referencing. Preoperative, intraoperative, and postoperative management are covered, with a focus on treatment and prevention. Highlights include anesthesia risk stratification (ASA classification) based on major risk factors and predictors of clinical complications (cardiopulmonary, anticoagulation, infectious), with a special focus on obesity, obstructive sleep apnea, and major associated comorbidities (cardiovascular, kidney disease, metabolic syndrome).


Anesthesia techniques (general, regional, peripheral nerve blocks) are detailed, along with their potential complications, leading to patient-specific and procedure-specific decision making about the choice of anesthesia.


Postoperative care is discussed, including contemporary techniques of pain management and treatment of postoperative nausea and vomiting.


A separate section discusses anesthesia complications during laparoscopic/robotic surgery including: pathophysiology and complications of CO 2 insufflation, operative management, and major complications of patient positioning (compartment syndrome, rhabdomyolysis, eye injuries).




Keywords

Anesthesia complications in urology, Anesthesia risks, ASA classification, Complications during general anesthesia, Complications during regional anesthesia, Postoperative nausea and vomiting, Malignant hyperthermia, Meperidine spinal anesthesia, Ephedrine for cardiovascular stability, Pudendal nerve block, Postoperative pain management, Pathophysiology of pneumoperitoneum, Complications during pneumoperitoneum, Complications of patient positioning, Compartment syndrome, Rhabdomyolysis, Shoulder pain

 







Key Points




  • 1.

    Urologic diagnostic and therapeutic procedures can often induce surgical site infections, urinary tract infections, and sepsis; most procedures need to be covered with prophylactic antibiotics. Prophylaxis should be done within 60 minutes of surgical incision. If there is an active infection or any infectious source (e.g., Foley catheter) preoperatively, it should be diagnosed (urinalysis, culture and sensitivity) and specifically treated before surgery. Choice of antibiotics is hospital-specific, and the most active antibiotics are reserved for therapy.


  • 2.

    The ASA classification system is a useful tool for perioperative risk stratification in conjunction with a specific surgery. Choice of anesthesia must be tailored specifically to the patient (e.g., age, comorbidities), the specific procedure (e.g., potential complications, surgical site, length and difficulty of surgery, patient positioning), and the skills of both the anesthesiologist and the surgeon. Deciding which anesthesia technique to use is a complex by-product of thorough preoperative assessment and good communication between the anesthesiologist and urologist.


  • 3.

    Adverse pulmonary events are the cause of most anesthetic complications under general anesthesia. Inadequate ventilation, esophageal intubation, and difficult tracheal intubation are responsible for most of these injuries. Less common but equally important mechanisms of adverse respiratory-related events include airway obstruction, bronchospasm, aspiration, airway trauma, and pneumothorax. Proper airway management is essential in order to avoid most of these complications.


  • 4.

    When there are no contraindications, regional anesthesia (spinal, epidural, CSE) and peripheral nerve blocks are good choices for most urologic surgeries. They ensure good surgical analgesia; fast, alert, comfortable recovery; and excellent postoperative pain relief (8–12 hours) when meperidine spinal anesthesia is used.


  • 5.

    Complications of regional anesthesia include hypotension, postdural puncture headache, cauda equina syndrome/transient neurologic symptoms, total spinal through inadvertent subarachnoid injection, and systemic local anesthetic toxicity through inadvertent intravascular injection. Although these complications are rare, awareness of them must be maintained and proper patient monitoring and safeguards used.


  • 6.

    Two of the most common debilitating conditions in the recovery room are pain and post­operative nausea and vomiting (PONV). Both conditions are largely preventable. The use of regional anesthesia, nerve blocks, and meperidine spinal anesthesia can prevent or minimize pain while providing stress-free anesthesia. Most PONV can be prevented by avoiding inhalational anesthetics, N 2 O, and unnecessary intraoperative sedatives. Using antiemetics early, along with propofol total intravenous anesthesia (TIVA), further reduces the incidence and severity of PONV, even in high-risk patients.


  • 7.

    Pudendal and penile nerve blocks are minimally invasive and easy to perform. They are good primary or adjuvant methods for surgical analgesia and postoperative pain relief. These blocks are especially safe and useful in old and sick ASA III/IV patients because they eliminate the risks and complications caused by general anesthesia while providing a stress-free operative and postoperative course (no pain, no PONV, clear postoperative mentation).


  • 8.

    The prevalence of obesity and frequently associated obstructive sleep apnea (OSA) are increasing. Morbid obesity, when associated with significant comorbidities (coronary artery disease, heart failure, atrial fibrillation, hypertension, kidney disease, metabolic syndrome), poses significant risk and increases poor outcomes. OSA may further aggravate these outcomes. Thorough preoperative evaluation combined with proper patient triage, use of regional anesthesia and perioperative supportive continuous positive airway pressure/bilevel positive airway pressure (CPAP/BiPAP) may improve morbidity and mortality.


  • 9.

    The best postoperative pain management is based on intravenous or epidural patient-controlled analgesia or a judicious multimodal pain management using narcotics, NSAIDs, acetaminophen, tramadol, etc. Ideally, specific protocol-based management will provide best outcomes.


  • 10.

    A wide array of urology cases are being performed laparoscopically and robotically. Intimate knowledge of CO 2 insufflation pathophysiology is essential. Intraoperative complications such as shoulder pain, subcutaneous emphysema, pneumopericardium, pneumomediastinum, pneumothorax, tension pneumothorax, and CO 2 gas embolism must be understood, recognized, treated, and prevented. Serious largely preventable positioning complications in laparoscopic/robotic surgery include specific nerve damage, compartment syndrome, and rhabdomyolysis.



Urologists gain significantly from understanding different anesthesia techniques – their risks, their benefits, and their complications. Thorough knowledge of the patient’s preexisting medical, surgical, and psychological condition is essential to design a judicious surgical and anesthesia plan. The best and safest results are produced when the urologist and anesthesiologist pursue an integrated strategy together.


This chapter is organized around preoperative, intraoperative, and postoperative management, with a focus on choice of anesthesia technique (general, regional, and peripheral nerve blocks), and the treatment and prevention of complications. Additionally, the chapter includes sections covering the special anesthetic management and complications of urologic laparoscopy/robotic-assisted laparoscopy.




Anesthesia Safety


Safety of anesthesia has been steadily improving for the past several decades. The incidence of anesthetic mortality in which anesthesia was the primary cause of death improved steadily from 1 per 14,075 to 1 per 300,000 anesthetics administered. There are multiple reasons for these significant improvements, including more targeted preoperative testing, better intraoperative monitoring, better expert clinical training for anesthesiologists including simulation training, creation of patient-centered clinical pathways and protocols developed from evidence-based medicine, and increased awareness and knowledge of potential surgical and anesthesia complications.




Preoperative Assessment


The best choice of anesthetic technique for any urologic procedure requires a thorough preoperative evaluation of the patient. This minimally includes a detailed assessment of cardiac risks, pulmonary risks and airway, infectious complication risks, and anticoagulation risks. All these data, along with the American Society of Anesthesiologists (ASA) anesthesia risk classification and an understanding of procedure-specific surgical and anesthetic risks, influence the choice of anesthesia technique.


Preanesthetic Evaluation


A preanesthesia evaluation involves assessment of information from multiple sources, including patient’s history and physical examination, previous medical records, and findings from preoperative tests. According to the ASA practice advisory for preanesthesia evaluation, the patient’s history and physical condition should dictate what kind of preoperative testing is appropriate, and routine preoperative testing should be avoided. A presurgical testing unit (PST) is very useful in determining what selective preoperative tests should be obtained. Each hospital should have its own experience-based decision-making parameters for the timing, quality, and quantity of the specific preoperative tests required for each given procedure. It is beyond the scope of this chapter to greatly detail all required preoperative testing regimens for urologic surgery.


At a minimum, however, complete blood cell count (CBC), basic metabolic panel, blood urea nitrogen (BUN)/creatinine, and urinalysis are obtained. If urinalysis is positive, a culture and sensitivity (C&S) test is obtained and patients are placed preoperatively on a culture-specific antibiotic in order to prevent bacteremia and possibly urosepsis during surgery.


The patient’s preexisting cardiac and pulmonary conditions are the two most common risks for anesthetic morbidity and mortality. Additionally, increasingly prevalent significant risks include morbid obesity and obstructive sleep apnea (OSA).


Anesthesia Risk: The American Society of Anesthesiologists Physical Status Classification System


Once all the preoperative information is evaluated, the anesthesiologist assigns an ASA score. The score is intended to create a uniform system of describing the patient’s preoperative physical condition. ASA classification is important because studies have demonstrated that with increasing ASA class, there is increased incidence of adverse events and adverse outcomes.


The modern classification system consists of the following six physical status categories:




  • ASA I: Normal healthy patient



  • ASA II: Patient with one mild systemic disease



  • ASA III: Patient with two severe systemic diseases



  • ASA IV: Patient with several systemic diseases, at least one life threatening



  • ASA V: Moribund patient who is not expected to survive without the operation



  • ASA VI: Declared brain-dead patient who will become an organ donor



Choice of Anesthesia Technique in Urologic Surgery


Adult patients requiring anesthesia for renal and genitourinary surgery are often very old, and they may have a host of comorbidities, which pose serious problems before, during, and after surgery and anesthesia. The choice of anesthetic technique depends on a myriad of factors, including the patient’s preexisting conditions; type, site, and length of surgery to be performed; skill of the urologist and anesthesiologist and their intimate knowledge of potential surgical and anesthetic complications; and predictability and limitations of the surgical and anesthesia procedures. Based on all of these factors, the ultimate decision of anesthesia method needs to be the product of a well-informed discussion between the surgeon and the anesthesiologist.


Patient-specific Risk Stratification


The modern ASA classification system, in conjunction with the full preoperative workup data of the patient, provides a degree of perioperative risk stratification that is very useful in choosing the optimal anesthetic technique for a given patient undergoing a particular surgery.


ASA I patients who are young, healthy, and with good exercise tolerance and no organic physiologic or psychiatric disturbance may have general anesthesia, regional anesthesia, nerve blocks, or clinical sedation for their procedure. Any obvious difficulty with general anesthesia (e.g., difficult airway, full stomach, allergies to anesthetics, hyperreactive airway) will necessitate modifications in the general anesthesia technique (e.g., fiberoptic intubation, fast sequence induction and endotracheal intubation, avoidance of certain drugs, modification or deepening of induction). General anesthesia will be used in cases in which patient stillness during the procedure is essential, for example, brachytherapy, renal and upper ureteral stone lithotripsy, and most laparoscopic and robotic surgeries.


ASA II patients with mild systemic disease who have no functional limitations and have a well-controlled one body system disease (e.g., diabetes, hypertension [HTN], smoking without chronic obstructive pulmonary disease [COPD]) can tolerate general anesthesia as well as regional anesthesia or nerve blocks. The one system disease must be stabilized. If a patient presents with a full stomach or hyperreactive airway, regional anesthesia or nerve blocks might provide extra safety for the patient and ease postoperative recovery.


ASA III patients have severe systemic disease, involving more than one major body system. They are in no immediate danger of death, but they have some functional limitations (e.g., stable angina, congestive heart failure [CHF], old heart attack, poorly controlled hypertension and diabetes, morbid obesity, OSA, chronic renal failure). With the advent of modern monitoring and mandatory use of pulse oximetry and end-tidal carbon dioxide monitoring (ETCO 2 ), contemporary general anesthesia has greatly improved. Most recent clinical studies comparing general with regional anesthesia show no substantial difference in outcomes. However, when using general anesthesia in this patient population, utmost care must be exercised in maintaining steady normal vital signs throughout the case (e.g., use etomidate for induction, use cardiovascular support, if needed, and maintain normal blood volume). If there are no contraindications, regional anesthesia or nerve blocks with their pulmonary and cardiovascular sparing effect, along with the prolonged postoperative analgesia they provide, are our favorite modalities for predictable, stable, safe, and comfortable outcomes in this patient group.


ASA IV patients have multiple system disease, where one or more diseases may present a constant threat to life. These diseases may be poorly controlled or at their end stage (e.g., unstable angina, symptomatic COPD, symptomatic CHF, hepatorenal failure). Preoperatively, these patients require time and specialist support to maximally control their unstable diseases. Intraoperatively, heavy monitoring (e.g., A-line, central venous pressure [CVP], Swan-Ganz catheter, cardiac output, transesophageal echocardiography [TEE]) and pharmacologic cardiovascular and pulmonary support are needed. In this patient group, general anesthesia poses high risk. For urologic procedures, regional anesthesia in skilled hands, using minidoses of local anesthetic, ensures minimum respiratory and cardiovascular risk, as well as stable, comfortable, and less eventful recovery. Importantly, using only minimum sedation with the regional block, the mental status of these sicker, older patients will remain unimpaired throughout the case and during the recovery period.


Procedure-specific Indications


Because most urologic procedures are performed in an anatomic area primarily innervated by thoracolumbar and sacral nerve supply, these procedures are excellent candidates for regional anesthesia and nerve blocks. The great versatility of regional anesthesia relies on the fact that, if skillfully done, it can greatly preserve pulmonary and cardiovascular functions in all patients. This gives maximum benefit to older patients or those with severe comorbidities. Major contraindications for regional anesthesia are patient refusal, skin infection, sepsis, cardiac outflow tract obstruction (aortic stenosis, idiopathic hypertrophic subaortic stenosis [IHSS]), serious previous neurologic deficiencies, anticoagulation, shock, hypotension, or allergies to local anesthetics.


In some urologic procedures patient awareness is an advantage, as in transurethral resection of the prostate (TURP) using monopolar resectoscope, in which the patient can voice any discomfort and early symptomatology. In other procedures, slight sedation or a total intravenous anesthesia (TIVA) helps the patient tolerate the operative surroundings (operating room noises, uncomfortable positioning) and length of procedure (e.g., long perineal reconstructive procedures done under combined spinal or epidural block, radical prostatectomy under regional block, penile prosthesis insertion, artificial urinary sphincter insertion, complex female incontinence surgery, endourethral procedures, longer procedures done under pudendal or penile block).


TIVA always successfully assures physical and emotional comfort when used before/during pudendal blocks and penile blocks. Patients are unaware of the block, and after the procedure they wake up comfortable and enjoy a prolonged postoperative analgesia. A propofol-based TIVA predictably prevents postoperative nausea and vomiting (PONV) in most patients, including those with a history of PONV. See “ Postoperative Nausea and Vomiting ,” later.




Key Points




  • 1.

    Urologic diagnostic and therapeutic procedures can often induce surgical site infections, urinary tract infections, and sepsis; most procedures need to be covered with prophylactic antibiotics. Prophylaxis should be done within 60 minutes of surgical incision. If there is an active infection or any infectious source (e.g., Foley catheter) preoperatively, it should be diagnosed (urinalysis, culture and sensitivity) and specifically treated before surgery. Choice of antibiotics is hospital-specific, and the most active antibiotics are reserved for therapy.


  • 2.

    The ASA classification system is a useful tool for perioperative risk stratification in conjunction with a specific surgery. Choice of anesthesia must be tailored specifically to the patient (e.g., age, comorbidities), the specific procedure (e.g., potential complications, surgical site, length and difficulty of surgery, patient positioning), and the skills of both the anesthesiologist and the surgeon. Deciding which anesthesia technique to use is a complex by-product of thorough preoperative assessment and good communication between the anesthesiologist and urologist.


  • 3.

    Adverse pulmonary events are the cause of most anesthetic complications under general anesthesia. Inadequate ventilation, esophageal intubation, and difficult tracheal intubation are responsible for most of these injuries. Less common but equally important mechanisms of adverse respiratory-related events include airway obstruction, bronchospasm, aspiration, airway trauma, and pneumothorax. Proper airway management is essential in order to avoid most of these complications.


  • 4.

    When there are no contraindications, regional anesthesia (spinal, epidural, CSE) and peripheral nerve blocks are good choices for most urologic surgeries. They ensure good surgical analgesia; fast, alert, comfortable recovery; and excellent postoperative pain relief (8–12 hours) when meperidine spinal anesthesia is used.


  • 5.

    Complications of regional anesthesia include hypotension, postdural puncture headache, cauda equina syndrome/transient neurologic symptoms, total spinal through inadvertent subarachnoid injection, and systemic local anesthetic toxicity through inadvertent intravascular injection. Although these complications are rare, awareness of them must be maintained and proper patient monitoring and safeguards used.


  • 6.

    Two of the most common debilitating conditions in the recovery room are pain and post­operative nausea and vomiting (PONV). Both conditions are largely preventable. The use of regional anesthesia, nerve blocks, and meperidine spinal anesthesia can prevent or minimize pain while providing stress-free anesthesia. Most PONV can be prevented by avoiding inhalational anesthetics, N 2 O, and unnecessary intraoperative sedatives. Using antiemetics early, along with propofol total intravenous anesthesia (TIVA), further reduces the incidence and severity of PONV, even in high-risk patients.


  • 7.

    Pudendal and penile nerve blocks are minimally invasive and easy to perform. They are good primary or adjuvant methods for surgical analgesia and postoperative pain relief. These blocks are especially safe and useful in old and sick ASA III/IV patients because they eliminate the risks and complications caused by general anesthesia while providing a stress-free operative and postoperative course (no pain, no PONV, clear postoperative mentation).


  • 8.

    The prevalence of obesity and frequently associated obstructive sleep apnea (OSA) are increasing. Morbid obesity, when associated with significant comorbidities (coronary artery disease, heart failure, atrial fibrillation, hypertension, kidney disease, metabolic syndrome), poses significant risk and increases poor outcomes. OSA may further aggravate these outcomes. Thorough preoperative evaluation combined with proper patient triage, use of regional anesthesia and perioperative supportive continuous positive airway pressure/bilevel positive airway pressure (CPAP/BiPAP) may improve morbidity and mortality.


  • 9.

    The best postoperative pain management is based on intravenous or epidural patient-controlled analgesia or a judicious multimodal pain management using narcotics, NSAIDs, acetaminophen, tramadol, etc. Ideally, specific protocol-based management will provide best outcomes.


  • 10.

    A wide array of urology cases are being performed laparoscopically and robotically. Intimate knowledge of CO 2 insufflation pathophysiology is essential. Intraoperative complications such as shoulder pain, subcutaneous emphysema, pneumopericardium, pneumomediastinum, pneumothorax, tension pneumothorax, and CO 2 gas embolism must be understood, recognized, treated, and prevented. Serious largely preventable positioning complications in laparoscopic/robotic surgery include specific nerve damage, compartment syndrome, and rhabdomyolysis.



Urologists gain significantly from understanding different anesthesia techniques – their risks, their benefits, and their complications. Thorough knowledge of the patient’s preexisting medical, surgical, and psychological condition is essential to design a judicious surgical and anesthesia plan. The best and safest results are produced when the urologist and anesthesiologist pursue an integrated strategy together.


This chapter is organized around preoperative, intraoperative, and postoperative management, with a focus on choice of anesthesia technique (general, regional, and peripheral nerve blocks), and the treatment and prevention of complications. Additionally, the chapter includes sections covering the special anesthetic management and complications of urologic laparoscopy/robotic-assisted laparoscopy.




Anesthesia Safety


Safety of anesthesia has been steadily improving for the past several decades. The incidence of anesthetic mortality in which anesthesia was the primary cause of death improved steadily from 1 per 14,075 to 1 per 300,000 anesthetics administered. There are multiple reasons for these significant improvements, including more targeted preoperative testing, better intraoperative monitoring, better expert clinical training for anesthesiologists including simulation training, creation of patient-centered clinical pathways and protocols developed from evidence-based medicine, and increased awareness and knowledge of potential surgical and anesthesia complications.




Preoperative Assessment


The best choice of anesthetic technique for any urologic procedure requires a thorough preoperative evaluation of the patient. This minimally includes a detailed assessment of cardiac risks, pulmonary risks and airway, infectious complication risks, and anticoagulation risks. All these data, along with the American Society of Anesthesiologists (ASA) anesthesia risk classification and an understanding of procedure-specific surgical and anesthetic risks, influence the choice of anesthesia technique.


Preanesthetic Evaluation


A preanesthesia evaluation involves assessment of information from multiple sources, including patient’s history and physical examination, previous medical records, and findings from preoperative tests. According to the ASA practice advisory for preanesthesia evaluation, the patient’s history and physical condition should dictate what kind of preoperative testing is appropriate, and routine preoperative testing should be avoided. A presurgical testing unit (PST) is very useful in determining what selective preoperative tests should be obtained. Each hospital should have its own experience-based decision-making parameters for the timing, quality, and quantity of the specific preoperative tests required for each given procedure. It is beyond the scope of this chapter to greatly detail all required preoperative testing regimens for urologic surgery.


At a minimum, however, complete blood cell count (CBC), basic metabolic panel, blood urea nitrogen (BUN)/creatinine, and urinalysis are obtained. If urinalysis is positive, a culture and sensitivity (C&S) test is obtained and patients are placed preoperatively on a culture-specific antibiotic in order to prevent bacteremia and possibly urosepsis during surgery.


The patient’s preexisting cardiac and pulmonary conditions are the two most common risks for anesthetic morbidity and mortality. Additionally, increasingly prevalent significant risks include morbid obesity and obstructive sleep apnea (OSA).


Anesthesia Risk: The American Society of Anesthesiologists Physical Status Classification System


Once all the preoperative information is evaluated, the anesthesiologist assigns an ASA score. The score is intended to create a uniform system of describing the patient’s preoperative physical condition. ASA classification is important because studies have demonstrated that with increasing ASA class, there is increased incidence of adverse events and adverse outcomes.


The modern classification system consists of the following six physical status categories:




  • ASA I: Normal healthy patient



  • ASA II: Patient with one mild systemic disease



  • ASA III: Patient with two severe systemic diseases



  • ASA IV: Patient with several systemic diseases, at least one life threatening



  • ASA V: Moribund patient who is not expected to survive without the operation



  • ASA VI: Declared brain-dead patient who will become an organ donor



Choice of Anesthesia Technique in Urologic Surgery


Adult patients requiring anesthesia for renal and genitourinary surgery are often very old, and they may have a host of comorbidities, which pose serious problems before, during, and after surgery and anesthesia. The choice of anesthetic technique depends on a myriad of factors, including the patient’s preexisting conditions; type, site, and length of surgery to be performed; skill of the urologist and anesthesiologist and their intimate knowledge of potential surgical and anesthetic complications; and predictability and limitations of the surgical and anesthesia procedures. Based on all of these factors, the ultimate decision of anesthesia method needs to be the product of a well-informed discussion between the surgeon and the anesthesiologist.


Patient-specific Risk Stratification


The modern ASA classification system, in conjunction with the full preoperative workup data of the patient, provides a degree of perioperative risk stratification that is very useful in choosing the optimal anesthetic technique for a given patient undergoing a particular surgery.


ASA I patients who are young, healthy, and with good exercise tolerance and no organic physiologic or psychiatric disturbance may have general anesthesia, regional anesthesia, nerve blocks, or clinical sedation for their procedure. Any obvious difficulty with general anesthesia (e.g., difficult airway, full stomach, allergies to anesthetics, hyperreactive airway) will necessitate modifications in the general anesthesia technique (e.g., fiberoptic intubation, fast sequence induction and endotracheal intubation, avoidance of certain drugs, modification or deepening of induction). General anesthesia will be used in cases in which patient stillness during the procedure is essential, for example, brachytherapy, renal and upper ureteral stone lithotripsy, and most laparoscopic and robotic surgeries.


ASA II patients with mild systemic disease who have no functional limitations and have a well-controlled one body system disease (e.g., diabetes, hypertension [HTN], smoking without chronic obstructive pulmonary disease [COPD]) can tolerate general anesthesia as well as regional anesthesia or nerve blocks. The one system disease must be stabilized. If a patient presents with a full stomach or hyperreactive airway, regional anesthesia or nerve blocks might provide extra safety for the patient and ease postoperative recovery.


ASA III patients have severe systemic disease, involving more than one major body system. They are in no immediate danger of death, but they have some functional limitations (e.g., stable angina, congestive heart failure [CHF], old heart attack, poorly controlled hypertension and diabetes, morbid obesity, OSA, chronic renal failure). With the advent of modern monitoring and mandatory use of pulse oximetry and end-tidal carbon dioxide monitoring (ETCO 2 ), contemporary general anesthesia has greatly improved. Most recent clinical studies comparing general with regional anesthesia show no substantial difference in outcomes. However, when using general anesthesia in this patient population, utmost care must be exercised in maintaining steady normal vital signs throughout the case (e.g., use etomidate for induction, use cardiovascular support, if needed, and maintain normal blood volume). If there are no contraindications, regional anesthesia or nerve blocks with their pulmonary and cardiovascular sparing effect, along with the prolonged postoperative analgesia they provide, are our favorite modalities for predictable, stable, safe, and comfortable outcomes in this patient group.


ASA IV patients have multiple system disease, where one or more diseases may present a constant threat to life. These diseases may be poorly controlled or at their end stage (e.g., unstable angina, symptomatic COPD, symptomatic CHF, hepatorenal failure). Preoperatively, these patients require time and specialist support to maximally control their unstable diseases. Intraoperatively, heavy monitoring (e.g., A-line, central venous pressure [CVP], Swan-Ganz catheter, cardiac output, transesophageal echocardiography [TEE]) and pharmacologic cardiovascular and pulmonary support are needed. In this patient group, general anesthesia poses high risk. For urologic procedures, regional anesthesia in skilled hands, using minidoses of local anesthetic, ensures minimum respiratory and cardiovascular risk, as well as stable, comfortable, and less eventful recovery. Importantly, using only minimum sedation with the regional block, the mental status of these sicker, older patients will remain unimpaired throughout the case and during the recovery period.


Procedure-specific Indications


Because most urologic procedures are performed in an anatomic area primarily innervated by thoracolumbar and sacral nerve supply, these procedures are excellent candidates for regional anesthesia and nerve blocks. The great versatility of regional anesthesia relies on the fact that, if skillfully done, it can greatly preserve pulmonary and cardiovascular functions in all patients. This gives maximum benefit to older patients or those with severe comorbidities. Major contraindications for regional anesthesia are patient refusal, skin infection, sepsis, cardiac outflow tract obstruction (aortic stenosis, idiopathic hypertrophic subaortic stenosis [IHSS]), serious previous neurologic deficiencies, anticoagulation, shock, hypotension, or allergies to local anesthetics.


In some urologic procedures patient awareness is an advantage, as in transurethral resection of the prostate (TURP) using monopolar resectoscope, in which the patient can voice any discomfort and early symptomatology. In other procedures, slight sedation or a total intravenous anesthesia (TIVA) helps the patient tolerate the operative surroundings (operating room noises, uncomfortable positioning) and length of procedure (e.g., long perineal reconstructive procedures done under combined spinal or epidural block, radical prostatectomy under regional block, penile prosthesis insertion, artificial urinary sphincter insertion, complex female incontinence surgery, endourethral procedures, longer procedures done under pudendal or penile block).


TIVA always successfully assures physical and emotional comfort when used before/during pudendal blocks and penile blocks. Patients are unaware of the block, and after the procedure they wake up comfortable and enjoy a prolonged postoperative analgesia. A propofol-based TIVA predictably prevents postoperative nausea and vomiting (PONV) in most patients, including those with a history of PONV. See “ Postoperative Nausea and Vomiting ,” later.




Obesity and Obstructive Sleep Apnea


The prevalence of obesity is rapidly increasing worldwide. Proportionately, the prevalence of OSA is increasing as well. Clinically, these two conditions frequently overlap. Therefore they will be treated together in this chapter.


In adults, the World Health Organization (WHO) and the National Institutes of Health (NIH) define and classify obesity with respect to body mass index (BMI) as:




  • Overweight: BMI ≥25–29.9 kg/m 2



  • Obesity: BMI ≥30 kg/m 2



  • Obesity Class 1: BMI of 30–34.9 kg/m 2



  • Obesity Class 2: BMI of 35–39.9 kg/m 2



  • Obesity Class 3: BMI ≥40 kg/m 2 (referred to as extreme, severe, or morbid obesity)



Planning for anesthesia must take account of two aspects of obesity: (1) physiologic changes of obesity, and (2) the presence of specific comorbidities. Other risk factors should be addressed as well.


Physiologic Changes of Obesity


Obesity produces changes in respiratory, cardiovascular, and airway physiology (difficult ventilation/intubation), which may impact anesthesia delivery to these patients.


Respiratory Physiology


Extra body weight will lead to increased work of breathing and oxygen consumption, as well as a disordered ventilation/perfusion (V/Q) ratio. The lung volumes, functional residual capacity (FRC), and expiratory reserve volume (ERV) are decreased while the respiratory rate (RR) is increased. V/Q mismatch and intrapulmonary shunts increase during general anesthesia (GA) to a greater degree in obese patients. Supine position and OSA will exaggerate these changes.


Cardiovascular Physiology


Extra body weight will lead to an increase in blood volume; decrease in systemic vascular resistance; and an increase in cardiac output (CO), which occurs mostly due to an increase in stroke volume, which may lead to heart failure, especially when associated with chronic hypoxia of OSA. Frequently, there is left ventricular hypertrophy (LVH) directly proportionate with the duration of obesity. Hypertension (HTN), which is prevalent in obese patients, may aggravate the entire picture and produces additional physiologic changes.


Dosing of anesthetic drugs is difficult and complex in obese patients. It should be modified because of significant changes in regional blood flow and increases in CO and blood volume. When the recommended dosing scheme is not known, the use of medications should be based on lean body weight (LBW), except with lipophilic drugs, where total body weight (TBW) should be used.


Comorbidities Associated With Obesity


Healthy Class 1 obese patients do not seem to be at increased risk of adverse outcomes following noncardiac surgery. However, there is an increase in postoperative morbidity and mortality in morbidly obese patients presenting with comorbidities. A targeted history and physical (H&P) and some additional testing must be obtained and discussed by the medical, surgical, and anesthesia team. It is very important to identify and optimize comorbidities as part of planning for surgery.


Comorbidities prevalent in obese patients may include OSA, obesity hypoventilation syndrome (OHS), heart disease (CAD, heart failure, arrhythmias, HTN), metabolic syndrome, diabetes mellitus (DM), and kidney disease. During preoperative screening, the stage of comorbidities should be evaluated to assess their impact on perioperative management in order to minimize complications from surgery and anesthesia.


Obstructive Sleep Apnea


Obstructive sleep apnea, a prevalent respiratory risk condition in morbidly obese patients, is characterized by repetitive bouts of apnea, hypopnea, and hypoxia during sleep. Obstructive sleep apnea impacts patients’ responses to narcotics and sedatives, exaggerating their respiratory depressant effect, and affects the airway (difficult ventilation, intubation). Obstructive sleep apnea is associated with specific cardiovascular effects, which include coronary artery disease (CAD), HTN, pulmonary hypertension, and frequent cardiac arrhythmias. A frequently associated condition is OHS, which is defined as chronic hypoventilation in an awake patient (a CO 2 >45 mm Hg). These patients tend to have pulmonary hypertension, and they are extremely sensitive to the respiratory depressant effects of narcotics and sedatives. Continuous positive airway pressure (CPAP) is frequently needed to support better oxygenation postoperatively. Preoperatively the OHS patient should have an echocardiogram to assess cardiac function and a baseline arterial blood gas (ABG) and chemistries (bicarbonate) to assess the degree of chronic hypercapnia.


Coronary Artery Disease, Heart Failure, and Atrial Fibrillation


CAD, HF, and AF are more common in obese patients and should be recently diagnosed and stabilized preoperatively. Exercise tolerance should be gauged by history and stress test. The American Heart Association (AHA) scientific advisory on obesity recommended in 2009 that obese patients with even one risk factor for CAD (smoking, DM, HTN, or hyperlipidemia) or with poor exercise tolerance should obtain a 12-lead EKG and chest X-ray (BMI >40) in addition to the regular preoperative workup recommended for patients with a normal BMI.


Hypertension


Hypertension is frequently associated with obesity and should be controlled/steadied preoperatively. If BP >170/110, the case should be postponed and the patient medically stabilized at lower levels of BP. Labile BP during surgery is frequently associated with serious cardiac, renal, and neurologic complications.


Metabolic Syndrome


Metabolic syndrome is associated with greater frequency of complications during surgery. It is characterized by a host of risk factors leading to cardiovascular disease and type 2 DM. Abdominal obesity, dyslipidemia, HTN, and hyperglycemia should be assessed and optimized preoperatively.


Kidney Disease


In morbidly obese patients, it is recommended to obtain a creatinine (Cr) and a GFR prior to major surgeries.


Other Preoperative Risk Factors in Obesity: Difficult Airway


There are certain predictors of difficult mask ventilation and difficult intubation.


Predictors of difficult mask ventilation are BMI >30 kg/m 2 , history of OSA, lack of teeth, presence of beard, age >55, Mallampati III-IV (difficult airway), limited mandibular protrusion test, male gender, and presence of airway masses (tumors, deformities).


Predictors of difficult laryngoscopy and intubation are Mallampati III-IV, previous difficult intubation, large circumference of neck, and male gender.


Preoperative Considerations for Obese and Obstructive Sleep Apnea Patients


Most general preoperative measures like nil per os (NPO) and medications (doses, timing, etc.) are the same as for nonobese patients. Additionally, BP, blood sugar, and screening for OSA (sleep clinic, home test, STOP-BANG) should be considered. Also, patients should be evaluated for difficult airway, difficult intubation, and chance of rapid hypoxia.


Lap Band


In order to avoid aspiration pneumonitis, patients with previous weight loss surgery (e.g., lap band) will need to have their band released preoperatively by the hospital bariatric team. Even after band release, patients with a history of frequent post–lab band reflux should have their airway protected (endotracheal intubation).


Ambulatory Versus Inpatient


Deciding whether to do surgery in an ambulatory or inpatient setting should be an individualized decision, based on close cooperation between the patient’s primary care physician (PCP), surgeon, and anesthesiologist. It is accepted that super-obesity (BMI >50 kg/m 2 ) might influence outcomes after ambulatory procedures, especially in patients with comorbidities. Several studies report factors influencing morbidity and mortality in ambulatory surgery on the super-obese: BMI >53, inability to walk over 200 feet, history of deep vein thrombosis (DVT), history of OSA, other coexisting medical conditions, and type of surgical procedure. Another study reports higher ASA physical status and longer operations significantly increase mortality for this group.


However, ambulatory surgeries of all kinds are routinely done on morbidly obese patients without undue complications or hospital admissions. To assure safety, proper equipment should be available, e.g., advanced respiratory and intubation tools, proper capacity beds, and appropriate x-ray and lab facilities. For best results, proper clinical protocols and pathways for the care of the morbidly obese should be established.


Obese Patients With Preoperative Diagnosis of Obstructive Sleep Apnea or Obesity Hyperventilation Syndrome


This patient population benefits from daily preoperative use of CPAP or bilevel positive airway pressure (BiPAP), which produces an increase in pharyngeal area, a decrease of tongue volume (which occurs in about 4–6 weeks of therapy), improved ventilatory drive, and improvement of most cardiac parameters. Furthermore, recent studies have suggested the utility of CPAP/BiPAP for several days postoperatively when a patient’s condition might worsen at home. These patients should be encouraged to use their CPAP or BiPAP both pre- and postoperatively. In some cases of newly diagnosed OHS and/or OSA, surgery might need to be delayed (if it is not an emergency) until the above positive changes can be effected. BiPAP appears to be somewhat superior to CPAP in obtaining these improvements.


Strategies for Anesthesia and Pain Management in Obese/Obstructive Sleep Apnea Patients


For obese/OSA patients, regional anesthesia is a safer choice than general anesthesia. Regional anesthesia also may obviate the need for postoperative narcotics and sedatives (thus avoiding their respiratory depressant effect).


If general anesthesia is required, dexmedetomidine is superior to inhalational anesthesia. Ketamine is a useful anesthetic, which also provides prolonged postoperative analgesia.


In the context of postoperative multimodal analgesia, acetaminophen IV and NSAIDS (e.g., Celebrex, diclo­fenac, ibuprofen IV, and ketorolac) prove effective (allowing decreased use of opioids). Other opioid-sparing drugs like steroids, pregabalin, tramadol, tapentadol, and dexmedetomidine can be used successfully.




Further Prevention of Regional Anesthesia Complications


Meperidine Spinal Anesthesia


In our practice, we use regional anesthesia extensively for a large number of urologic procedures. Judicious use of meperidine spinal anesthesia prevents many major and minor anesthetic complications and provides superior long-lasting postoperative pain relief.


We have perfected a technique over the past several decades in which regular doses or minidoses of meperidine have been used without any respiratory depressant effect or otherwise deleterious side effects in thousands of ASA III–IV patients. We have used this regimen with great success in a wide variety of urologic procedures, ranging from cystoscopy to long TURPs, procedures for female and male incontinence, radical retropubic prostatectomy, and endourology procedures, including transurethral and/or percutaneous lithotripsy.


Meperidine has a fast onset and, when used alone, provides a deep sensory and motor block completely resembling plain lidocaine and/or mepivacaine spinal (50 mg doses yield a similar T6 sensory level, which covers ~1.5 hours of surgical anesthesia). Subarachnoid meperidine is the only short-acting narcotic with local anesthetic properties that provides 8 to 12 hours of postoperative analgesia. In the PACU, patients who received meperidine during surgery are completely awake, have a clear sensorium, are recovered fully from the initial motor block, and do not require pain medications.


As a rare side effect, itchiness occurs in <1% of cases. If itchiness becomes intense, it is treated with naloxone 40 µg IV, followed by naloxone 80 to 100 µg IM for prolonged effect.


Meperidine does not increase the risk of spinal headache (we have observed 0% in our patient population). Meperidine does not produce TNS as do the other local anesthetics.


Meperidine may be used alone or in combinations. We add minidoses of long-acting local anesthetics (bupivacaine, pontocaine) in order to prolong meperidine anesthesia during longer surgeries. This allows great versatility in matching a spinal anesthesia regimen to the length of a particular surgical procedure, so that the motor blockade will wear off very soon after the conclusion of surgery while still providing very long postoperative analgesia.


Meperidine can provide the spinal component of the CSE technique used in extra-long cases where the epidural catheter may be kept in place for several days for prolonged postoperative analgesia.


Combined Intravenous and Intramuscular Ephedrine for Cardiovascular Stability


In order to counteract the potential drop in BP secondary to any spinal anesthesia, we use ephedrine prophylactically immediately following spinal injection, as 5 mg IV bolus, with simultaneous IM injection of 25 mg to 40 mg (depending on patient’s size). The IV dose starts working within a minute, without producing undue tachycardia, and lasts up to 10 minutes. The IM dose becomes effective within 10 minutes and works for 2.5 hours (using the muscle as a depot), with only minor increases in BP or heart rate (<10%), thus ensuring a continuum of BP support. This IV/IM regimen may be safely repeated several times, every 2.5 hours in longer procedures.


If given early enough, at the onset of sympathectomy secondary to spinal administration, this ephedrine regimen will always maintain the patient’s original heart rate and BP, independent of the actual hydration status. This allows ample time to rehydrate the patient. Thus, a completely stable cardiovascular status is assured for the length of the case and recovery. This ephedrine regimen confers great cardiovascular stability to spinal anesthesia, making it an extremely attractive choice for all patients, and especially older and sicker ASA III–IV patients.


The combined IV/IM ephedrine also is useful to maintain BP in early hemorrhagic shock until the patient is rehydrated to euvolemia (crystalloids, colloids, blood), and to counteract orthostatic hypotension in the PACU (after rehydration fails).




Nerve Blocks in Urology


Nerve blocks offer a safe anesthetic approach to a multitude of urologic procedures and a rapid painless recovery for all patients. These blocks prove to be especially safe and useful in old and sick ASA III–IV patients because these blocks eliminate the risks and complications that general and regional anesthesia cause while providing a stressless operative and postoperative course (pain free, no PONV, clear postoperative mentation).


Contraindications to these nerve blocks include patient refusal, anticoagulation, allergy to the local anesthetic, and local infection.


Pudendal block and penile block are the nerve blocks most frequently used in hospital-based urologic surgery.


Pudendal Nerve Block


Pudendal nerve block may be used in all superficial male and female perineal surgeries; male and female lower urinary reconstructive procedures; sling procedures for incontinence; rectal and urinary sphincter procedures; and procedures on the penis, clitoris, scrotum, and labia majora. The pudendal nerve block can be used in conjunction with a short spinal anesthesia, general anesthesia, or continuous propofol/fentanyl TIVA.


The pudendal nerve innervates the perineum, the anal and urethral sphincters, the penis, and the clitoris. A number of male and female urologic procedures depend on knowledge of pudendal innervation, including anal and stress incontinence surgeries via suprapubic, perineal, or vaginal approaches, and pudendal canal decompression for pudendal canal syndrome and pudendal artery syndrome (with erectile dysfunction).


The sacral plexus gives off the pudendal nerve by using the S 2 , S 3 , and S 4 anterior rami. The pudendal nerve roots emerge from the anterior sacral foramen. The pudendal nerve contains autonomic and motor nerve fibers together, making it a mixed nerve.


Out of the pudendal canal, the pudendal nerve gives off three terminal branches: the inferior rectal nerve, the perineal nerve, and the dorsal nerve of penis or dorsal nerve of clitoris.


The inferior rectal nerve supplies the external anal sphincter, the mucous membrane, and the lower half of the perianal skin and the inner anal canal. The perineal nerve gives off deep branches to the muscles of the urogenital triangle and superficial branches to the skin of the lower labia majora and lower scrotum. The dorsal nerve of the penis or clitoris supplies sensory nerve endings to the skin surface of the clitoris and penis.


The pudendal nerve runs through three significant anatomic regions: the gluteal region, the pudendal canal, and the perineum. The course of the pudendal nerve in the area of the ischial spine is important because this is where the pudendal nerve block is placed.


There are three approaches to the pudendal nerve block:



  • 1.

    Transvaginal approach


  • 2.

    Midperineal approach


  • 3.

    Direct percutaneous approach (Vaida method).



Transvaginal Approach


This method, often used in obstetrics, provides perineal analgesia during the third stage of delivery, when the presenting part of the newborn is visibly bulging the perineum. It is also useful in female urologic surgery.


The block is done with the patient in the lithotomy position. Palpate with the left hand (5–6 cm intravaginally) the left ischial spine through the left lateral vaginal wall. Affix the tip of an Iowa Trumpet between the palpating fingers and the tip of the ischial spine. Pass a long injecting needle through the trumpet and through the vaginal wall until it punctures the sacrospinous ligament and advances another 1 cm. Perform two 90-degree safety aspirations, and, if there is no blood return, inject 5–8 mL local anesthetic.


Repeat the same exact technique on the patient’s right side, using the right hand for vaginal examination and the left hand for the aspiration-injection sequence. The sensory block obtained between the anus and clitoris can be ascertained by pinprick testing the skin of this area. Any local anesthetic may be used, such as 3% 2-chloroprocaine (providing a 1–2 hour block), lidocaine 1.5% or 2% (providing a 2–3 hour block), bupivacaine 0.25% or 0.5% (providing a 6–8 hour block) or ropivacaine 0.5% (providing an 6–8 hour block).


Complications.


Potential problems may include accidental rectal puncture, bleeding (rare), pudendal blood vessel puncture (with local anesthetic systemic toxicity), and infection (rare). Avoid injecting large volumes of local anesthetic because toxicity may occur. See “ Local Anesthetic Systemic Toxicity ,” earlier.


Prevention.


The 90-degree double safety aspiration before the injection (to ascertain that the needle tip is not in intravascular position) is essential. When the patient is in the lithotomy position, the rectum is located medial and inferior to the ischial spine; therefore the palpating hand entirely protects the rectum. Do not do any puncture until the Iowa Trumpet is firmly affixed between the palpating fingers and the ischial spine.


Midperineal Approach


The midperineal approach can be used in female and male urology cases. With the patient in the lithotomy position, the block is done midway between the rectum and the base of the penis or vagina on the midperineal line. With the area thoroughly prepared, and with the contralateral gloved index finger palpating the ipsilateral ischium, pass the injecting needle posteriorly and laterally from this point, aiming toward the ischial spines, one at a time. When the ischial spine is contacted, walk the needle off the bone, medioinferiorly, about 1 cm past the sacrospinous ligament. After two 90-degree safety aspirations (ensuring no blood return), deposit 5–8 mL local anesthetic. The reverse is applied for the other side.


Complications.


Complications include accidental rectal puncture, pudendal vascular puncture (local anesthetic systemic toxicity), and infections (rare). Avoid injecting large volumes of local anesthetic because toxicity may occur. See “ Local Anesthetic Systemic Toxicity ,” earlier.


Prevention.


Rectal puncture is prevented by guiding the needle with simultaneous transrectal palpation of the ischial spine. Inadvertent puncture of blood vessels is prevented by the 90-degree double safety aspirations.


Direct Percutaneous Approach (Vaida Method)


This method is an attractive approach for male or female urology, because it is easily performed using the ischial spines as landmarks. It is done with the patient in the lithotomy position, with the entire perineum and gluteal areas thoroughly prepared with antiseptic solution. A syringe containing 10 to 16 mL local anesthetic is outfitted with a 20-gauge spinal needle. In the lithotomy position the ischial spine can be palpated easily directly through the skin about 3–4 cm lateral from the midperineal point. Through a puncture done at this level (over the ischial spine), insert the needle in a 10-degree posterolateral direction. When the needle tip contacts the ischial spine, walk it off medially, through the sacrospinous ligament, for an extra 1 cm. After two 90-degrees aspirations, deposit 5–8 mL local anesthetic. Repeat again over the other ischial spine.


Complications.


The direct percutaneous approach avoids rectal injury, which is more likely in the midperineal approach, and inadvertent intravascular injection (the slight angulation keeps the injecting needle in a more medial position away from the pudendal vessels). However, infection is a potential (although rare) complication.


Prevention.


Double 90-degree safety aspirations are used in order to prevent local anesthetic systemic toxicity. Thorough skin preparation is essential to prevent infections.


Penile Block


Thorough understanding of pudendal nerve anatomy is necessary to administer the penile block. Terminal branches of the pudendal nerve innervate the rectum, the perineum, the scrotum, and the penis.


Perineal Nerve


After emerging from the pudendal canal, the perineal nerve courses downward for 2–3 cm and gives rise to two terminal divisions: a lateral scrotal branch and the medial striated urethral branch. The scrotal branch unites with the inferior rectal nerve to form the common scrotal branch, which innervates the posterior aspect of the scrotum.


Deep Dorsal Nerve of Penis


This is one of the two branches of pudendal nerve leaving the pudendal canal. It courses forward along the inferior pubic ramus, along the end of the ischiorectal fossa, into the deep perineal pouch. The nerve courses forward into the suspensory ligament of the dorsum of penis, sending terminal branches to the entire dorsum. It is noteworthy that very often a well done dorsal penile block spares the anterior lower part of the penis, which is innervated by rami of the perineal branch of the pudendal nerve as well. By contrast, the circumferential block done at the base of the penile shaft is a complete block of the dorsal nerve of penis and the perineal branches of the pudendal nerve, which provide sensory innervation to the mid-anterior aspect of the penis all the way up to the frenulum.


Indications of Penile Block (Adults Only)


Although circumcision is performed on an estimated one in six newborn males worldwide and about 60% of newborn males in the United States, adult circumcision is much less frequently performed. The usual indications for adult circumcision are social, personal, or medical, including the following: phimosis, paraphimosis, acute paraphimosis (emergency), recurrent infections such as balanitis and posthitis, or preputial neoplasms. General anesthesia, penile block, or a combination of both is used in the majority of these cases.


The penile block is always done before the surgery begins, preferably using long-acting local anesthetics (e.g., 30 mL bupivacaine 0.375% or 0.5% provides 8–15 hours analgesia). Because the penis is an organ with terminal circulation, the local anesthetic used for penile block must never contain epinephrine. See “ Penile Ischemia and Necrosis ,” later. The block is intensely painful; therefore, it should be done under a TIVA using continuous propofol/fentanyl technique, with the patient spontaneously breathing oxygen by mask. This technique may be continued throughout the entire surgical procedure, as a light or medium sedation. See “ Propofol Total Intravenous Anesthesia (Propofol TIVA) ,” earlier.


Penile Nerve Block Techniques


There are two accepted penile nerve block techniques that may be used separately or together. Keep in mind that a bilateral pudendal nerve block will effectively provide full sensory block of the penis.


Dorsal Penile Nerve Block.


Dorsal penile nerve block is done by injecting 5–8 mL local anesthetic through a 27-gauge needle, deep to Buck’s fascia, where the two (left and right) dorsal nerves of the penis emerge from under the pubic bone. Inject at the 10-o’clock and 2-o’clock positions at the base of the penis, walking the needle off caudad the pubic bone and popping through Buck’s fascia.


A 4–6.7% failure rate has been reported using the dorsal block alone. See “ Deep Dorsal Nerve of Penis ,” earlier. To complete the block on the upper ventral side of the penis, a subcutaneous ring block must be done at the base of the frenulum.


Circumferential Block.


This is our preferred technique because it provides 100% sensory block of the penis. With the penis pulled up vertically and thoroughly prepped, 15–30 mL of local anesthetic is injected subcutaneously at the very base of the penile shaft, circumferentially. The injection is done with a 25-gauge needle, continuously moving the needle forward then backward while injecting, raising a contiguous ring around the base of the penis. When close to the dorsal vein of the penis, lift the needle over the vein subcutaneously while constantly advancing and injecting, making sure that no local anesthetic is deposited intravenously. The needle must be kept subcutaneous at all times.


Complications and Prevention


Bleeding and Hematomas.


Bleeding and hematomas can be prevented by using a continuous mode of injection with small 25- or 27-gauge needles. When approaching the large dorsal vein of the penis, it is possible to skillfully lift the needle and course it subcutaneously above the vein while still injecting. This will avoid inadvertent IV injection of local anesthetic and bleeding or hematoma.


Local Anesthetic Toxicity.


Even small amounts of local anesthetic, if directly injected intravenously, may cause toxicity. Additionally, if overly large volumes of local anesthetics are used for the block, they may get absorbed and cause delayed systemic toxicity. It is important to calculate and stay below the tissue toxic dose of the local anesthetic used. See “ Local Anesthetic Systemic Toxicity ,” earlier.


Penile Ischemia and Necrosis.


The arterial supply of the penis is through terminal branches of the pudendal artery, which gives rise to the bulbourethral arterial branches. The glans is supplied by the dorsal arteries, which give off circumflex branches perforating the tunica albuginea and supplying the distal end of corpora penis.


Penile ischemia/necrosis is a grave complication, usually caused by accidental use of vasoconstrictors (e.g., epinephrine). All end organs with terminal vasculature are at risk of prolonged ischemia and necrosis (nose, fingers, toes, penis). Many cases of penile necrosis have been described in the pediatric literature; never use epinephrine in a penile block.


A possible temporary ischemia (presenting as pallor, pain, swelling, necrosis) has been successfully treated with vasodilation provided either by a regional block (caudal, spinal, epidural) or use of prostacyclin (PGI 2 ), the major prostanoid produced by the blood vessels. PGI 2 relaxes smooth vasculature, inhibits platelet aggregation, and can be administered intravenously or intraarterially.


Infection.


Both methods of penile block must be done respecting full sterility precautions. In case of any infection, suspect skin flora.

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Sep 11, 2018 | Posted by in UROLOGY | Comments Off on Anesthetic Complications in Urologic Surgery

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