6 Ambulatory and Anorectal Procedures
Abstract
Ambulatory procedures are those in which the patient returns home on the day of the operation, regardless of the type of anesthesia or location. An increasing number of colorectal procedures are being performed on an outpatient basis, especially those involving the anus and rectum. Factors contributing to this increase include the development of improved local and general anesthetics, the public’s increased interest in and knowledge of medical matters, the willingness of ambulatory patients and their families to participate in nursing, spiraling health care costs, and the desire of insurance carriers to minimize surgery-related expenses. To accommodate these changes better, outpatient postoperative care systems were developed. Not suited for the outpatient environment are those patients who may have postoperative pain unrelieved by oral analgesics, those whose operations are likely to be followed by postoperative bleeding, patients who have severe emotional objections to the idea, those who live alone, patients with significant medical comorbidities requiring postoperative observation, individuals unable to tolerate oral intake, and patients at significant risk for complications requiring immediate care (such as hemorrhage).
6.1 Introduction
By definition, ambulatory procedures are those in which the patient returns home on the day of the operation, regardless of the type of anesthesia or location (physician’s office, emergency department, hospital operating room, or a freestanding, independent ambulatory surgery unit). Other terms that have been used to apply to this situation include one-day surgery, same-day surgery, office-based surgery, and outpatient surgery.
An increasing number of colorectal procedures are being performed on an outpatient basis, especially those involving the anus and rectum. Factors contributing to this increase include the development of improved local and general anesthetics, the public’s increased interest in and knowledge of medical matters, ambulatory patients’ willingness to participate in nursing themselves, as well as the willingness of their families, spiraling health care costs, and the desire of insurance carriers to minimize surgery-related expenses. The changes have been achieved through technological advances, sustained by patient and provider preference, and driven largely by payment system changes. 1 In the United States, it has been estimated that over 90% of anorectal cases can be performed on an outpatient basis. 2
To accommodate these changes better, outpatient postoperative care systems were developed. This begins with patient and family education. Discharge personnel inform family members what to expect with regard to diet, pain, bowel function, medications, activity, and wound care. Home health and visiting nurses are available to provide expert care in the patient’s homes, and to act as liaisons to the physician should any questions or problems arise.
Not suited for the outpatient environment are those patients who may have postoperative pain unrelieved by oral analgesics, those whose operations are likely to be followed by postoperative bleeding, patients who have severe emotional objections to the idea, those who live alone, patients with significant medical comorbidities requiring postoperative observation, individuals unable to tolerate oral intake, and patients at significant risk for complications requiring immediate care (such as hemorrhage). 3
6.2 Preoperative Assessment and Patient Evaluation
For patients having procedures under local anesthesia, a simple history about bleeding diatheses and allergies to local anesthesia or medications such as anticoagulants should be obtained. Particular attention should be focused on comorbid medical conditions and medications (such as cardiac medications and anticoagulants), which may need to be manipulated to maximize patient safety. In addition, disabilities limiting an individual’s ability to care for him- or herself (such as blindness, stroke, or dementia) should be evaluated. Patients receiving a general procedure should be evaluated as described in Chapter 5. A preoperative discussion with the patient should describe the procedure and include any of the patient’s concerns, such as pain control, complications, and recommended activity at home. Bowel preparation will vary from nothing for an anal fissure, to an enema for hemorrhoids to a full mechanical preparation for a transanal minimally invasive surgical procedure.
6.3 Patient Preparation
In addition to being diagnosed and evaluated for operation, individuals should be prepared for postoperative discharge at their preoperative visit. Patients and families should be informed as to the nature of the operation including alternative approaches, benefits, and potential complications. The postoperative home course should be detailed, including normal pain, wound, and drainage expectations. Alterations in bowel habits (particularly medication-induced constipation) should be predicted and remedies provided. In addition, individuals and families should be educated regarding events which should prompt calls to their physician, such as high fever, excessive vomiting, inability to void, intractable pain, and significant bleeding. Ideally, all of this information should be available in a pre-printed postoperative instruction sheet or booklet, and should include a number to call 24 hours a day in case of emergency.
In addition to patient education, office and perioperative medical personnel should be educated regarding their roles in outpatient surgical procedures. Office assistants and nurses will be the first points of contact when patients develop problems or have questions following operation. Therefore, they too should be informed of the normal postoperative course and worrisome complaints that might indicate a significant postoperative complication. Perioperative nursing specialists may also provide follow-up phone calls the evening of the operation. The patient is also instructed about preoperative dietary limitations, as described in Chapter 5.
6.4 Operative Management
Procedures are often performed in the prone jackknife or left lateral (Sims’) position. Anesthesia should be effective and should allow rapid recovery with minimal side effects. Anesthetic techniques should have little impact on the ability to discharge patients following anorectal operations, with the exception of issues described in the following.
Regional anesthesia presents a special set of considerations. 4 Spinal, epidural, and caudal anesthesia have the following problems in common: time consumed during the block, potential technical difficulties with the block, variability in degree of block produced, and problems during the recovery period. Any degree of motor paralysis significantly prolongs time in the recovery room. Although it is possible to send a patient from the recovery room to the surgical ward with a small amount of residual block, the ambulatory patient must be able to walk to his or her car. The problem of post–lumbar puncture headache is always a consideration and can significantly complicate the ambulatory surgical patient’s course of recovery and early return to work.
Long-acting spinal anesthetics, particularly combined with large, intraoperative fluid administration, will increase urinary retention rates and delay discharge. 5 Alpha-adrenergic blockers have been administered prophylactically in this setting to decrease the spasm of the autonomically innervated internal sphincter at the bladder neck in attempts to decrease urinary retention, but have not met with success. 6 Limiting postoperative fluids in combination with short-acting spinal anesthetic has, however, decreased urinary retention rates. 7 General anesthesia with heavy emphasis on narcotics may cause postoperative nausea and vomiting, leading to prolonged recovery room stay or even overnight hospitalization.
Perianal shaving is not necessary except for patients with pilonidal disease.
6.5 Procedures
The majority of anorectal cases can be performed on an outpatient basis. Procedures related to specific disease processes are discussed in the respective chapter, while other outpatient procedures are discussed in the following sections.
6.5.1 Examination under Anesthesia
An examination under anesthesia is valuable in a number of conditions. These include patients whose anus is too painful to adequately examine, patients with complex fistulas, and patients with a nonhealing perineal wound.
6.5.2 Rectal Biopsy
A biopsy is essential for the diagnosis of neoplasms, particularly malignant ones, and in the diagnosis of inflammatory conditions, including specific infections such as amebic dysentery. Serial biopsies can be valuable in the diagnosis of ulcerative colitis and Crohn’s disease and can be useful in judging the response to treatment. Biopsy may detect changes not apparent to the endoscopist. The correlation between proctosigmoidoscopic observations and the histology of biopsies of the rectal mucosa is not always accurate. For this reason, biopsy can, in certain circumstances, add refinement to the clinical opinion. It also confirms the presence of normal rectal mucosa.
Unusual local conditions that can be identified by rectal biopsy include pneumatosis cystoides intestinalis, mucoviscidosis, melanosis coli, oleogranuloma, and parasitic infections such as schistosomiasis. 8 Rectal biopsy may be useful in detecting certain systemic conditions such as neurolipidoses, metachromatic leukodystrophy, Hurler’s syndrome, amyloidosis, the arteritis of rheumatoid arthritis, periarteritis nodosa, malignant hypertension, cystinosis, and Whipple’s disease. 8
Various forceps and suction biopsy apparatus are available for obtaining specimens from the rectum for histologic evaluation. For the pathologist to provide maximal information to the clinician, a correct anatomic orientation is necessary. The specimen is submitted with the submucosal surface downward against a flat, ground-glass slide or on paper to which it adheres by its own stickiness or sutured in place.
6.5.3 Foreign Body Removal
A host of foreign bodies may be found in the rectum. They often can be removed with the aid of local anesthesia. Occasionally, a general or regional anesthetic is necessary. Patients are usually discharged after a short period of observation. Selected patients may require observation for 24 hours to ensure that no bowel perforation has occurred (see Chapter 34).
6.6 Local Anesthesia
Local anesthetic agents produce a loss of sensation and muscle paralysis in a circumscribed area of the body by a localized effect on peripheral nerve endings or fibers. 9 The anal canal and the perianal skin can be anesthetized with minimal pain or discomfort, and become fully relaxed.
6.6.1 Selection of Patients
A highly nervous and apprehensive patient or one with a very painful anal canal is not a good candidate for local anesthesia. Success requires a cooperative patient, who should be given a thorough explanation of the procedure and be told what to expect and be apprised of the advantages and disadvantages of local anesthesia.
Almost all kinds of simple anorectal conditions are suitable for local anesthesia. These conditions include hemorrhoids (even thrombosed, strangulated, or gangrenous), anal fissure, simple intersphincteric anal fistula, small perianal abscess, pilonidal abscess and sinus, low rectal adenoma, and perianal and anal condyloma acuminatum, as well as in carefully selected cases of sphincter repair and many other anorectal conditions. 10
Most perianal abscesses can be drained with the patient under local anesthesia, especially with catheter drainage. However, patients with very large abscesses require an excessive amount of the anesthetic agent because the tissue is acidotic, which causes slower diffusion of the anesthetic solution through the nerve sheath. Patients with significant scar tissue such as that found in cases of a complicated anal fistula also do not respond well to a local anesthetic. Anorectal procedure expected to exceed 2 hours may not be suitable for a local anesthetic because of positional discomfort.
6.6.2 Actions of Local Agents
Local anesthetic agents inhibit the excitatory process in nerve endings or fibers. Their location of action is in the nerve membrane, which has a lipid and protein structure. The anesthetic potency of different agents is a function of their lipid solubility, while protein binding is the primary determinant of anesthetic duration. 9
Local anesthetics exist in both a charged and an uncharged (free base) form, with the equilibrium determined by the pH of the surrounding medium. As the pH of the solution decreases (hydrogen ion concentration increases), the equilibrium shifts toward the charged cation form. Conversely, as the pH increases, the equilibrium shifts toward the free-base form. The uncharged (free) base form diffuses more readily through the nerve sheath and is reflected clinically in the onset of anesthesia. 9 This explains why local anesthesia is less effective for large abscesses, because the tissue is acidotic.
The susceptibility of nerve fibers to local anesthetics is related to the size of the fiber and its myelin coating. Smaller nerves are blocked first, and lightly myelinated nerves are more susceptible than more heavily coated nerves. In general, the first nerves blocked are the last ones to recover. Sensory nerves are blocked before motor nerves. The usual order of sensory loss is pain, temperature, touch, and deep pressure.
6.6.3 Disposition of Agent
Knowing the vascular absorption, tissue distribution, metabolism, and excretion of local anesthetic agents is important in understanding their potential toxicity. Absorption varies according to site of injection, dosage, addition of a vasoconstrictor agent, and specific agent used. 9
After their absorption from the injection site, local anesthetic agents distribute themselves throughout total body water. An initial rapid disappearance from blood (alpha phase) occurs because of uptake by tissues with a high vascular perfusion. A secondary slower disappearance rate (beta phase) reflects distribution to slowly perfused tissues and metabolism and excretion of the compound. Although all tissues will take up local anesthetics, the highest concentrations are found in the more highly perfused organs such as the lungs and kidneys. The greater percentage of an injected dose of a local anesthetic agent is distributed to skeletal muscle because of the large mass of tissue in the body. 9
The metabolism of local anesthetic agents varies according to their chemical classification. The ester- or procainelike agents undergo hydrolysis in plasma by the enzyme pseudocholinesterase. The amide- or lidocainelike agents undergo enzymatic degradation primarily in the liver. Lidocaine (Xylocaine), mepivacaine (Carbocaine), and etidocaine (Duranest) are intermediate in terms of rate of degradation, whereas bupivacaine (Marcaine) is metabolized most slowly. 9
6.6.4 Choice of Agent
Although several local anesthetic agents are available for clinical use in anorectal surgery, lidocaine and bupivacaine are most suitable and most widely used. 11 Both lidocaine and bupivacaine are amide compounds that undergo enzymatic degradation in the liver. On the other hand, ester compounds such as procaine are metabolized to para-aminobenzoic acid. Unlike the ester compounds, the amide groups rarely produce an allergic phenomenon. Lidocaine and bupivacaine are available in various concentrations. The lowest effective concentration should be selected; thus, 0.5% lidocaine and 0.25% bupivacaine are the concentrations of choice.
6.6.5 Epinephrine
All local anesthetic agents except cocaine cause peripheral vasodilatation by producing a direct relaxant effect on the musculature of the blood vessels. The degree of vasodilator activity appears related to intrinsic anesthetic potency. The more potent and longer-acting local anesthetic agents produce a greater degree and longer duration of vasodilatation. Epinephrine incorporated into local anesthetic solutions constricts blood vessels, thereby slowing absorption and minimizing any toxic reaction. Epinephrine accomplishes three purposes: (1) it reduces capillary bleeding; (2) it prevents rapid absorption of the local anesthetic agent, thus avoiding a high blood level of the anesthetic agent while minimizing any toxic reaction; and (3) it prolongs analgesia during surgery. Systemic toxic reactions may occur when the epinephrine in the blood reaches a high level. The common signs and symptoms of these reactions are pallor, tachycardia, perspiration, palpitation, apprehension, dyspnea, rapid respiration, and hypertension. 12 The side effects are rare when the dilution of 1:200,000 is used.
There are several useful methods of administration that minimize the pain. The needle should be small and the injecting pressure should be low. For practical purposes and availability, a 1.5-inch (3.5 cm) 27- to 30-gauge needle with 3-mL disposable syringe works well. The lower the concentration of the anesthetic solution, the less painful it is. Superficial wheal-producing dermal injection is uniformly much more painful than that into the deep dermal-subcutaneous tissue. Rapid injection almost always hurts more than slow infiltration. 13 , 14
Most local anesthetic solutions are quite acidic, with a pH ranging from 5.0 to 7.0. Lidocaine has a pH of 6.8 and bupivacaine is 5.5. Local anesthetic is more soluble and has a shelf life of 3 to 4 years. Raising the pH to 7.2 to 7.4 would substantially reduce effective storage shelf life and solubility. Raising the pH above 7.4 increases the risk of precipitation of local anesthetic out of solution. A study by Christoph et al showed that infiltration of 1% lidocaine is 5 times more painful than buffered 1% lidocaine, 1% lidocaine with epinephrine is 2.8 times more painful than buffered 1% lidocaine without epinephrine, and 1% mepivacaine (an intermediate action local anesthetic) is 5.7 times more painful than buffered mepivacaine. 15 These results are statistically highly significant. Buffering can be easily and safely accomplished by the addition of sodium bicarbonate solution so that the resultant ratio of local anesthetic to sodium bicarbonate equals 10:1. In doing so, the efficacy of the local anesthetic is not compromised. Local anesthetic buffering should be performed immediately before its use to eliminate concerns regarding shortened shelf life of the anesthetic caused by the alkalinization. 15
6.6.6 Adverse Reactions
Toxicity of different anesthetic agents varies, usually in parallel with potency. To some extent, the rate of biotransformation will affect toxicity. The rate of absorption also will influence toxicity, and this may be determined by the route of administration. ▶ Table 6.1 lists the signs and symptoms of local anesthetic toxicity. There are two types of adverse reaction to local anesthetic agents: allergic reaction and toxic reaction.
Central nervous system | effects Cardiovascular effects |
Mild | |
Lightheadedness | ↑PR interval |
Dizziness | ↑QRS duration |
Tinnitus | ↓Cardiac output |
Drowsiness | ↓Blood pressure |
Disorientation | |
Severe | |
Muscle twitching | ↑↑PR interval |
Tremors of face and extremities | ↓↓QRS duration |
| |
Unconsciousness |
|
Generalized convulsions | ↓↓Cardiac output |
Respiratory arrest | ↓↓Hypotension |
| |
Allergic reaction, a rare occurrence, may be systemic or local. More than 80% of reactions are cell mediated, resulting in contact dermatitis. The remaining reactions are caused by circulating antibodies that give rise to systemic anaphylaxis. Acute anaphylactic reactions are rare, but they are invariably fatal unless promptly treated. Localized systemic anaphylactic reactions manifested by urticaria, laryngeal edema, and extrinsic asthma are less serious and are amenable to treatment. There is no foolproof test for screening susceptible persons. The intradermal test is of no value in determining possible systemic sensitivity. The patch test is useful in the detection of contact allergy. 16
Toxic reactions to local anesthetic agents are far more common than allergic sequelae. The majority of adverse reactions to local anesthetics are due to high plasma levels resulting from the administration of excessive quantities of the drug. The major manifestations of local anesthetic toxicity occur in the central nervous system (CNS) and the cardiovascular system.
All local anesthetics have the capacity to stimulate the CNS at low toxic doses and suppress the CNS at high toxic doses. Initial signs and symptoms of a high toxic dose are CNS excitation, resulting from the suppression of inhibitory cortical neurons, which permits unopposed functioning of facilitatory pathways.
Subsequent signs and symptoms of a high toxic dose include lightheadedness, dizziness, nystagmus, sensory disturbances (e.g., visual difficulties, tinnitus, perioral tingling, metallic taste), restlessness, and disorientation or psychosis. Slurred speech and muscle twitching or tremors may immediately precede seizures. If serum levels of the drug continue to increase, generalized depression of the entire CNS occurs, with resultant drowsiness, coma, and respiratory arrest. 9 , 17
The cardiovascular system is relatively resistant to local anesthetic toxicity in comparison with the CNS and does not exhibit toxic reactions until blood levels are much higher. Cardiovascular complications result from negative inotropism, peripheral vasodilatation, and slowing of the myocardial conductive system. The end results of local anesthetic toxicity are hypotension, bradycardia, prolonged electrocardiographic intervals, and cardiac arrest. 9 , 17
Anaphylactic shock is the least common yet most serious of the allergic reactions. It is characterized by a sudden circulatory and respiratory collapse, loss of consciousness, laryngeal edema, and urticaria. Anaphylaxis must be dealt with promptly. The immediate treatment consists of the subcutaneous injection of 0.5 mL of 1:1,000 epinephrine. To increase the rate of absorption, the injection site should be vigorously massaged. Meanwhile, ventilation should be maintained with oxygen under pressure. If the patient does not show rapid improvement, the administration of epinephrine can be repeated in 5 to 15 minutes. If severe bronchospasm persists, 250 to 500 mg of aminophylline should be administered intravenously. Once an improvement has been noted, corticosteroids and an antihistamine can be administered intramuscularly to prevent recurrence of symptoms and avoid the use of additional epinephrine. 16 , 18
Toxic reactions must be recognized and treated as follows without delay:
Clear airway (if patient is unconscious).
Prevent aspiration.
Administer oxygen.
Induce intravenous fluid (for administration of intravenous medication).
Stop convulsion.
Administration of oxygen alone may stop convulsion.
If oxygen does not stop convulsion, intravenous medications such as thiopental (50–100 mg), midazolam (2–5 mg), and propofol (1 mg/kg) can terminate seizures. 19 If seizures fail to respond to such treatment, short-acting neuromuscular blocking agents such as succinylcholine (Anectine) or vecuronium (Norcuron) should be administered until serum levels of local anesthetic agents fall. 20
Raise blood pressure by giving a vasopressive drug.
Perform cardiac massage if patient’s heart has arrested.
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