Perioperative Assessment


ASA grade

Status

Absolute mortality (%)

1

Normal healthy patient

0.1

2

Mild systemic disease or patient over 80 years old

0.2

3

Systemic disease that causes definite functional limitation on life

1.8

4

Severe systemic disease that is a constant threat to life

7.8

5

Moribund patient unlikely to survive 24 h without surgery

9.4




Cardiovascular Effects


There are many cardiovascular and hemodynamic changes during laparoscopic surgery as well as concomitant changes with positioning (Table 1.2). These do not usually affect cardiac output in healthier patients but can be important in patients with preexisting cardiovascular disease [2]. Important changes include hypotension, decreased preload, and increased afterload. Pneumoperitoneum results in decreased venous return, decreased right-sided heart filling, and decreased cardiac output, resulting in the potential for hypotension if systemic vascular resistance cannot compensate.


Table 1.2
Summary of physiologic effects with pneumoperitoneum and positioning










































































 
Pneumoperi-toneum

Magnified in Trendelen-burg

Magnified in reverse Trendelenburg

Cardiovascular changes

Systemic vascular resistance (SVR)

Increases

Yes
 

Central venous pressure (CVP)

Increases

Yes
 

Mean arterial pressure (MAP)

Decreases

Yes
 

Cardiac output (CO)

Decreases
 
Yes

Respiratory changes

Airway resistance

Increases
   

Pulmonary capillary wedge pressure (PCWP)

Increases

Yes
 

Functional residual capacity (FRC)

Decreases

Yes
 

Chest wall compliance

Decreases
   

Renal changes

Renal function

Decreases
   

Urine output

Decreases
   

Acid–base changes

Respiratory acidosis
   


Pulmonary Effects


The respiratory changes seen in laparoscopic surgery result from a combination of the mechanical effects of pneumoperitoneum, patient positioning, and carbon dioxide absorption. Mechanical effects relate to displacement of the lungs due to increased intra-abdominal pressure. As the diaphragm is elevated, increases in peak inspiratory pressure, plateau pressures, and end-tidal CO2 are seen [3]. Lung compliance may decrease by as much as half during laparoscopy [4].

Carbon dioxide is continually added during insufflation; therefore, it continuously dissolves in blood, increasing arterial and alveolar CO2. This increase in alveolar carbon dioxide is routinely monitored intraoperatively by following end-tidal carbon dioxide levels. Hypercarbia can usually be counteracted by an increasing respiratory rate; however, with prolonged cases, steep positioning, and underlying pulmonary disease, it can be difficult to manage.


Renal Effects


Laparoscopic surgery is associated with decreased urine output. In part, this is secondary to the negative effect of pneumoperitoneum on renal blood flow. This can be exacerbated by bowel preparation, which depletes intravascular volume even before the operation begins. While a normal goal for urine output is 1–2 ml/kg/h, this should be halved in laparoscopy [5]. This decrease, does not affect renal function postoperatively. It is important to ensure that anesthesia providers (especially those in training) are aware of this effect, such that excess intraoperative fluid administration which may cause untoward effects postoperatively can be avoided.



Benefits of Laparoscopy


Laparoscopic colorectal surgery has grown in prevalence since the first described laparoscopic colectomy in 1991. As of 2006, approximately one in three elective colorectal operations is being performed laparoscopically [6] and likely approaching 50 % currently.

Evidence now shows that laparoscopic surgery is safe in benign disease. Patients have faster recoveries, shorter length of hospital stay, decreased ileus [7], and lower morbidity following laparoscopic surgery [710]. This is true for such varied operations as rectopexy for rectal prolapse [10] and elective resection for diverticular disease. Indeed, in a randomized controlled trial of elective surgery for diverticulitis, patients undergoing laparoscopic surgery had lower incidence of major complications, such as anastomotic leak, intra-abdominal bleeding, abscess, and evisceration [11]. Biomarker studies have also pointed to decreased surgical trauma following laparoscopic compared to open colectomy [12].

Patients with inflammatory bowel disease are also ideal candidates for laparoscopic surgery, though these procedures may be some of the most technically challenging. Benign conditions do not require extended lymphadenectomy or wide mesenteric excision. Furthermore, patients are often young and undergo multiple procedures over their lifetime. They are highly likely to benefit from the decreased adhesions and improved cosmesis following laparoscopic surgery. This has been borne out in laparoscopic ileocecal resection for Crohn’s disease [13], where a meta-analysis showed decreased morbidity and shorter hospital stay. Randomized trials have shown similar rates of recurrent disease and better body image in patients postoperatively [14]. A Cochrane review of laparoscopic ileal pouch-anal anastomosis (IPAA) for ulcerative colitis, however, found little difference with regard to overall morbidity [15]. Operative times were longer when IPAA was performed laparoscopically, and unlike all other laparoscopic colorectal operations, hospital stays were the same as in open surgery.

There is now level 1 evidence to support laparoscopy in surgery for colon cancer [16]. The COST non-inferiority randomized trial demonstrated similar overall survival and recurrence rates between open and laparoscopic surgery [17]. In addition to equivalent oncologic outcomes, multiple clinical trials have now also consistently shown lower perioperative mortality, fewer wound complications, less blood loss, and reduced postoperative pain scores with a reduction in narcotic requirements after laparoscopic surgery [1821]. In spite of early concerns over port-site metastasis, cancer recurrence in wounds is similar to the 0–1 % seen in open surgery [17, 19].

Laparoscopic surgery for rectal cancer is often even more technically challenging and may be best recommended only in a clinical trial setting until we await further data [22]. Several trials are ongoing to provide more high-quality data on outcomes following laparoscopic rectal surgery for cancer (COLOR II, JCOG 0404, ACOSOG Z6051). Early data suggests similar oncologic outcomes in experienced hands [23].

In sum, previous concerns over the safety of laparoscopic surgery for both benign and malignant conditions have been dispelled. We anticipate that the rates of laparoscopic surgery will continue to grow over the coming years.


Preoperative Evaluation for Elective Patients


Proper preoperative patient assessment is the first step in improving outcomes following laparoscopic colorectal surgery. While there are many similarities between the preoperative evaluation of patients for laparoscopic and open surgery, nuances do exist. Decisions for preoperative testing and evaluation should be made in conjunction with the anesthesiology staff, medical physicians, and the surgeon. Laparoscopic colorectal surgery will generally be performed under general anesthesia with endotracheal intubation; patients must therefore be able to tolerate a general anesthetic.

Increasing evidence is supporting laparoscopy in emergency colorectal surgery patients. In these patients, a thorough preoperative evaluation may not be possible (see below—“Special Patient Populations”), yet even a brief evaluation can often identify risk factors for perioperative comorbidity that can be closely monitored and intervened upon.


Laboratory Testing


Anesthesiologists have mixed opinions regarding the need for specific preoperative laboratory screening, as there is little controlled data to support guidelines [24]. In general, all patients undergoing an abdominal surgery should have routine laboratory tests drawn, including hemoglobin, serum chemistry, and coagulation studies. Women of childbearing age must have a urine pregnancy test. For patients with colorectal malignancies, a CEA level should be drawn prior to definitive surgery as levels may be followed postoperatively to monitor for recurrence.

The American Diabetes Association recommends preoperative screening for diabetes in overweight patients (BMI ≥ 25) with one additional risk factor, such as hypertension, family history, or inactivity [25]. Some experts suggest a fasting blood glucose level drawn on the morning of surgery [26]. We prefer to screen patients prior to the day of surgery.

There is some evidence to support checking random hemoglobin A1C levels in patients without diabetes. For instance, one study found that nondiabetic patients with a preoperative hemoglobin A1C above 6.0 were more likely to have complications after major colorectal surgery [27]. Additionally, the stress of surgery may unmask borderline diabetic (i.e., insulin resistant) patients, significantly affecting their ability to control glucose levels, postoperatively.


Cardiac Evaluation


Cardiac evaluation may be advisable for patients with known cardiac or other systemic diseases. There is limited evidence to support routine preoperative electrocardiogram in patients without documented coronary artery disease or other risk factors for cardiac disease, such as peripheral arterial disease and cerebrovascular disease [25, 28].

All laparoscopic colorectal procedures are considered of intermediate risk. In such cases, the American Heart Association (AHA) recommends stress testing only in patients with an active cardiac condition, designated AHA class I. This includes patients with unstable or severe angina, recent myocardial infarction, decompensated heart failure, significant arrhythmia, or severe valvular disease [25].

Additionally, AHA class II patients may require cardiac stress testing if the testing will change management. This includes patients with intermediate risk factors, such as a history of ischemic heart disease, prior heart failure, cerebrovascular disease, diabetes mellitus, and/or renal insufficiency. For patients in whom the decision for stress testing is unclear, it may be best to discuss planning with the anesthesia staff that will be performing the operation. Although recent evidence shows increasing overuse of preoperative stress testing resulting in higher costs, [29] it is incumbent on the surgery team to identify patients at risk and evaluate them properly.


Pulmonary Evaluation


Current guidelines do not support preoperative pulmonary function testing in patients without evidence of preexisting lung disease for non-thoracic surgery [30]. Patients with chronic obstructive pulmonary disease (COPD) or other pulmonary disorders should be considered for spirometry prior to surgery. Further testing should be based on the results and degree of dysfunction. Patients on steroid inhalers and bronchodilators should be identified to ensure that these medications are taken as scheduled perioperatively.


Special Patient Populations


There is no patient population in whom laparoscopic surgery has been proven unsafe. One study even suggests equivalent outcomes in the hemodynamically unstable patient [31], long considered an absolute contraindication to laparoscopy. There are, however, special patient populations and situations to consider.


The Elderly


Elderly patients may be the least able to tolerate the increased operative times seen in laparoscopic surgery, as they more often have diminished cardiopulmonary reserve. Preoperative cardiovascular evaluation in these patients should be carried out according to the AHA guidelines described above. Noninvasive testing may also be considered in elderly patients with poor functional capacity if it will change management [25]. Studies have shown similar postoperative outcomes in octogenarian patients compared to younger patients following laparoscopic colorectal surgery [32]. We tend to favor laparoscopic surgery for elderly patients as they may especially benefit from decreased postoperative pain and shorter recovery times. Drs. Bleier and Kann present an in-depth discussion on the evaluation, technical aspects, and outcomes for minimally invasive approaches in the elderly in Chap. 28.


Morbidly Obese Patients


Obesity is a risk factor for worse postoperative outcome, both because surgery is more technically difficult in obese patients and because obese patients often have comorbid conditions, such as hypertension and diabetes. Results of studies examining body mass index (BMI) as a risk factor for poor outcome have been mixed, with some showing higher rates of conversion and postoperative complication [33] and others showing no difference [34]. Given the well-described benefits of laparoscopic colorectal surgery (accelerated recovery of bowel function, decreased postoperative pain, shorter hospital stay, as discussed above) and the fact that surgery in obese patients can be technically challenging regardless of operative technique, we recommend laparoscopy. Surgeons should be prepared for longer operative times in these patients. Also, specialized equipment including footboards, safety straps, large-size operating room tables, and extra-long laparoscopic instruments must be made available. Please see Chap. 29 for a more detailed discussion by Drs. Siripong and Vargas on laparoscopy in the obese patient.


Emergency Colorectal Surgery Patients


Accumulating evidence also supports laparoscopic surgery in emergency colorectal surgery patients. For instance, Myers et al. [35] demonstrated the feasibility of laparoscopic peritoneal lavage in the treatment of 100 patients with perforated diverticulitis. All eight patients presenting with Hinchey grade 4 diverticulitis were treated with a Hartmann’s procedure. The remaining 92 study patients had Hinchey grades 2 and 3 disease and were treated with laparoscopic peritoneal lavage. Only two required postoperative intervention for pelvic abscesses and two represented with diverticulitis after a median follow-up of 36 months. Additional randomized clinical trials evaluating laparoscopic peritoneal lavage for the treatment of complicated diverticulitis are ongoing [36, 37]. Studies have also demonstrated the safe and effective use of laparoscopic colectomy for other emergent indications, including gastrointestinal bleeding, colonic obstruction, and colonic perforation [38]. The preoperative evaluation of emergency colorectal surgery patients is limited to rapid and critical tests, including assessment of cardiovascular vital signs, volume status, hematocrit, electrolytes, renal function, urine analysis, and ECG. These allow the surgeon and anesthesiologist to tailor both operative strategy and perioperative monitoring and resuscitation accordingly. Additional tests and interventions are deferred until after surgery. Dr. Haas and colleagues present an excellent overview of minimally invasive approaches in the emergent setting in Chap. 27.


Reoperative Surgery


Although Dr. Migaly presents a more comprehensive review of the use of a minimally invasive approach for reoperative surgery in Chap. 20, a few points pertinent to preoperative assessment are warranted. Laparoscopic reoperative surgery can be technically challenging, although reoperation after laparoscopic surgery is often less difficult than after open surgery [39]. Adhesions and dilated bowel may preclude adequate visualization. However, as long as a sufficient field of view can be established and bleeding and contamination can be controlled, laparoscopy is safe in the management of complications, such as postoperative bleeding and anastomotic leak. Peritoneal access via an open (Hasson) technique should be considered in reoperative laparoscopy [40]. Patients must be counseled that there is an increased likelihood of prolonged operative times, conversion to open surgery, and risk for inadvertent enterotomy or other visceral injury. Surgeons preparing for reoperative laparoscopic surgery should obtain previous operative records in order to anticipate such challenges as extensive adhesions and prosthetic meshes. This knowledge may facilitate safe trocar placement and allow for customized preoperative interventions, including placement of ureteral stents.


Preoperative Management


Our individualized approach to perioperative patient management is multifaceted. Some of the considerations are important for all patients, while others are more specific to certain patient populations or operations.


Bowel Preparation


Bowel preparation in colorectal surgery remains controversial. Studies have shown no difference in rates of surgical site infection or anastomotic leak with or without bowel preparation [41, 42]. Furthermore, bowel preparation may predispose patients to dehydration and electrolyte abnormalities, particularly in the elderly [43]. However, there are several benefits to bowel preparation specifically for laparoscopic surgery. First, as the bowel is lighter and more compressible after mechanical preparation, manipulation with instruments is easier and more ergonomically favorable. Additionally, laparoscopic colorectal surgery often relies on gravity to serve as a bowel retractor; this is often more effective with an empty colon. A prepared colon also allows for intraoperative endoscopy to localize a tumor if necessary and/or to assess left-sided anastomoses after creation for intactness, leak, and hemostasis. A final benefit is easier specimen extraction, possibly through smaller extraction incisions. In a combined statement, the Society of Alimentary Gastrointestinal Endoscopic Surgeons and the American Society of Colon and Rectal Surgeons endorsed the use of mechanical bowel preparations in laparoscopic colorectal surgery [44].


Preoperative Fasting


Patients routinely fast for over 8 h prior to surgery in an effort to avoid pulmonary aspiration, in spite of the lack of evidence in support of this practice [45, 46]. The best evidence suggests preoperative fasting should begin 2 h prior to operation for liquids and 6 h for solid foods [45]. An exception to this rule may be diabetic patients with known neuropathy, who are at risk of delayed gastric emptying [47].


Lesion Localization


Preoperative lesion localization is important in laparoscopic surgery, where tactile feedback is reduced. The site of colorectal tumors should routinely be marked. Colonoscopic tattooing of lesions with India ink is the gold standard [48, 49]. However, in as many as one in five cases, the tattoo will not be evident at surgery [50]. Four-quadrant tattooing may improve the likelihood that the tattoo will be visualized and not hidden on the mesenteric or retroperitoneal side of the colon (Video 1.1) [51].

Preoperative mapping is also important in benign conditions, such as in Crohn’s disease, where skip lesions are not uncommon. This is especially true in cases of reoperative surgery, as adhesions may preclude safe running of the bowel. Disease localization can be accomplished using imaging studies, such as enterography, and also via endoscopy.


Ostomy Marking


Patients undergoing colorectal surgery may require temporary or permanent fecal diversion. Whenever possible, patients should undergo preoperative marking and education by an enterostomal therapist in order to decrease postoperative stoma complications [52]. It is often important to mark not only the primary suggested site but other potential stoma sites as alternative options as well, in case the disease pathology prohibits stoma placement in the optimal location (Figs. 1.1 and 1.2). Of note, there is some evidence that parastomal hernias are more common after laparoscopic surgery, especially when the surgical specimen is extracted through the future ostomy site [53]. We therefore recommend avoiding stoma site specimen extraction in cases of permanent stoma creation.

A309502_1_En_1_Fig1_HTML.jpg


Fig. 1.1
Preoperative marking of possible stoma sites


A309502_1_En_1_Fig2_HTML.gif


Fig. 1.2
Ostomy triangle stoma site marking


Corticosteroids


Previously steroid-dependent IBD patients may exhibit some degree of adrenal insufficiency for up to 1 year after discontinuing therapy [54]. Because of concern for cardiovascular collapse due to surgical stress, patients are often given high-dose steroids perioperatively, with little evidence to support this practice. In fact, recent studies have shown no evidence of hemodynamical instability when low- rather than high-dose corticosteroids are administered around surgery [55, 56]. The exception to this is patients with primary disease of the hypothalamic-pituitary-adrenal axis [56].

A prospective study assessing perioperative steroid dosing in patients with IBD is underway. It is our typical practice to continue steroids at their preoperative dose levels rather than administer “stress” doses perioperatively. Postoperative steroid tapering is then adjusted according to the chronicity of patients’ preoperative exposure; most commonly prednisone is used and tapered by 5 mg/week.


Perioperative Antibiotics


Surgical site infections are the leading cause of postoperative morbidity and mortality in colorectal surgery, whether laparoscopic or open. Prophylactic antibiotics are known to decrease the risk of infection. A single dose administered within 60 min of incision and discontinuation of therapy within 24 h of surgery are generally advised [57]. Second-generation beta-lactam antibiotics, such as cefoxitin and cefotetan, are established choices. The addition of preoperative oral antibiotics to mechanical bowel preparation was once the standard of care following the influential work of Nichols et al. in the 1970s [58]. More recently, however, a move away from mechanical bowel preparation occurred after studies failed to demonstrate an associated improvement in rates of infectious complications [42]. Oral antibiotic administration was similarly abandoned, largely because the efficacy of this practice was not established in uncleansed bowel. New studies show decreased rates of surgical site infection when oral antibiotics are given, with or without concomitant mechanical bowel preparation [59, 60]. Accordingly, our colorectal patients receive erythromycin and neomycin on the day prior to surgery.


Analgesic Considerations


Though epidural anesthesia appears to improve analgesia and decrease ileus after open colorectal surgery [61], there is a paucity of data assessing the benefits of postoperative analgesic regimens following laparoscopy. In one recent trial, patients with spinal analgesia or patient-controlled analgesia had shorter length of stay and faster return of bowel function as compared to epidural analgesia [62]. We currently do not recommend routine epidural placement prior to laparoscopic colorectal surgery. Epidural anesthesia should be considered, however, in certain circumstances, such as in patients with a history of chronic pain and chronic narcotic use and also those in whom a high likelihood of conversion to open surgery is expected.

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Apr 6, 2017 | Posted by in GASTROENTEROLOGY | Comments Off on Perioperative Assessment

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