Best Practice Recommendations for Anesthetic Perioperative Care ...

Best Practice Recommendations for Anesthetic Perioperative Care and Pain Management in Weight Loss Surgery Roman Schumann,* Stephanie B. Jones,† Vilma E. Ortiz,‡ Kathleen Connor,§ Istvan Pulai,¶ Edwin T. Ozawa,** Alan M. Harvey,†† and Daniel B. Carr*

Abstract SCHUMANN, ROMAN, STEPHANIE B. JONES, VILMA E. ORTIZ, KATHLEEN CONNOR, ISTVAN PULAI, EDWIN T. OZAWA, ALAN M. HARVEY, AND DANIEL B. CARR. Best practice recommendations for anesthetic perioperative care and pain management in weight loss surgery. Obes Res. 2005;13:254 –266. Objective: To develop evidence-based recommendations that optimize the safety and efficacy of perioperative anesthetic care and pain management in weight loss surgery (WLS) patients. Research Methods and Procedures: This Task Group examined the scientific literature on anesthetic perioperative care and pain management published in MEDLINE from January 1994 to March 2004. We also reviewed additional data from other sources (e.g., book chapters). The search yielded 195 abstracts, of which 35 references were reviewed in detail. Task Group consensus was used to provide recommendations when evidence in the literature was insufficient. Results: We developed anesthesia practice and patient safety advisory recommendations for preoperative evaluation, intraoperative management, and postoperative care and pain management of WLS patients. We also provided suggestions related to medical error reduction and systems improvements, credentialing, and future research. Discussion: Obesity-related comorbidities including obstructive sleep apnea place WLS patients at increased risk for complications perioperatively. Regarding perioperative

The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. *Tufts-New England Medical Center; †Beth Israel Deaconess Medical Center; ‡Massachusetts General Hospital; §Newton-Wellesley Hospital; ¶Baystate Medical Center; **The Lahey Clinic; and ††Brigham and Women’s Hospital. Address correspondence to Roman Schumann, Department of Anesthesia, Tufts-New England Medical Center, 750 Washington Street, Boston, MA 02111. E-mail: [email protected] Copyright © 2005 NAASO

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safety and outcomes, conclusive evidence beyond the accepted standard of care in the reviewed literature is limited. Few reports specifically address the perioperative needs of severely obese patients. In this advisory, we synthesize current knowledge and make best practice recommendations for perioperative care and pain management in WLS patients. These recommendations require periodic review as further medical knowledge and evidence evolve. Key words: preoperative evaluation, intraoperative management, postoperative management, pain management, sleep apnea

Introduction

Weight loss surgery (WLS)1 is considered a treatment option in a lifetime effort for loss of excess weight. Many patients present with multiple obesity-related comorbidities that can sharply increase surgical risk (1). Complications and comorbidities related to severe obesity include coronary artery disease, hypertension, type 2 diabetes, nonalcoholic steatohepatitis, sleep apnea, and pulmonary hypertension (2). The population-level risk of dying within 30 days of gastric bypass surgery has been found to be four times higher than that reported in most published case series (3). Implications for anesthetic and perioperative care of severely obese patients are considerable (4) and escalate in the presence of comorbidities. Induction of anesthesia has the potential to be particularly hazardous because of an increased risk of difficult intubation (5– 8) and pulmonary aspiration of gastric contents (9,10). Periods of hypoxemia and hypercapnia perioperatively may increase pulmonary

1 Nonstandard abbreviations: WLS, weight loss surgery; ASA, American Society of Anesthesiologists; OSA, obstructive sleep apnea; BP, blood pressure; RCT, randomized controlled trial; CPAP, continuous positive airway pressure; RYGB, Roux-en-Y gastric bypass; BiPAP, bilevel positive airway pressure; PCA, patient-controlled intravenous analgesia; TEA, thoracic epidural analgesia.

Anesthesia for WLS, Schumann et al.

vascular resistance and precipitate right heart failure particularly in patients with pre-existing cardiac disease. The limited information available concerning pharmacodynamics and pharmacokinetics of perioperatively administered medications in severe obesity poses a challenge to proper drug dosing in these patients (11–14). In a retrospective study, severe obesity was associated with prolonged mechanical ventilation, prolonged ventilator weaning, and a longer intensive care unit and hospital length of stay (15). Millions of Americans are now considered severely obese (16,17). With ⬎104,000 WLS procedures anticipated in 2004 — up from 16,000 in the early 1990s (18)—anesthesiologists can expect to provide care for a growing number of severely obese individuals. This practice advisory—this term is defined elsewhere in the literature (19)—synthesizes current knowledge and provides recommendations for anesthetic perioperative care and pain management of WLS patients.

Research Methods and Procedures This task group, which included eight anesthesiologists experienced in anesthesia for WLS patients, examined the pertinent scientific literature on anesthetic perioperative care and pain management published in MEDLINE from January 1994 to March 2004. The search also included studies from sources other than MEDLINE (e.g., book chapters). Selected key words were used related to: patient safety and outcomes focused on preoperative evaluation; induction, maintenance, and emergence from anesthesia; postoperative recovery room care; and pain management. These were integrated with the five topics charged to each Task Group by the Expert Panel (18). The search yielded 195 scientific abstracts, 73 of which were considered potentially useful. An analysis of their full-text versions yielded 45 references; 35 of these were used for extraction of data, and the quality of each report was subsequently graded according to an evidence-based system derived from established models (Table 1 Appendix A) (20). The remaining 10 references (i.e., review articles, indirectly related trials, an editorial, and book chapters) served as supporting literature in the context of this advisory or provided indirectly related results rather than evidence in support of specific patient management recommendations. In the absence of sufficient literature evidence in important areas of anesthetic perioperative care and pain management, the Task Group developed consensus-based evidence recommendations.

improves WLS patients’ safety and outcomes. Possible advantages of such an approach may include improved patient satisfaction and education, early identification of potential airway management difficulties and vascular access issues, detection of sleep apnea and its implications, and a reduced case cancellation rate (21). Miller (22) suggests that in a significant proportion of claims related to difficult airway management, no preoperative assessment occurred, and in 25%, no preoperative airway history was conducted. Severely obese patients are considered at high risk for perioperative complications and often undergo extensive testing for preoperative clearance, including chest X-ray examination, pulmonary function tests, noninvasive cardiac testing, and blood work (4,23). Although needed for some patients, recent data indicate that extensive preoperative testing is not necessary for every severely obese patient undergoing gastric bypass surgery (23). However, standard minimal preoperative laboratory tests may aid in diagnosing clinically inapparent conditions that impact perioperative care. Recommendations (Categories B and D): ●

● ●

A pre-anesthesia evaluation by an anesthesia clinician at least 1 day before and, when possible, within 1 month of scheduled WLS; Minimum labs: hematocrit, glucose, creatinine, and blood urea nitrogen within 6 months of WLS; Extended preoperative testing as indicated by comorbidities, according to the American Society of Anesthesiologists (ASA) practice advisory on pre-anesthesia evaluation (24).

Results

Sleep Apnea Undiagnosed obstructive sleep apnea (OSA) is common in severely obese patients (7,25,26). In two recent studies, ⬎70% of patients presenting for gastric bypass surgery had sleep apnea by polysomnography (25,26). Several authors emphasize the need for surgeons and anesthesiologists to be aware of potential preoperative and postoperative complications in patients with OSA (7,25–27). An increased risk for difficult intubation (7,8) and for postextubation complications has been reported (7) in obese adult patients with OSA, and many of these patients may be particularly sensitive to opioid and sedative medications (7,28). Although looking for clinical signs and symptoms of sleep apnea syndromes in WLS patients is important, it is unclear whether routine polysomnography would improve safety and outcomes. An ASA task force is presently developing a practice advisory for the perioperative management of OSA, which, when available, may give further guidance.

Patient Safety Preoperative Evaluation and Care of WLS Patients: Anesthesia Consultation and Extent of Preoperative Testing. No data are available to determine whether routine preoperative anesthesia evaluation before the day of surgery

Smoking The benefits of perioperative smoking cessation have been well established in the general surgical population and may be extrapolated to this group. OBESITY RESEARCH Vol. 13 No. 2 February 2005

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256

98

193

Miller (22)

Ramaswamy (23)

RYGB

NA

Population


101

Nguyen (48)

Perilli (33)

20

7

15

Dumont (49)

El-Dawlatly (51)

N

Study

BPD

LAGB

RYGB A, open RYGB; B, laparoscopic RYGB

Laparoscopic gastroplasty

Population

Intra- and post-operative management

N

Study

Preoperative testing

Case series

Design

Prospective cohort

Database analyses

Design

48 (20)

50 (7)

Case series

Case series

A, 50 (50); RCT B, 48 (51)

45 (15)

Mean BMI (N)

50 (193)

Mean BMI (N)

Table 1. Appendix A: literature summary and evidence grading

Results

A preoperative airway history was not conducted in 25% of these claims. Routine preoperative testing is not mandatory for morbidly obese patients undergoing gastric bypass and should be performed selectively based upon medical history.

Results

Pulmonary mechanics and Decreased pulmonary compliance, blood gas analysis during increased peak airway pneumoperitoneum, pressures, mild hypercapnia, compared with baseline stable oxygenation, no increase in pulmonary shunt with insufflation. All, upper extremity Intraoperative core temperature warming blanket and did not differ between the passive airway groups. humidification Hemodynamic parameters Obese patients tolerated including noninvasive pneumoperitoneum without cardiac output measured deleterious hemodynamic during procedure changes. Measured effect of PEEP Both measures improved and reverse Trendelenburg oxygenation to an equal extent. positioning on respiratory Lower airway pressures with mechanics and reverse Trendelenburg cardiovascular parameters postioning.

Intervention

Evaluation of standard preoperative testing protocol

None

Intervention

C

C

A

C

Grade

B

B

Grade


10

LAGB

1067

26

50

Huerta (52)

Boyce (32)

Ezri (34)

Laparoscopic WLS

RYGB

RYGB

Elective surgery, morbidly obese

100

Brodsky (5)

Population Obese patients with suspected or confirmed OSA

N

Benumof (7)

Study

Airway management, sleep apnea

El-Dawlatly (50)

Case series

Review

Design

Case series

None

None

Intervention

Pulmonary mechanics measured during pneumoperitoneum, compared to baseline

53 (1067), Prospective None 420 OSA, observational 159 CPAP A, 56 (9); RCT Patient position at induction B, 59 (9); of anesthesia: A, 30° C, 53 (8) reverse Trendelenburg; B, supine; C, 30° back up Fowler 43 (50) Case series None

48 (100)

Mean BMI (N)

51 (10)

Abundance of pretracheal soft tissue at the level of the vocal cords as assessed by ultrasound is a good predictor of difficult laryngoscopy.

Obese patients with OSA may be at increased risk of difficult intubation. If opioids are used postoperatively, there is an increased risk of pharyngeal collapse. Continuous visual and electronic monitoring should be considered. Large neck circumference and high Mallampati score were predictive of potential intubation problems; weight and BMI were not. No correlation between CPAP utilization and incidence of major anastomotic leakage Safe apnea period is longest in the reverse Trendelenburg position

Results

The airway peak inspiratory and plateau pressures increased significantly during pneumoperitoneum. Dynamic lung compliances decreased.

C

A

C

C

C

Grade

C



257

258

98

10

27

40

Alvarez (43)

Michaloudis (57)

Salihoglu (44)

N

2

263

Martinotti (42)

Study

Choice of anesthetic

Vasquez (53)

Juvin (6)


Stoma-regulated A, gastric banding B

VBG

LAGB

VBG (17); lipectomy (17); BPD (10)

Population

Open RYGB

50 (20) 50 (20)

50 (27)

47 (10)

44 (98)

Mean BMI (N)

53 (2)

Intervention

Total IV anesthetic: midazolam, remifentanil, propofol, cisatracurium

Balanced sevoflurane anesthetic

None

Combined general and continuous bupivacaine spinal analgesia, PCIA (bupivacaine, fentanyl) with basal rate postoperatively Nonrandomized A, sevoflurane; B, TIVA control trial

Case series

Case series

Case series

Design

Case report

Laparoscopic gastroplasty A, 23 Prospective None (obese), (134); observational inguinal hernia repair, B, 46 (129) or Laparoscopic cholecystectomy (lean)

No differences in recovery characteristics but lower hemodynamic values in TIVA group (B) intra- and postoperatively.

Sevoflurane anesthesia provided cardiovascular stability, rapid awakening, early mobilization. Adequate time and conditions for induction and tracheal intubation, stable maintenance, low incidence of perianesthetic complications, good recovery performance, and institutional efficiency. Regimen provided safe anesthesia intraoperatively and satisfactory postoperative pain relief.

Results

A Mallampati score of III to IV was the only independent risk factor for difficult intubation in obese patients (B) but with poor specificity and positive predictive value. Massive bowel distention and development of anastomotic leakage attributed to use of BiPAP postoperatively.

C

C

C

C

Grade

C

C


30

Torri (46)

44

30

25

24

Joris (56)

Choi (61)

Meyer (59)

N

Fu (63)

Study

LAGB, abdominal hysterectomy

Open RYGB

VBG, LAGB

Abdominal surgery

Population

Morbidly obese intensive care unit patients

Erstad (11)

Postoperative pain management

Population

LAGB

BPD

Drug dosing

Drug dosing

90

Sollazzi (45)

Intervention

Drug dosing schemes

Intervention

A: isoflurane; B: sevoflurane

A, isoflurane; B, sevoflurane

Results

Insufficient information available for dosing of many drugs in this population; studies needed.

Results

Sevoflurane group had faster extubation time and better initial recovery (Aldrete) score. Sevoflurane group emerged from anesthesia more quickly and were discharged from PACU sooner.

A, ketamine bolus with Decreased postoperative morphine induction, intraoperative consumption in the preemptive infusion; B, ketamine Group A. No difference in pain bolus after incision closed scores. Nonobese population. A, 41 (15); Nonrandomized A, open VBG; B, LAGB LAGB resulted in less postoperative B, 41 (15) control trial pain, less opioid consumption, and less pulmonary dysfunction compared with open VBG NA Case series All patients given PCA IV PCA provided satisfactory morphine. Patients with analgesia in morbidly obese history of OSA excluded. patients without deleterious effect on O2 saturation, BP, heart rate, respiration. A, NA (10); Case series A, rofecoxib; B, no Rofecoxib reduced narcotic use B, NA (14) rofecoxib

Design

A, NA (20); RCT B, NA (20)

Mean BMI (N)

Literature review

Design

A, NA (60); RCT B, NA (30); BMI ⬎ 45 A, 42 (15) RCT B, 43 (15)

C

C

C

A

Grade

B

Grade

A

A



259

260


30

915 (37 obese)

Rigg (65)

Feld (58)

36

Niemi (69)

86

22

Niemi (68)

Charghi (62)

70

Nguyen (59)

A, 24 (12); B, 24 (12); C, 24 (12)

A, NA (11) B, NA (11)

A, 48 (36); B, 43 (34)

Open RYGB

Open RYGB

A, 54 (15) B, 56 (15)

A, 53 (40); B, 52 (46)

Major abdominal A, NA (464); surgery B, NA (456)

Major upper abdominal or thoracic surgery

Elective laparotomy

RYGB

RCT

Retrospective chart review

RCT

RCT

RCT (crossover)

RCT

Epinephrine improved the efficacy of bupivacaine/fentanyl epidural analgesia in a dose-related fashion, with a minimum effective dose of approximately 1.5 ␮g/mL in a nonobese population. Epidural analgesia provided better postoperative analgesia and fewer respiratory complications in a highrisk population. No difference in pain control. Increased wound infection rate in epidural group.

Laparoscopic gastric bypass resulted in less postoperative suppression of pulmonary function, decreased pain, improved oxygenation, and less atelectasis than open gastric bypass. Fentanyl markedly improved the pain-relieving effect of bupivacaine and epinephrine in a generalized population.

None. A, morphine PCA; B, epidural: morphine (35), bupivacaine/fentanyl (11) A: intraoperative fentanyl No difference in pain control. NonB: multimodal pain opioid group (B) was less sedated management: and used less morphine in PACU Ketamine, magnesium, methyprednisolone, ketorolac, clonidine, lidocaine (IV) Both groups postoperative morphine PCA

All patients received TEA with bupivacaine and epinephrine. Fentanyl added during treatment arm. All patients received TEA with bupivacaine and fentanyl plus: A, 0.5 ␮g/mL epinephrine; B, 1.0 ␮g/mL epinephrine; C, 1.5 ␮g/mL epinephrine A, epidural; B, nonepidural

A, laparoscopic RYGB; B, open RYGB

A

C

A

A

A

A


Various procedures

Open RYGB

100 studies Various procedures

3016

114

All

A, 53 (39); B, 52 (39); C, 52 (36)

Meta-analysis

Prospective cohort

RCT

A, multimodal pain Epidural (B) provided best analgesia, A management but incisional infiltration with local (bupivacaine infiltration, anesthetic (A) can be effective as a PCA morphine); B, TEA component of multimodal (bupivacaine, meperidine); perioperative analgesia. C, PCA morphine. All groups received scheduled ketorolac. Continuous regional Increased side effects and respiratory B analgesia (n ⫽ 1096) and depression with continuous systemic opioids (PCA) systemic opioid infusion. ⫾ continuous infusion. Epidural analgesia provided better A postoperative analgesia compared with parenteral opioids in a generalized population.

NA, not applicable; RYGB, Roux-en-Y gastric bypass; RCT, randomized controlled trial; LAGB, laparoscopic adjustable gastric banding; BPD, biliary pancreatic diversion; PEEP, positive end expiratory pressure; OSA, obstructive sleep apnea; WLS, weight loss surgery; BiPAP, bilevel positive airway pressure; VBG, vertical banded gastroplasty; PCIA, patient-controlled intrathecal analgesia; PACU, Post Anesthesia Care Unit; PCA, patient-controlled intravenous analgesia; TEA, thoracic epidural analgesia.

Block (66)

Schug (70)

Schumann (60)



261


Recommendations (Categories A, B, and D): ● ● ●

Standard clinical preoperative assessment for sleep apnea of every WLS patient; polysomnography in selected patients. Integration of possible implications of suspected OSA into perioperative care. Smoking cessation at least 6 weeks before surgery, including active support for this approach by the patients’ WLS program.

Intraoperative Patient Management Anesthesia Induction and Emergence. Alterations in pulmonary function and physiology are common in severely obese patients (29 –31), impairing their capacity to tolerate periods of apnea (31). Boyce et al. (32) have shown a significant extension of a “safe apnea period” in these patients by employing the 30° reverse Trendelenburg position during induction of anesthesia. Perilli et al. (33) have shown benefits of this position for oxygenation during anesthesia. Juvin et al. (6) have reported a higher rate of difficult intubation in obese patients compared with lean ones, and a high risk of desaturation in obese patients with difficult intubation. Brodsky et al. (5) have reported that a large neck circumference and a high Mallampati score were predictors of a potentially difficult intubation, whereas BMI or weight per se was not. Abundant pretracheal soft tissue as demonstrated by ultrasound may predict difficult laryngoscopy (34). However, Miller (22) has found obesity to be a factor in 31% of medical malpractice claims for difficult intubation, compared with 14% of all other claims (p ⬍ 0.01). These data are supported by findings from other studies (35–37). The association among severe obesity, sleep apnea, and difficult airway management further complicates airway management at induction and emergence from anesthesia (7,8). The ASA has provided detailed guidelines for the management of the difficult airway (38). Based on early research, obesity alone has long been considered as a risk factor for aspiration of gastric contents during induction of anesthesia (9). For obese patients undergoing elective interventions, this concept has recently been challenged (39,40). Although the actual incidence of clinically significant aspiration in this patient population is difficult to determine, and it is probably quite low, management of a difficult airway contributes to its occurrence (10,41). Positioning severely obese patients in 45° or 30° reverse Trendelenburg may aid in the prevention of gastroesophageal reflux and, thus, aspiration by alleviating increased intra-abdominal pressure (31,32). Apart from the ASA guidelines for the management of the difficult airway (38), few authors comment on the availability of different airway devices perioperatively (27). No information on the benefits of additional clinicians during induction and emergence from anesthesia to aid in potentially critical difficult airway management situations is available. No literature was found regarding specific extubation criteria for WLS patients. 262


Recommendations (Categories B, C, and D): ●

●

●

●

Standard use of the 30° reverse Trendelenburg (head up) position during preoxygenation, induction, and emergence from anesthesia. Induction techniques to facilitate expeditious tracheal intubation, which may include a “rapid sequence induction.” Immediate availability of difficult airway management devices (i.e., Fast-Trach laryngeal mask airway), as well as an additional anesthesia clinician, the circulating operating room nurse, and the surgeon during induction and emergence. Prior to extubation, the patient should be fully awake and complete reversal of neuromuscular blockade should be established in addition to achieving standard extubation criteria.

Maintenance of Anesthesia Although recent studies propose the use of specific anesthetic maintenance agents, there is insufficient evidence at this time to conclude improved safety and outcomes by this approach (42– 46). Limited information is available regarding intraoperative fluid replacement and maintenance of normothermia in severely obese patients (47,48). However, intraoperative mild hypothermia, common during open and laparoscopic bariatric procedures, improved with active warming in at least one study (48). Intraoperative euvolemia and normothermia may aid in physiological homeostasis and adequate organ perfusion. The effects of the pneumoperitoneum during laparoscopic WLS surgery on pulmonary physiology and hemodynamic parameters have been investigated (49 –51). Perioperatively, blood pressure (BP) assessment may be challenging because of the patient’s body habitus and the inability to correctly position a noninvasive BP cuff on a conically shaped arm. However, there is no evidence to suggest reduced patient safety and outcome due to the common practice of using standard noninvasive BP equipment at alternate sites such as the patient’s forearm. There are no data showing that routine invasive hemodynamic monitoring improves safety and outcome in WLS patients. Recommendations (Categories B and D): ●

● ●

Tailoring of the anesthetic to promote early return of the patient’s protective airway reflexes and maintenance of oxygenation. Maintaining euvolemia, monitoring body temperature, and maintaining normothermia. The use of alternate sites for noninvasive BP assessment (e.g., the forearm) if needed, and invasive hemodynamic monitoring as medically indicated.

Intra- and Perioperative Drug Dosing Pharmacodynamic and kinetic data guiding dosing in severely obese patients are frequently not available for


many perioperatively administered medications. Assessment of serum concentrations is a more reliable method of monitoring dosing than empirical dosing based on previously published nomograms (31). A recent study shows that use of actual body weight for dosing fentanyl overestimates requirements in obese patients (12). Two recent randomized controlled trials (RCTs) of neuromuscular blockers show prolonged action of cisatracurium in morbidly obese patients when dosed according to total body weight (13) and significantly prolonged duration of action of rocuronium when dosed according to total body weight (14). Recommendation (Category C): ●

For medications with limited pharmacodynamic and kinetic data, begin dosing closer to the patient’s estimated lean body mass (⬃120% of ideal body weight) and adjust as needed (47).

Postanesthesia Care The literature provides little guidance for postanesthesia care interventions to improve safety and outcomes in WLS patients, including those with a diagnosis of sleep apnea. Huerta et al. (52) have reported that continuous positive airway pressure (CPAP) can be used safely in patients with sleep apnea following Roux-en-Y gastric bypass (RYGB) without increasing the risk of postoperative anastomotic leak. Conversely, Vasquez et al. (53) have suggested that postoperative bilevel positive airway pressure (BiPAP) may lead to anastomotic leaks. Recommendations (Categories B, C, and D): ●

● ●

●

Use of ASA Standards for Postoperative Care (54), taking the implications of a diagnosis of sleep apnea into consideration, as well as the patient’s overall medical condition. Availability of CPAP/BiPAP, as needed, postoperatively for noninvasive positive pressure ventilation. Consensus discussion of whether or not to use CPAP or BiPAP among the anesthesiologist, surgeon, and respiratory therapist before its initiation. Administration of CPAP or BiPAP by specially trained nursing or respiratory therapy staff.

Postoperative Pain Management The safety and efficacy of postoperative intravenous and epidural pain management are well established in the general surgical population, and practice guidelines for acute pain management in the perioperative setting have been published (55). Several authors report on postoperative pain management in WLS patients (47,56 – 63). Some evidence suggests preemptive opioid sparing effects of adjunct nonopioid analgesic regimens used during anesthesia in normalweight patients (64). Most commonly used strategies employ either patient-controlled intravenous analgesia (PCA) or thoracic epidural analgesia (TEA). Uncertainty remains

as to the superiority of one pain treatment modality versus another (65). Surgical technique— open versus laparoscopic—may influence the patient’s and anesthesiologist’s choice of pain treatment. Either pain management strategy may offer specific advantages for specific patient outcomes, such as a reduced rate of pulmonary complications after abdominal surgery and superior pain control with TEA (65– 67) or less impairment to ambulate with PCA (61). Improved efficacy and safety have been shown when PCA management includes adjunct analgesics such as nonsteroidal antiinflammatory medications and local anesthetic wound infiltration in a multimodal approach (60,68). TEA can be improved by adding opioids and possibly epinephrine to the epidural solution (69,70). Recommendations (Categories A and B for efficacy, B): ● ●

●

● ●

A combination of local anesthetics with opioids and possibly epinephrine in the epidural solution for TEA. Standardized nursing protocols for monitoring, maintaining, and troubleshooting daily epidural management; availability of an acute pain service. An opioid-based PCA with local anesthetic wound infiltration and adjunct (nonnarcotic) analgesic medications (unless contraindicated). Initial PCA dose setting based on estimated lean body mass. Avoidance of routine use of continuous opioid background infusion PCA mode (71).

Medical Error Reduction and Systems Improvements We found no literature on perioperative anesthetic care and pain management specific to the safety of WLS patients. In the general surgical population, unimpaired intraoperative communication among clinicians is important for patient safety during crisis situations (72). Communication Recommendations (Category D): ●

●

Effective and unimpaired intraoperative and perioperative communication among the anesthesia, nursing, and surgical members of the WLS care team. Identification of an anesthesiologist with a special interest in anesthetic care and pain management for WLS patients to serve as an interdepartmental liaison to bariatric surgeons.

Equipment and Skills Recommendations (Category D): ●

●

Availability of at least one portable storage unit with specialized equipment for management of difficult airways throughout the perioperative period, maintained and operated by clinicians. Availability of a clinician with airway management skills perioperatively.

Patient Monitoring Recommendations (Category D): ●

Formulation of, and adherence to, institutional protocols OBESITY RESEARCH Vol. 13 No. 2 February 2005

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●

of continued close monitoring of patients with documented or suspected sleep disordered breathing such as sleep apnea as clinically indicated. Adherence to forthcoming ASA recommendations, when they become available, for perioperative care of patients with sleep apnea.

Credentialing for Systems and Practitioners An anesthesia residency program accredited by the Accreditation Council for Graduate Medical Education (73) provides extensive experience in the anesthetic and perioperative care of severely obese surgical patients. No specific recommendations for additional credentialing of anesthesia practitioners or systems can be made at this time.

Discussion With demand for WLS likely to increase, physicians and health officials face twin challenges. The first is to improve safety. The second is to learn more about long-term outcomes, which approaches are best, the mechanisms through which WLS results in weight reduction, and the effects of coexisting conditions (74). A thorough understanding of the pathophysiology and specific implications of obesity should allow more effective and safer treatment for this unique group of patients (4). Outcomes data on anesthetic care and perioperative pain management in WLS patients are scarce. Literature on the impact of specific care plans on short- and long-term perioperative outcomes in WLS patients is in a beginning stage. We identified the following areas as important for future research: studies on patient safety and outcomes; pharmacokinetic and pharmacodynamic studies of anesthetics, analgesics, and other perioperative medications for safe, effective, and accurate dosing schedules in WLS patients; studies of reduced-opioid or nonopioid-based pain management strategies; development of an evidencebased algorithm for preoperative evaluation of WLS patients; development of evidence-based algorithms for risk stratification and perioperative patient care; studies on the impact of sleep-disordered breathing syndromes (e.g., OSA) on perioperative care and WLS outcomes; and development of accurate and well-tolerated physiological monitoring devices for severely obese patients, particularly for BP assessment.

Acknowledgments We thank George Blackburn, Frank Hu, and Rita Buckley for manuscript preparation, and Barbara Ainsley for administrative services. Manuscript preparation was supported, in part, by the Center for Healthy Living at Harvard Medical School and by the Boston Obesity Nutrition Research Center Grant P30DK46200. This report on WLS was prepared for the Betsy Lehman Center for Patient Safety and Medical Error Reduction (Department of Public Health, Boston, MA). 264


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