Bariatic surgery and anesthesia

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anesthetic management/ anesthetic implications / anesthetic consideration during bariatric surgery


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Bariatric surgery and anesthesia:

Bariatric surgery and anesthesia Dr. Habib Md Reazaul Karim Dept. of Anesthesiology. NEIGRIHMS, Shillong . India.


introduction Obesity is a physiologic dysfunction of the human organism with environmental, genetic, and endocrinologic causes and a major health problem with clearly established health implications


classes Overweight- BMI between 25 and 29.9 kg/m 2 Obese- BMI between 30 and 49.9 kg/m. 2 BMI of 50 kg/m 2 or greater are considered superobese The obese classification is further subdivided into class 1 (BMI range of 30 to 34.9 kg/m 2 ) class 2 (35 to 39.9 kg/m 2 ) class 3 (40 to 49.9 kg/m 2 ) also called morbid obese ( Baskin ML, Ard J, Franklin F, et al: Prevalence of obesity in the United States. Obes Rev 2005; 6:5-7)

Risk :

Risk Associated with an increased risk for coronary artery disease Hypertension Dyslipidemia diabetes mellitus gallbladder disease degenerative joint disease obstructive sleep apnea socioeconomic and psychosocial impairment ( NIH conference: gastrointestinal surgery for severe obesity— Consensus Development Conference Panel. Ann Intern Med 1991;115:956–61)

Indications for drug treatment:

Indications for drug treatment Pharmacological treatments are typically used as an adjunct to diet and exercise for patients with BMI of 30 or greater BMI of ≥27 for patients with obesity-related risk factors or comorbid diseases. Drugs approved for the specific indication of weight loss— phentermine , sibutramine , and orlistat . ( Low AK, Bouldin MJ, Sumrall CD, et al: A clinician's approach to medical management of obesity. Am J Med Sci 2006; 331:175-182 )

Indications for surgery:

Indications for surgery An absolute BMI more than 40 kg/m2 BMI more than 35 kg/m2 in combination with life threatening cardiopulmonary problems or severe diabetes mellitus ( NIH conference: gastrointestinal surgery for severe obesity— Consensus Development Conference Panel- 1991)


contraindications Factors that may be considered contraindications include unstable CAD uncontrolled severe OSA uncontrolled psychiatric disorder mental retardation (IQ < 60) inability to understand the surgery perceived inability to adhere to postoperative restrictions continued drug abuse malignancy with a poor 5-year survival prognosis Cirrhotic liver disease with portal hypertension

Preoperative Evaluation:

Preoperative Evaluation Attention should focus on issues unique to the obese patient, particularly cardiorespiratory status and the airway. Consideration of co morbidities i.e. hypertension, diabetes, heart failure, IHD, obesity-hypoventilation syndrome, metabolic syndrome etc. Results of the sleep study History of previous surgeries, their anesthetic challenges, need for ICU admission Current medications Patients scheduled for repeat bariatric surgery should be screened preoperatively for long-term metabolic and nutritional abnormalities


Investigations… Recommended preoperative laboratory evaluations include fasting blood glucose, lipid profile electrolytes serum chemistries (to evaluate renal and hepatic function) complete blood count Serum ferritin , vitamin B 12 , thyrotropin , & 25-hydroxyvitamin D. (Miller 7 th edition- anesthesia for Bariatic Surgery) ABG measurements help evaluate ventilation, as well as the need for perioperative oxygen administration and postoperative ventilation. Routine pulmonary function tests and liver function tests are not cost-effective in asymptomatic obese patients Coaugulation profile ( liver problem, repeat surgery, orlistat ) ECG, echocardiography Sleep study if suspected OSA ( Barash 6 th edition, anesthesia and obesity)

Concurrent, Preoperative, and Prophylactic Medications:

Concurrent, Preoperative, and Prophylactic Medications Patients' usual medications should be continued until the time of surgery, with the possible exception of insulin and oral hypoglycemics Antibiotic prophylaxis is usually indicated Obesity itself does not increase the risk for aspiration. acid aspiration prophylaxis, including H 2 receptor agonists or proton pump inhibitors, must be considered in patients with identifiable risk for aspiration Anxiolysis and prophylaxis against deep vein thrombosis (DVT) should be addressed at premedication.

DVT consideration:

DVT consideration Morbid obesity is a major independent risk factor for sudden death from acute postoperative pulmonary embolism. Subcutaneous heparin 5,000 IU administered before surgery and repeated every 8 to 12 hours until the patient is fully mobile reduces the risk of DVT LMWH can also be used Preoperative prophylactic placement of an inferior vena cava filter should be considered in venous stasis disease BMI ≥60, truncal obesity and OHS and/or OSA, ( Sapala JA, Wood MH, Schuhknecht MP et al: Fatal pulmonary embolism after bariatric operations for morbid obesity: A 24-year retrospective analysis. Obes Surg 2003; 13: 819)

Intraoperative Care:

Intraoperative Care special challenges for the anesthesiologist airway management Positioning Monitoring choice of anesthetic technique and anesthetic agents pain control and fluid management


Airway… Correlation between morbid obesity and difficult laryngoscopy and intubation is not universally observed in clinical practice. It is possible that no difference exists between laryngoscopy and intubation in thin and obese patients if one follows the simple, but important, approach to clinical care of paying careful attention to patient positioning before induction of GA. Equipment for emergency airway management, including laryngeal masks and a fiberoptic bronchoscope, should be immediately available. Alternative airway management techniques


Laryngoscopy … Stacking Head elevated laryngoscopy position Preformed troop pillow


Positioning… Specially designed tables or two regular tables joined together may be required Strapping obese patients to the operating table in combination with a malleable bean bag helps keep them from falling off the operating table. Particular care should be paid to protecting pressure areas


Monitoring… Obesity per se does not require invasive monitoring Invasive arterial pressure monitoring may be indicated for super morbidly obese patient patients with cardiopulmonary disease noninvasive blood pressure cuff does not fit properly Central venous catheter can be used selectively in patients with significant cardiopulmonary disease patients undergoing extensive surgery may also be required for intravenous access The morbidly obese with serious comorbid diseases like obesity-hypoventilation syndrome with pulmonary hypertension and cor pulmonale may require a pulmonary artery catheter or intraoperative use of transesophageal echocardiography.


Preoxygenation … Adequate preoxygenation is vital in obese patient Preoxygenation using 25-degree head-up (back inclined) Application of positive pressure ventilation during preoxygenation Use of 10 cm H 2 O CPAP during preoxygenation in the supine position results in a higher Pa o 2 after intubation and decreased the amount of atelectasis 3 – 5 minute preoxygenation with 100% oxygen is usually practised Four vital capacity breaths with 100% oxygen within 30 seconds have been suggested as superior to the usually recommended 3 minutes of 100% preoxygenation in obese patients.


Induction… Preparation should be made for the possibility of a difficult intubation, and a surgeon familiar with surgical airways should be readily available. If a difficult intubation is anticipated, awake intubation using topical or regional anesthesia is a prudent approach. During awake intubation, sedative-hypnotic medications should be reduced to a minimum Larger doses of induction agents may be required. An increased dose of succinylcholine is necessary because of an increase in activity of pseudocholinesterase Any of the commonly available intravenous induction agents may be employed after taking into consideration problems peculiar to individual patients

Pharmacology/Weight-Based Dosing:

Pharmacology/Weight-Based Dosing Highly lipophilic substances such as barbiturates and benzodiazepines, show significant increases in volume of distribution (Vd) for obese individuals relative to normal-weight individuals Less-lipophilic compounds have little or no change in Vd with obesity. Certain exceptions to this rule include digoxin , procainamide, and remifentanil


Maintenance… Continuous infusion of a short-acting intravenous agent, such as propofol , or any of the inhalation agents, or a combination, may be used to maintain anesthesia. Desflurane , sevoflurane, and isoflurane are minimally metabolized and are therefore useful agents in the obese patient, with desflurane possibly providing better hemodynamic stability and faster washout Short-acting opioids, combined with a low-solubility inhalation anesthetic, facilitate a more rapid emergence without increasing opioid -related side effects Cis-atracurium ia a favourable NDMR for use during maintenance of anesthesia. Vecuronium and rocuronium are also useful choices.


Ventilation… Ventilatory tidal volumes >13 mL/kg offer no added advantages during ventilation of anesthetized morbidly obese patients. PEEP is the only ventilatory parameter that consistently has been shown to improve respiratory function in obese subjects. After induction, it is reasonable to maintain 10 to 12 cm H 2 O PEEP intraoperatively, but care must be taken to treat any hypotension that may occur

Fluid management…:

Fluid management… Intraoperative fluid requirements are usually larger if postoperative acute tubular necrosis is to be prevented. Patients usually require up to 4–5 L of crystalloid for an average 2-h operation. This adds up to twice the calculated maintenance fluid requirement plus the calculated deficit based on a 12-h fasting period The next hour usually requires the same amount of crystalloid, Afterwards the amounts are reduced to approximately twice the calculated maintenance requirement, based on LBM For the next 12 h (200 mL/h overnight). ( Ogunnaike BO, Jones SB, Jones DB et al: Anesthetic considerations for bariatric surgery. Anesth Analg 2002; 95; 1801)


Emergence… The patient should be preferably extubated in the semirecumbent position Maintain on pressure support during emergence as soon as spontaneous ventilation has resumed Note that, neuromuscular blockade must be fully reversed and adequate muscle strength has to be returned before the patient is extubated. Supplemental oxygen should be administrated after extubation. Pressure support or CPAP or bilevel positive airway pressure is advocated and can be delivered immediately after extubation by mask applied to the face and in post op period.

Pain management:

Pain management Analgesia can be provided via Intravenous IV via patient-controlled analgesia (PCA) or Epidural analgesia. Multimodal Injection of local anesthetic into the incision site before incision- pre-emptive analgesia. Add adjunctive analgesia with non-narcotic medications, unless contraindicated. Opioid-based PCA with local anesthetic infiltration of the wound and adjunctive non-narcotic medication is a reasonable approach for most patients.


Note…… Delayed respiratory depression with centrally administered neuraxial opioids , when coupled with a potentially difficult airway in the obese patient, suggests that close monitoring in a step-down or intensive care unit is prudent.

Post op atelectasis:

Post op atelectasis Adequate analgesia CPAP/ BiPAP/ PSV with PEEP Incentive spirometry, deep breathing, and intermittent positive pressure breathing were equally more effective than no treatment in preventing postoperative pulmonary complications after upper abdominal surgery

Other technical issue:

Other technical issue Ensure that the endotracheal tube cuff maintains a tight seal before performing leak test with methylene blue through the NG tube Remove completely all endogastric tubes (not just merely pull them back into the esophagus) before gastric division. After an RYGB pouch is created, the anesthesiologist should not blindly insert the NG tube. Patient transfer devise is helpful.

Ambulatory anesthesia:

Ambulatory anesthesia Obese patient should not be excluded from day-case surgery based solely on absolute weight or BMI. Airway surgery, such as uvulopalatopharyngoplasty and tonsillectomy, should not be performed on an outpatient basis. OSA patients should generally be treated as inpatients; however, outpatient surgery can be considered under certain circumstances, including mild OSA use of local or regional anesthesia with minimal sedation availability of a 23-hour observation postanesthesia care unit, and when patients can resume oral medication at the time of discharge.

Regional anesthesia:

Regional anesthesia Evidence showing that regional anesthesia, especially epidural and spinal, is safe and feasible in patients with large body habitus . ( Passannante AN, Rock P: Anesthetic management of patients with obesity and sleep apnea . Anesthesiol Clin North Am 2005; 23:479-491) Special equipment, in terms of longer needles or special ultrasound probes, may be needed Care should be exercised in dosing


complications…. In-hospital mortality rates for LGB and open GBP surgery are 0.27% and 0.81%, respectively. Complication rates are significantly lower in each category for patients undergoing laparoscopic rather than open procedures Morbidity occurring during the immediate postoperative in-hospital period typically falls into one of four categories: wound, gastrointestinal, pulmonary, and cardiovascular complications The most common complications requiring reoperation include postoperative intra-abdominal bleeding, anastomotic leakage, suture line dehiscence, small bowel obstruction, and deep wound infection

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