Anaesthetic management of an extremely obese woman undergoing open gastric bypass

EDITOR: Obesity poses significant anaesthetic and surgical challenges [1–4]. Overweight is defined as a body mass index (BMI) ≥ 30 kg m−2, whereas extreme obesity is defined as a BMI >40 kg m−2 [5]. Management of obese patients requires careful appraisal of anaesthetic and operative risks. Compared to non-obese patients, obese patients are at higher risk for perioperative pulmonary complications and associated morbidity and mortality [6]. Comprehensive preoperative assessment, intraoperative management and postoperative anaesthetic care require an understanding of the pathophysiological and pharmacological dynamics of extreme obesity [7,8]. First-line treatment for obesity includes diet, exercise and behavioural therapies. Extremely obese patients who are refractory to first-line treatment frequently undergo bariatric surgery. The two most commonly performed procedures are vertical banding gastroplasty and Roux-en-Y gastric bypass, the latter having been associated with more favourable outcomes in long-term weight reduction and comorbidity management [9]. The following case report describes the anaesthetic management of an extremely obese patient with significant comorbidities who underwent Roux-en-Y gastric bypass. The patient was 48-yr-old woman who weighed 179 kg and had a BMI of 79. 5 kg m−2. She was classified as ASA III and was scheduled for a laparotomy for cholelithiasis and Roux-en-Y gastric bypass. Anaesthesiology assessment 9 days prior to surgery revealed a history of hypertension for the past 5 yr, which was controlled with amlodipine 10 mg, as well as obesity hypoventilation syndrome and left ventricular diastolic dysfunction with an ejection fraction of 55%. Lung function tests showed forced vital capacity (FVC), 2.31 L (79%); forced expiratory volume (FEV1), 1.67 L (73%); FEV1 /FVC, 72%; and maximum midexpiratory flow (MMF), 51%. Arterial blood gas analysis showed pH, 7.4; PO2, 55.9 mmHg; PCO2, 46.1 mmHg; SaO2, 87.5; HCO3, 30.9 on room air. The patient received salbutamol 4 mg, fluticasone 4 mg, O2 1 L min−1 via face mask, esomeprazol 40 mg, and metoprolol succinate 50 mg preoperatively. With the patient seated comfortably, an 18-G Tuohy needle was inserted via a median approach into the T9–T10 interspace using the loss of resistance technique with saline. A multiorificed epidural catheter was inserted 3 cm cephalad via the Tuohy needle. To commence epidural anaesthesia, 0.5% bupivacaine was injected at a rate of approximately 7 mL min−1. After assessing the level of sensory block, an additional 30 mg of bupivacaine was injected epidurally 20 min after the first dosage. The sensory block level was T6, and the motor block score was three on the Bromage scale. Midazolam (7 mg) was intravenously (i.v.) administered for sedation following epidural anaesthesia prior to surgery. The patient's non-invasive blood pressure (BP) was between 160/105 and 90/45 mmHg, and her heart rate (HR) was between 72 and 83 bpm. The operation lasted 120 min. During the operation, urinary output was 1200 mL, and 1800 mL of crystalloid solution was administered. Cholecystectomy and Roux-en-Y gastric bypass were performed. Epidural analgesia with top-up bupivacaine (20 mg) was administered in the postoperative care unit every 4 h. Postoperatively, the patient's vital signs were BP, 106/68 mmHg; HR, 82 bpm rhythmic; and nasal temperature, 37.2°C. Postoperative arterial blood gas analysis showed pH, 7.35; PO2, 77.3 mmHg; PCO2, 55.4 mmHg; HCO3, 30; BE, 3.1; and SaO2, 94.4. The patient was mobilized 20 h after the operation and discharged from the postanaesthetic care unit after 24 h. At 13 days following surgery, the patient's condition was uneventful. She successfully lost 11 kg during the first month after the operation. Most bariatric surgeries have been successfully performed with laparoscopic techniques under general anaesthesia [10–12]. However, laparoscopic techniques are expensive and often are not covered by health insurance, which was the case with our patient. After failing diet, exercise and medical therapies, open Roux-en-Y gastric bypass was scheduled. Because of the patient's limited respiratory and cardiac function, the anaesthetist considered epidural anaesthesia [13]. Epidural anaesthesia is not only cost-effective, but also offers several advantages over general anaesthesia. Obesity is associated with many diseases, including Type II diabetes mellitus, hypertension, coronary artery disease and cholelithiasis. In our patient, hypertension, hypoventilation and cholelithiasis were present. As evidenced by the patient's elevated oxygen demand (PO2, 55.9), carbon dioxide production (PCO2, 46.1) and alveolar ventilation (SaO2, 87.5 in room air), her metabolic rate was proportional to her body weight. In general, obese patients are hypoxic; however, our patient was hypercapnic, which was suggestive of impending complications [5]. Von Ungern-Sternberg and colleagues [14] demonstrated that the use of epidural analgesia in obese patients undergoing midline laparotomy improved postoperative spirometry. Gander and colleagues [15] showed that the application of positive airway pressure during induction of general anaesthesia in extremely obese patients increased non-hypoxic apnoea duration by 50%. Epidural anaesthesia offers the benefits of pain relief and fewer respiratory complications in the postoperative period. Respiratory failure is a major postoperative complication experienced by extremely obese patients. The risk of postoperative hypoxia is increased by preoperative hypoxia and by surgery involving the thorax or upper abdomen (especially vertical incisions, as were performed in our patient). Demiroluk and colleagues [16] found no differences in the respiratory mechanics of 40 extremely obese patients who underwent either laparoscopic or open surgery. Premedication with respiratory depressant drugs should be avoided in patients with evidence of preoperative hypoxia, hypercapnia or obstructive sleep apnoea. Benzodiazepine loading doses should be adjusted according to actual weight, and maintenance doses should be adjusted according to ideal body weight. In our patient, i.v. midazolam (7 mg; 0.04 mg kg−1 actual weight) was used for sedation prior to surgery and maintenance doses were not needed. Obese patients are at risk for developing aspiration pneumonia, especially under general anaesthesia. Kocian and colleagues [17] reported that bronchial aspirations occurred during anaesthetic induction in patients undergoing gastric banding. In extremely obese patients, airway management difficulty during induction and upper airway obstruction during recovery should be anticipated. Other common postoperative complications may include wound infection, deep venous thrombosis and pulmonary embolism. Preoperative evaluation of extremely obese patients undergoing major surgery should include a chest radiograph to assess the cardiopulmonary reserve, an electrocardiogram, arterial blood gas analysis and pulmonary function tests [18]. Obscured landmarks, difficult positioning and extensive layers of adipose tissue may make regional anaesthesia difficult; nonetheless, a high rate of successful block and overall satisfaction levels has been reported in extremely obese patients [13]. Although dose requirements for epidural and spinal anaesthesia may be difficult to estimate, obese patients usually require 20–25% less local anaesthetic because of epidural fat and distended epidural veins [19]. A high level of sensory block can easily result in respiratory compromise. In our patient, bupivacaine (65 mg) provided satisfactory anaesthesia associated with a T6 level of sensory block. In extremely obese patients, the elevation in cardiac output is generally achieved through an increase in stroke volume and frequently results in arterial hypertension and left ventricular hypertrophy; this occurrence was noted in our patient. Elevations in pulmonary blood flow and pulmonary artery vasoconstriction from persistent hypoxia can lead to pulmonary hypertension and cor pulmonale. Salihoglu and colleagues [20] reported that alfentanil, fentanyl and remifentanil had similar effects in controlling the haemodynamic response to tracheal intubation in extremely obese ASA I–II patients undergoing general anaesthesia. Hofer and colleagues [21] described a 433-kg patient with obstructive sleep apnoea and pulmonary hypertension who underwent Roux-en-Y gastric bypass. The authors used intraoperative dexmedetomidine instead of narcotics to avoid postoperative respiratory depressant effects and found that dexmedetomidine was effective in reducing narcotic requirements both intraoperatively and postoperatively. Pandazi and colleagues [22] described their experience with 23 patients who had undergone open gastric bypass surgery with thoracic epidural analgesia combined with light general anaesthesia using propofol and nitrous oxide. The authors concluded that propofol–nitrous oxide combined with thoracic epidural analgesia under Bispectral Index monitoring provided effective and satisfactory anaesthesia. In conclusion, thoracic epidural anaesthesia should be considered in extremely obese patients who are candidates for open bariatric surgery. In our patient, this technique provided adequate anaesthesia with the advantages of early mobilization, pain relief and supportive effects on respiratory mechanics, as well as earlier hospital discharge with faster convalescence compared to general anaesthesia. Kocaman B. Akbay F. Hayit M. Pehlivan C. Agartan 1Department of Anesthesiology and Intensive Care, Duzce Medical Faculty, Abant Izzet Baysal University, Duzce, Turkey 2Department of General Surgery, Duzce Medical Faculty, Abant Izzet Baysal University, Duzce, Turkey 3Department of Pediatric Surgery, Duzce Medical Faculty, Abant Izzet Baysal University, Duzce, Turkey