Ideal versus corrected body weight for dosage of sugammadex in morbidly obese patients

To date, the dosing of sugammadex is based on real body weight without taking fat content into account. We compared the reversal of profound rocuronium-induced neuromuscular blockade in morbidly obese patients using doses of sugammadex based on four different weight corrections. One hundred morbidly obese patients, scheduled for laparoscopic bariatric surgery under propofol-sufentanil anaesthesia, were randomly assigned four groups: ideal body weight; ideal body weight + 20%; ideal body weight + 40%; and real body weight. Patients received sugammadex 2 mg.kg(-1), when adductor pollicis monitoring showed two responses. The primary endpoint was full decurarisation. Secondary endpoints were the ability to get into bed independently on arrival to the post-anaesthetic care unit and clinical signs of residual paralysis. There was no residual paralysis in any patient. Morbidly obese patients can safely be decurarised from rocuronium-induced neuromuscular blockade T1-T2 with sugammadex dosed at 2 mg.kg(-1) ideal body weight + 40% (p < 0.0001).     

Neuromuscular effects of cisatracurium in morbidly obese patients

Obesity is associated with significant changes in body composition and function that may alter the pharmacodynamics and pharmacokinetics of various drugs. In this study, we investigated the neuromuscular effects of cisatracurium in morbidly obese as compared to control group of normal body weight patients. In the morbidly obese group (n = 20), corrected weight was used to calculate the drug doses. In the control group (n = 20), the dose was calculated on ideal body weight (IBW). 0.15 mg/kg(-1) cisatracurium was administered as the neuromuscular blocker. Neuromuscular effects were recorded at T0 (onset time), T1 (appearance of first stimulus of TOF), T25 (25% recovery of T1) and T25-75 (time of T25 to T75, recovery time). T0 was determined as 177 +/- 23 s and 168 +/- 19 s in the morbidly obese, and control group, respectively. T25 was determined as 46 +/- 7 min and 56 +/- 8 min, in the morbidly obese and control group, respectively (p < 0.05). T25-75 was determined as 11 +/- 5 min and 14 +/- 6 min in the morbidly obese and control group, respectively (p < 0.05). Intubation conditions were determined as good in 13, excellent in 7 patients in the morbidly obese group, and as good in 4 and excellent in 16 patients in the control group (p < 0.05). As different neuromuscular effects of cisatracurium were detected, we conclude that ne uromuscular agents must be monitored in the morbidly obese patients.     

Composition of weight loss in morbidly obese patients after gastric bypass

Optimal treatment of morbid obesity requires reduction of excess body fat while minimizing lean tissue loss. In order to determine if gastric bypass surgery satisfies both these requirements, we have studied changes in body composition and weight loss in adult (mean age = 33 years) morbidly obese patients (14 males, 68 females) after gastric bypass surgery. The preoperative weight of this cohort was 136 ± 27 (SD) kg, which was 228 ± 37% of ideal body weight by actuarial standards. Lean body mass (LBM) was estimated from potassium-40 measurements obtained from a wholebody potassium-40 counter and by urine creatinine excretion on a subgroup of 20 patients. The average weight loss at 3, 6, and 12 months after surgery was 25, 35, and 46 kg, respectively. The weight loss phase lasted approximately 1 year, at which time 34% of the initial weight was lost and the percentage of loss of excess weight above ideal body weight plateaued at 61%. LBM accounted for 32% of the total weight loss at 1 month, 11% at 6 months, and only 3% at the end of 1 year. The percentage of body weight represented by LBM increased from 35% prior to surgery to 51% by 18 months after gastric bypass. Actual LBM content increased steadily after the first month following surgery. Mean total weight loss following three different surgical procedures for gastric bypass did not differ significantly. Gastric bypass surgery appears to satisfy the objectives of reducing excess weight contributed by fat while minimizing lean tissue loss in morbidly obese patients.     

The physiologic effects of pneumoperitoneum in the morbidly obese

OBJECTIVE: To review the physiologic effects of carbon dioxide (CO2) pneumoperitoneum in the morbidly obese. SUMMARY BACKGROUND DATA: The number of laparoscopic bariatric operations performed in the United States has increased dramatically over the past several years. Laparoscopic bariatric surgery requires abdominal insufflation with CO2 and an increase in the intraabdominal pressure up to 15 mm Hg. Many studies have demonstrated the adverse consequences of pneumoperitoneum; however, few studies have examined the physiologic effects of pneumoperitoneum in the morbidly obese. METHODS: A MEDLINE search from 1994 to 2003 was performed using the key words morbid obesity, laparoscopy, bariatric surgery, pneumoperitoneum, and gastric bypass. The authors reviewed papers evaluating the physiologic effects of pneumoperitoneum in morbidly obese subjects undergoing laparoscopy. The topics examined included alteration in acid-base balance, hemodynamics, femoral venous flow, and hepatic, renal, and cardiorespiratory function. RESULTS: Physiologically, morbidly obese patients have a higher intraabdominal pressure at 2 to 3 times that of nonobese patients. The adverse consequences of pneumoperitoneum in morbidly obese patients are similar to those observed in nonobese patients. Laparoscopy in the obese can lead to systemic absorption of CO2 and increased requirements for CO2 elimination. The increased intraabdominal pressure enhances venous stasis, reduces intraoperative portal venous blood flow, decreases intraoperative urinary output, lowers respiratory compliance, increases airway pressure, and impairs cardiac function. Intraoperative management to minimize the adverse changes include appropriate ventilatory adjustments to avoid hypercapnia and acidosis, the use of sequential compression devices to minimizes venous stasis, and optimize intravascular volume to minimize the effects of increased intraabdominal pressure on renal and cardiac function. CONCLUSIONS: Morbidly obese patients undergoing laparoscopic bariatric surgery are at risk for intraoperative complications relating to the use of CO2 pneumoperitoneum. Surgeons performing laparoscopic bariatric surgery should understand the physiologic effects of CO2 pneumoperitoneum in the morbidly obese and make appropriate intraoperative adjustments to minimize the adverse changes.     

The effects of cisatracurium on morbidly obese women

There is conflicting evidence on the duration of action of atracurium in obese patients. Cisatracurium is one of the stereoisomers of atracurium. We investigated the neuromuscular effects of cisatracurium in morbidly obese patients. Twenty obese female patients (body mass index >40) were randomized in two groups. Group I (n = 10) received 0.2 mg/kg of cisatracurium on the basis of real body weight (RBW), whereas in Group II (n = 10) the dose was calculated on ideal body weight (IBW). In a control group of 10 normal weight female patients (body mass index 20-24), the dose of cisatracurium was based on RBW. Neuromuscular transmission was monitored using acceleromyography of the adductor pollicis, and anesthesia was induced and maintained with remifentanil and propofol. Onset time was comparable between Group I and the control group (132 s versus 135 s; P = ns). The duration 25% was longer in Group I than in the control group (74.6 min versus 59.1 min; P = 0.01) and in the control group compared with Group II (45.0 min; P = 0.016). In conclusion, the duration of action of cisatracurium was prolonged in morbidly obese patients when dosed according to RBW compared with a control group of normal weight patients. Duration was also prolonged in the control group patients compared with morbidly obese patients to whom the drug was administered on the basis of IBW.     

Post-operative course after conventional or laparoscopic gastroplasty in morbidly obese patients.

The post-operative period is particularly dangerous for obese patients. The aim of this study was to compare the immediate post-operative course after either laparoscopic or open gastroplasty. We studied retrospectively 20 and 14 consecutive patients who underwent laparoscopic or open adjustable silicone gastric banding, respectively. After the laparoscopic procedure, patients had a significantly shorter stay in the post-anaesthesia care unit (0.3 +/- 0.4 and 1.1 +/- 1 days), reduced analgesic requirements, a shorter period of intravenous catheter use (2.3 +/- 1.9 and 4.8 +/- 1.4 days), were able to walk sooner (1 +/- 0.4 and 2.1 +/- 1.6 days) and had a significantly shorter duration of in-hospital stay (5.4 +/- 2.3 and 15.8 +/- 4.5 days) than after an open procedure. This report suggests that the use of laparoscopy for gastroplasty in morbidity obese patients may significantly improve the immediate post-operative course.     

beta-cell function in morbidly obese subjects during free living: long-term effects of weight loss

Insulin hypersecretion and insulin resistance are physiologically linked features of obesity. We tested whether extreme hypersecretion impairs beta-cell function under free-living conditions and whether major weight loss modifies insulin hypersecretion, insulin sensitivity, and beta-cell function. Plasma glucose, C-peptide, and free fatty acid concentrations were measured at hourly intervals during 24 h of normal life (including calorie-standardized meals) in 20 morbidly obese nondiabetic patients (BMI 48.4 +/- 1.7 kg/m2) and 7 nonobese age- and sex-matched control subjects; 8 of the obese patients were restudied 6 months and 2 years following biliopancreatic diversion. Insulin secretion was reconstructed from C-peptide levels by deconvolution and related to concurrent glucose levels through a mathematical model incorporating key features of beta-cell function: rate sensitivity, beta-cell glucose sensitivity, and potentiation. Insulin sensitivity (by the euglycemic insulin clamp technique) was reduced by 50% in obese subjects (23.1 +/- 2.5 of obese subjects vs. 52.9 +/- 4.9 micromol.min(-1) . kg(FFM)(-1) of control subjects, means +/- SE, P = 0.0004) as was mean 24-h insulin clearance (median 809 [interquartile range 451] vs. 1,553 [520] ml.min(-1) . m(-2), P < 0.001) due to a 50% reduction in hepatic insulin extraction (P < 0.01). Over 24 h, insulin secretion was doubled in obese subjects (468 nmol [202] in obese subjects vs. 235 [85] of control subjects, P=0.0002). Despite the hypersecretion, beta-cell glucose sensitivity, rate sensitivity, and potentiation were similar in obese and control subjects. Six months postoperatively (weight loss = 33 +/- 3 kg), both insulin hypersecretion (282 nmol [213]) and insulin sensitivity (51.6 +/- 3.7 micromol.min(-1).kg(FFM)(-1)) were normalized. At 2 years (weight loss = 50 +/- 8 kg), insulin sensitivity was supernormal (68.7 +/- 3.3 micromol.min(-1).kg(FFM)(-1)) and insulin secretion was lower than normal (167 nmol [37]) (both P < 0.05 vs. control subjects). In conclusion, severe uncomplicated obesity is characterized by gross insulin hypersecretion and insulin resistance, but the dynamic aspects of beta-cell function are intact. Malabsorptive bariatric surgery corrects both the insulin hypersecretion and the insulin resistance at a time when BMI is still high. With continued weight loss over a 2-year period, moderately obese subjects become supersensitive to insulin and, correspondingly, insulin hyposecretors.     

The effects on oxidative DNA damage of laparoscopic gastric band applications in morbidly obese patients

Background

Obesity may induce oxidative stress, causing oxidative damage of DNA. We examined associations between decreasing serum and urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels and weight loss in morbidly obese patients before and 6 months after laparoscopic adjustable gastric banding (LAGB).

Methods

We compared patients who had surgery for morbid obesity with healthy, nonobese controls. Urine and fasting blood samples were collected once from the controls and from the morbidly obese patients before and 6 months after the LAGB. The serum and urinary 8-OHdG levels were evaluated in these groups using an enzyme-linked immunosorbent assay kit.

Results

We included 20 patients who had surgery for morbid obesity (8 men, 12 women, mean body mass index [BMI] 46.82 ± 4.47) and 20 healthy, nonobese people (10 men, 10 women, mean BMI 22.52 ± 2.08) in our study. There was no significant difference in serum 8-OHdG levels between the groups, whereas urinary 8-OHdG levels were significantly higher in morbidly obese patients than in controls. Weight, BMI and serum and urinary 8-OHdG levels were significantly decreased in morbidly obese patients 6 months after LAGB.

Conclusion

The LAGB provides efficient weight loss in patients with morbid obesity. The systemic oxidative DNA damage was increased by the morbid obesity, but this increase was not related to weight gain, and it was more evident in serum than urine samples. After LAGB for morbid obesity, the oxidative DNA damage declined both in serum and urine.     

Clinical effect of mivacurium in morbidly obese patients

OBJECTIVES: To compare the clinical effect of mivacurium in morbidly obese and normal-weight patients. PATIENTS AND METHODS: Ten morbidly obese patients (body mass index >40) and 10 normal-weight patients (body mass index, 21-24) with normal plasma cholinesterase levels. Anesthesia was provided with propofol and remifentanil in continuous infusion and a mixture of oxygen and nitrous oxide. Mivacurium was administered at a dose based on the patient's weight (0.15 mg x kg(-1)). The neuromuscular block was monitored by train-of-four (TOF) acceleromyography after stimulation of the cubital nerve at the forearm. We measured the onset time (time from administration of the muscle relaxant to 95% twitch depression), duration of block (times from dosing to 5% recovery after the first twitch [T1] of a TOF stimulus and to a TOF ratio of 80%), and the recovery indices (time between 25% and 75% recovery after T1 and between recovery of TOF ratios of 25% and 80%). Groups were compared with the Student t test. RESULTS: Mean (SD) onset time was similar in the 2 groups (normal weight 2.73 [1] minutes vs morbidly obese 1.91 [0.6] minutes). Other measures of duration and recovery were also similar in the 2 groups, respectively: duration of dose-T1 5%, 12.23 (2.1) vs 11.45 (3) minutes; dose-TOF ratio 80%, 24.71 (4.6) vs 24.81 (5) minutes); recovery index T1 25%-75%, 6.45 (2) vs 5.56 (1) minutes; recovery of TOF ratio T1 25%-80%, 9 (2) vs 10.11 (2) minutes. CONCLUSION: We found no differences in the clinical effect of mivacurium between morbidly obese and normal-weight patients when doses were based on real weight.     

Optimal propofol induction dose in morbidly obese patients: A randomized controlled trial comparing the bispectral index and lean body weight scalar

Purpose

Propofol dosing based on total body weight (TBW) can lead to overdosing in morbidly obese (MO) patients. Our aim was to determine whether an induction dose of propofol based on a bispectral index (BIS) target is better for achieving loss of consciousness in MO patients than dosing based on lean body weight (LBW).

Methods

Sixty MO patients with a body mass index (BMI) of ≥ 40 kg·m^?2 were randomized to either BIS- or LBW-based propofol dosing groups. Anesthesia was induced with a propofol infusion of 100 mg·kg^?1·hr^?1 to an initial target endpoint of a BIS of 50 (BIS group) or until a precalculated dose of 2.6 mg·kg^?1 LBW based on the Janmahasatian equation was administered (LBW group). Induction was assessed using the observer’s assessment alertness/sedation scale (OAA/S). If an OAA/S score of 0 was not achieved, infusions continued until it reached 0. The groups were compared for the primary outcome which was the difference in the propofol doses at the initial target endpoint.

Results

The median [interquartile range] OAA/S score at the initial target endpoint was lower in the BIS group than in the LBW group (0 [0-0] vs 1 [0-3], respectively; median difference 1, 95% confidence interval [CI] 0 to 3; P = 0.001). The number of patients requiring additional propofol doses was also higher for the LBW group [1 vs 18 patients, respectively; relative risk of requiring additional propofol 18; 95% CI 3 to 126; P = 0.001]. The mean (SD) propofol dose at the target endpoint was significantly lower in the LBW group than in the BIS group [164 (36) mg vs 225 (44) mg, respectively; mean difference 61 mg; 95% CI 41 to 83 mg; P = 0.002]. There was no difference between the two groups, however, regarding the total induction dose of propofol needed for the OAA/S to reach 0 (P = 0.07).

Conclusion

The induction dose of propofol based on the BIS index was different from the induction dose based on LBW in MO patients. Patients in the LBW group required additional propofol to achieve an OAA/S of 0.

     

Return to work after gastric bypass in Medicaid-funded morbidly obese patients

OBJECTIVE: To determine whether medically disabled (Medicaid-funded) morbidly obese patients return to the workforce after Roux-en-Y gastric bypass (RYGB). DESIGN: Retrospective clinical data review. SETTING: A tertiary referral center. PATIENTS: From January 1, 1997, to December 31, 2002, 38 medically disabled patients underwent RYGB performed by a single surgeon. Sixteen medically disabled patients seen by the same surgeon did not undergo surgery and served as a control group. INTERVENTION: Roux-en-Y gastric bypass. MAIN OUTCOME MEASURE: Full-time employment. RESULTS: The patients who underwent RYBG were more likely to return to work, with 14 (37%) working, compared with 1 (6%) of the nonoperative control patients (P = .02). Elimination of comorbidities was associated with a greater likelihood of return to work. Patients who had greater than the mean decrease in comorbid conditions at the time of follow-up were statistically more likely to return to work than those who did not have a reversal in comorbid conditions (P = .001). Health-related quality of life was very poor preoperatively and improved in all domains after surgery. CONCLUSIONS: Morbid obesity is associated with many medical conditions that often render patients disabled. We found that 37% of morbidly obese patients with Medicaid coverage returned to work after RYGB, compared with 6% of patients in the nonoperative control group. This study suggests that RYGB, the most effective available means to achieve durable weight loss and reduction of comorbidities in morbidly obese patients, results in significant rehabilitation of Medicaid-funded morbidly obese individuals.     

Pharmacokinetics of rocuronium bromide in obese female patients.

Following administration of 0.6 mg kg-1 rocuronium, the pharmacokinetics and the pharmacodynamics were studied in six obese and six control (normal weight) patients receiving balanced anaesthesia. Twelve gynaecological patients were allocated into two groups, according to body mass index (normal weight: body mass index: 20-24, obese weight: body mass index > 28). Venous plasma concentrations were determined by high-pressure liquid chromatography before administration of rocuronium, at 1, 2, 4, 6, 8, 10, 15, 20, 25, 30, 35, 40, 48, 60, 75, 120, 180, 240, 300, 360 and 420 min after administration of rocuronium and at recovery of single twitch to 25% and 75% of control twitch height. Onset time was shorter (NS) in the obese compared with normal weight (obese weight: 65 +/- 16, normal weight: 100 +/- 39 s, mean +/- SD). Duration 25% (obese weight: 29.5 +/- 5.3, normal weight: 28.4 +/- 5.3 min) and spontaneous recovery time (obese weight: 12.6 +/- 2.7, normal weight: 12.5 +/- 2.3 min) did not show any differences between the two groups. The pharmacokinetics of rocuronium were comparable in the two groups. The volume of distribution at steady state Vss (mL kg-1) was 208 +/- 56 in normal weight and 169 +/- 37 in obese weight. Distribution (T1/2 alpha) and elimination half-life (T1/2 beta) as well as mean residence time were 15.6 +/- 3.7, 70.3 +/- 23.9 and 53.2 +/- 9.8 min in normal weight and 16.9 +/- 3.8, 75.5 +/- 25.5 and 51.1 +/- 18.9 min in obese weight, respectively. Also, no differences were observed in plasma clearance (3.89 +/- 0.58 in normal weight and 3.62 +/- 1.42 mL kg-1 min-1 obese weight). This study indicates that the pharmoacodynamics and pharmacokinetics of rocuronium are in female patients not altered by obesity.