Roberto M. Tacchino

The effects of the reverse Trendelenburg position on respiratory mechanics and blood gases in morbidly obese patients during bariatric surgery

Anesthesia adversely affects respiratory function, particularly in morbidly obese patients. Although many studies have been performed to determine the optimal ventilatory settings in these patients, this question has not been answered. The aim of this study was to evaluate the effect of reverse Trendelenburg position (RTP) on gas exchange and respiratory mechanics in 15 obese patients undergoing biliopancreatic diversion. A standardized anesthetic regimen was used and patients were examined at standard times: 1) after tracheal intubation, 2) after laparotomy, 3) after positioning of subcostal retractors, 4) with retractors in RTP. The measurements of respiratory mechanics were repeated for a wide range of tidal volumes by using the technique of rapid occlusion during constant flow inflation. We noted a wide alveolar-arterial oxygen difference [P(A−a)o2] in all patients, particularly during Phase 3. When the patients were placed in RTP, P(A−a)o2 showed a significant improvement and a return toward baseline values. As for mechanics, total respiratory system compliance was significantly higher in RTP than in the other phases. In conclusion, our data suggest that RTP is an appropriate intraoperative posture for obese subjects because it causes minimal arterial blood pressure changes and improves oxygenation. Implications The aim of the study was to assess whether the reverse Trendelenburg position could improve pulmonary gas exchange in obese patients undergoing abdominal surgical procedures. Our work may have a clinical value because few studies deal with this issue.

Comparison of Positive End-Expiratory Pressure with Reverse Trendelenburg Position in Morbidly Obese Patients Undergoing Bariatric Surgery: Effects on Hemodynamics and Pulmonary Gas Exchange

Background: Anesthetized morbidly obese patients often exhibit impaired pulmonary gas exchanges, mostly because of a reduction in functional residual capacity. At present, several approaches are suggested to ventilate these patients. Methods: The efficiency of positive end-expiratory pressure (PEEP) and reverse Trendelenburg position (RTP) were compared in order to improve oxygenation in 20 morbidly obese patients undergoing bariatric surgery. Results: Both PEEP and RTP determined a significant decrease in alveolar-arterial oxygen difference and an increase in total respiratory compliance (Ctot). RTP resulted in lower airway pressures than PEEP with similar improvements in Ctot and oxygenation. Concerning hemodynamic parameters, cardiac output (CO) significantly decreased with both PEEP and RTP. Conclusions: RTP and PEEP can be considered adequate ventilatory settings for morbidly obese patients, without any significant difference with regard to gas exchange improvement. However, the decrease in CO may partially counteract the beneficial effects on oxygenation of these ventilatory settings.

Normalization of Insulin Sensitivity in the Obese Patient after Stable Weight Reduction with Bilio-Pancreatic Diversion

Insulin resistance is a common feature in obese patients. To evaluate the modifications in insulin sensitivity after a bariatric operation such as Bilio-pancreatic diversion (BPD), three groups of subjects (14 normal controls (N); seven eX-obese patients (X) with at least 2 years at weight-stable conditions after BPD surgery; and eight morbidly obese patients (O)) were studied with intravenous (IVGTT) and oral (OGTT) glucose tolerance tests. The ratio of the area under the curve (AUC) for glucose over that of insulin was used as a measure of insulin sensitivity. All the following tests were conducted as Bonferroni-corrected pairwise t-tests, in case overall ANOVA was significant. No significant difference was found between N and X subjects, while obese patients showed a reduced AUCg/AUCi ratio with respect to the normal controls (O vs N: 0.01164 ± 0.00039 vs 0.02392 ± 0.0039, p < 0.05). IVGTT, AUCs: significant differences were found in each case: N vs X: 0.0591 ± 0.0075 vs 0.1402 ± 0.0399, p < 0.05; N vs O: 0.0591 ± 0.0075 vs 0.0223 ± 0.0031, p < 0.01; X vs O: 0.1402 ± 0.0399 vs 0.0223 ± 0.0031, p < 0.05. IVGTT-derived data were also analyzed using the minimal model of glucose kinetics; with this method, glucose effectiveness was significantly different between normal subject and obese subjects (0.0248 ± 0.00288 vs 0.00905 ± 0.00135 per min, p < 0.001). The insulin sensitivity index was not significantly different between normal and ex-obese subjects, while both of these groups were significantly different from obese patients (N vs O: 12.04 × 10−5 ± 2.61 × 10−5 vs 3.29 × 10−5 ± 0.61 × 10−5, p < 0.066; X vs O: 16.42 × 10−5 ± 4.23 × 10−5 vs 3.29 × 10−5 ± 0.61 × 10−5 per min per pM, p < 0.02). In conclusion, the present study indicates that, after a body weight reduction operation capable of almost re-establishing ideal body weight like BPD, obese individuals with a family history of obesity show a normalization of insulin response to glucose load.

Clinical Evaluation of Fibrin Glue in the Prevention of Anastomotic Leak and Internal Hernia after Laparoscopic Gastric Bypass: Preliminary Results of a Prospective, Randomized Multicenter Trial

Background: Gastro-jejunal anastomotic leak and internal hernia can be life-threatening complications of laparoscopic Roux-en-Y gastric bypass (LRYGBP), ranging from 0.1-4.3% and from 0.8-4.5% respectively. The safety and efficacy of a fibrin glue (Tissucol®) was assessed when placed around the anastomoses and over the mesenteric openings for prevention of anastomotic leaks and internal hernias after LRYGBP. Methods: A prospective, randomized, multicenter, clinical trial commenced in January 2004. Patients with BMI 40-59 kg/m2, aged 21-60 years, undergoing LRYGBP, were randomized into: 1) study group (fibrin glue applied on the gastro-jejunal and jejuno-jejunal anastomoses and the mesenteric openings); 2) control group (no fibrin glue, but suture of the mesenteric openings). 322 patients, 161 for each arm, will be enrolled for an estimated period of 24 months. Sex, age, operative time, time to postoperative oral diet and hospital stay, early and late complications rates are evaluated. An interim evaluation was conducted after 15 months. Results: To April 2005, 204 patients were randomized: 111 in the control group (mean age 39.0±11.6 years, BMI 46.4±8.2) and 93 in the fibrin glue group (mean age 42.9±11.7 years, BMI 46.9±6.4). There was no mortality or conversion in both groups; no differences in operative time and postoperative hospital stay were recorded. Time to postoperative oral diet was shorter for the fibrin glue group (P=0.0044). Neither leaks nor internal hernias have occurred in the fibrin glue group. The incidence of leaks (2 cases, 1.8%) and the overall reoperation rate were higher in the control group (P=0.0165). Conclusion: The preliminary results suggest that Tissucol® application has no adverse effects, is not time-consuming, and may be effective in preventing leaks and internal hernias in morbidly obese patients undergoing LRYGBP.

Laparoscopic Gastric Banding Without Visible Scar: a Short Series with Intraumbilical SILS

Single-incision laparoscopic surgery has been developed with the aims of further reducing the invasiveness of traditional laparoscopy. The technique of lap-band placement from a single intraumbilical incision is described. Three patients underwent a single-incision laparoscopic surgery gastric banding (SILS-GB) for morbid obesity from May to September 2008. All interventions were uneventful and patients were discharged on first postoperative day, after an upper gastrointestinal series. SILS-GB is virtually scarless intervention and may be performed as a day-surgery procedure for the treatment of morbid obesity.

Volatile Anesthesia in Bariatric Surgery

Background: Obesity causes anesthesiologists a broad variety of perioperative theoretical and practical problems. The aim of this study was to compare two protocols of anesthesia employing Isoflurane and Sevoflurane and evaluate the cardiorespiratory parameters, postoperative recovery and analgesia. Methods: 90 patients underwent biliopancreatic diversion. 60 patients (group A) received Isoflurane and 30 patients (group B) were anesthetized with Sevoflurane. Intraoperative monitoring consisted of EKG, invasive arterial pressure, Sp02, EtCO2, Etanest, Spirometry, urinary output and TOF. Cardiorespiratory parameters and end tidal expiratory concentrations of volatile agents were collected during specific phases of surgery: 1) before induction of anesthesia, 2) after intubation, 3) after skin incision, 4) after positioning of costal retractors, 5) in the reverse Trendelenburg position, 6) end of surgery. During the postoperative period the Aldrete test was carried out to evaluate the recovery from anesthesia. VAS was administered for 6 hours after the end of surgery to set the quality of analgesia. Results: No statistically significant differences in cardiorespiratory parameters were found between the two groups. Extubation time was significantly less in the Sevoflurane Group than in the Isoflurane (15 ± 7 min vs 24 ± 5 min, p< 0.05). The Sevoflurane Group showed an Aldrete score significantly higher than the Isoflurane (8.8 ± 0.3 vs 8.1 ± 0.4, p < 0.05). VAS values did not show statistical differences. Conclusion: The introduction of Sevoflurane, a volatile agent with rapid pharmacokinetic properties, seems to offer an interesting application in these patients.

Effect of bariatric surgery on peripheral flow-mediated dilation and coronary microvascular function

BACKGROUND AND AIMS To assess the effects of bariatric surgery (BS) on peripheral endothelial function and on coronary microvascular dilator function. METHODS AND RESULTS We studied 50 morbidly obese patients (age 38 ± 9, 13 M) who underwent BS and 20 comparable obese controls (age 41 ± 11, 6 M) without any evidence of cardiovascular disease. Peripheral vascular dilator function was assessed by brachial artery diameter changes in response to post-ischemic forearm hyperaemia (flow-mediated dilation, FMD). Coronary microvascular function was assessed by measuring coronary blood flow (CBF) velocity response to i.v. adenosine and to cold pressor test (CPT) in the left anterior descending coronary artery by transthoracic Doppler echocardiography. The tests were performed at baseline and at 3-month follow-up. At baseline, FMD and CBF response to adenosine and CPT were similar in the 2 groups. Compared to baseline, FMD at follow-up improved significantly in BS patients (5.9 ± 2.7% to 8.8 ± 2.4%, p < 0.01), but not in controls (6.3 ± 3.2% vs. 6.4 ± 3.1%, p = 0.41). Similarly, a significant improvement of CBF response to adenosine (1.63 ± 0.47 to 2.45 ± 0.57, p < 0.01) and to CPT (1.43 ± 0.26 to 2.13 ± 0.55, p < 0.01) was observed in BS patients but not in controls (1.55 ± 0.38 vs. 1.53 ± 0.37, p = 0.85; and 1.37 ± 0.26 vs. 1.34 ± 0.21, p = 0.48, respectively). The favourable vascular effects of BS were similar independently of the presence and changes of other known cardiovascular risk factors and of basal values and changes of serum C-reactive protein levels. CONCLUSIONS Our data show that, in morbidly obese patients, together with peripheral endothelial function, BS also improves coronary microvascular function. These effects suggest global improvement of vascular function which can contribute significantly to the reduction of cardiovascular risk by BS reported in previous studies.

Metabolic Effects and Disposition of Sebacate, an Alternate Dicarboxylic Fuel Substrate

Disodium sebacate is a 10-carbon-atom dicarboxylic acid, proposed as substrate for parenteral nutrition. We investigated its pharmacokinetic profile and thermogenic effect during a short-time infusion (5 h at 10 g/h) in 7 male volunteers. Sebacate in serum and urine was measured by high-performance liquid chromatography. A single-compartment model with two linear elimination routes was fitted. Metabolic measurements (VO2, VCO2, respiratory quotient, metabolic rate) were continuously performed for 8 h (5 h during and 3 h after the infusion) by a canopy indirect calorimeter. The apparent volume of distribution of sebacate was 8.39 +/- 0.69 liters, and the plasma fractional removal rate constant was 0.0086 +/- 0.00077 min-1. The average half-life and plasma clearance were 80.6 min and 72 ml/min, respectively. The increase in metabolic rate, the decrease in respiratory quotient and the changes in ketone body, glucagon and insulin levels during the infusion were not significant. 24-hour catecholamine excretion was within normal limits. Calories administered by sebacate seem to be available for utilization without relevant metabolic side effects.

Preinductive use of clonidine and ketamine improves recovery and reduces postoperative pain after bariatric surgery

BACKGROUND In obese patients, concomitant use of clonidine and ketamine might be suitable to reduce the doses and minimize the undesired side effects of anesthetic and analgesic drugs. In this study, we evaluated the perioperative effects of administration of clonidine and ketamine in morbidly obese patients undergoing weight loss surgery at a university hospital in Rome, Italy. METHODS A total of 50 morbidly obese patients undergoing open biliopancreatic diversion for weight loss surgery were enrolled. The patients were randomly allocated into a study group (n = 23) receiving a slow infusion of ketamine-clonidine before anesthesia induction and a control group (n = 27) who received standard anesthesia. The hemodynamic profile, intraoperative end-tidal sevoflurane and opioid consumption, tracheal extubation time, Aldrete score, postoperative pain assessment by visual analog scale, and analgesic requirements were recorded. RESULTS The patients in the study group required less end-tidal sevoflurane, lower total doses of fentanyl (3.8 +/- 0.3 gamma/kg actual body weight versus 5.0 +/- 0.2 gamma/kg actual body weight, respectively; P <.05) and had a shorter time to extubation (15.1 +/- 5 min versus 28.2 +/- 6 min, P <.05). The Aldrete score was significantly better in the postanesthesia care unit in the study group. The study group consumed less tramadol than did the control group (138 +/- 57 mg versus 252 +/- 78 mg, P <.05) and had a lower visual analog scale score postoperatively during the first 6 hours. CONCLUSION The preoperative administration of low doses of ketamine and clonidine at induction appears to provide early extubation and diminished postoperative analgesic requirements in morbidly obese patients undergoing open bariatric surgery.

Bowel length: measurement, predictors, and impact on bariatric and metabolic surgery.

BACKGROUND Small bowel length (SBL) determines the caloric absorptive capacity. The aim of this study was to evaluate SBL to identify patient-specific predictors and the interrelationships of SBL with anthropometric variables. METHODS Sex, age, and weight were recorded at the time of surgery when SBL and the estimated jejunal length (JLe) were measured by 3 different methods. RESULTS The mean SBL of 443 patients undergoing laparotomy (78% female) was 690±93.7 cm (range 350-1049 cm). Sex was correlated with SBL, as men had a longer small bowel than women (729±85 versus 678±92, P<.0001) and were significantly taller (173±8.2 versus 161±6.9, P<.001). Age did not correlate with SBL. The differences in length between fully stretched small bowel and nonstretched small bowel and between fully stretched small bowel and laparoscopic bowel were 137±19 cm and 32.4±11.4 cm, respectively. In a multivariate linear regression analysis model that included sex, age, height, and weight, only height was significantly correlated with SBL (P<.00001) and explained 12% of the variance in SBL. Sex, age, height, and JLe, but not SBL, were statistically highly significant in predicting 75% of the variance of body weight. CONCLUSIONS A positive association between height and SBL was found. Sex, age, height, and JLe may be strong predictors of weight. Individual JLe may be of importance in determining the weight loss and resolution of metabolic co-morbidities. Measuring the SBL can prevent the risk of nutritional consequences in malabsorptive, revisional, and metabolic procedures.