Perioperative fluid guidance with transthoracic echocardiography and pulse-contour device in morbidly obese patients.

BACKGROUND: In bariatric surgery, non- or mini-invasive modalities for cardiovascular monitoring are addressed to meet individual variability in hydration needs. The aim of the study was to compare conventional monitoring to an individualized goal-directed therapy (IGDT) regarding the need of perioperative fluids and cardiovascular stability. METHODS: Fifty morbidly obese patients were consecutively scheduled for laparoscopic bariatric surgery (ClinicalTrials.gov Identifier: NCT01873183). The intervention group (IG, n=30) was investigated preoperatively with transthoracic echocardiography (TTE) and rehydrated with colloid fluids if a low level of venous return was detected. During surgery, IGDT was continued with a pulse-contour device (FloTrac™). In the control group (CG, n=20), conventional monitoring was conducted. The type and amount of perioperative fluids infused, vasoactive/inotropic drugs administered, and blood pressure levels were registered. RESULTS: In the IG, 213 ± 204 mL colloid fluids were administered as preoperative rehydration vs. no preoperative fluids in the CG (p<0.001). During surgery, there was no difference in the fluids administered between the groups. Mean arterial blood pressures were higher in the IG vs. the CG both after induction of anesthesia and during surgery (p=0.001 and p=0.001). CONCLUSIONS: In morbidly obese patients suspected of being hypovolemic, increased cardiovascular stability may be reached by preoperative rehydration. The management of rehydration should be individualized. Additional invasive monitoring does not appear to have any effect on outcomes in obesity surgery.

Morbid obesity and optimization of preoperative fluid therapy.

BACKGROUND: Preoperative venous return (VR) optimization and adequate blood volume is essential in management of morbidly obese patients (MO) in order to avoid perioperative circulatory instability. In this study, all subjects underwent a preoperative 3-week preparation by rapid-weight-loss-diet (RWL) as part of their treatment program for bariatric surgery. METHODS: This is a prospective, observational study of 34 morbidly obese patients consecutively scheduled for bariatric surgery at Sunderby County Hospital, Luleå, Sweden. Preoperative transthoracic echocardiography (TTE) was performed in the awake state before and after intravascular volume challenge (VC) of 6 ml colloids/kg ideal body weight (IBW). Effects of standardized VC were evaluated by TTE. Dynamic and non-dynamic echocardiographic indices for VC were studied. Volume responsiveness and level of VR before and after VC were assessed by TTE. An increase of stroke volume ≥13% was considered as a volume responder. RESULTS: Twenty-nine out of 34 patients were volume responders. After VC, a majority of patients (23/34) were euvolemic, and only 2/34 were hypovolemic. Post-VC hypervolemia was observed in 9/34 of patients. CONCLUSIONS: The IBW-based volume challenge regime was found to be suitable for preoperative rehydration of RWL-prepared MO. Most of the patients were volume responders. Preoperative state of VR was not associated with volume responsiveness. IBW estimates and appropriate monitoring avoids potential hyperhydration in MO. For VC assessment, conventional Doppler indices were found to be more suitable compared to tissue Doppler, giving sufficient information on pressure-volume correlation of the left ventricle in morbidly obese.

Rapid weight loss is associated with preoperative hypovolemia in morbidly obese patients.

BACKGROUND: In morbidly obese patients (MO), adequate levels of venous return (VR) and left ventricular filling pressures (LVFP) are crucial in order to augment perioperative safety. Rapid weight loss (RWL) preparation with very low calorie diet is commonly used aiming to facilitate bariatric surgery. However, the impact of RWL on VR and LVFP is poorly studied. METHODS: In this prospective, controlled, single-center study, we hypothesized that RWL-prepared MO prior to bariatric surgery can be hypovolemic (i.e., low VR) and compared MO to lean controls with conventional overnight fasting. Twenty-eight morbidly obese patients were scheduled consecutively for bariatric surgery and 19 lean individuals (control group, CG) for elective general surgery. Preoperative assessment of VR, LVFP, and biventricular heart function was performed by a transthoracic echocardiography (TTE) protocol to all patients in the awake state. Assessment of VR and LVFP was made by inferior vena cava maximal diameter (IVCmax) and inferior vena cava collapsibility index- (IVCCI) derived right atrial pressure estimations. RESULTS: A majority of MO (71.4 %) were hypovolemic vs. 15.8 % of lean controls (p < 0.001, odds ratio = 13.3). IVCmax was shorter in MO than in CG (p < 0.001). IVCCI was higher in MO (62.1 ± 23 %) vs. controls (42.6 ± 20.8; p < 0.001). Even left atrium anterior-posterior diameter was shorter in MO compared to CG. CONCLUSIONS: Preoperative RWL may induce hypovolemia in morbidly obese patients. Hypovolemia in MO was more common vs. lean controls. TTE is a rapid and feasible tool for assessment of preload even in morbid obesity.

Volatile rapid sequence induction in morbidly obese patients.

BACKGROUND AND OBJECTIVE: The interest in bariatric surgery is growing. Morbidly obese patients have an increased risk of hypoxia and decreased blood pressure during rapid sequence induction (RSI). Alternate RSI methods that provide cardiovascular and respiratory stability are required. With this in mind, we evaluated a method for volatile RSI in morbidly obese patients. DESIGN: Observational study. METHODS: Thirty-four patients with mean BMI 42.4 kg m undergoing bariatric surgery (morbidly obese group) and 22 patients with mean BMI 25.6 kg m as a control group were included in the study. Anaesthesia was induced with sevoflurane, propofol, suxamethonium and alfentanil, designed to avoid respiratory and haemodynamic adverse events and to minimise depressing effect on the brain respiratory centre under ongoing RSI. Peripheral oxygen saturation (SpO2) and mean arterial blood pressure were registered before and after endotracheal intubation. In addition, two time periods were measured during RSI: spontaneous breathing time (SBT) and apnoea time. RESULTS: We found no significant differences between the groups. No periods of desaturation were detected. SpO2 was 100% before and after endotracheal intubation in all patients. Mean arterial pressure was maintained at a stable level in both groups. Mean SBT and apnoea time were 65.6 and 45.8 s in the morbidly obese group, and 70.7 and 47.7 s in the control group, respectively. CONCLUSION: A combination of sevoflurane, propofol, suxamethonium and alfentanil is a suitable method for RSI which maintains cardiovascular and respiratory stability in both morbidly obese and lean patients.

Insulin resistance after cardiopulmonary bypass in the elderly patient.

OBJECTIVES: Preoperative carbohydrate administration attenuates insulin resistance. We studied effects of preoperative oral carbohydrate loading in elderly patients undergoing coronary artery bypass grafting. DESIGN: Eighteen patients were assigned either to get a carbohydrate drink or to be controls. Perioperatively, glucose was administered. A gastric emptying test was performed. Glucose and insulin concentrations were measured. Levels of glucose, insulin and stress hormones were studied pre-, per- and postoperatively. RESULTS AND DISCUSSION: Preoperative carbohydrate loading did not affect stress hormones. Gastric residual after the carbohydrate drink was 11+/-3% (mean+/-SEM). Glucose concentration was lower before anaesthesia induction in the carbohydrate group, possibly due to increased insulin release. Insulin levels differed at baseline, induction and day six. All patients returned to baseline on day six. CONCLUSIONS: The study group was insulin resistant on postoperative day one and two. The effects were explainable by the traumatic stress response. No adverse effect was noted from the carbohydrate drink. If glucose is administered intravenously during surgery, there is no obvious advantage of preoperative carbohydrate loading on insulin resistance or stress hormone response.

Body mass index and albumin in the preoperative evaluation of cardiac surgery patients.

BACKGROUND AND AIMS: An increasing proportion of cardiac surgery is performed in the elderly where nutritional status is an important predictor of outcome. Our aim was to evaluate serum albumin concentration (S-albumin) and body mass index (BMI) as markers of malnutrition in relation to outcome measured as mortality and frequency of infections. PATIENTS AND METHODS: We studied 886 consecutive patients who underwent cardiac surgery with extra-corporeal circulation for valve procedures, coronary artery bypass grafting or a combination of those. Preoperative assessment included age, gender, BMI, smoking habits, diabetes, left-ventricular function, S-albumin and C-reactive protein. Postoperative data was type of surgery, in-hospital stay, signs of infections and mortality. Risk factors for mortality were identified using the Cox proportional hazard model and risk factors for infections by using the logistic-regression model. RESULTS: The patients (age 67+/-9.5 years) were followed for 22+/-6 months. In an univariate analysis low BMI and low S-albumin increased relative hazard for death and risk for infection. In a multivariate analysis low BMI, but not S-albumin, increased relative hazard for death and low S-albumin, but not BMI, increased risk for infection. Age, diabetes and longer bypass time increased the risk for infection. CONCLUSION: In cardiac surgery patients a low BMI increased the relative hazard for death and low S-albumin increased the risk for infection. We suggest that these parameters provide useful information in the preoperative evaluation.