Perioperative management of pulmonary and cardiovascular comorbidities in patients undergoing bariatric surgery

Aim and outline of this thesis The purpose of this thesis is to gain further insight into both pulmonary and cardiovascular comorbidities in bariatric patients and to optimize perioperative care. In particular, Part A will focus on obstructive sleep apnea; whether preoperative assessment is needed in order to safely undergo bariatric surgery, and if so, what type of assessment is necessary and cost-efficient. In Part B, preoperative assessment of the presence of a CV disease is evaluated, and additionally the effect of weight loss on the incidence of CV disease in obese patients in reported. Part A - OBSTRUCTIVE SLEEP APNEA IN PATIENTS UNDERGOING BARIATRIC SURGERY To answer the question what the best type of perioperative care is for undiagnosed OSA in patients undergoing bariatric surgery, we looked into the different strategies that are currently used. Outcomes that we were particularly interested in were optimal patient care with an optimal safety profile regarding postoperative complications, optimize quality of life, and efficient use of available healthcare resources. In Chapter 2 we retrospectively evaluate perioperative care of potential OSA patients undergoing bariatric surgery without preoperative OSA screening. Instead, patients were postoperatively monitored using continuous pulse oximetry. In Chapter 3 we compare two different types of preoperative screening. We analysed whether less-invasive, home-based testing with polygraphy is also suited for preoperative OSA screening in the bariatric population, and we did so by comparing the results following polygraphy testing with the results from the golden standard, the in-hospital test polysomnography. In Chapter 4 we retrospectively analyse the patients that have already undergone formal sleep studies, and aimed to identify risk factor for prevalence of OSA and predict postoperative complications. With the growing obesity epidemic, utilization of resources should be accounted for, and the balance between too little and too much diagnostic efforts should be assessed. Therefore, in the POPCORN study, we compared continuous pulse oximetry monitoring with routine preoperative OSA assessment with sleep studies in terms of complications and quality of life, we analysed cost-effectiveness. In this way, justification of expenses can be made based on actual data instead of assumption-based calculations. In Chapter 5 we describe the research protocol of the POPCORN study, and in Chapter 7 we report the primary outcomes; cost-effectiveness expressed in costs vs. quality-adjusted life years (QALYs), and surgical outcomes such as postoperative complications, intensive care admissions and quality of life. In Chapter 6 we report on secondary outcomes of the patient group that underwent polygraphy and consequent CPAP treatment, and see the impact of routine screening on actual implications in daily life. We analysed the adherence to CPAP of patients newly diagnosed with OSA, and compare these outcomes to patients who have been CPAP users for years, and express this in hours per night of CPAP use, but also to (sleep related) quality of life. PART B – CARDIOVASCULAR DISEASES AND RISK FACTORS IN BARIATRIC PATIENTS The majority of patients that suffer from CV disease are older than the average bariatric patients, with an mean age of 40-45 years. Even so, patients that undergo bariatric surgery usually have many risk factors for development of CV disease and together with high BMI, one could argue these patients are biologically older than their non-obese peers. Therefore, in Chapter 8 we screened the ‘elderly’ bariatric population for the prevalence of CV disease using NT-proBNP assessment in all in consecutive patients 50 year and older, to evaluate actual CV disease prevalence and related echocardiographic features. In Chapter 9 we used a different approach to evaluate the influence of abundant body weight on the risk of development of CV disease, by performing a systematic review and meta-analysis that assessed the incidence of mortality and CV disease following bariatric surgery and compare this to obese controls.