Sudden cardiac arrest in morbidly obese surgical patients unexplained after autopsy

Anesthetic management of obese and morbidly obese parturients

The prevalence of obese parturients is increasing worldwide. This review describes safe analgesic techniques for labor and anesthetic management during cesarean sections in obese parturients. The epidural analgesic technique is the best way to provide good pain relief during the labor phase and can be easily converted to a surgical anesthetic condition. However, the insertion of the epidural catheter in obese parturients is technically more difficult compared to that in non-obese parturients. The distance from the skin to the epidural space increases in proportion to the body mass index (BMI): 4.4 cm in mothers of normal weight and 7.5 cm in mothers with BMI 50 and above. Neuraxial blocks are the ideal anesthetic methods and gold standard techniques for cesarean section in pregnant women with obesity. Single-shot spinal anesthesia is the most common type of anesthesia used for cesarean sections. The advantage of single-shot spinal anesthesia is a dense-sufficient block of rapid onset. A combined spinal-epidural (CSE) anesthetic technique is also recommended as an attractive alternative method. In obese parturients, the operation time can be longer than expected, and therefore, the CSE technique provides the advantage of rapid onset and intense block for prolonged operation with postoperative pain control. The risk of postoperative complications is very high in obese parturients. Therefore, detailed communication of the parturient's medical condition and the details of surgery and anesthesia between the anesthesiologist and obstetrician is important prior to cesarean section in obese pregnant women.

Different body parts' fat mass and corrected QT interval on the electrocardiogram: The Fasa PERSIAN Cohort Study

Background

Previous studies suggested that obesity and fat mass are associated with QT interval prolongation, but the role of different body parts' fat mass is unclear. The associations between total and regional fat mass (FM) and corrected QT interval (QTc) were investigated for the first time in this study.

Methods

In this sub-analysis of Fasa PERSIAN cohort Study data, 3217 subjects aged 35–70 entered our study. Body fat mass was assessed by bioelectrical impedance analysis and QTc interval calculated by the QT interval measured by Cardiax^® software from ECGs and Bazett’s formula. Uni- and multi-variable linear and logistic regression was performed in IBM SPSS Statistics v23.

Results

In males, the fat mass to fat-free mass (FM/FFM) ratio in the trunk, arms, total body, and legs were significantly higher in the prolonged QTc group (QTc > 450 ms). Trunk (B = 0.148), total (B = 0.137), arms (B = 0.124), legs (B = 0.107) fat mass index (FMI) showed significant positive relationship with continuous QTc (P-value < 0.001). Also, just the fat-free mass index of legs had significant positive associations with QTc interval (P-value < 0.05). Surprisingly, in females, the mean of FM/FFM ratio in trunk and legs in the normal QTc group had higher values than the prolonged QTc group (QTc > 470 ms). Also, none of the body composition variables had a significant correlation with continuous QTc.

Conclusion

Our study suggested that FMI ratios in the trunk, total body, arms, and legs were positively associated with QTc interval in males, respectively, from a higher to a lower beta-coefficient. Such associations were not seen in females. Our study implies that body fat mass may be an independent risk factor for higher QTc interval and, consequently, more cardiovascular events that should be investigated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02095-2.

Does obesity have an effect on the ECG in children?

This review summarizes current data on influences of childhood obesity on the 12-lead electrocardiogram (ECG). Studies on obese adults showed a higher risk of cardiovascular complications and also, partly pathological, ECG alterations. Data on ECG alterations in obese children is rare. In current studies, no pathological findings were found. All alterations, which mimic the later pathological phenomena in obese adults, were within normal ranges. Studies reported significantly longer P-wave time and P-wave dispersion (Pd) in obese children [Üner A, Doğan M, Epcacan Z, Epçaçan S. The effect of childhood obesity on cardiac functions. J Pediatr Endocr Met 2014;27:261-71.], no correlation of heart rate, P-wave, or QT dispersions (QTd) [Akyüz A, Alpsoy S, Akkoyun DC, Nalbantoǧlu B, Tülübaș F, et al. Effect of overweight on P-wave and QT dispersions in childhood. Turk Kardiyol Dern Ars 2013;41:515-21.], significantly higher QTd in obese children [Yildirim S, Binnetoglu FK, Battal F, Aylanc H, Nazan Kaymaz N, et al. Relation between QT variables and left ventricular geometry in athletes and obese children. Acta Med Port 2016;29:95-100.], no significant association between obesity and QTc interval (QTc), but longer PR intervals, wider QRS duration and left axis shifting of frontal P-wave, QRS and T-wave axes [Sun G, Li Y, Zho X, Guuo X, Zhang X, et al. Association between obesity and ECG variables in children and adolescents: a cross-sectional study. Exp Ther Med 2013;6:1455-62.], significant prolongation of QTc, T peak-to-end, and QTd in the obese children [Paech C, Liebold A, Gebauer RA, Wagner F, Vogel M, et al. Relative QT interval prolongation and electrical inhomogeneity of cardiac repolarization in childhood obesity. Prog Pediatr Cardiol 2017;47:64-7.], slight shift to the left in the QRS axis (with no changes in the P axis), increased amplitudes of the left-sided leads in obese children, and no correlation of the heart rate with the weight [Paech C, Anhalt M, Gebauer RA, Wagner F, Vogel M, et al. New normal limits for pediatric ECG in childhood obesity? Influence of childhood obesity on the ECG. Prog Pediatr Cardiol 2018;48:119-23.]. Altogether, the study results are inconsistent. Clearly, pathological phenomena in the ECG of obese children were not reported: only preliminary stages like QTc prolongation within the norm were found. The pathological alterations seen in adult obese patients are not (yet) seen in childhood. The slight changes reported in childhood obesity are likely to manifest later and to develop into pathological phenomena in obese adults and, therefore, might increase the risk of cardiovascular events like arrhythmia and sudden cardiac death in adulthood.

[The obese patient and acute respiratory failure, a challenge for intensive care]

As a result of the constantly increasing epidemic of obesity, it has become a common problem in the intensive care unit. Morbid obesity has numerous consequences for the respiratory system. It affects both respiratory mechanics and pulmonary gas exchange, and dramatically impacts on the patient's management and outcome. With the potential for causing devastating respiratory complications, the particular anatomical and physiological characteristics of the respiratory system of the morbidly obese subject should be carefully taken into consideration. The present article reviews the management of obese patients in respiratory failure, from noninvasive ventilation to tracheostomy, including postural and technical issues, and explains the physiologically based ventilatory strategy both for NIV and invasive mechanical ventilation up to the weaning from the ventilatory support.

The obesity supine death syndrome (OSDS)

The obesity supine death syndrome refers to a catastrophic cascade of cardiorespiratory complications resulting from the supine positioning of a morbidly obese subject which can ultimately lead to death. It was first described in 1977 in two massively obese patients who were forced to lie down for medical procedures. But surprisingly, despite the current worldwide epidemic of obesity, very few cases have been reported yet. It can be assumed that the syndrome is poorly recognized in clinical practice and may participate in the high rate of unexplained death in morbidly obese patients. Based on the previously published cases and on those we met, this review aims at helping clinicians to early detect at-risk patients, to correctly diagnose this dramatic syndrome and to understand the underlying pathophysiology. More importantly, the main objective is to convince the attending clinicians that they have to do everything in their power to prevent obesity supine death syndrome occurrence by maintaining morbidly obese patients in the sitting or upright position whenever possible. When the syndrome unfortunately occurs, the best therapeutic approach is based on the immediate return to sitting position.

Ethnic differences among implantable cardioverter defibrillators recipients in Israel

Heart failure is an increasingly common condition arising from a variety of different pathophysiological processes. Little is known about the unique features of Israeli Arabs who present with heart failure and who undergo cardiac device implantation. The study population comprised of 4,671 patients who were enrolled in the national Israeli Implantable Cardioverter Defibrillator registry. We compared demographic, clinical, and echocardiographic characteristics; device-related indications; and outcomes between Israeli Arabs (n = 733) and Jews (n = 3,938), who were enrolled in the registry from July 2010 through December 2013. Israeli Arabs constituted 15.7% of the study population. They were younger at presentation compared with Jews (57 ± 15 vs 66 ± 12 years, respectively; p <0.001), with a greater burden of co-morbidities, including diabetes mellitus and chronic obstructive lung disease and smoking. In addition, Arab patients had a greater frequency of non-ischemic cardiomyopathy (40.2% vs 24.6%, respectively; p <0.001), which was associated with a greater frequency of familial history of sudden cardiac death. During 15 ± 9 month follow-up, the mortality rates and appropriate device therapy were similar in both ethnic groups. In conclusion, Israeli Arab patients implanted with implantable cardioverter defibrillators display unique clinical features with greater prevalence of non-ischemic cardiomyopathy characterized by an early-onset and rapid deterioration.

High prevalence of prolonged QT interval in obese hypogonadal males

Obese subjects show several electrocardiographic alterations, including prolonged QT interval, a marker for fatal cardiac arrhythmias. Prolonged QT interval has recently been linked to low testosterone levels, a frequent occurrence in male obese patients but no study has yet assessed whether hypoandrogenism contributes to QT interval prolongation in this population. Aim of this study was to evaluate whether prolonged QT interval is linked to hypogonadism in male obese subjects. QT interval corrected for heart rate (QTc) was measured from standard electrocardiogram recordings in 136 obese men (BMI 30 >kg/m(2), range 30.1-75.4 kg/m(2)). Obese men were classified as eugonadal or hypogonadal according to serum total testosterone levels (i.e., greater or less than 9.9 nmol/l). Our study showed that QTc measurements corrected by either Bazett (419 ± 3.2 vs. 408 ± 3.4 ms, P < 0.05), Fridericia (406.3 ± 3.39 vs. 396.4 ± 3.03 ms, P < 0.05) or Hodges (407.0 ± 3.12 vs. 397.3 ± 2.84 ms, P < 0.05) were longer in hypogonadal compared with eugonadal obese men; further, prolonged QTc interval (i.e., >440 ms) was more frequent among hypogonadal compared with eugonadal obese men (23% vs. 10%, P < 0.05). The degree of weight excess, diabetes, sleep apnoea and potassium levels were not associated with prolonged QTc. In conclusion, obese hypogonadal men show a greater prevalence of prolonged QT interval compared with their eugonadal counterparts. It appears therefore that low levels of testosterone in obese men may contribute to the arrhythmogenic profile of these patients, a heretofore unknown link which warrants further clinical attention.

Obesity and Obstetric Anaesthesia

Obesity is increasing in the population as a whole, and especially in the obstetric population, among whom pregnancy-induced physiological changes impact on those already present due to obesity. In particular, changes in the cardiovascular and respiratory systems during pregnancy further alter the physiological effects and comorbidities of obesity. Obese pregnant women are at increased risk of diabetes, hypertensive disorders of pregnancy, ischaemic heart disease, congenital malformations, operative delivery, postpartum infection and thromboembolism. Regional analgesia and anaesthesia is usually preferred but may be challenging. Obese pregnant women appear to have increased morbidity and mortality associated with caesarean delivery and general anaesthesia for caesarean delivery in particular, and more anaesthesia-related complications. This article summarises the physiological and pharmacological implications of obesity and pregnancy and describes the issues surrounding the management of these women for labour and delivery.

Implications of obesity for drug therapy: limitations and challenges

Obesity has become a worldwide challenge with significant health and socioeconomic implications. One of the major implications is its impact on drug therapy. In order to gain a better understanding of this impact, we surveyed the regulatory guidances, the newly approved molecular entity drug products, and drug product labels in the Physician's Desk Reference. This review summarizes the findings of the survey along with the existing knowledge on pharmacokinetic and pharmacodynamic changes associated with obesity.

The myth of QT shortening by weight loss and physical training in obese subjects with coronary heart disease

This study aims to describe the changes that a period of low-calorie diet and physical training determines in heart rate and in corrected QT (QTc) interval in obese patients with coronary heart disease (CHD) and to verify whether it is effective in shortening the QT interval using three different methods for QT correction. Two hundred and seventy obese white patients (162 males--60%) affected with stable CHD and treated with β-blockers were retrospectively studied in the setting of a program aimed at losing weight through training (aerobic activity + strength exercise) and diet (80% of estimated resting energy expenditure). Age was related to RR interval, QTc was related to left ventricular ejection fraction (EF) while sex exerted no effects. At the end of the study period heart rate decreased by 8.3% and noncorrected QT increased by 3.0%; QT corrected with the Bazett formula decreased by 0.7% (P = 0.007), QT corrected with the Fridericia formula increased by 0.5% (P = 0.023), whereas the modifications were nonsignificant when the Framingham correction was used. In conclusion, contrary to the current views, physical training and diet, which are effective in reducing heart rate, produced no clinically relevant change in the QT interval.

Improved heart rate recovery after marked weight loss induced by gastric bypass surgery: two-year follow up in the Utah Obesity Study

BACKGROUND

Obesity is associated with significantly increased cardiovascular mortality that has been attributed, in part, to sympathetic activation. Gastric bypass surgery (GBS) appears to increase long-term survival in the severely obese, but the mechanisms responsible for this increase are still being sought. Heart rate (HR) recovery after exercise reflects the balance of cardiac autonomic input from the sympathetic and parasympathetic systems. Blunted HR recovery is a very powerful predictor of increased mortality, whereas enhanced HR recovery portends a good prognosis.

OBJECTIVE

The purpose of this study was to evaluate the effect of marked weight loss achieved via GBS on HR recovery.

METHODS

Severely obese patients underwent submaximal exercise testing (80% predicted maximum HR) at baseline and 2 years after GBS (n = 153) or nonsurgical treatment (n = 188).

RESULTS

Patients in the GBS group lost an average of 100 ± 37 lb compared to 3 ± 22 lb in the nonsurgical group (P <.001, GBS vs nonsurgical). Resting HR decreased from 73 bpm to 60 bpm in the GBS group and from 74 bpm to 68 bpm in nonsurgical patients (P <.001). HR recovery improved by 13 bpm in the GBS group but did not change in the nonsurgical group (P <.001 GBS vs nonsurgical). In multivariable analysis, the independent correlates of HR recovery at the 2-year time point were resting HR, treadmill time, age, body mass index, and HOMA-IR (an index of insulin resistance).

CONCLUSION

Marked weight loss 2 years after GBS resulted in a significant decrease in resting HR and an enhancement in HR recovery after exercise. These changes likely are attributable to improvement in insulin sensitivity and cardiac autonomic balance. Whether and to what extent this contributes to a reduction in cardiovascular mortality with GBS remains to be determined.

The effects of an exercise program on anthropometric, metabolic, and cardiovascular parameters in obese children

Background and Objectives

Obesity is a chronic disease that requires good eating habits and an active life style. Obesity may start in childhood and continue until adulthood. Severely obese children have complications such as diabetes, hypercholesterolemia, hypertension and atherosclerosis. The goal of this study was to determine the effects of exercise programs on anthropometric, metabolic, and cardiovascular parameters in obese children.

Subjects and Methods

Fifty four obese children were included. Anthropometric data such as blood pressures, body mass index (BMI) and obesity index (OI) were measured. Blood glucose, total cholesterol, triglycerides, low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), aspartate aminotransferase (AST), alanine aminotransferase (ALT), high sensitive-CRP (hs-CRP), brachial-ankle pulse wave velocity (BaPWV) and ankle brachial index (ABI) were measured. Physical fitness measurements were done. Obese children were divided into three groups: an aerobic exercise group (n=16), a combined exercise group (n=20), and a control group (n=18). Obese children exercised in each program for 10 weeks while those in the control group maintained their former lifestyle. After 10 weeks, anthropometric data and cardiovascular parameters were compared with the data obtained before the exercise program.

Results

LDL-C, waist circumference, and systolic blood pressure decreased significantly in the aerobic exercise group compared to the control group (p<0.05). Waist circumference and systolic blood pressure decreased significantly in the combined exercise group compared to controls (p<0.05). Physical fitness level increased significantly after the exercise programs (p<0.05 vs. control). PWV did not show a significant change after exercise.

Conclusion

A short-term exercise program can play an important role in decreasing BMI, blood pressure, waist circumference, LDL-C and in improving physical fitness. Future investigations are now necessary to clarify the effectiveness of exercise on various parameters.

Laparoscopic conversion of adjustable gastric banding and vertical banded gastroplasty to duodenal switch

BACKGROUND

The aim of this retrospective consecutive study was to evaluate the feasibility, safety, and efficacy of the conversion of laparoscopic adjustable gastric banding (LAGB) and open vertical banded gastroplasty (VBG) into duodenal switch (DS) by laparoscopy.

METHODS

From November 2003 to February 2007, laparoscopic conversion into DS was performed in 1-step in 43 patients, 31 after LAGB and 12 after VBG. The reason for conversion was weight loss issues, such as insufficient excess weight loss (EWL) or weight regain. The mean interval from LAGB and VBG to conversion to the DS was 42.7 +/- 28.7 months and 172.2 +/- 86.9 months, respectively. The mean %EWL at conversion was 8.3% +/- 19.3% after LAGB and 20.8% +/- 30% after VBG.

RESULTS

The mean operative time was 205.8 +/- 44.8 minutes for LAGB and 210.9 +/- 53.7 minutes for VBG. No conversions to open surgery occurred. One patient in the LAGB group died on the third postoperative day of sudden death syndrome, as shown by the postmortem examination. Major complications occurred in 6.4% of patients with LAGB (1 hemoperitoneum and 1 ileoileostomy leak) and in 50% with VBG (1 sleeve gastrectomy leak with subsequent duodenoileostomy leak, 3 duodenoileostomy leaks, 1 pancreatitis, and 1 respiratory insufficiency). The mean hospital stay was 5.5 +/- 5 days for the LAGB group and 34.5 +/- 50.3 days for the VBG group. After a mean follow-up of 28 +/- 15.7 months for LAGB to DS and 43.5 +/- 6 months for VBG to DS, reoperations for late complications were required in 6 patients (20.6%) in the LAGB to DS group and in 5 patients (62.5%) in the VBG to DS group. Three patients (25%) died within 8 months after conversion of VBG. The 29 surviving patients (LAGB to DS) showed a mean %EWL and percentage of excess body mass index loss of (%EBMIL) 78.4% +/- 24.9% and 77.8% +/- 23.7%, respectively. The 8 surviving patients (VBG to DS) had a mean %EWL and %EBMIL of 85.1% +/- 20% and 85.8% +/- 18.7%, respectively.

CONCLUSION

According to these results, laparoscopic conversion of LAGB to DS seems feasible and effective, despite the 1 death. However, in our hands, laparoscopic conversion of VBG to DS had an unacceptable rate of complications and deaths.

Cardiac remodeling in obesity

The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic.

Obstetric anesthesia for the obese and morbidly obese patient: an ounce of prevention is worth more than a pound of treatment

BACKGROUND

The incidence of obesity has been dramatically increasing across the globe. Anesthesiologists, are increasingly faced with the care for these patients. Obesity in the pregnant woman is associated with a broad spectrum of problems, including dramatically increased risk for cesarean delivery, diabetes, hypertension and pre-eclampsia. A thorough understanding of the physiology, associated conditions and morbidity, available options for anesthesia and possible complications is therefore important for today's anesthesiologist.

METHODS

This is a personal review in which different aspects of obesity in the pregnant woman, that are relevant to the anesthesiologist, are discussed. An overview of maternal and fetal morbidity and physiologic changes associated with pregnancy and obesity is provided and different options for labor analgesia, the anesthetic management for cesarean delivery and potential post-partum complications are discussed in detail.

RESULTS AND CONCLUSION

The anesthetic management of the morbidly obese parturient is associated with special hazards. The risk for difficult or failed intubation is exceedingly high. The early placement of an epidural or intrathecal catheter may overcome the need for general anesthesia, however, the high initial failure rate necessitates critical block assessment and catheter replacement when indicated.

Polysarcia Adiposa

From October 1988 to March 2005, there were at least 92 autopsy cases where morbid obesity was present and/or where it was attributed to the cause of death in the coronial district of Auckland, New Zealand, a city with a population of over 1 million people. Obesity has been researched internationally, and much is known about associated comorbidities such as atherosclerotic disease, hypertension, and diabetes, to name a few. However, in the morbidly obese (body mass index>or=40 kg/m2), only 14 of 92 cases were found to have ischemic heart disease due to coronary atherosclerosis as the principal cause of death, and slightly over half (48/92) have some degree (mild, moderate, severe) of coronary atheroma. There is a strong positive correlation between heart weight and body weight. Only 8 livers were normal, all others showing some form of steatosis, venous congestion, and fibrosis/cirrhosis. The mean weights of the heart, lungs, and liver were above the normal reference range in almost all cases. In conclusion, the study did not follow the widely published finding of the positive correlation between morbid obesity and ischemic heart disease in terms of mortality, but the study was consistent with other studies on the organ manifestations of morbid obesity, particularly for the heart, lungs, and liver.

Postmortem findings in morbidly obese individuals dying after gastric bypass procedures

Mortality has been reported to complicate gastric bypass, with common causes of death attributable to anastomotic leaks, sepsis, hemorrhage, and bowel obstruction. We evaluated autopsy reports from 10 patients having undergone gastric bypass. Medical records were reviewed to identify comorbidities. Data of interest included preoperative electrocardiogram (EKG) abnormalities, cause of death, body weight, anastamosis appearance, heart weight, extent of coronary artery disease, ventricular size, liver weight, and gall bladder status. A total of 7 men and 3 women were autopsied. Average age was 40 years (range, 30-49 years), and mean body mass index at autopsy was 60.3 kg/m(2) (range, 33.2-80.9 kg/m(2)). Evidence of anastomotic leaks was present in 7 cases, resulting in 4 deaths. Death was attributed to pulmonary embolism in one case. There were 5 cardiac-related deaths, all attributed to arrhythmias. Microscopic evidence of coronary artery disease was observed in 6. Cardiomegaly was seen in all patients, left ventricular hypertrophy in 8, right ventricular hypertrophy in 3, and hepatomegaly in all 10. Nine patients were status post cholecystectomy. Of the 8 preoperative EKG available, abnormalities were identified in 5. After gastric bypass, death was attributed to cardiac-related causes, pulmonary embolism, and operative complications. A significant proportion of cardiac-related deaths occured in the absence of atherosclerosis. Most patients had preoperative EKG abnormalities. As a high incidence of cardiomegaly was observed, operative stress associated with the procedure may increase the risk of arrhythmia in morbid obesity. Consequently, in morbidly obese patients, a detailed preoperative cardiovascular evaluation is warranted to reduce postoperative mortality.

Obesity and Cardiovascular Disease

Obesity is becoming a global epidemic in both children and adults, and it is associated with numerous co-morbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, is an independent risk factor for CVD and CVD risks have been also documented in obese children, and is associated with reduced life expectancy. A variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amount. As a whole, overweight/obesity predispose or is associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death through its impact on the cardiovascular system.

Obesity and obstetric anaesthesia

The prevalence of obesity continues to increase despite preventive strategies. Obese parturients are at increased risk of having either concurrent medical problems or superimposed antenatal diseases such as pre-eclampsia and gestational diabetes. Moreover, they have a tendency to labour abnormally contributing to increased instrumental delivery and Caesarean section. Obesity is a risk factor for anaesthesia related maternal mortality. Morbidly obese women must be considered as high-risk and deserve an anaesthetic consultation during their antenatal care. The significant difficulty in administering epidural analgesia should not preclude their use in labour. A more liberalised use of regional techniques may be a means to further reduce anaesthesia-related maternal mortality in the obese population. The mother's life should not be jeopardised to save a compromised fetus. Prophylactic placement of an epidural catheter when not contraindicated in labouring morbidly obese women would potentially decrease anaesthetic and perinatal complications associated with attempts at emergency provision of regional or general anaesthesia. Early mobilisation, aggressive chest physiotherapy and adequate pain control are essential components of effective postoperative care.

Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism

Obesity is becoming a global epidemic in both children and adults. It is associated with numerous comorbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, obesity is an independent risk factor for CVD, and CVD risks have also been documented in obese children. Obesity is associated with an increased risk of morbidity and mortality as well as reduced life expectancy. Health service use and medical costs associated with obesity and related diseases have risen dramatically and are expected to continue to rise. Besides an altered metabolic profile, a variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amounts, even in the absence of comorbidities. Hence, obesity may affect the heart through its influence on known risk factors such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, obstructive sleep apnea/hypoventilation, and the prothrombotic state, in addition to as-yet-unrecognized mechanisms. On the whole, overweight and obesity predispose to or are associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death because of their impact on the cardiovascular system. The pathophysiology of these entities that are linked to obesity will be discussed. However, the cardiovascular clinical evaluation of obese patients may be limited because of the morphology of the individual. In this statement, we review the available evidence of the impact of obesity on CVD with emphasis on the evaluation of cardiac structure and function in obese patients and the effect of weight loss on the cardiovascular system.

Anesthesia in the obese patient: Pharmacokinetic considerations

The prevalence of obesity has increased 15% up to 20% and represents an important challenge for the anesthesiologist in drug-dosing management. The aim of this work is to provide an overview on physiological changes and pharmacokinetic implications of obesity for the anesthesiologist. Obesity increases both fat and lean masses; however, the percentage of fat tissue increases more than does the lean mass, affecting the apparent volume of distribution of anesthetic drugs according to their lipid solubility. Benzodiazepine loading doses should be adjusted on actual weight, and maintenance doses should be adjusted on ideal body weight. Thiopental sodium and propofol dosages are calculated on total body weight (TBW). The loading dose of lipophilic opioids is based on TBW, whereas maintenance dosages should be cautiously reduced because of the higher sensitivity of the obese patient to their depressant effects. Pharmacokinetic parameters of muscle relaxants are minimally affected by obesity, and their dosage is based on ideal rather than TBW. Inhalation anesthetics with very low lipid solubility, such as sevoflurane and desflurane, allow for quick modification of the anesthetic plan during surgery and rapid emergence at the end of surgery, hence representing very flexible anesthetic drugs for use in this patient population. Drug dosing is generally based on the volume of distribution for the loading dose and on the clearance for maintenance. In the obese patient, the volume of distribution is increased if the drug is distributed both in lean and fat tissues whereas the anesthetic drug clearance is usually normal or increased.

Emergency management of the morbidly obese

OBJECTIVES

To identify the difficulties encountered with the emergency management of morbidly obese patients and formulate recommendations to streamline care.

METHODS

An English language literature search was undertaken using Medline (1966-2003) with key words 'morbid obesity' 'anaesthesia' 'imaging' 'obesity' 'emergency' 'transportation' 'retrieval' 'critical illness' and 'monitoring'. Potential articles were selected for content applicable to emergency medicine based on title and abstract and reviewed in detail. Reference lists were manually searched for further relevant articles. In view of the very limited systematic study in this area, all information deemed by the authors' to be of assistance to the emergency physician was included regardless of evidence level. Additional information was sought from standard critical care textbooks and their bibliographies and through personal communication with local ambulance and retrieval services. The authors' unpublished personal experience in providing emergency care to the morbidly obese was included for aspects of management not documented in medical literature.

RESULTS

Obesity levels and associated health problems are rapidly rising in Australia. Few studies were identified dealing with critical illness in the morbidly obese and none specifically addressing ED management. Problems identified included size related logistical issues, and limitations of physical assessment, monitoring and routine investigations. Invasive procedures, intubation and ventilation can be particularly problematic, and modified techniques may be required. Limited data indicates a poorer outcome from critical illness most marked in the case of blunt traumatic injury.

CONCLUSION

Very obese patients present a variety of logistical and medical challenges for EDs. A series of recommendations are made based on available data. Further studies in this area would be desirable to more specifically address ED issues.

Obesity: physiologic changes and challenges during laparoscopy

OBJECTIVE

The purpose of this report was to describe the evidence for the benefits of laparoscopic surgery in obese patients, to review the physiologic abnormalities that are associated with obesity, and to explore surgical techniques that will enable surgeons to perform laparoscopy successfully in obese patients.

STUDY DESIGN

This article is a review of the available literature on obesity, the physiologic changes that occur in obese patients, and the impact of these changes on laparoscopy outcomes.

RESULTS

Obesity is associated with sudden death and a wide range of morbid conditions such as hypertension, atherosclerosis, angina, chronic obstructive disease, and diabetes mellitus. Recent studies have demonstrated that obese patients who undergo laparoscopy have shorter hospital stays, less postoperative pain, and fewer wound infections when compared with obese patients who undergo laparotomy. Laparoscopy patients also have fewer postoperative ileus and fevers.

CONCLUSION

With thorough preparation and careful preoperative evaluation, laparoscopy can be performed safely and is the preferred surgical method in obese patients.

Autopsy findings following gastric bypass surgery for morbid obesity

BACKGROUND

Roux-en-Y gastric bypass, currently the most frequently performed surgical procedure for morbid obesity, has a low but significant mortality rate. There are limited data documenting the findings at necropsy in patients who have died following this procedure.

OBJECTIVE

To determine cause of death and pathologic processes present in obese subjects dying after gastric bypass surgery.

PATIENTS

We studied 10 patients who underwent autopsy following gastric bypass surgery for morbid obesity between the years 1994 and 2000.

RESULTS

There were 6 men and 4 women. The mean age of the patients was 48 years (range, 28-62 years). The mean preoperative weight was 162 kg (range, 112-245 kg), and the mean body mass index was 54 kg/m(2) (range, 39-76 kg/m(2)), similar to all patients undergoing gastric bypass at our institution during the same period. Five deaths were directly attributable to technical complications. Five deaths were attributed to underlying comorbid conditions. One patient died of cirrhosis and one of pulmonary hemorrhage. Three patients died from pulmonary embolism. However, 8 of 10 patients had microscopic evidence of pulmonary emboli, despite prophylaxis for deep vein thrombosis. Most patients had some degree of steatohepatitis and hepatic fibrosis (80% and 70%, respectively). There were no deaths from primary cardiac events.

CONCLUSIONS

In patients who die after Roux-en-Y gastric bypass, half die due to technical complications, whereas the other half die of complications of their obesity. Clinically, only 20% of patients were suspected to have pulmonary emboli, yet at autopsy, 80% of patients had pulmonary emboli. In morbidly obese patients undergoing Roux-en-Y gastric bypass, there is an unexpectedly high rate of clinically silent pulmonary emboli contributing to morbidity and mortality.

Morbidity of severe obesity

Although obesity is an easy diagnosis to make, its etiologies, pathophysiology, and symptomatology are extraordinarily complex. Progress in surgical technique and anesthesiological management has substantially improved the safety of performing operations on the severely obese in the last 20 years. These improvements have occurred more or less empirically, without a full understanding of etiology or pathophysiology, although this has advanced concomitantly with improvements in practice. This review has attempted to provide a framework to facilitate progress in the neglected areas of patient selection and choice of operation, in an effort to improve long-term outcome. Despite the disparate etiologies of obesity and its diverse comorbidities and complications, there are unifying interdependent pathogenetic mechanisms of great relevance to the practice of antiobesity surgery. The rate of eating, whether driven by HPA dysfunction, ambient stress, or related hereditary susceptibility factors including the increased energy demands of an expanded body fat mass, participates in a cycle that results in disordered satiety (see Fig. 3). This leads to substrate overload, causing extensive metabolic abnormalities such as atherogenesis, insulin resistance, thrombogenesis, and carcinogenesis. This interpretation of the pathophysiology of obesity ironically accords with the original meaning of the word obesity: "to overeat." The ultimate solution to the problem of obesity--preventing it--will not be forthcoming until the food industry is forced to lower production and change its marketing strategies, as the liquor and tobacco industries in the United States were compelled to do. This cannot occur until the large and fast-growing populations of industrialized nations become educated in the personal implications of the energy principle. Regardless of whether school curricula are modified to prioritize health education, the larger problems of cultural and economic change remain for the groups most susceptible to obesity. In this context, antiobesity surgery will continue to thrive, especially in the absence of effective alternatives.

Pulmonary complications of obesity

Obesity can profoundly alter pulmonary function and diminish exercise capacity by its adverse effects on respiratory mechanics, resistance within the respiratory system, respiratory muscle function, lung volumes, work and energy cost of breathing, control of breathing, and gas exchange. Weight loss can reverse many of the alterations of pulmonary function produced by obesity. Obesity places the patient at risk of aspiration pneumonia, pulmonary thromboembolism, and respiratory failure. It is the most common precipitating factor for obstructive sleep apnea and is a requirement for the obesity hypoventilation syndrome, both of which are associated with substantial morbidity and increased mortality. There are numerous medical and surgical therapies for obstructive sleep apnea and obesity hypoventilation. Weight reduction in the obese is among the most effective of these measures.

Obesity cardiomyopathy: pathophysiology and evolution of the clinical syndrome

Obesity produces an increase in total blood volume and cardiac output because of the high metabolic activity of excessive fat. In moderate to severe cases of obesity, this may lead to left ventricular dilation, increased left ventricular wall stress, compensatory (eccentric) left ventricular hypertrophy, and left ventricular diastolic dysfunction. Left ventricular systolic dysfunction may occur if wall stress remains high because of inadequate hypertrophy. Right ventricular structure and function may be similarly affected by the aforementioned morphologic and hemodynamic alterations and by pulmonary hypertension related to the sleep apnea/ obesity hypoventilation syndrome. The term obesity cardiomyopathy is applied when these cardiac structural and hemodynamic changes result in congestive heart failure. Obesity cardiomyopathy typically occurs in persons with severe and long-standing obesity. The predominant causes of death in those with obesity cardiomyopathy are progressive congestive heart failure and sudden cardiac death.

Cardiovascular complications of weight reduction diets

Weight reduction diets may reduce the severity of risk factors for coronary heart disease such as diabetes mellitus, hypertension, and dyslipidemia. Several case reports and small studies of patients receiving starvation diets have reported hypotension and sudden cardiac death. Myofibrillar damage was documented in 1 case. Very-low-calorie diets are generally safe and well-tolerated. However, low QRS voltage, QT interval prolongation, and both nonsustained ventricular arrhythmias and sudden cardiac death have been described in subjects treated with such diets. Orthostatic hypotension may complicate very-low-calorie protein diets because of sodium depletion and depressed sympathetic nervous system activity. Bariatric surgery is associated with disproportionately high mortality rates in both the perioperative and postoperative periods.

Management of the obese critically ill patient

The management of the morbidly obese critically ill patient is a challenging and formidable task. A better understanding of the pathophysiologic changes that occur with obesity and the complications unique to this group of patients may improve their outcome.