Hemodynamic dysfunction in obesity hypoventilation syndrome and the effects of treatment with surgically induced weight loss

Lipid risk profile and weight stability after gastric restrictive operations for morbid obesity

There are no longitudinal data that address weight loss stability and lipid levels in bariatric surgical patients. The goal of this study was to determine whether weight regain adversely affected reduction in lipid levels after gastric bariatric operations. Of 651 consecutive patients undergoing gastric restrictive surgery for morbid obesity, 227 (35%) had increased serum levels of total cholesterol (TC), triglycerides, or both preoperatively. High-density lipoprotein cholesterol (HDL-C) levels were subnormal (</=35 mg/dl) in 45 (20%) of the hyperlipidemic patients. Fasting lipid profiles were determined at 6-month intervals postoperatively. This series included the following three operations: gastroplasty (GP; N = 13), standard Roux-en-Y gastric bypass (RYGB; N = 205), and distal Roux-en-Y gastric bypass (DRY; N = 9). By 6 months postoperatively, patients had a >/=15% mean reduction in TC and a >/=50% mean reduction in triglycerides, both of which were significant in comparison with preoperative levels (P </=0.05). Mean HDL-C levels had increased significantly vs. preoperative levels by 12 months postoperative y (P <0.05) and continued to increase through 5 years. By 18 months both HDL-C and TC were significantly lower after DRY than after GP or RYGB. In 91 patients who were followed for 2 years or longer (mean 48 +/- 25 months), mean excess weight loss was 55% with mean body mass index reduced from 48 to 33 kg/m(2). This group was divided into patients whose weight remained stable (N = 54) and patients who regained >/=15% of their lost weight or lost less than 50% of excess weight (N = 37). Although mean excess weight loss and body mass index were significantly different between the two groups (P <0.0001) at 2 years, there was no difference in the lipid profile (TC/HDL) between the two groups at any interval through 5 years. These results show that abnormal lipid profiles can be permanently improved after gastric bariatric surgery and are not adversely affected by mediocre weight loss or regaining >/=15% of lost weight. DRY appears to be a superior operation for TC reduction in comparison with GP and RYGB.

Effects of increased renal parenchymal pressure on renal function

OBJECTIVE

Acute renal failure is seen with the acute abdominal compartment syndrome (AACS). The cause of acute renal failure in AACS is thought to be multifactorial, including increased renal venous pressure, renal parenchymal pressure (RPP), and decreased cardiac output. Previous studies have established the role of renal venous pressure as an important mediator of this renal derangement. In this study, we evaluate the role of renal parenchymal compression on renal function.

METHODS

Two groups of swine (20-26 kg) were studied after left nephrectomy and placement of a renal artery flow probe and ureteral cannula. Two hours were allowed for equilibration, and an inulin infusion was begun to calculate inulin clearance as a measurement of glomerular filtration. In group 1 animals (n = 6), RPP was elevated by 30 mm Hg for 2 hours with renal parenchymal compression. RPP then returned to baseline for 1 hour. In group 2 (n = 6), the RPP was not elevated. The cardiac index, preload, and mean arterial pressure remained stable. Blood samples for plasma renin activity and plasma aldosterone were taken at baseline and at hourly intervals.

RESULTS

Elevation of RPP in the experimental group showed no significant decrease in renal blood flow index or glomerular filtration when compared with control animals. There were no significant elevations of plasma aldosterone or plasma renin activity in the experimental animals when compared with control.

CONCLUSION

Elevated renal compression alone did not create the pathophysiologic derangements seen in AACS. However, prior data from this laboratory found that renal vein compression alone caused a decreased renal blood flow and glomerular filtration and an increased plasma renin activity, plasma aldosterone, and urinary protein leak. These changes are partially or completely reversed by decreasing renal venous pressure as occurs with abdominal decompression for AACS. These data strengthen the proposal that renal vein compression, and not renal parenchymal compression, is the primary mediator of the renal derangements seen in AACS.

Effect of increased renal venous pressure on renal function

OBJECTIVE

Acute renal failure is seen with the acute abdominal compartment syndrome (AACS). Although the cause of acute renal failure in AACS may be multifactorial, renal vein compression alone has not been investigated. This study evaluated the effects of elevated renal vein pressure (RVP) on renal function.

METHODS

Two groups of swine (18-22 kg) were studied after left nephrectomy and placement of a renal artery flow probe to measure renal artery blood flow, renal vein catheter, and ureteral cannula. Two hours were allowed for equilibration and an inulin infusion was begun to calculate inulin clearance for measurement of glomerular filtration rate. Group 1 animals (n = 4) had RVP elevated by 30 mm Hg for 2 hours with renal vein constriction. RVP was then returned to baseline for 1 hour. In group 2 (n = 4), the RVP was not elevated. The cardiac index (2.9 +/- 0.5 L/min/m2) and mean arterial pressure (101 +/- 9 mm Hg) remained stable. Plasma renin activity and serum aldosterone were measured every 60 minutes.

RESULTS

Elevation of RVP (0-30 mm Hg above baseline) in the experimental group showed a significant decrease in renal artery blood flow index (2.7 to 1.5 mL/min per g) and glomerular filtration rate (26 to 8 mL/min) compared with control. In addition, there was significant elevation of plasma serum aldosterone (14 to 25 microng/dL) and plasma renin activity (2.6 to 9.5 microng/mL per h) as well as urinary protein leak in the experimental animals compared with control. These changes were partially or completely reversible as RVP returned toward baseline.

CONCLUSION

Elevated RVP alone leads to decreased renal artery blood flow and glomerular filtration rate and increased plasma renin activity, serum aldosterone, and urinary protein leak. These changes are consistent with the renal pathophysiology seen in AACS, morbid obesity, and preeclampsia. The changes are partially or completely reversed by decreasing renal venous pressure as occurs with abdominal decompression for AACS.

Laparoscopic-assisted Roux-en-Y gastric bypass

Eight patients underwent laparoscopic Roux-en-Y gastric bypass from May 1998 to September 1998 in which a hand-assist technique was used. The operation consisted of a 7.5-cm periumbilical midline incision along with three trocars placed in the upper abdomen. The operative times ranged from 2.25 to 4.5 h. The average preoperative body mass index was 44 kg/m2. Three-month postoperative follow-up revealed an average weight loss of 59 lb. Cosmetic results to date have been excellent even when compared with those of a total laparoscopic operation. The hand-assist technique allows the surgeon to have more control over the most difficult part of the case, which is manipulation of the small bowel in a morbidly obese abdomen.

A health status assessment of the impact of weight loss following Roux-en-Y gastric bypass for clinically severe obesity

BACKGROUND

The field of "medical outcomes" emphasizes effects of medical treatments on quality of life as seen from the patient's perspective. The increasing incidence of obesity has had tremendous impact on the physical, psychological, social, and economic health of our nation with important longterm implications for the development of future social and health care policies. This study evaluated the effects of clinically severe obesity on overall health status measured in a standardized fashion and the impact of durable weight loss achieved through surgical intervention.

STUDY DESIGN

Patients scheduled for Roux-en-Y gastric bypass for treatment of obesity were prospectively evaluated. At the preoperative visit, each patient completed Short Form 36 (SF-36). Postoperatively, patients were again asked to complete SF-36, in person or through a telephone interview at an interim point (3 to 12 months) and after their weight had reached a plateau (>18 months).

RESULTS

The mean body mass index (BMI) was 51+/-10 kg/m2 preoperatively (range 38 to 85 kg/m2). Mean BMI was 45+/-10 kg/m2 (range 33 to 78 kg/m2) at the interim point and 35+/-8 kg/m2 (range 28 to 55 kg/m2) at plateau. The weight change for the group was from 306+/-8 lb (138+/-4 kg) preoperatively to 211+/-55 lb (96+/-25 kg) at the plateau, with the average percent of excess body weight lost being 63+/-23% at the plateau. Preoperatively, patients with clinically severe obesity scored significantly lower than the normal population in all areas except Role Activities (Emotional Factors). At the plateau period, patients demonstrated significant improvement in limitations in all areas compared with preoperative values and scores were the same as (Physical Activities, Role Activities [Physical Factors], General Mental Health, General Health Perceptions), or significantly better than (Social Functioning, Role Activities [Emotional Factors], Bodily Pain, Vitality), the national "normal" population.

CONCLUSION

Clinically severe obesity is a chronic disabling disease that results in significantly decreased health status in seven of the eight areas measured by SF-36. This disability resolves with successful weight reduction. In some areas, function even surpasses the national "normal" population. Surgical treatment of clinically severe obesity has a profoundly positive impact on patients' perception of their health status.

Gastric surgery for pseudotumor cerebri associated with severe obesity

OBJECTIVE

To study the efficacy of gastric surgery-induced weight loss for the treatment of pseudotumor cerebri (PTC).

SUMMARY BACKGROUND DATA

Pseudotumor cerebri (also called idiopathic intracranial hypertension), a known complication of severe obesity, is associated with severe headaches, pulsatile tinnitus, elevated cerebrospinal fluid (CSF) pressures, and normal brain imaging. The authors have found in previous clinical and animal studies that PTC in obese persons is probably secondary to a chronic increase in intraabdominal pressure leading to increased intrathoracic pressure. CSF-peritoneal shunts have a high failure rate, probably because they involve shunting from a high-pressure system to another high-pressure zone. In an earlier study of gastric bypass surgery in eight patients, CSF pressure decreased from 353+/-35 to 168+/-12 mm H2O at 34+/-8 months after surgery, with resolution of headaches in all.

METHODS

Twenty-four severely obese women underwent bariatric surgery--23 gastric bypasses and one laparoscopic adjustable gastric banding--62+/-52 months ago for the control of severe obesity associated with PTC. CSF pressures were 324+/-83 mm H2O. Additional PTC central nervous system and cranial nerve problems included peripheral visual field loss, trigeminal neuralgia, recurrent Bell's palsy, and pulsatile tinnitus. Spontaneous CSF rhinorrhea occurred in one patient, and hemiplegia with homonymous hemianopsia developed as a complication of ventriculoperitoneal shunt placement in another. There were two occluded lumboperitoneal shunts and another functional but ineffective lumboperitoneal shunt. Additional obesity comorbidity in these patients included degenerative joint disease, gastroesophageal reflux disease, hypertension, urinary stress incontinence, sleep apnea, obesity hypoventilation, and type II diabetes mellitus.

RESULTS

At 1 year after bariatric surgery, 19 patients lost an average of 45+/-12 kg, which was 71+/-18% of their excess weight. Their body mass index and percentage of ideal body weight had fallen to 30+/-5 kg/m2 and 133+/-22%, respectively. In four patients, less than 1 year had elapsed since surgery. Five patients were lost to follow-up. Surgically induced weight loss was associated with resolution of headache and pulsatile tinnitus in all but one patient within 4 months of the procedure. The cranial nerve dysfunctions resolved in all patients. The patient with CSF rhinorrhea had resolution within 4 weeks of gastric bypass. Of the 19 patients not lost to follow-up, 2 regained weight, with recurrence of headache and pulsatile tinnitus. Additional resolved associated comorbidities were 6/14 degenerative joint disease, 9/10 gastroesophageal reflux disorder, 2/6 hypertension, and all with sleep apnea, hypoventilation, type II diabetes mellitus, and urinary incontinence.

CONCLUSIONS

Bariatric surgery is the long-term procedure of choice for severely obese patients with PTC and is shown to have a much higher rate of success than CSF-peritoneal shunting reported in the literature, as well as providing resolution of additional obesity comorbidity. Increased intraabdominal pressure associated with central obesity is the probable etiology of PTC, a condition that should no longer be considered idiopathic.

Abdominal compartment syndrome

The ACS is a clinical entity that develops from progressive, acute increases in IAP and affects multiple organ systems in a graded fashion because of differential susceptibilities. The gut is the organ most sensitive to IAH, and it develops evidence of end-organ damage before the development of the classic renal, pulmonary, and cardiovascular signs. Intracranial derangements with ACS are now well described. Treatment involves expedient decompression of the abdomen, without which the syndrome of end-organ damage and reduced oxygen delivery may lead to the development of multiple organ failure and, ultimately, death. Multiple trauma, massive hemorrhage, or protracted operation with massive volume resuscitation are the situations in which the ACS is most frequently encountered. Knowledge of the ACS, however, is also essential for the management of critically ill pediatric patients (especially those with AWD) and in understanding the limitations of laparoscopy. The role of IAH in the pathogenesis of NEC, central obesity co-morbidities, and pre-eclampsia/eclampsia remains to be fully studied.

Surgical implications of obesity

Obesity is perhaps the most significant public health problem facing the United States today. Obese patients are at increased risk for numerous medical problems, which can adversely affect surgical outcome. However, these risks have not uniformly translated into increased or prohibitive operative morbidity and mortality in this population. With appropriate perioperative precautions and monitoring, the incidence of serious cardiovascular and pulmonary complications can be minimized. Obese patients can be treated as safely and effectively as their normal weight counterparts under most circumstances and should not be denied surgical treatment for any disorder when surgery constitutes the most appropriate therapy. When indicated, surgical treatment should be considered for patients with clinically severe obesity, since currently it appears to offer the best long-term results for weight control and amelioration of comorbidity.

Long-Term Pharmacologic Treatment of Morbid Obesity in a Community Practice

OBJECTIVE

To determine the safety, efficacy, and metabolic changes in patients with morbid obesity treated with d,l-fenfluramine and phentermine in an open-label trial.

METHODS

In patients with a body mass index (BMI) =40.0 kg/m 2 (N = 298) who sought assistance at a private medical practice for treatment of obesity, 60 mg of d,l-fenfluramine and 15 to 30 mg of phentermine resin were administered daily in an open-label trial, without placebo controls, for up to 24 months. The setting was a community-based private practice. Study subjects were given instructions for a 1,200 to 1,400 kcal/day diet, exercise, and behavior modification. Follow-up included a monthly medical visit, behavior modification group attendance, quarterly laboratory evaluation, and electrocardiographic monitoring.

RESULTS

BMI decreased from 45.8 kg/m2 to 37.4 kg/m2 (P<0.0001) in those who completed 12 months of treatment and to 38.2 kg/m2 (P<0.0001) in those who continued the protocol for 24 months. Statistically significant decreases in fasting blood glucose, total and high-density lipoprotein cholesterol, triglycerides, systolic and diastolic blood pressures, and fasting insulin concentrations were noted. The dropout rate was 42.3% at 12 months and 69.8% at 24 months. The most common reason given for discontinuing participation in the study was "success" with the program (mean BMI loss of 7.8 kg/m2). Five patients discontinued treatment because of side effects. No laboratory or electrocardiographic abnormalities were noted that could be attributed to the medications. No statistically significant regain of weight occurred in those who completed 12 or 24 months of treatment.

CONCLUSION

In this study, treatment of morbid obesity with d,l-fenfluramine and phentermine was safe and efficacious in promoting and maintaining weight loss. Moreover, statistically significant changes were noted in metabolic variables associated with risk of heart disease. Future efforts must focus on methods to improve long-term compliance.

Surgery for obesity

The medical risks of obesity increase exponentially as weight increases, and these risks are reduced by sustained weight loss. Behavior modification and dieting provide an approximately 6% loss of body weight at 1 year. Fenfluramine provides an approximately 8% weight loss at 1 year, which can be doubled to 16% when a drug such as phentermine, which works through a different biochemical mechanism, is added to it. This amount of weight loss is insufficient for many severely obese individuals. It was with these facts in mind that the National Institutes of Health Consensus Conference in 1992 recommended that obesity surgery is an appropriate treatment for patients with a body mass index greater than 40 kg/m2 who had failed in attempts at medical treatment and for patients with a body mass index greater than 35 kg/m2 with severe complications of obesity. Vertically banded gastroplasty and Roux-en-Y gastric bypass are the two operations presently recommended because of their relative safety and effectiveness. This article reviews previous procedures that have provided insight into the mechanisms by which these surgeries cause weight loss. The presently used surgeries and their results also are reviewed because until medical therapy improves substantially, surgery remains the most reasonable treatment option for most morbidly obese patients.

Cardiac hypertrophy in obstructive sleep apnea syndrome

Fifty-one middle-aged male patients with obstructive sleep apnea syndrome (OSAS) were evaluated using two-dimensional echocardiography, 24-h blood pressure measurements, polysomnography, and plasma norepinephrine (NE) measurements. Among these patients, left ventricular hypertrophy (LVH) (left ventricular posterior wall thickness [LVPWT] or interventricular septal thickness [IVST] > or = 12 mm) and right ventricular hypertrophy (RVH) (right ventricular wall thickness [RVT] > or = 5 mm) were present in 41.2% (21/51) and 11.8% (6/51). LVH was present in 50.0% of group 2 patients (apnea index > or = 20) and in 30.5% of group 1 patients (apnea index < 20). All patients with LVH had hypertension. RVH was present in 21.4% of group 2 patients and none of the group 1 patients. IVST, LVPWT, LV mass, LV mass/body surface area (BSA), and obesity index were significantly greater in group 2 than in group 1. Apnea index and the duration in which nocturnal oxygen saturation was decreased under 90% (duration of SaO2 < 90%), were significantly correlated with LV mass/BSA and 24-h mean blood pressure. Apnea index, number of apneas, duration of nocturnal oxygen saturation less than 90%, weight, and obesity index were significantly greater in patients with both LVH and RVH than in patients without LVH and RVH, or those with only LVH. Plasma NE after waking significantly increased compared with that before sleep (p < 0.05). The ratio of plasma NE levels after waking to those before sleep was significantly correlated with the duration of SaO2 < 90% (r = 0.83, p < 0.05), but not with apnea index. These results suggest that frequent episodes of oxygen desaturation and/or arousal responses caused by apnea may contribute to the complication of LVH and RVH in the long term, and apnea-induced cyclical increases in blood pressure and the resulting sustained elevation in blood pressure associated with the increase in afterload and sympathetic activity may play a role in the development of LVH.

The role of gastric surgery in the multidisciplinary management of severe obesity

Severe obesity affects the health and quality of life of 4 million Americans. The major cost of treating severe obesity and its associated comorbidities of hypertension, diabetes, cardiovascular disease, pulmonary insufficiency, cancer, and degenerative arthritis as well as the poor long-term results of medical, drug, and behavioral therapy has increased the numbers of patients being referred for surgical treatment. Gastric bypass and vertical banded gastroplasty are the two procedures recommended for severely obese patients. These operations currently have low morbidity and mortality. Surgery should be considered adjuvant therapy and must be part of a multidisciplinary approach. The significant long-term weight control resulting from the surgical therapy is associated with improvement and, often, resolution of comorbidities, including diabetes, hypertension, hyperlipidemia, and pulmonary insufficiency.

Options for the management of obesity

The need to treat obesity successfully can be measured by the medical penalty paid by the obese individual and the financial price paid by society in general. The management of obesity has 2 objectives: first, to produce significant weight reduction (10% of pretreatment bodyweight) and, second, to maintain this weight reduction. For the purpose of this paper, we have defined successful treatment as that maintaining significant weight loss for at least 5 years. A review of the literature confirms that there is no single outstanding treatment for obesity, and that clinicians must consider an individual's needs before selecting a particular method of weight reduction. The main determinants of suitability of any specific treatment are degree of obesity, concomitant medical disorders, urgency of treatment, and the individual's willingness to undergo the programme prescribed.

Impact of gastric restrictive surgery on hypertension in the morbidly obese

Hypertension is a major health risk factor in patients who are morbidly obese. Two hundred eighty-nine morbidly obese patients undergoing gastric restrictive surgery were evaluated for the presence of hypertension (blood pressure greater than or equal to 160/90 mm Hg or currently undergoing antihypertensive therapy) pre- and postoperatively. Of 74 (26%) preoperatively hypertensive patients, 67 (91%) were available for follow-up. Preoperative hypertension resolved in 66% (44 of 67) of patients following gastric restrictive surgery. Superobese and morbidly obese patients had similar reductions in hypertension after surgery (69% versus 63%). Patients not receiving antihypertensives preoperatively had a greater reduction of hypertension than those medically treated preoperatively (78% versus 58%). The amount of weight loss significantly predicted the reduction of hypertension, whereas follow-up weight achieved did not. The amounts of weight loss for patients with resolved and persistent hypertension were 89.3 +/- 5.6 lbs (mean +/- standard error of the mean +ADSEM+BD) and 66.0 +/- 8.3 lbs, respectively (p less than 0.02). For patients with resolved hypertension, follow-up weights for the morbidly obese and superobese were 162.0 +/- 10.8 lbs (133% +/- 4% ideal body weight +ADIBW+BD) and 220.4 +/- 9.5 lbs (170% +/- 7% IBW). Gastric restrictive surgery is effective therapy for hypertension in morbidly obese patients. Patients need not achieve weights approaching IBW to enjoy the benefits of gastric restrictive surgery on hypertension.

Surgical treatment of obesity

Surgical treatment of obesity by methods that have withstood over 5 years of clinical evaluation is effective in ameliorating and even curing manifest serious co-morbid diseases such as diabetes, hypertension, and respiratory distress in the majority of patients. Despite numerous shortcomings and limitations, surgical methods are the only viable alternative for achieving and maintaining substantial weight loss in dangerously obese patients and, therefore, represent a legitimate, often life-saving, intervention. Nevertheless, the magnitude of weight loss varies widely, as does the number of patients lost to follow-up or requiring multiple operations. Safety of performing the surgery and recognition and successful treatment of side effects in cooperating patients has improved greatly over the past 10 years. More effort needs to be put into improving patient selection to allocate patients to specific types of operations and to identify those patients who may not require surgery.