Hemodynamics, Salt Sensitivity and Body Composition in Patients With Morbid Obesity

Obesity Clinical Trial

Official title:

Hemodynamics, Salt Sensitivity and Body Composition in Patients With Morbid Obesity - Effect of Weight Loss Following Laparoscopic Gastric Bypass

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00998465
• Other study ID #: SJ-99
• Status: Completed
• Phase: N/A
• First received: October 19, 2009
• Last updated: March 19, 2013
• Start date: November 2009
• Est. completion date: January 2013

Study information

• Verified date: March 2013
• Source: Roskilde County Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: Denmark: The Regional Committee on Biomedical Research EthicsDenmark: The Danish National Committee on Biomedical Research EthicsDenmark: Danish Dataprotection Agency
• Study type: Observational

Clinical Trial Summary

The purpose of this study is to evaluate the effect of high vs. low sodium intake on blood pressure and system hemodynamics in patients with morbid obesity and to evaluate the impact of laparoscopic gastric bypass on blood pressure, salt sensitivity and body composition in morbidly obese patients. Furthermore, we wants to describe the hemodynamic mechanisms involved in the amelioration of blood pressure during long-term weight loss.

Description:

Overweight and obesity are rapidly increasing in Western countries and are associated with increased mortality and morbidity. The increased morbidity is assumed to be mediated mainly by insulin resistance, diabetes, hypertension and lipid disturbances, but obesity also represents an independent risk factor for cardiovascular disease.

Obesity is associated with an increased risk of hypertension but the pathophysiological basis is not fully established. Several studies have indicated that blood pressure of obese patients could be more dependent on dietary sodium intake than the blood pressure of non-obese patients(as it is the case for patients with essential hypertension)and that this sodium sensitivity of blood pressure is lost after weight loss.

To date, bariatric surgery is the only therapy resulting in substantial and durable long-term weight loss, and the beneficial effects on obesity-related co-morbidities have been well documented. Laparoscopic gastric bypass results in a remarkable improvement of glucose homeostasis and a resolution of diabetes, that typically occurs too fast to be accounted for by weight loss alone. Furthermore, an immediate reduction of blood pressure following laparoscopic gastric bypass has been demonstrated in morbidly obese patients with hypertension as early as one week after the operation. As with the rapid reduction of diabetes, the antihypertensive effect of the procedure might be a consequence of the rearrangement of the gastrointestinal anatomy.

With this study, we want to evaluate the effect of high vs. low sodium intake on blood pressure and system hemodynamics in patients with morbid obesity and to evaluate the impact of laparoscopic gastric bypass on blood pressure, salt sensitivity and body composition in morbidly obese patients. Furthermore, we wants to describe the hemodynamic mechanisms involved in the amelioration of blood pressure during long-term weight loss. Therefore, patients are examined before, 4-6 weeks after and one year after laparoscopic gastric bypass.

Before and one year after the operation, the patients are examined two times; in a five days period of a low dietary sodium consumption and in a five days period of a high sodium consumption respectively. Four-six weeks following the operation, the patients are examined once on their usual diet.

The protocol comprise three sub studies:

1. The effect of high vs low sodium intake on blood pressure and hemodynamics in the morbid obese patient - preoperative study.

2. Effect of gastric bypass surgery on blood pressure, hemodynamics and salt-sensitivity - 1 year follow-up.

3. Effect of gastric bypass surgery on echocardiographic parameters - 1 year follow-up.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 36
• Est. completion date: January 2013
• Est. primary completion date: December 2012
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 70 Years

Eligibility

Inclusion Criteria (cases):

• Caucasians fulfilling the criteria for laparoscopic gastric bypass.

• 12 participants with hypertension, defined as blood pressure > 140/90 and/or use of antihypertensive medication and 12 participants without hypertension.

• Body mass index 40-50 kg/m2

Inclusion Criteria (controls):

• Caucasian.

• No hypertension or use of antihypertensive medication.

• Body mass index < 30 kg/m2

Exclusion Criteria (all):

• Pregnancy

• Chronic obstructive pulmonary disease

• Diabetes mellitus

• Medical treatment with sibutramine.

Study Design

Observational Model: Case Control, Time Perspective: Cross-Sectional

Related Conditions & MeSH terms

• Hypertension
• Obesity
• Obesity, Morbid

Intervention

Other:
• 24-hour blood pressure
Blood pressure is measured every 15 minutes in the daytime and every 30 minutes at night
• Echocardiography
Standard 2-D and m-mode echocardiography with determination of dimensions, systolic, and diastolic function.
• Inert gas rebreathing
Cardiac output, stroke volume and total peripheral resistance are tested at rest and during exercise (bicycle ergometer) using non-invasive equipment (inert gas rebreathing - Innocor)

Radiation:
• Dexa-scan
Fat mass and fat free mass is determined with a whole body Dexa scan, and bone mineral density is tested with Dexa-scans of the lumbar spine and proximal femur.
• Plasma volume
The test is performed using 5 MBq technetium-labeled albumine (99mTc-albumine - Vasculosis) with several postinjection samples for accurate zero-time extrapolation.
• Glomerular filtration rate (GFR)
GFR and ECV are determined following injection of 3,7 MBq 51Cr-EDTA and postinjection samples three-four hours after injection.

Other:
• Blood samples
p-glucose, p-insulin, NT-proBNP, hemoglobin, potassium, sodium, creatinine, albumine
• Urine analyses
24-hour urine collections with determination of u-sodium, u-potassium and u-creatinine.

Dietary Supplement:
• Diets with low and high sodium content
Participants are subjected to 5 days of low (90 mmol/day) and high (250 mmol/day) sodium intake in a randomized order before and 1 year after laparoscopic gastric bypass surgery.

Locations

Country	Name	City	State
Denmark	University Hospital Koege, Department of Clinical Physiology and Nuclear Medicine	Koege

Sponsors (3)

Lead Sponsor	Collaborator
Roskilde County Hospital	Glostrup University Hospital, Copenhagen, University Hospital Koge

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Sodium induced change in 24-hour blood pressure before and one year after laparoscopic gastric bypass.		One year	No
Secondary	Echocardiography: Dimensions, systolic and diastolic function before and one year after laparoscopic gastric bypass		One year	No
Secondary	Non-invasive hemodynamic measurements (inert gas rebreathing) before and one year after laparoscopic gastric bypass		One year	No
Secondary	Body composition: Dexa-scan, plasma volume and extracellular volume before and one year after laparoscopic gastric bypass		One year	No
Secondary	Blood samples: MR-proANP, p-glucose, p-insulin		One year	No