One of the possible side effects of rapid weight loss after undergoing weight loss surgery is orthostatic hypotension or orthostatic intolerance. These terms describe a significant drop in blood pressure upon standing from a seated or reclined position. Drip in blood pressure causes a decrease in blood flow to the brain. There are several studies discussing this after RNY gastric bypass and sleeve gastrectomy. However, this can also be an issue post Duodenal Switch. The process is still not completely understood but can be due to several factors. Rapid weight loss, sympathetic nervous system dysfunction, dehydration, electrolyte imbalance, malnutrition, thyroid issues, cardiac issues, post prandial hypotension (blood pressure lowering after meals due to blood flow shifting to the gut) or medications are all suspected as possible causefor orthostatic hypotension.
Symptoms can include dizziness, lightheadedness, nausea, blurry vision, weakness, fatigue, palpitations, headache, exercise intolerance, intermittent confusion and can culminate to passing out. This can be diagnoses with blood pressure monitoring while positioning change, ECG, laboratory studies, echocardiogram, tilt table test and possibly Valsalva maneuver.
There is a direct link between obesity and hypertension. A large number of patients undergoing weight loss surgery are on anti-hypertension medications. Patients need to be followed closely in the hospital and in the rapid weight loss phase post surgery for medication changes and eventually termination of anti-hypertensive medications. Follow up and monitoring with a primary care physician is crucial due to these rapid changes.
Dehydration, anemia, and low protein intake need close surveillance after weight loss surgery. The patient may require laboratory studies to investigate these causes.
Treatments may include increasing hydration, protein intake, changing medications and treating anemia. Also, allowing time for the body to adjust to the rapid weight loss if all the underlying issues are within normal limits. If symptoms persist, after all underlying issues are investigated, the patient will need to be diligent with hydration, protein intake, supplements and other treatments. Things that may also help is to slow down in moving from one position to the other, take a moment to adjust to your new position. Compression stocking and increasing salt intake can also help if all other causes are investigated. Post prandial hypotension can be avoided with low carbohydrate and small meals. Also, moderately increasing salt intake can improve symptoms.