Attending Rounds Attending Rounds: A Patient with Intradialytic Hypotension

Intradialytic hypotension is the most common adverse event that occurs during the hemodialysis procedure. Despite advances in machine technology, it remains a difficult management issue. The pathophysiology of intradialytic hypotension and measures to reduce its frequency are discussed. An accurate assessment of dry weight is crucial in all patients on dialysis and especially those patients prone to intradialytic hypotension. The presence of edema and hypertension has recently been shown to be a poor predictor of volume overload. Noninvasive methods to assess volume status, such as whole body and segmental bioimpedance, hold promise to more accurately assess fluid status. Reducing salt intake is key to limiting interdialytic weight gain. A common problem is that patients are often told to restrict fluid but not salt intake. Lowering the dialysate temperature, prohibiting food ingestion during hemodialysis, andmidodrine administration are beneficial. Sodiummodeling in the absence of ultrafiltration modeling should be abandoned. There is not enough data on the efficacy of L-carnitine to warrant its routine use. Clin J Am Soc Nephrol 9: 798–803, 2014. doi: 10.2215/CJN.09930913 Case Presentation A 65-year-old man was on hemodialysis since 2006 as a result of long-standing type II diabetes mellitus. Other medical problems included hypertension, hyperthyroidism treated with total thyroidectomy, history of subtotal parathyroidectomy, sickle cell trait, gastroesophageal reflux disease, severe peripheral vascular disease, coronary artery disease, moderate concentric left ventricular hypertrophy (LVH), and diabetic retinopathy. His medications were metoprolol, lisinopril, gabapentin, cinacalcet, calcium acetate, lanthanum carbonate, levothyroxine, and omeprazole. On physical examination, lungs were clear to auscultation, cardiac rhythmwas regular, an S4was audible, no edemawas present, and there was a brachiobasilic fistula in the left arm. Relevant laboratory studies included sodium5139 mEq/L, potassium54.6 mEq/L, calcium 8.95mg/dl, phosphorus56.5 mg/dl, parathyroid hormone5558 pg/ml, albumin53.4 g/dl, and hemoglobin511.5 g/dl. Dialysis duration was 4 hours. Dialysate composition was 2.0 mEq/L potassium and 2.5 mEq/L calcium with a citrate, and not acetate-based, acid concentrate. The single pool Kt/V on this prescription was 1.49. His average interdialytic weight gain was 4 kg per treatment, and his dry weight was 98.5 kg. During a chronic outpatient dialysis session, he developed intradialytic hypotension (IDH). BPs during the treatment are shown in Table 1 (treatment 1). His predialysis temperature was 36.2°C. At the BP indicated in Table 1, he felt poorly and was diaphoretic. In response, saline was administered, ultrafiltration was stopped, and the patient was placed in a reclining position with resolution of the hypotension. He had a previous history of IDH and as a result, was already being dialyzed with cool dialysate (temperature535.5°C) and ultrafiltration modeling. Given the apparent absence of signs of volume, his dry weight was increased to 99.5 kg. Despite this increase, 9 days later, he developed another episode of IDH at the BP indicated in Table 1 (treatment 2). On this day, his predialysis temperature was 35.8°C. Once again, his dry weight was increased (to 100.5 kg.) At that time, he received dietary counseling on limiting salt intake, which resulted in a reduction of his interdialytic weight gain from 4 to 2.5 kg. Over the subsequent 2 months, there were no additional episodes of IDH. His predialysis BP has been stable around 130/60 mmHg. Introduction When initially evaluating the patient with hypotension on hemodialysis, it is important to rule out acute conditions that can lower BP. These conditions include, but are not limited to, infections (especially involving the access if the patient has a permcath or a graft), pneumonia, cellulitis, and osteomyelitis; blood loss; new onset of cardiac arrhythmias, such as supraventricular tachycardia or atrial fibrillation; and pericardial effusion. The patient had none of these diagnoses. After these diagnoses were ruled out, evaluation and management became evaluation and management of IDH in an otherwise stable patient. Background and Definition IDH remains one of the most vexing management challenges for nephrologists. It has three essential components: a drop in BP generally defined as $20 mmHg systolic BP or $10 mmHg in mean arterial pressure; the presence of symptoms of end organ ischemia; and an Division of