Hypotension with hemodialysis

Pathophysiology Hypotension associated with hemodialysis manifests as a symptomatic sudden drop of more than 30 mm Hg in mean arterial or systolic pressure or a systolic pressure drop to less than 90 mm Hg during the dialysis session. The primary cause is fluid removal from the bloodstream. Ultrafiltration removes fluid from the plasma, which... 

A 67-year-old woman took about 7 g of procainamide and developed nausea, vomiting, lethargy, a junctional tachycardia, hypotension, and oliguria (61). She was treated with hemodialysis. 

Flynn JJ III, Mitchell MC, Caruso FS, McElligott MA. Midodrine treatment for patients with hemodialysis hypotension. Clin Nephrol 1996 45 261-267. 

Yalcin AU, Sahin G, Frol M, Bal C. Sertraline hydrochloride treatment for patients with hemodialysis hypotension. Blood Purif 2002 20 150-153. 

Yalcin AU, Kudaiberdieva G, Sahin G, et al. Effect of sertraline hydrochloride on cardiac autonomic dysfunction in patients with hemodialysis-induced hypotension. Nephron Physiology 2003 93 21-28. 

Hemofiltration is similar to hemodialysis, but uses convective transport across high cutoff point membranes to clear toxins. Clearance is slower and requires up to 24 h of continuous use in the clinical setting, which can he advantageous because this reduces the impact the device has on hemodynamic stability, unlike standard hemodialysis devices that can cause hypotension during treatment. Fluid is lost with this method and must be replaced in the patient, typically with a sterile isotonic solution. Hemofiltration can be used in combination with hemodialysis and is called hemodiafiltration. 

With either type of dialysis, studies suggest that recovery of renal function is decreased in ARF patients who undergo dialysis compared with those not requiring dialysis. Decreased recovery of renal function may be due to hemodialysis-induced hypotension causing additional ischemic injury to the kidney. Also, exposure of a patient s blood to bioincompatible dialysis membranes (cuprophane or cellulose acetate) results in complement and leukocyte activation which can lead to neutrophil infiltration into the kidney and release of vasoconstrictive substances that can prolong renal dysfunction.26 Synthetic membranes composed of substances such as polysulfone, polyacrylonitrile, and polymethylmethacrylate are considered to be more biocompatible and would be less likely to activate complement. Synthetic membranes are generally more expensive than cellulose-based membranes. Several recent meta-analyses found no difference in mortality between biocompatible and bioincompatible membranes. Whether biocompatible membranes lead to better patient outcomes continues to be debated. 

Hypotension is the most common complication seen during hemodialysis. It has been reported to occur with approximately 10% to 30% of dialysis sessions, but maybe as frequent as 50% of sessions in some patients.46... 

Pathophysiology Muscle cramps can occur with up to 20% of dialysis sessions.48 The cause is often related to excessive ultrafiltration, which causes hypoperfusion of the muscles. Other contributing factors to the development of muscle cramps include hypotension and electrolyte and acid-base imbalances that occur during hemodialysis sessions. 

Evaluate the patient for complications associated with dialysis. Does the patient develop hypotension or cramps during hemodialysis Does the patient have symptoms consistent with peritonitis or a catheter infection ... 

General supportive care should be provided. Aggressive gut decontamination should be carried out using repeated doses of activated charcoal and whole bowel irrigation. Propranolol or other blockers (eg, esmolol) are useful antidotes for B-mediated hypotension and tachycardia. Phenobarbital is preferred over phenytoin for convulsions most anticonvulsants are ineffective. Hemodialysis is indicated for serum concentrations greater than 100 mg/L and for intractable seizures in patients with lower levels. 

A 42-year-old man developed nausea and vomiting and felt suicidal. He had type 2 diabetes and was taking metformin (56). His blood lactate concentration was 8.9 mmol/1, bicarbonate 16 mmol/1, and pH 7.2. Severe hypotension required intensive care. The lactate concentration rose to 22 mmol/1 and the bicarbonate fell to 6.7 mmol/1 and the pH to 6.89. The metformin concentration was high at 191 mg/1. He survived, having been treated with intermittent hemodialysis. 

Five patients with metformin-associated severe lactic acidosis, seen between 1 September 1998 and 31 May 2001, have been reported (58). Two had attempted suicide. All had severe metabolic acidosis with a high anion gap and raised blood lactate concentrations. Four developed profound hypotension and three had acute respiratory failure. Three had normal preceding renal function. Three required conventional hemodialysis and two continuous renal replacement therapy. 

Losartan was evaluated in 406 patients with end-stage renal insufficiency undergoing hemodialysis (24). Only 15 patients discontinued losartan because of adverse effects. In seven the adverse reaction was hypotension. Two patients reported a possible anaphylactoid reaction on treatment with AN69 dialysis membranes. However, nine patients with a history of previous anaphylactoid reactions on treatment with AN69 have not shown this complication with losartan and AN69. 

Midodrine has been extensively tested in several of the orthostatic hypotension sjmdromes, including neurogenic hjrpertension due to autonomic neuropathies (2,3) neu-rocardiogenic syncope (4-8) the controversial syndrome of orthostatic hypotension and tachycardia that may be associated with chronic fatigue (9,10) the hypotension seen during hemodialysis (11) and hypotension due to neuroleptic drugs (12). 

The utility of continuous renal replacement therapies (CRRT) such as continuous venous-venous hemodialysis (CWHD) in the treatment of poisoning is uncertain. As CRRT provides slower clearance than conventional hemodialysis it may not be appropriate for drug removal in acute intoxications [25]. However, the lower blood flow rates and longer treatment times of continuous modalities may be desirable for vulnerable, hemodynamically unstable, patients who are not candidates for conventional hemodialysis [7]. Unlike hemodialysis, CRRT can give effective clearances in hypotensive patients. If the clinical condition of the patient requires a low intensity treatment that will necessarily decrease diffusive clearance, slow extended dialysis (SLED) or continuous treatment times with additional convective clearance (CVVHF and CVVHDF) can likely provide adequate total drug clearance [24]. 

Individuals overexposed to isopropanol should be removed from exposure, affected areas of the skin should be washed with soap and water, and the eyes should be irrigated with water. Isopropanol is rapidly absorbed from the gastrointestinal tract. Efforts to decrease absorption are unlikely to be beneficial. Severe isopropanol overdoses have been managed successfully with either peritoneal dialysis or hemodialysis. Since the vast majority of patients respond completely with only supportive therapy, dialysis (hemodialysis much more effective than peritoneal) should be instituted in those patients with a history and physical exam consistent with a very large ingestion (blood isopropyl alcohol >400 mg dl ), those patients with hemodynamic instability (hypotension) and coma. 

The basis of clinical management is supportive care. The airway should be secured and protected as needed. Symptomatic patients should have intravenous access and cardiac monitoring. Accidental ingestions exceeding 500-800 mg, and all intentional overdoses, should be treated with oral activated charcoal if patients present within 60 min of exposure. Seizures should be treated with benzodiazepines, or phenobarbital if refractory. Hypotension should be treated with intravenous fluids and vasopressors (dopamine or norepinephrine) if needed. Hemodialysis or hemoper-fusion may enhance elimination of both the parent compound and metabolites, but the clinical value of... 

Hypotension not responsive to intravenous fluids should be managed with vasopressors, such as dopamine, norepinephrine, epinephrine, and/or phenylephrine. If seizures occur, benzodiazepines should be administered. Due to their pharmacokinetic characteristics, moderate volume of distribution, and low protein binding, procainamide and NAPA may be removed via hemodialysis and hemoperfu-sion. Both procainamide and NAPA serum concentrations should be obtained. Normal therapeutic ranges are procainamide, 3-14pgml NAPA, 12-35 pg ml Measurement of electrolytes, renal function tests, and arterial blood gases should be considered. 

Currently there is no consensus on the target blood pressure for patients with ESKD. Maintaining a blood pressure of <150/90 mm Hg has been proposed to maintain hemodynamic stability, particularly in the hemodialysis patient, who has frequent shifts in volume status and is thus at high risk for hypotension during and postdialysis. 

The most common complications that occur during the hemodialysis procedure include hypotension, cramps, nausea and vomiting, headache, chest pain, hack pain, and fever or chiUs. Table 45-3 hsts these comphcations and the etiology with predisposing factors... 

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