Lecture Code : NBR02-S2
Session Name : Nephrology Board Review Course 2
Session Topic : -
Date & Time, Place : June 22 (Sun) / 10:40-12:40 / Room 4 (Room 203)
HD: Updated Review of Intradialytic Hypotension: Prediction and Management
JAESEOK KIM
Wonju Severance Christian Hospital, Republic of Korea
Intradialytic hypotension (IDH) is the most common complication associated with hemodialysis. It interferes with the normal progression of dialysis, reduces its efficiency, and can lead to ischemic injury in vital organs such as the heart and brain. Ultimately, IDH is a clinically significant issue that can contribute to increased mortality.
Pathophysiology of IDH
IDH results from a complex interplay of various factors. A common mechanism involves a relative mismatch between the amount of fluid removed from the intravascular compartment and the amount of fluid refilled from the interstitial and extravascular spaces. When this refill is insufficient, the intravascular volume decreases, leading to hypotension.
Definition of IDH
There are several definitions of IDH:
- A decrease in systolic blood pressure (SBP) by ≥20 mmHg or mean arterial pressure (MAP) by ≥10 mmHg during dialysis compared to pre-dialysis values.
- A nadir SBP during dialysis dropping below 90 mmHg.
Among these, the definition based on a nadir SBP <90 mmHg has been shown to best predict adverse outcomes in patients.
Factors Associated with IDH and Its Management
1. Excessive Ultrafiltration (UF)
Excessive UF is the primary cause of IDH. Inadequate fluid management between dialysis sessions, leading to significant weight gain, is a key contributor.
Studies recommend avoiding UF rates greater than 10 mL/kg/h.
In addition to clinical assessment and chest radiography, the use of bioimpedance analysis has been proposed for more accurate assessment of dry weight and fluid status.
2. Use of Peripheral Vasoconstrictors
Medications that induce peripheral vasoconstriction can help prevent IDH.
Midodrine is a representative agent, acting on alpha-1 adrenergic receptors to increase blood pressure. It is typically administered 30–60 minutes before dialysis to reduce the frequency of IDH.
3. Dialysate Temperature Control
Lowering the dialysate temperature can promote peripheral vasoconstriction and activate the sympathetic nervous system, thereby reducing the risk of IDH.
Some researchers suggest that the clinical benefits of online hemodiafiltration (HDF) in IDH prevention may partly be due to the use of cooler replacement fluids.
4. Adjustment of Antihypertensive Medications
Modifying the timing of antihypertensive medications (e.g., administering them after dialysis) can help prevent IDH.
Additionally, understanding the pharmacokinetics of different antihypertensive classes is essential.
In general, calcium channel blockers (CCBs) are considered more suitable for IDH prevention compared to angiotensin receptor blockers (ARBs) or angiotensin-converting enzyme inhibitors (ACEIs).
Keywords: Hemodialysis, Hypotension, Ultrafiltration, Temperature, Medication