What is the likely diagnosis for an intradialytic episode of sudden palpitations, diaphoresis, hypertension and tachycardia in a hemodialysis patient with recent 3‑kg weight gain?

Intradialytic Hypertension with Sympathetic Activation

This patient is experiencing an episode of intradialytic hypertension (IDHYPER) with sympathetic nervous system activation, manifested by the paradoxical blood pressure rise (140/90 to 160/90 mmHg), tachycardia (68 to 92 bpm), palpitations, and diaphoresis during hemodialysis. 1, 2

Pathophysiologic Mechanism

The clinical presentation strongly suggests sympathetic overdrive as the primary mechanism:

• Sympathetic activation during hemodialysis causes marked increases in systolic blood pressure variability, increased heart rate, suppressed baroreceptor sensitivity, and enhanced sympatho-vagal balance, precisely matching this patient's presentation of palpitations, sweating, hypertension, and tachycardia 2

• The 3.0-3.3 kg interdialytic weight gain indicates extracellular fluid overload, which is the most crucial determinant of intradialytic hypertension and triggers sympathetic nervous system overdrive, renin-angiotensin-aldosterone system activation, and endothelial dysfunction 3

• Hypoxemia-induced sympathetic response may be contributing, as intradialytic hypertension is associated with lower arterial oxygen saturation (though this patient's SpO2 is 98%, making this less likely in this specific case) 4

Immediate Management During This Episode

Stop or reduce ultrafiltration immediately to prevent further sympathetic activation and allow hemodynamic stabilization 5

• Place the patient in a comfortable position and provide reassurance, as anxiety can further amplify sympathetic tone 1

• Monitor blood pressure every 5 minutes during this episode to detect any progression toward hypertensive emergency (BP ≥180/110 mmHg with end-organ damage) 6

• Do not administer saline boluses, as this patient is hypertensive and volume-overloaded; saline would worsen extracellular volume expansion 6, 5

Diagnostic Confirmation

An SBP increase of >10 mmHg from pre- to post-dialysis into the hypertensive range in at least 4 of 6 consecutive dialysis treatments defines persistent intradialytic hypertension and warrants comprehensive evaluation 1

• Document this episode and track the pattern over subsequent sessions to determine if this represents persistent intradialytic hypertension (occurs in approximately 5-15% of hemodialysis patients) 1, 7

• Predialysis baroreceptor sensitivity in the low frequency range is the main predictor of intradialytic hypertension; patients with impaired baroreflex function are at highest risk 2

Long-Term Management Strategy

Primary Intervention: Aggressive Volume Management

Strict dietary sodium restriction to 2-3 g/day (4.7-5.8 g sodium chloride) is essential to reduce thirst, limit interdialytic weight gain, and address the root cause of volume-mediated hypertension 6, 3

• Target interdialytic weight gain <3% of body weight (for this patient, <2.1-2.4 kg assuming 70-80 kg body weight) to avoid the dangerous cycle of excessive ultrafiltration, sympathetic activation, and cardiovascular stress 6, 5

• Gradually achieve true dry weight through systematic assessment and incremental reductions, as volume overload is the primary driver of intradialytic hypertension 6, 3

Dialysis Prescription Modifications

Lower dialysate sodium concentration to ≤140 mmol/L (ideally 135-138 mmol/L) to facilitate sodium removal without stimulating thirst or increasing interdialytic weight gain 6, 8, 3

• Extend dialysis treatment time or increase frequency to reduce ultrafiltration rates below 6 mL/kg/hr, which decreases sympathetic activation and improves volume control 6, 5

• Consider isothermic hemodialysis (maintaining constant blood temperature) on a case-by-case basis, though randomized evidence is limited 3

Antihypertensive Medication Management

ACE inhibitors or ARBs are first-line agents for patients at dry weight with persistent BP >140/90 mmHg, as they provide cardiovascular protection, promote left ventricular hypertrophy regression, and are nondialyzable 6, 3

• Administer antihypertensives at night rather than before dialysis to reduce nocturnal blood pressure surge and minimize intradialytic complications 6

• Avoid dialyzable antihypertensive agents immediately before dialysis (such as short-acting ACE inhibitors or beta-blockers), as their removal during dialysis can precipitate rebound hypertension or hemodynamic instability 6, 5

Critical Pitfalls to Avoid

Do not use high dialysate sodium (≥140 mmol/L) or sodium profiling in this patient, as these strategies worsen hypertension, increase thirst, and perpetuate the cycle of excessive interdialytic weight gain 6, 8

• Do not treat this as intradialytic hypotension by administering saline or increasing dialysate sodium; this patient requires the opposite approach focused on volume removal 6, 5

• Do not ignore the 3.0-3.3 kg weight gain, as high interdialytic weight gain exceeding 4% of dry weight markedly raises cardiovascular mortality, forces dangerous ultrafiltration rates, and creates a vicious cycle of volume overload and cardiac dysfunction 6

Prognosis and Monitoring

Intradialytic hypertensive episodes are associated with higher end-of-dialysis blood pressure and may generate interdialytic hypertension, suggesting that these acute episodes have chronic consequences 2

• Intradialytic hypertension is associated with increased hospitalization and mortality risk compared to patients with modest blood pressure decreases during dialysis 1, 7, 3

• Monitor for cardiovascular events, as the sympathetic activation and volume overload underlying this condition promote left ventricular hypertrophy, arterial stiffness, and endothelial dysfunction 1, 3