How to manage a traumatic brain injury patient with unresponsive wakefulness syndrome who develops tachycardia after receiving sodium bicarbonate (NaHCO3) via tracheostomy (trach) and a suppository for constipation?

Management of Tachycardia Following Sodium Bicarbonate Administration in TBI Patient with Unresponsive Wakefulness Syndrome

The sudden tachycardia is most likely a sympathomimetic response to the sodium bicarbonate administration via tracheostomy, potentially exacerbated by vagal stimulation from the suppository, and should be managed with benzodiazepines for agitation control while monitoring for sodium channel blockade on ECG.

Immediate Assessment and Differential Diagnosis

The clinical scenario presents two potential triggers occurring simultaneously:

• Sodium bicarbonate via tracheostomy can cause direct airway irritation and vagal stimulation, triggering a sympathetic surge 1
• Rectal suppository administration after failed enema can cause vagal stimulation and autonomic dysreflexia, particularly in patients with neurological injury 2
• Rule out sodium channel blockade by obtaining immediate 12-lead ECG to assess QRS duration (normal <120 ms) and look for terminal R wave in aVR 2

Critical ECG Evaluation

Obtain immediate ECG to differentiate between sympathomimetic tachycardia versus sodium channel blockade:

• If QRS <120 ms and normal morphology: This represents sympathomimetic response, not toxicity 2
• If QRS ≥120 ms or terminal R wave in aVR present: This indicates sodium channel blockade requiring specific antidotal therapy 3
• Monitor continuously for QRS widening, as sodium bicarbonate itself does not cause sodium channel blockade but the clinical presentation mimics other toxidromes 2

Management Algorithm Based on ECG Findings

If Narrow-Complex Tachycardia (QRS <120 ms):

This represents sympathomimetic response requiring sedation-based management:

• Administer benzodiazepines (lorazepam 1-2 mg IV or diazepam 5-10 mg IV) as first-line therapy for agitation and sympathetic surge 2
• Benzodiazepines control agitation, relax muscles, and reduce psychomotor activity that generates heat and cardiovascular stress 2
• Avoid physical restraints without sedation, as this is potentially harmful and can worsen sympathomimetic response 2

Monitor for hyperthermia:

• Check core temperature immediately, as hyperthermia can be rapidly life-threatening in sympathomimetic states 2
• If temperature >38.5°C, initiate rapid external cooling with evaporative or immersive methods 2

If Wide-Complex Tachycardia (QRS ≥120 ms):

This indicates sodium channel blockade requiring immediate antidotal therapy:

• Administer hypertonic sodium bicarbonate 1-2 mEq/kg (50-100 mEq or 50-100 mL of 8.4% solution) IV bolus given slowly 2, 3
• Target serum pH 7.45-7.55 to overcome sodium channel blockade 3
• Repeat boluses every 5-10 minutes until QRS narrows to <120 ms and hemodynamic stability achieved 2
• Consider lidocaine 1-1.5 mg/kg IV as second-line therapy if sodium bicarbonate fails to narrow QRS 2

Monitoring Requirements During Acute Phase

Continuous monitoring every 2-4 hours:

• Arterial blood gases to assess pH (target 7.2-7.3 for acidosis, 7.45-7.55 for sodium channel blockade) 1, 3
• Serum sodium (maintain <150-155 mEq/L to avoid iatrogenic hypernatremia) 2, 3
• Serum potassium (sodium bicarbonate causes intracellular shift and hypokalemia requiring replacement) 2
• Ionized calcium (bicarbonate can decrease free calcium, worsening cardiac contractility) 1
• Continuous ECG monitoring for QRS duration and dysrhythmias 3

Specific Considerations for Constipation Management

The suppository administration likely contributed to vagal stimulation:

• In patients with severe neurological injury, rectal manipulation can trigger autonomic dysreflexia with sudden hypertension and tachycardia 2
• Consider alternative bowel management strategies (oral laxatives, scheduled enemas with premedication) to avoid future episodes 2
• If rectal interventions are necessary, premedicate with benzodiazepines to blunt autonomic response 2

Common Pitfalls to Avoid

Critical errors that worsen outcomes:

• Do not administer beta-blockers for tachycardia without ruling out sodium channel blockade, as they can precipitate hypotension and cardiac arrest 4
• Do not use class Ia or Ic antiarrhythmics (procainamide, quinidine, flecainide), as they worsen sodium channel blockade 4
• Do not give additional sodium bicarbonate if serum sodium >150 mEq/L or pH >7.55, as this causes iatrogenic harm 2
• Do not mix sodium bicarbonate with calcium-containing solutions or vasoactive amines in the same IV line, as this causes inactivation 1
• Flush IV line with normal saline before and after bicarbonate administration to prevent catecholamine inactivation 1

When to Escalate Care

Consider advanced interventions if refractory to initial management:

• If wide-complex tachycardia persists despite 200-300 mEq sodium bicarbonate, consider VA-ECMO for refractory cardiogenic shock 2
• If narrow-complex tachycardia with severe hypertension persists despite benzodiazepines, consider vasodilators (phentolamine 5-10 mg IV, nitrates, or calcium channel blockers) 2
• Mechanical circulatory support (intra-aortic balloon pump or VA-ECMO) is reasonable for cardiogenic shock refractory to other measures 2

Resolution Criteria

Stop interventions when:

• Heart rate normalizes to baseline (typically 60-100 bpm for this patient population) 2
• QRS duration returns to <120 ms if widened 3
• Hemodynamic stability achieved without vasopressor support 2
• Core temperature <38.5°C if hyperthermia was present 2
• Patient returns to baseline neurological status (though limited in unresponsive wakefulness syndrome) 5