How to manage autonomic storm in a patient with brain stem death?

Management of Autonomic Storm in Brain Stem Death

Provide physiological stabilization with mechanical ventilation and inotropic support to maintain adequate mean arterial pressure and cerebral perfusion while progressing toward formal brain stem death diagnosis, as continuation of intensive care support to allow diagnosis of brain stem death is appropriate and aids communication with families. 1

Immediate Physiological Support

The primary goal is cardiorespiratory stability to facilitate accurate neurological assessment, not prolongation of inevitable death. 1

Hemodynamic Management During Autonomic Storm

• Maintain mean arterial pressure ≥80-90 mmHg using mechanical ventilation and inotropic support as required during the period of physiological instability and organ dysfunction that commonly develops. 1, 2

• Administer vasopressors (metaraminol or norepinephrine infusion) when fluid resuscitation alone is inadequate to offset hypotensive effects and maintain cerebral perfusion pressure. 1, 2

• Use invasive arterial blood pressure monitoring with the transducer placed at the level of the tragus to facilitate continuous hemodynamic assessment during this unstable period. 1

Respiratory Support

• Ensure mechanical ventilation targeting PaCO2 4.5-5.0 kPa and PaO2 ≥13 kPa to maintain physiological stability during the observation period. 1

• Monitor end-tidal CO2 continuously and validate with arterial blood gas analysis to ensure adequate ventilation and oxygenation. 1

• Apply minimum 5 cmH2O PEEP to prevent atelectasis while avoiding excessive positive pressure that could compromise venous return. 2

Progressing Toward Brain Stem Death Diagnosis

The stabilization and interval to reassessment typically lies between 24 and 72 hours, with continuation and escalation of support appropriate to allow diagnosis of brain stem death when this is a possibility. 1

Clinical Monitoring During Stabilization

• Perform simple repeated clinical monitoring of conscious level (Glasgow Coma Scale) and pupillary reactions after physiological stability has been achieved and confounders (drugs, seizures, physiological derangement, spinal cord injury) have been recognized and treated. 1

• When rapid and significant escalation in therapy is required to maintain physiological stability, the responsible consultant should review the relative harms and burdens of continued intensive care regularly. 1

Formal Brain Stem Death Testing

• Document absence of all brain stem reflexes including pupillary, corneal, oculovestibular, gag, and tracheal reflexes once physiological stability is achieved. 1

• Perform apnea testing demonstrating PaCO2 >60 mmHg and >20 mmHg increase above baseline with complete absence of respiratory effort, after preoxygenation with 100% oxygen for 5-10 minutes and normalization of pH, temperature >35°C, and blood pressure. 1

• If oxygen saturations fall below 85% or hemodynamic instability limits completion of apnea testing, place the patient back on ventilator support and consider ancillary studies (EEG showing electrocerebral silence or radionuclide cerebral blood flow studies showing absent flow) to assist diagnosis. 1

Treatment Limitations and Communication

Treatment limitations should be agreed and communicated with the patient's family and ICU team at the outset, as admission to ICU for devastating brain injury is for physiological support during observation rather than prolongation of inevitable death. 1

Appropriate Limitations

• Consider limitation of additional organ support and interventions including renal replacement therapy, neurosurgical interventions, intracranial pressure monitoring, and application of DNACPR decisions. 1

• Mechanical ventilation and inotropic support are usually required and appropriate during the observation period, even when other interventions are limited. 1

Family Communication

• Inform the family of the expectation of continued deterioration with death as the most likely outcome, but that additional time will increase the certainty of this prognosis and allow formal brain death diagnosis. 1

• The diagnostic certainty of brain stem death confirms prognostication and futility, and aids communication with families regarding end-of-life decisions and potential organ donation. 1

Organ Donation Considerations

• Organ donation should be a routine consideration in end-of-life care planning, with approach for consent occurring only after the family understands and accepts the diagnosis of brain death, undertaken in collaboration with a specialist nurse for organ donation. 1

Common Pitfalls to Avoid

• Do not mistake the autonomic storm (characterized by hypertension, tachycardia, and hyperdynamic cardiovascular state) as a sign of neurological recovery - research demonstrates this sympathetic storm precedes irreversible apneic coma and prolonged cerebral hypoperfusion. 3, 4

• Do not prematurely withdraw support before achieving physiological stability and completing the observation period, as this may lead to inaccurate prognostication and potentially abandoning retrievable patients. 1

• Do not use bolus doses of sedatives to rapidly correct blood pressure during autonomic storm, as this may worsen hypotension and compromise cerebral perfusion. 2

• Recognize that low frequency blood pressure oscillations may persist despite brain stem injury due to spinal sympathetic circuitry, while heart rate variability is almost completely lost, requiring comprehensive clinical assessment rather than relying on single physiological parameters. 5