EVD Management During Nausea and Vomiting
Do not routinely clamp the EVD when a patient becomes nauseated and vomits. The evidence shows that routine EVD clamping during activities like intrahospital transport is associated with significant intracranial pressure complications, and there is no guideline recommendation supporting EVD clamping specifically for nausea and vomiting 1.
Understanding the Risks of EVD Clamping
The practice of routine EVD clamping carries substantial risks in neurocritically ill patients:
- Routine EVD clamping during intrahospital transport is associated with post-transport ICP complications in 11.8% of cases, with ICP escalation occurring in 18.5% of transports 1
- Patients whose EVDs were open prior to transport had complications in 26.7% of cases when the EVD was clamped, compared to 0% complications when the EVD remained clamped throughout 1
- Risk factors for post-clamping ICP elevation include pre-clamping ICP ≥15 mmHg, increasing hourly CSF output, and each 1 mL of hourly CSF drained prior to clamping 1
When EVD Clamping Is Appropriate
EVD clamping has specific, limited indications that do not include routine nausea and vomiting:
- EVD clamping is appropriate during the weaning process to assess shunt dependency, typically using a gradual weaning approach rather than rapid weaning 2
- For ICP documentation, the EVD should be closed for a minimum of 5 minutes to obtain a true ICP reading, though only 16.3% of closures in practice meet this standard 3
- The median EVD closure duration in clinical practice is only 25 seconds, which is insufficient for accurate ICP measurement 3
Managing Nausea and Vomiting in EVD Patients
Instead of clamping the EVD, focus on treating the underlying cause and symptoms:
- First-line antiemetic therapy includes dopamine antagonists like metoclopramide (10-20 mg PO/IV every 6 hours) or prochlorperazine (5-10 mg PO/IV every 6 hours) 4
- For persistent nausea, add a 5-HT3 antagonist like ondansetron (4-8 mg PO/IV every 8-12 hours) 4
- For refractory cases, consider dexamethasone (4-8 mg PO/IV per day) or olanzapine (2.5-5 mg PO every 6-8 hours) 4
Critical Pitfall to Avoid
The most important pitfall is assuming that nausea and vomiting in an EVD patient is benign. These symptoms may indicate:
- Increased intracranial pressure requiring urgent evaluation with brain imaging (CT or MRI) and neurosurgical consultation 4
- EVD malfunction or blockage, which occurs in 37.3% of cases without fibrinolysis 5
- Infection, which occurs in 27.6-30% of EVD patients, with risk increasing exponentially after 5 days of catheterization 6, 7
Monitoring Considerations
While the EVD remains open during symptomatic treatment:
- Monitor ICP continuously if the system allows, as elevated ICP may be the underlying cause of nausea and vomiting 8
- Assess hourly CSF output, as increasing output is a risk factor for ICP complications if clamping becomes necessary 1
- Ensure the EVD is properly leveled at the tragus or external auditory meatus to maintain accurate pressure readings 3