External ventricular drain management in subarachnoid haemorrhage: a systematic review and meta-analysis

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures. Despite this, the optimal drainage and weaning strategies are still unknown. This PRISMA-compliant systematic review and meta-analysis analysed the outcomes of patients undergoing EVD procedures, comparing continuous versus intermittent drainage and rapid versus gradual weaning. Four databases were searched from inception to 01/10/2020. Articles reporting at least 10 patients treated for hydrocephalus secondary to subarachnoid haemorrhage were included. Other inclusion criteria were the description of the EVD drainage and weaning strategies used and a comparison of continuous versus intermittent drainage or rapid versus gradual weaning within the study. Random effect meta-analyses were used to compare functional outcomes, incidence of complications and hospital length of stay. Intermittent external CSF drainage was associated with lower incidence of EVD-related infections (RR = 0.20, 95% CI 0.05-0.72, I-squared = 0%) and EVD blockages compared to continuous CSF drainage (RR = 0.45, 95% CI 0.27-0.74, I-squared = 0%). There was no clear advantage in using gradual EVD weaning strategies compared to rapid EVD weaning; however, patients who underwent rapid EVD weaning had a shorter hospital length of stay (SMD = 0.34, 95% CI 0.22-0.47, I-squared = 0%). Intermittent external CSF drainage after SAH is associated with lower incidence of EVD-related infections and EVD blockages compared to continuous CSF drainage. Patients who underwent rapid EVD weaning had a shorter hospital length of stay and there was no clear clinical advantage in using gradual weaning.