Intracranial pressure monitoring in patients with subarachnoid haemorrhage

Introduction

ICP monitoring is part of intensive care management of subarachnoid hemorrhage patients (SAH). However, patterns of ICP and their relationship with cerebral ischemia or quality of outcome have not yet been clearly defined.

Objective

This study describes the occurrence of intracranial hypertension; its correlation with clinical presentation; its relationship with cerebral ischemia and its association with outcome.

Methods

This prospective study was performed in patients who suffered aneurismal SAH, admitted into our Intensive Care Unit (ICU) from 1998 to 2000. Hemodynamic parameters, ICP, cerebral perfusion pressure (CPP) and jugular bulb O₂ saturation (SjO₂) were monitored and collected up to 7 days after admission. Continuous ICP and CPP were summarised by 24-h mean values. In addition, patients were classified by their 'worst mean data', ie worst data of the daily means; this allowed us to identify three groups based on their 'worst mean ICP' (wmICP): < 20, 20–29 and ≥ 30 mmHg. Hypodense lesions were detected on serial CT scans. Outcome at ICU discharge was classified as: obeying orders, alive but not obeying, died.

Results

Fifty-four patients (64% female, mean age 54 ± 12 years) were studied. Patients were classified according to the Hunt-Hess (HH) scale: I 25%, II 30%, III 20%, IV 14% and V 11% respectively. Thirty-two (60%) of patients had ICP monitoring and was performed in HH classes as follow: HH1 9%, HH2 35%, HH3 28%, HH4 19%, HH5 9% (P = 0.02). Elevated ICP (ICP ≥ 20 mmHg – HICP) was recorded in 27 patients (84.3% of monitored patients). Worst mean ICP was 21.7 ± 17.8 (range 3–85). HICP was detected in HH1-2 (28.6%), in HH3 (11.1%) and HH4-5 (55.6%) (P = 0.12). Ischemia was more frequent in wmICP ≥ 20 than in wmICP < 20 group (62% vs 11% – P = 0.003). Patients with higher wmICP suffered a poorest outcome: 4.5% patients with wmICP < 20; 33.3% with wmICP 20–29 and 75% with wmICP ≥ 30 died (P = 0.006).

Conclusion

In our sample of selected patients, HICP occurred frequently, in all HH grade, and an association with low-density changes on CT scans was observed. Persistently HICP was associated with poor clinical outcome even in good HH classes.