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The pressure–volume index (PVI) can be used to assess the cerebrospinal fluid dynamics and intracranial elastance in critically ill brain injured patients. The dependency of PVI on the state of cerebral autoregulation within the physiologic range of cerebral perfusion pressure (CPP) can be described by mathematical models that account for changes in cerebral blood volume during PVI testing. This relationship has never been verified clinically using direct PVI measurement and independent cerebral autoregulation assessment. PVI and cerebral autoregulation were prospectively assessed in a cohort of 19 comatose patients admitted to an academic intensive care unit in Brescia, Italy. None. PVI was measured injecting a fixed volume of 2 ml of 0.9% sodium chloride solution into the cerebral ventricles through an intraventricular catheter. Cerebral autoregulation was assessed using transcranial Doppler transient hyperaemic response (THR) test. Fifty-nine PVI assessments and 59 THR tests were performed. Mean PVI was 20.0 (SD 10.2) millilitres in sessions when autoregulation was intact (THR test ≥1.1) and 31.6 (8.8) millilitres in sessions with defective autoregulation (THR test <1.1) (ΔPVI = 11.7 ml, 95% CI = 4.7–19.3 ml; P = 0.002). Intracranial pressure, CPP and brain CT findings were not significantly different between the measurements with intact and disturbed autoregulation. Cerebral autoregulation status can affect PVI estimation despite a normal CPP. PVI measurement may overestimate the tolerance of the intracranial system to volume loads in patients with disturbed cerebral autoregulation. [ABSTRACT FROM AUTHOR]

Objective: (1) To describe the pattern of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in a group of severe head-injured patients, (2) to quantify complications of ICP monitoring, and (3) to describe a management protocol and its results.Design: Prospective observational study.Setting: General intensive care unit in a teaching hospital.Patients: 138 comatose patients, selected according to the following criteria: age > 16 years, coma [Glasgow Coma Scale (GCS) < or = 8] with at least one pupil reactive after resuscitation, digital recording of intracranial and arterial pressure, and jugular saturation measurements.Measurements and Results: Median GCS was 5, and 62 patients had significant extracranial injuries; 71 had intracranial hematomas, which were urgently evacuated. Mean ICP was 20.5 mmHg (SD 8.34), mean CPP was 71.86 mmHg (SD 11.22); cerebral extraction of oxygen averaged 29 %. Medical therapy was used to control ICP in 130 cases; 93 patients required hyperventilation. Vasopressors were infused in 16 cases; in 14 cases a barbiturate infusion was started. In 6 patients all pharmacological treatments failed and surgical decompression was done. The only complication of ICP monitoring was meningitis in 3 patients. Outcome at 6 months was a good recovery and moderate disability for 82 patients (59.4%), severe disability and vegetative status for 37 (26.8%), and 19 patients died (13.7%). The severity of intracranial hypertension was related to poorer results at 6 months.Conclusions: Intracranial hypertension is very frequent in severe head injury but can be reasonably well controlled by combined surgical and medical therapy. [ABSTRACT FROM AUTHOR]