The National Institute for Health Research Health Technology Assessment programme.

Assessments of dynamic cerebral autoregulation usually measure the cerebral blood flow velocity (CBFV) response to changes in arterial blood pressure (ABP). We studied the effect of substituting ABP by cerebral perfusion pressure (CPP), expressed as the difference between ABP and intracranial pressure (ICP), in estimates of dynamic autoregulation obtained by transfer function analysis. CBFV, ABP and ICP were recorded during periods of physiological stability in 30 patients with severe head injury. Transfer function analysis was performed using the following combinations of input-output variables: ABP-CBFV, CPP-CBFV and CBFV-ICP. Frequency and time-domain (step response) functions were averaged for recordings with mean ICP < 20 mmHg (group A) and mean ICP > or = 20 mmHg (group B). The ABP-CBFV transfer function parameters and step response for group A were similar to previous studies in normal subjects, but group B showed deterioration of dynamic autoregulation. Radically different step responses were obtained from both groups for the CPP-CBFV transfer function and the coherence was not significantly improved. The CBFV-ICP transfer function had the highest values of coherence and indicates that changes in CBFV are the cause of spontaneous fluctuations in ICP. Furthermore, the ICP step response plateau was significantly higher for group B than for group A. An alternative calculation of the CBFV step response to changes in CPP resembled the corresponding responses for the ABP input. For spontaneous fluctuations in ABP, ICP and CBFV, it is not possible to calculate the CPP-CBFV transfer function directly due to the high positive correlation between ICP and CBFV, but an alternative estimate can be obtained by using the CBFV-ICP transfer function. The latter could also be useful as a method to assess intracranial compliance in head injury patients.

1 . Thirty-six patients with complete irrecoverable brachial plexus lesions have been studied. 2. Function has been compared after 1) arthrodesis of the shoulder with amputation through the arm, 2) so-called reconstructive procedures, and 3) no operative treatment. 3. The results of reconstructive operations have been so disappointing that we believe that this type of treatment should be abandoned. 4. Amputation-arthrodesis offers a better functional result than either reconstruction or no operation. Its value depends to a considerable extent on the manual dexterity of the patient. 5. A clerical worker who is not mechanically minded is less likely to use an artificial limb, and in this type of patient operation is perhaps best avoided.

The AIS, based on initial CT scan, provides useful prognostic information in patients with severe head injury.