[Awareness under remifentanil-propofol anaesthesia]. / Wachheitserlebnis unter Remifentanil- und Propofolanästhesie ohne vegetative Reaktionen für den erinnerten Zeitraum.

We report on a 49-year-old female patient suffering from recurrent carcinoma of the rectum, who underwent a palliative Hartmann operation for an anus praeter reconstruction. After a remifentanil bolus of 90 microg and a propofol bolus of 200 mg, anaesthesia was maintained with 0.25 microg/kg/min remifentanil and 4 mg/kg propofol, and after skin incision with 1.0 microg/kg/min remifentanil and 5 mg/kg/h propofol. Throughout the operation, the patient showed a stable blood pressure of 120-130/80 mmHg but 15 min after skin incision the heart rate suddenly rose to 140 beats/min, so remifentanil was increased to 1.8 microg/kg/min and propofol to 8 mg/kg/h. Over a time period of 15 min the heart rate decreased to 90 beats/min. Subsequently vegetative parameters stayed within the normal range (heart rate 90 beats/min, blood pressure 120-130/80 mmHg) so that continuous administration of remifentanil and propofol could be tapered. After completion of skin sutures, administration of remifentanil and propofol was terminated. After extubation the patient reported having heard conversations contributable to the end of the operation and the sentence: "now we're done" was clearly remembered. The patient stated that she had not been able to move any part of her body, that she had perceived the situation as extremely unpleasant and dangerous and that she had felt severe pain. At the postoperative rounds the patient refused any psychological and psychiatric help.

Concurrence of cortex and platelet serotonin2 receptor binding characteristics in the individual and the putative regulation by serotonin.

Changes in the central and peripheral serotonergic receptor activity have been reported to be involved in depression and suicidality. To elucidate the interdependence between central and peripheral receptor sites and their regulation by serotonin, we estimated intra-individual serotonin2 receptor binding characteristics in porcine cortex synaptosomes and in platelet membranes using 3H-LSD as ligand and ketanserin as competitor and quantified the relevant serotonin concentrations. A positive correlation between the apparent half maximal saturation concentration, KD, of the receptor in cortex synaptosomes and platelet membranes (r = 0.65, p = 0.0046, n = 18), and between the apparent maximal binding capacity, Bmax, of the receptor in cortex synaptosomes and platelets (r = 0.52, p = 0.027, n = 18) was observed. The blood serotonin concentrations correlated negatively with the maximal binding capacity, Bmax, in platelets (r = -0.77, p = 0.0002, n = 18). These results suggest that the binding characteristics of the central and peripheral serotonin2 receptor are similar, and that the platelet receptor activity may be regulated by blood levels of serotonin.

Human brain cortex and platelet serotonin2 receptor binding properties and their regulation by endogenous serotonin.

In patients with affective disorder and suicidality up-regulation of the serotonin2 receptor has been observed in brain and on platelets. Although the pharmacological profiles of the receptor in brain synaptosomes and platelet membranes are similar, it is a matter of debate whether the platelet serotonin2 receptor reflects the characteristics of the receptor in the brain and whether serotonin regulates the receptor activity. To answer these questions we measured in healthy human subjects the platelet serotonin2 receptor activity and blood serotonin concentrations. In an attempt to find whether the serotonin2 receptor activity in brain cortex synaptosomes and on platelets is similarly expressed we investigated the receptor's binding characteristics in neurosurgical patients. The results suggest that in men and women increased platelet serotonin concentrations correlate with a decrease in platelet membrane serotonin2 receptor affinity. The affinities of the brain cortex synaptosomal and platelet membrane serotonin2 receptor correlate intra-individually. These data suggest that the platelet serotonin2 receptor affinity appears to be regulated at the cellular level by blood serotonin and that the binding characteristics of the serotonin2 receptor in brain cortex synaptosomes corresponds to that on platelets. The latter finding supports the hypothesis of the platelet as a model for neuronal function.