Pre-operative information and patient-controlled analgesia: much ado about nothing.

We examined whether pre-operative information benefited patients receiving patient-controlled analgesia (PCA) after major surgery. We investigated whether patients felt better informed about PCA and also whether pre-operative information altered the use of PCA, the adequacy of pain relief, worries about addiction and safety, and knowledge of side-effects. We investigated the effectiveness of information provided in two ways, namely by a patient-determined leaflet or an interview by a trained nurse from the pain team, compared with routine pre-operative information. We studied 225 patients, 75 in each group. Patients in the leaflet group were better informed about PCA, became familiar with using PCA more quickly and were less confused about PCA than the control group. However, there were no effects on pain relief, worries about addiction and safety, and knowledge of side effects. The pre-operative interview resulted in no benefits. Our findings indicate that the detailed provision of pre-operative information failed to improve patients' experiences of PCA.

Why do patients feel positive about patient-controlled analgesia?

We studied 200 patients to identify the aspects of their experience of patient-controlled analgesia (PCA) that made them feel 'extremely positive' about this technique. After PCA had been withdrawn, patients completed a questionnaire which included the following topics: pre-operative information, pain relief, the degree of control that PCA afforded the patient, side-effects and safety. Multiple regression analysis identified three factors of their experience which were associated uniquely with feeling 'extremely positive' about PCA: having better pain relief, not worrying about 'giving oneself too much drug' and not experiencing feeling 'peculiar in the head'. Control over pain relief, although highly correlated with feeling 'extremely positive' about PCA, was unimportant when these variables were controlled. Because of the well-recognised difficulties in measuring satisfaction with analgesic regimens, we suggest that a satisfaction score based on these variables would be a significant advance on existing methods.

Patient-controlled analgesia: an assessment by 200 patients.

Two hundred patients completed a questionnaire about their experiences of patient-controlled analgesia. The questionnaire covered the following topics: pre-operative information, reasons for pressing and not pressing the button, pain relief, side-effects, safety, advantages and disadvantages of patient-controlled analgesia, worries associated with its use and control over pain. A high level of satisfaction with the device, together with a view that it afforded control over pain, emerged from replies to simple, general questions. However, more detailed questions revealed side-effects and fears that constrained its use and hence patients' ability to control pain. Control is predominantly a feature of the professional's view of patient-controlled analgesia, rather than the patient's experience of this analgesic technique.

Organization of the hTMnm gene. Implications for the evolution of muscle and non-muscle tropomyosins.

We have isolated clones of human genomic DNA which contain the structural elements of the hTMnm gene. In non-muscle tissue this gene produces a 2.5 kb (1 kb = 10(3) bases or base-pairs) mRNA encoding TM30nm, a 248 amino acid cytoskeletal tropomyosin. In muscle, alternative splicing of this gene results in the expression of a 1.3 kb mRNA encoding a 285 amino acid skeletal muscle alpha-tropomyosin. The hTMnm gene spans at least 42 kb of DNA and consists of 13 exons, only five of which are common to both the 2.5 kb and 1.3 kb transcripts. The boundaries of the exons giving rise to the muscle-specific isoform are identical to the base to those of other genes encoding muscle tropomyosins. A comparison of the structures of exons encoding the amino-terminal sequences of the muscle and non-muscle isoforms suggests that the hTMnm gene has evolved by a specific pattern of exon duplication with alternative splicing.