[Improved detection of the pulse oximeter signal with a digital nerve block in patients in poor health status]

OBJECTIVE

To demonstrate the efficacy of a digital nerve block for improving pulse oximetry in conditions of low tissue perfusion.

METHOD

A randomized single-blind study of adult patients undergoing surgery under general anesthesia for conditions characterized by hypoperfusion. Patients were assigned to a control group or an experimental group. The experimental group received a digital nerve block in the middle finger of the left hand; a sensor was then placed on the finger for between 120 and 300 minutes. Age, sex, diagnosis, total observation time (TOT), percentage of time with no pulse oximeter signal (NoPO), and percentage of time with an unstable pulse oximeter signal (UnstPO) were recorded. Each patient was questioned between 16 and 24 hours after surgery and was examined for flushing, paresthesia, hypoesthesia, pain, and ecchymosis. The chi2 test was used to compare dichotomized or nominal variables and the t test was used to compare age, TOT, NoPO, and UnstPO. Values of P<.05 were considered statistically significant in both cases.

RESULTS

Fifty patients were randomized to each group. A total of 82 patients remained in the study (control group=42, experimental group=40). There were no significant between-group differences in diagnoses or TOT. The mean values for NoPO and UnstPO were higher in the control group than in the experimental group (11.1% vs 4.4% and 35.9% vs 15.7%, respectively; P<.001).

CONCLUSION

A digital nerve block can be used to prevent pulse oximetry failures in conditions of low peripheral perfusion.

[Construction and validation of a severity of illness index of patients hospitalized in clinical areas]

Severity of illness indexes for hospitalized patients are frequently used for the assessment of hospital performance. The purpose here was to develop and validate a quantitative index for clinical areas which could measure severity of illness during hospitalization period and would be easy to obtain from the information contained in a regular clinical chart. The construction included item selection and search for items weights. Experts and literature were consulted and 74 clinical records provided empirical information. The result was the proposal of an index with two alternatives: one quantitative and the other ordinal with four levels of severity. Validation included four aspects of validity, general reliability, interrater agreement and internal consistency. Sixteen specialized physicians assessed content and face validity. One hundred clinical records of discharged patients were used to assess criterion, construct validity and reliability. Results show satisfactory validity in almost all aspects. The reliability coefficient was 0.95, Kappa coefficient was 0.4 for the ordinal index and correlation coefficients over 0.93 for the quantitative one. The index is ready for current applications in this context although some suggestions for future improvements were also included.

[Variations in the postoperative length of stay according to patient characteristics in a general surgery service]

With the purpose of identifying factors that explain variations in length of postoperative stay in a general surgery unit, information from 666 clinical records of discharged alive patients was collected. Factors related to the surgical procedure, the severity of the disease and the medical team together with sociodemographic characteristics of the patients were analyzed. Statistical analysis was based on analysis of variance and multiple linear regression. Variables with statistically significant regression coefficients (p < 0.001) were in this order: severity of complications, type of intervention, need for reintervention and severity of diagnosis. Sixty-seven percent of length of stay variation was explained by the included variables. Results allow to suggest an evaluation procedure which takes into account patient and operation characteristics.