A Quantile Regression Approach to Estimating the Distribution of Anesthetic Procedure Time during Induction.

Although procedure time analyses are important for operating room management, it is not easy to extract useful information from clinical procedure time data. A novel approach was proposed to analyze procedure time during anesthetic induction. A two-step regression analysis was performed to explore influential factors of anesthetic induction time (AIT). Linear regression with stepwise model selection was used to select significant correlates of AIT and then quantile regression was employed to illustrate the dynamic relationships between AIT and selected variables at distinct quantiles. A total of 1,060 patients were analyzed. The first and second-year residents (R1-R2) required longer AIT than the third and fourth-year residents and attending anesthesiologists (p = 0.006). Factors prolonging AIT included American Society of Anesthesiologist physical status ≧ III, arterial, central venous and epidural catheterization, and use of bronchoscopy. Presence of surgeon before induction would decrease AIT (p < 0.001). Types of surgery also had significant influence on AIT. Quantile regression satisfactorily estimated extra time needed to complete induction for each influential factor at distinct quantiles. Our analysis on AIT demonstrated the benefit of quantile regression analysis to provide more comprehensive view of the relationships between procedure time and related factors. This novel two-step regression approach has potential applications to procedure time analysis in operating room management.

An investigation on influential factors of patient-controlled epidural analgesic requirement over time for upper abdominal surgeries.

BACKGROUND: Patient-controlled epidural analgesia (PCEA) is commonly used to relieve postoperative pain for upper abdominal surgeries. However, there is still a lack of studies exploring factors associated with PCEA consumption over time after upper abdominal surgery; our study intended to provide further elucidation about this issue. METHODS: This study retrospectively evaluated postoperative PCEA consumption over time after upper abdominal surgery. Cumulative PCEA consumption in the first four 12-hour intervals was directly retrieved from the data recorded by infusion pumps. Potentially influential factors of PCEA requirements, including demographic variables and infusion pump settings, were also collected. A linear mixed model was applied to investigate the relationships between these factors and PCEA consumption over time. A backward elimination strategy was used to select independent factors significantly associated with PCEA consumption. RESULTS: A total of 1001 patients were included in the analysis. On average, PCEA consumption after upper abdominal surgery peaked during the 2(nd) 12-hour interval and then decreased gradually over time. After the model selection processes were completed, four independent factors were identified to have significant effects on PCEA consumption. Surgery for malignant disease and background infusion rate were positively associated with PCEA consumption and did not interact with time. Additionally, female patients tended to consume less and less PCEA over time relative to males. Age had a negative effect on PCEA consumption, which peaked during the 2(nd) 12-hour interval and then decreased gradually over time. The final selected model exhibited acceptable predictive power relative to the observed data. CONCLUSION: Our analyses provided valuable information about the factors associated with PCEA consumption over time after upper abdominal surgery. However, the mechanism of how these factors interact over the course of time awaits further investigation.

Difficult weaning from mechanical ventilator in a patient with corticosteroid insufficiency after low anterior resection of sigmoid colon.

A 75-year-old man underwent low anterior resection for sigmoid colon cancer under general anesthesia. Comprehensive preoperative surveys showed normal cardiopulmonary functions. In spite of adequate fluid administration, persistent intraoperative hypotension required vasopressors to maintain an acceptable blood pressure. Although the patient was fully awakened from anesthesia with adequate oxygenation, repeated attempts to wean him from the ventilator failed in the postanesthesia intensive care unit, despite recovery from the effect of muscle relaxant. Low plasma cortisol level was found in a series of laboratory analyses. After supplementation with corticosteroid, the patient was successfully weaned from the mechanical ventilator without any sequelae.