Evaluation of a new method for measurement of minute ventilation recovery time.

PURPOSE: To determine if the measurement of minute ventilation recovery time (V (E)RT), a recently proposed predictor of extubation outcome, can be reproduced using a more practical, simpler method. METHODS: A case series with convenience sampling was performed in the surgical intensive care unit of a tertiary-care hospital. Nineteen patients were enrolled during weaning from mechanical ventilation, prior to the initial extubation attempt. Within-subject comparisons of V (E)RT were performed, using 2 alternative methods for measuring baseline V (E) and one alternative method for determining the threshold for recovery of V (E) during the final spontaneous breathing trial prior to extubation. Comparison methods for baseline V (E) included an 8-hour average and the last V (E) measurement prior to the spontaneous breathing trial. The alternative threshold for defining recovery of V (E) was 100% of the baseline value (vs 110% in the original method). RESULTS: The study subjects were primarily cardiac surgery patients (63%) and were ventilated for a median of 5 days prior to extubation. V (E)RT calculated using the 8-hour average or the last V (E) measurement prior to the spontaneous breathing trial as baseline, and a threshold of 100% of baseline V (E) to define recovery most closely approximated V (E)RT obtained by the original method and similarly classified patients at high risk for reintubation (kappa statistic = 0.78 +/- 0.2). CONCLUSIONS: V (E)RT can be determined using a simpler method for measuring both baseline V (E) and the recovery threshold. These methodological modifications may increase the feasibility of measuring V (E)RT, while reproducing the results obtained by the original method.

Change in forced expiratory time and spirometric performance during a single pulmonary function testing session.

BACKGROUND: Among patients with obstructive lung disease, the correlation between clinical improvement and bronchodilator response is poor. Forced expiratory time (FET) may explain some discrepancy, but FET has received little attention. METHODS: We analyzed change in FET during the 3 initial satisfactory flow-volume loops in 102 consecutive patients, 37 with normal spirometry and 65 with airflow obstruction referred to a Veterans Administration pulmonary function testing (PFT) laboratory over 5 months. Patients included both PFT-naïve and PFT-experienced individuals. We also evaluated the relationship between FET and spirometric performance (sum of forced expiratory volume in the first second and forced vital capacity) and the effect of inhaled bronchodilator on FET among patients with airflow obstruction. RESULTS: Normals and patients with airflow obstruction showed significant increments in FET and in spirometric performance during the 3 initial successive pre-bronchodilator attempts (p < 0.001 for both groups). This was true for PFT-naïve and PFT-experienced individuals. There were significant associations between increments in FET and improvements in spirometric performance in all subgroups. After inhaled bronchodilator there was a further FET increment among patients with airflow obstruction (p = 0.009), but there was no significant difference between bronchodilator responders and nonresponders. CONCLUSIONS: Patients with normal pulmonary function and those with obstruction develop longer FET during the initial phases of spirometric testing, regardless of previous PFT experience. Longer FET is associated with better spirometric performance. Bronchodilator administration is associated with modest prolongation of FET, but change in FET did not help identify bronchodilator responders.

Race and electronically measured adherence to immunosuppressive medications after deceased donor renal transplantation.

Nonadherence to immunosuppressive medications may partly explain the worse allograft outcomes among black recipients of renal transplants. In a prospective cohort study of recipients of deceased donor renal transplants, microelectronic cap monitors were placed on bottles of one immunosuppressive medication to (1) measure average daily percentage adherence during the first posttransplantation year and (2) determine the factors associated with adherence. A total of 278 transplant recipients who provided sufficient microelectronic adherence data were grouped into four categories of average daily percentage adherence: 95 to 100% adherence (41.0% of patients), 80 to 95% adherence (32.4%), 50 to 80% adherence (12.9%), and 0 to 50% adherence (13.7%). In the unadjusted ordinal logistic regression model, black race was associated with decreased adherence (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.26 to 0.72; P = 0.001). Cause of renal disease, Powerful Others health locus of control, transplant center, and dosing frequency were also associated with adherence. After adjustment for transplant center and dosing frequency, the association between black race and decreased adherence was substantially attenuated (OR, 0.65; 95% CI, 0.38 to 1.14, P = 0.13). Transplant center (P = 0.003) and increased dosing frequency (OR, 0.43; 95% CI, 0.22 to 0.86, for three or four times per day dosing; OR, 2.35; 95% CI, 1.01 to 5.45, for daily dosing; versus two times per day dosing; P = 0.003) remained independently associated with adherence. Other baseline demographic, socioeconomic, medical, surgical, and psychosocial characteristics were not associated with adherence. The transplant center and dosing frequencies of immunosuppressive medications are associated with adherence and explain a substantial proportion of the race-adherence relationship.