Incidence of malposition of polyvinylchloride and red rubber left-sided double-lumen tubes and clinical sequelae.

Currently, fiberoptic bronchoscopy (FB) is recommended for correct positioning of double-lumen endobronchial tubes (DLTs) because of the high incidence of malpositions not appreciated by clinical signs. The aims of this study were to assess whether clinical signs allow accurate confirmation of adequate positioning with left red rubber (RR) or polyvinyl-chloride (PVC) double-lumen tubes and to compare the incidence of malpositions between the two tubes. Another goal was to assess whether these malpositions, not appreciated by clinical assessment, adversely affected outcome. Twenty-one adult patients scheduled for elective thoracic surgery were randomly assigned to the RR (11 patients) or PVC group (10 patients). After endobronchial intubation, the position of the tubes was adjusted until clinically satisfactory lung separation had been achieved. A single investigator performed all the FB assessments were performed in the supine (SUP) and lateral positions. The anesthesiologists responsible for the clinical evaluation were "blinded" to the bronchoscopic findings. While in the SUP position, the tube was "too deep" to permit visualization of the carina during tracheal bronchoscopy in 5 patients (2 RR, 3 PVC). In 17 of 21 (10 RR, 7 PVC), the bronchial cuff could not be visualized, although in 1 patient (RR group), the cuff was overinflated and bulged out to partially obstruct the right main bronchus orifice. Bronchial bronchoscopy showed 4 of 11 patients in the RR group in whom the left upper lobe orifice was occluded compared with 1 only in the PVC group.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-response effect of intrathecal alfentanil on canine lower urinary tract dynamics.

The effect of intrathecal (IT) administration of three different doses (1, 2.5, and 5 micrograms/kg) of alfentanil on lower urinary tract dynamics was examined by urodynamic studies, cystometrograms (CMG), and urethral pressure profiles (UPP) in seven anesthetized dogs. Simultaneous serum drug concentrations were determined by specific radioimmunoassay for time-response analysis. A significant dose-dependent relaxation of urethral musculature expressed by a reduction in UPP values of 41.5% and 38.4% (P < 0.03) was noted 30 min after 5 and 2.5 micrograms/kg IT alfentanil, respectively, whereas the decrease of 13.4-22% in mean CMG values was not significant. All changes in UPP and CMG returned to baseline values by 60 min. The pharmacokinetics of alfentanil from the cerebrospinal fluid to the systemic circulation were linear, i.e., dose-independent with maximal serum concentrations of 0.6, 1.4, and 3.5 ng/mL 10 min after the three respective IT doses. The low serum alfentanil concentrations and the lack of time correlation between the peak values and the changes in urinary tract activity, point to a spinally mediated mechanism. The short-lived effect of IT alfentanil on lower urinary tract dynamics and the relaxation of the bladder neck allow for unobstructed micturition pathways and may avoid urinary retention.