BACKGROUND AND OBJECTIVES: Epidural anesthesia is administered commonly for total knee arthroplasty, a procedure using a thigh tourniquet. Tourniquet use has been associated with intraoperative hypertension and with occasional circulatory collapse after deflation. The purpose of this study was to define the hemodynamic changes in this setting. METHODS: We prospectively studied 373 consecutive patients having a total knee arthroplasty performed under epidural anesthesia, with continuous electrocardiogram and radial artery pressure monitoring. Results were analyzed using Student's t-test, correlation coefficients, analysis of variance, or chi-square analysis. Alpha was set at 0.01. RESULTS: There was a 4 +/- 11 mmHg rise in mean arterial pressure throughout the period of tourniquet application (p less than 0.001); no clinically significant hypertension occurred. After tourniquet deflation, there was a 19.2 +/- 12% reduction in mean arterial pressure, occurring within one minute. The magnitude of mean arterial pressure reduction failed to correlate with any clinical parameter other than vasopressor use. There was a small subset of patients who had a fall in heart rate and a more profound degree of hypotension after tourniquet deflation, but these patients could not be identified before tourniquet release. CONCLUSIONS: In this setting, tourniquet-induced hypertension is rare. However, hypotension after deflation is common, occurs rapidly, and correlates poorly with clinical parameters.

Adult↗

PubMedDate not supplied

Blood pressure, not heart rate, as a marker of intravascular injection of epinephrine in an epidural test dose.

Investigators have generally examined the heart rate response after injection of a test dose containing a beta-adrenergic agonist as an indicator of intravascular placement of an epidural catheter. Some have reported an increase in blood pressure accompanying the increase in heart rate after an intravascular injection. We report two elderly patients (aged 76 and 62 years, respectively) in whom apparent intravascular injections of epinephrine-containing local anesthetic solutions resulted in marked blood pressure elevations without noticeable increases in heart rate. As far as we know, this phenomenon previously has been described only in patients receiving beta-adrenergic blocking drugs. In these patients it may be related to decreased beta-adrenergic receptor responsiveness in elderly patients; this and other possible mechanisms are discussed.

Aged↗

PubMedDate not supplied

A pilot study of polymerization inhibition of poly (vinyl siloxane) materials by latex gloves.

Intraoral inhibition of two poly (vinyl siloxane) low-viscosity impression materials was experienced when making an impression of prepared anterior teeth. It was hypothesized that the noted inhibition was a result of contamination with latex gloves. A screening test demonstrated inhibition of polymerization of three different materials when placed in contact with a surface that had been touched with one brand of latex gloves. This inhibition also occurred even if the gloves were washed prior to contact or if the surface was washed after contact with the gloves. Further studies are underway to determine which brands of gloves are safe to use.

Chemical Phenomena↗

PubMedDate not supplied

Interaction of gloves and rubber dam with a poly(vinyl siloxane) impression material: a screening test.

Polymerization inhibition of poly(vinyl siloxane) impression materials has been reported with the use of latex gloves. This study evaluated the effect on polymerization of a poly(vinyl siloxane) impression material in both direct and indirect contact with 25 brands of latex gloves, two brands of vinyl gloves, and two weights of rubber dam. Use of all but one of the latex products (96%) resulted in inhibition of polymerization with direct contact. Forty percent of the latex gloves tested inhibited polymerization with indirect contact. The vinyl gloves tested had no effect on polymerization. The implications of inhibited polymerization were discussed.

Dental Impression Materials↗