Transrectal ultrasound-guided biopsy; vacuum mixing systems; regional anesthesia; laparoscopic cholecystectomy

AORN Journal,  March, 2005  by George Allen

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Local anesthesia use in transrectal ultrasound-guided biopsy

The Surgeon

August 2004

Transrectal ultrasound (TRUS)-guided biopsy of the prostate is a common diagnostic procedure for prostate cancer. It involves the use of an ultrasound probe that is passed into the rectum where sound waves are used to visualize the prostate on a monitor. Under this direct visualization, a special biopsy needle is precisely introduced through the rectal wall into the prostate to obtain tissue from a number of sites. Although this procedure has routinely been performed without anesthesia, it is associated with significant pain in some individuals. The purpose of this prospective, randomized, placebo-controlled study was to determine the efficacy and safety of using local anesthesia (ie, periprostatic lidocaine injection) for TRUS-guided biopsy of the prostate. (1)

Ninety-six patients undergoing TRUS-guided biopsy of the prostate were randomly assigned to one of two groups. Forty-eight patients were assigned to the local anesthesia (LA) group and 48 to the placebo group. In the LA group, lidocaine 1% was injected into the angle between the seminal vesicle and base of the prostate and the apex of the prostate before the usual six to 12 biopsies were performed with an 18-gauge core-biopsy needle. The identical procedure was performed in the placebo group without the injection of lidocaine.

Patients' level of anxiety was determined before the procedure using a visual analog scale (ie, expected pain score). Similarly, at the end of the procedure, the actual pain score was determined using the same visual analog scale, and the patients were asked if they would undergo the procedure again in the same way. Immediately after the procedure, patients were monitored for complications, including hematuria, hemospermia, rectal bleeding, infection, and urinary retention. After they were discharged, patients were contacted by telephone to assess the incidence of these complications. Common statistical techniques, including, Student's t test and Mann-Whitney U tests, were used to analyze differences between the groups.

Findings. Both groups were similar with regard to age and mean prostate-specific antigen levels. The mean expected pain score was similar in both groups (5.19 [+ or -] 1.6 in the LA group, 5.02 [+ or -] 1.4 in the placebo group, P = .587). The mean actual pain score was significantly higher in the placebo group (6.46 [+ or -] 2.2 in the placebo group, 3.0 [+ or -] 1.8 in the LA group, P = .0001). Complication rates were comparable in both groups. All patients in the LA group (ie, 100%) were significantly more likely to indicate that they would be happy to undergo the procedure in the same way the next time compared to 65% in the placebo group (P = .0001).

Clinical implications. Perioperative nurses should understand that when patients expect to experience pain and discomfort, their anxiety increases. This study revealed that periprostatic injection of local anesthesia is safe and effective and significantly reduces discomfort during TRUS-guided prostate biopsy.

Efficacy of vacuum mixing systems in reducing methylmethacrylate fumes

Acta Orthopaedica Scandinavica

October 2004

Polymethyl methacrylate (PMMA) bone cement is used mainly during the implantation of orthopedic prostheses. Methylmethacrylate (MMA) fumes are generated during the mixing procedure. These fumes are toxic and may have irritating effects on mucous membranes of the respiratory tract and eyes. Additionally, direct contact with PMMA may lead to toxic dermatitis. Vacuum mixing of PMMA bone cement is advocated to reduce cracks within the cement mantle and minimize exposure to MMA fumes evaporating during the cement mixing process. The objective of this study was to determine if vacuum mixing of PMMA bone cement is effective in reducing exposure to MMA vapors. (2)

During joint replacement surgery in a conventional OR with laminar air flow, the emission of MMA fumes in the breathing zone was quantified. Seven commonly available vacuum mixing systems were compared with hand mixing in an open bowl. Humidity and temperature were measured and recorded every two hours. The mixing systems being examined were placed on a table near the scrub person during joint replacement surgery. The fume detection systems were mounted on a second table within the breathing zone of a nurse during the mixing process. Air and fume samples were collected during a three-minute period, using both a photo ionization detector and gas chromatography. Ten separate mixes were made, and measurements were taken for each mixing device. Common statistical techniques, including univariate analysis of variance (ANOVA) were used to analyze differences.

Findings. Methylmethacrylate evaporated continuously from the mixing systems into the breathing zone during mixing. Gas chromatography revealed significantly lower concentrations of MMA fumes compared to hand mixing when six of the seven mixing systems were used (one-way ANOVA: F = 70, df = 7, P < .001, R-square = 0.69). Photo ionization detection revealed significantly lower concentrations of MMA compared to hand mixing when four of the seven mixing systems were used (one-way ANOVA: F = 25, df = 7, P < .001, R-square = 0.71). All the vacuum mixing systems reduced MMA fume exposure by approximately 50% to 75% compared to hand mixing in an open bowl.