Desflurane

Surgical team members' exposure to inhalational anesthetics

Annals of Thoracic Surgery June 2003

Threshold values for exposure to waste anesthetic gases, including nitrous oxide, have been established; however, the debate about whether chronic exposure to these gases results in negative health effects in health care workers continues. The objective of this study was to determine the occupational exposure of perfusionists, cardiac surgeons, and anesthesiologists to nitrous oxide and other volatile agents, such as sevoflurane and desflurane, when they are used before cardiopulmonary bypass (CPB) procedures. (1)

Ten adult patients undergoing elective coronary artery bypass grafting using CPB were induced and maintained with nitrous oxide and sevoflurane or desflurane until the beginning of CPB. Samples of the ambient air in the breathing zone of the perfusionists, surgeons, and anesthesiologists were collected every 90 seconds throughout the procedures, and simultaneous measurements of the anesthetic gas concentrations at both outlet nozzles of the oxygenator were performed. Time weighted averages during the time of exposure were calculated.

Findings. The average concentration of anesthetic gases was low in the breathing zones of both the anesthesiologists and surgeons before CPB. The National Institute of Safety and Health (NIOSH) average time-weighted threshold value of 25 parts per million (ppm) for nitrous oxide was not violated at any time for the perfusionists, cardiac surgeons, and anesthesiologists. The desflurane load exposure findings for the surgeons increased significantly during CPB, however, and exceeded the NIOSH limit of 0.5 ppm during concomitant use of nitrous oxide.

Clinical implications. This study revealed that although waste anesthetic gas concentrations were measurable during procedures, the average time-weighted threshold value was not exceeded for nitrous oxide. When both nitrous oxide and desflurane were used, however, the threshold was exceeded. Perioperative nurses were not specifically monitored in this study, but the scrub person works in close proximity to the surgeon and, consequently, shares the same risk of exposure. Perioperative nurses should ensure that the ventilation system in the OR is functioning adequately and that waste scavenging systems on CBP equipment are used routinely.

Preoperative screening for breeding disorders in pediatric patients

Clinical Pediatrics April 2003

This retrospective study was conducted to determine if preoperative screening is useful in identifying bleeding disorders in pediatric patients. (2) Records were reviewed for 3,950 pediatric hematology outpatients, and 131 children were identified as having been referred for a prolonged preoperative activated partial thromboplastin (aPTT) level. Biographical data, family history of bleeding, aPTT performed by the referring pediatrician, evaluation performed by the hematologist, and the incidence of bleeding were abstracted from the records. The families of the children were contacted to identify patients who suffered postoperative bleeding. Additionally, the pediatricians and surgeons were asked to review their surgical records and postoperative follow-up notes to verify surgical outcomes. Common statistical measures were employed for comparisons.

Findings. Twenty-eight children (21%) with a prolonged preoperative aPTT were found to have a previously undiagnosed bleeding disorder. Seventy-five percent of the 28 did not have a personal history of a bleeding disorder, and 83% did not have a family history of a bleeding disorder. The most frequent bleeding disorders were von Willebrand disease (11%) and factor XI deficiency (6%). Two patients had factor VIII or vitamin K deficiency, one patient had liver disease, and one patient had circulating anticoagulant. None of the patients experienced perioperative bleeding complications.

Clinical implications. The study showed that preoperative screening with prothrombin time (PT) and aPTT is useful in identifying occult bleeding disorders. Such diagnosis would result in appropriate preoperative management and the reduction in hemorrhagic complications. If PT and aPTT assessments are not done routinely on pediatric patients scheduled for surgery, perioperative nurses should bring the results of this study to the attention of surgeons and anesthesia care providers.

Comparison of hand hygiene methods and effects of ring wearing on hand contamination

Clinical Infectious Diseases June 1, 2003

As health care workers' perform their duties, their hands easily become contaminated. Consequently, hand hygiene is an important process in preventing the transmission of infections. This study assessed risk factors for hand carriage of potential nosocomial pathogens and evaluated the efficacy of three hand hygiene methods--hand hygiene using an alcohol-based hand rub with 62% ethyl alcohol; hand hygiene using a medicated hand wipe measuring 15 cm by 19 cm formulated with an antibacterial substrate, including 0.1% benzalkonium chloride; and hand washing with plain soap and water. (3) A convenience sample of nurses participated in the study. A single hand of each participant was cultured during routine working hours on a surgical intensive care unit after a patient care episode. The nurses then were assigned randomly to one of the three hand hygiene methods. After hand hygiene, the participant's other hand was cultured. Concurrent data, including skin condition, dominant hand, glove use immediately before sampling, presence and number of rings, and length and type of fingernails also were collected. Logistic regression models and univariate analysis were used to analyze the data.

Findings. Ring wearing was associated with a higher hand contamination rate and higher contamination with Staphylococcus aureus, gram negative bacilli, and Candida species. The risk of contamination with any of these pathogens was increased when more than one ring was worn (odds ratio [OR] for 1 ring, 2.6; OR for > 1 ring, 4.6). Contamination with any transient pathogen was significantly less likely after use of the alcohol-based hand rub than after hand washing with plain soap and water (OR, 0.3; 95% confidence interval [CI], 0.1-0.8). The antibacterial hand wipes were less likely to control hand contamination compared to the waterless alcohol-based product (OR, 0.9; 95% CI, 0.5-1.6).

Clinical implications. This study showed that the use of an alcohol-based hand rub resulted in significantly less frequent hand carriage of potential nosocomial pathogens than hand washing with plain soap and water. Additionally, the presence of rings on nurses' hands resulted in an increased frequency of potential nosocomial pathogens, with the frequency becoming larger when two or more rings were worn. Perioperative managers should consider installing alcohol-based hand hygiene dispensers in each OR. Additionally, serious consideration should be given to reviewing and modifying existing dress codes to restrict the number of rings that can be worn by personnel when they are performing patient care responsibilities.

Infections associated with injections from a multiple-dose vial

Clinical Infectious Diseases June 2003

An outbreak of Staphylococcus aureus infections of joints and soft-tissue occurred in an outpatient setting after therapeutic corticosteroid injections were given by a physician during a four-day period in August 2001. This retrospective cohort study was conducted to determine the risk factors for infectious complications. (4) A case was defined as a joint or soft tissue infection where there was no evidence of a preexisting infection at the site of an injection administered by the physician. Microbiology records were reviewed for Staphylococcus aureus isolates from synovial fluid or wounds. Nasal specimens from the physician and nurse were obtained and cultured. Environmental samples, including the surface used to prepare the medication and the alcohol swabs used to clean the top of the multiple-dose vials were collected, and the in vitro persistence of low-dose inocula of Staphylococcus aureus in multiple-dose vials of lidocaine was assessed. Common statistical procedures, including chi square tests, were used to analyze the data.

Findings. Of the 17 patients who received intraarticular or soft tissue corticosteroid injection, 10 (59%) were injected with a combination of lidocaine and triamcinolone. Five (50%) of those injected with a combination of lidocaine and triamcinolone developed infection for an attack rate of 71% (undefined relative risk P = .04). None of the seven patients who were injected with triamcinolone alone developed infection. The in vitro survival curves for low dose inocula of Staphylococcus aureus in multiple-dose vials of lidocaine demonstrated a persistence of viable bacteria at day seven at refrigerator temperature. In contrast, none of the multiple-dose vials maintained at room temperature had detectable bacteria at day two. The multiple-dose vials of lidocaine used during the outbreak period were stored in a refrigerator against the manufacturer's recommendation.

Clinical implications.

Contamination of a multiple-dose vial of lidocaine with Staphylococcus aureus coupled with refrigeration was the likely source of an outbreak of joint and soft tissue infections. Perioperative nurses must maintain aseptic procedures when using multiple-dose vials and develop procedures to ensure that the manufacturer's recommendations for storage are followed. Additionally, perioperative managers should review procedures for the use of multiple-dose medication vials and consider limiting or eliminating their use wherever feasible.

NOTES

(1.) S Mierdl et al, "Occupational exposure to inhalational anesthetics during cardiac surgery on cardiopulmonary bypass," Annals of Thoracic Surgery 75 (June 2003) 1924-1927.

(2.) C Sandoval et al, "The usefulness of preoperative screening for bleeding disorders," Clinical Pediatrics 42 (April 2003) 247-250.

(3.) W E Trick et al, "Impact of ring wearing on hand contamination and comparison of hand hygiene agents in a hospital," Clinical infectious Diseases 36 (June 1, 2003) 1383-1390.

(4.) D L Kirschke et al, "Outbreak of joint and soft-tissue infections associated with injections from a multi-dose medication vial," Clinical infectious Diseases 36 (June 1, 2003) 1369-1373.

GEORGE ALLEN RN, PHD, CNOR, CIC DIRECTOR OF INFECTION CONTROL DOWNSTATE MEDICAL CENTER BROOKLYN, NY

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