Is postoperative intrathecal catheter use associated with central nervous system infection?

BACKGROUND: Continuation of intrathecal anesthesia into the postoperative period has been limited by important safety concerns. Principal among these has been the assumption that extended intrathecal therapy leads to spinal (epidural and intrathecal) space infections. To address the role of extended intrathecal catheter therapy as a cause of infections, we cultured all intrathecal catheters used to provide postoperative analgesia. METHODS: All intrathecal catheters were inserted in the operating room using sterile technique. The catheters were used either for the duration of the patients stay in the intensive care unit or until they were no longer judged to provide a therapeutic advantage. They were removed without skin preparation. The distal 2-3 cm of the catheters was cultured using semiquantitative culture methods. Results were divided into four groups: group 1, negative culture results; group 2, ten or fewer colonies of growth; group 3, more than 10 colonies on initial plates and/or growth from broth cultures; and group 4, any bacterial growth, along with evidence of local or central nervous system infections. RESULTS: Cultures were obtained from 139 patients with a mean indwelling catheter time of 66.1 h. Group 1 (102 patients) had a mean indwelling duration of 55 h. Group 2 (26 patients) and group 3 (11 patients) had significantly longer indwelling duration (83.2 h P = .0023, 129.6 h P = < .0001, respectively) than group 1. Cultures of cerebrospinal fluid obtained simultaneously with catheter cultures in 9 cases (5 in group 2 and 4 in group 3) showed no growth. No patient had evidence of local or central nervous system infection. Difficulty of catheter placement (number of attempts made and the number of levels explored), antibiotic administration, the composition of the postoperative infusions and the number of catheter breaks in the postoperative period were similar in each group. With the exception of two catheters in group 3, (cultured at 49 and 54 h), significant bacterial growth (more than ten colonies) was observed only after more than 96 h of indwelling duration. CONCLUSIONS: Application of semiquantitative culture methods assisted in explaining the results seen in group 2 as secondary to contamination of the catheter that occurred on removal. Higher numbers of bacteria (group 3) may define a population at increased risk for infectious complications. The results of this study do not absolutely resolve the issue of infectious risk associated with postoperative intrathecal catheter use, nor do they define a safe period beyond which the risk of continued catheter use would be unacceptable. However, it appears that limited periods of use (96 h or less) is not associated with either frequent local or spinal infections. Semiquantitative culture methods may help identify individuals (with catheter cultures yielding more than ten colonies) at increased risk for infectious complications and in need of closer observation.

An unusual case of endotracheal tube cuff dysfunction.

We report an unusual case of endotracheal tube obstruction secondary to alteration of the preoperative fasting period. A patient scheduled for coronary artery bypass grafting had been instructed to take nothing by mouth except scheduled medication with sips of water prior to surgery. Induction of anesthesia and tracheal intubation were accomplished without incident. However, ventilation was impaired by a nonfunctional endotracheal tube cuff. Various maneuvers (e.g., inflation and deflation of the cuff and advancement of the tube) were attempted without success. When the tube was removed, we found an adherent mass of chewing gum. The patient's trachea was reintubated, and surgery proceeded uneventfully. We believe that the mass of gum caused enough deviation of the endotracheal tube to impair ventilation. The safety of preoperative gum chewing and liquid ingestion is discussed. Other incidents of anesthetic problems caused by modification of the traditional preoperative fast are highlighted.

Characteristics of 11 rabies virus isolates in mice: titers and relative invasiveness of virus, incubation period of infection, and survival of mice with sequelae.

Mice were inoculated intracerebrally or in the footpad with 11 salivary gland suspensions from rabid foxes, skunks, and bobcats. The 11 isolates differed in their ratios of intracerebral titer to footpad titer, a result indicating that the "invasiveness" of different isolates varies markedly. The degree of invasiveness could not be correlated with the species of animal. The inoculation of the less invasive isolates resulted in an appreciable number of permanently paralyzed animals (survivors with sequelae). These animals had high titers of neutralizing antibody in serum but no neutralizing antibody in the brain, a finding suggesting that virus had invaded only the peripheral nervous system or the spinal ganglia. Pathological examination of the paralyzed mice and normal mice confirmed this finding.

Effective protection of monkeys against death from street virus by post-exposure administration of tissue-culture rabies vaccine.

Three series of experiments on rabies vaccines were carried out on rhesus monkeys using suckling-mouse-brain vaccine, rabbit-brain vaccine, duck-embryo vaccine, and purified, concentrated tissue-culture vaccine. The latter was prepared in a human diploid cell strain and inactivated with beta-propiolactone, and consisted of tissue-culture fluid concentrated 200-fold with a final infectivity titre of 10(9.8) plaque-forming units per ml before inactivation. In the first two series of experiments, several vaccines were tested for relative immunogenicity on a pre-exposure basis. In the third series, a successful model was developed in which a single inoculation of the tissue-culture vaccine administered after exposure to rabies virus, with or without accompanying standard doses of antirabies serum, was evaluated as a method of prevention. A single dose of the tissue-culture vaccine protected 7 out of 8 monkeys from death by street virus. Homologous or heterologous antirabies serum alone gave poor results. The results indicate great promise for prophylaxis in man with one dose, or perhaps a few doses, of highly concentrated, purified tissue-culture vaccine.