Acute tachyphylaxis to propofol sedation during ethanol withdrawal.

We treated a patient with a 30-year history of ethanol and benzodiazepine abuse who, on emerging from general anesthesia, was combative and confused. Our working diagnosis was acute ethanol withdrawal, and the patient received intravenous (i.v.) propofol, and midazolam. Initially small doses (10 to 20 mg) of propofol, combined with a midazolam infusion (50 mg/hr), produced sedation. Later, however, the patient became increasingly combative, confused, hypertensive, and tachycardic despite an i.v. propofol infusion at doses up to 1,000 micrograms/kg/min (total propofol dose: 1,755 mg). Immediate sedation was produced by thiopental bolus (500 mg) and i.v. infusion (200 mg/hr). The implication of the patient's initial appropriate response to propofol, followed by the lack of effect when much higher doses were employed, is discussed. While tachyphylaxis has been reported after long-term propofol use, we believe this to be the first case of acute tachyphylaxis.

A clinical measure of the posterior epidural space depth.

BACKGROUND AND OBJECTIVES: The object of this study was to measure the clinically relevant depth of the posterior epidural space (ES) while placing subarachnoid catheters. METHODS: "Hanging drop" technique was used to locate the ES via a midline approach in the lumbar area. The distance from the skin to the ES was measured, and the needle was advanced until free flow of cerebrospinal fluid was observed. The distance between entry into the ES and the subarachnoid space-the posterior ES depth-was then measured. Regression analysis was used to investigate relationships between skin-to-ES distance, posterior ES depth, and patient characteristics (height, weight, body surface area [BSA] and age). RESULTS: The 55 patients studied had a mean skin-to-ES distance of 50.9 +/- 12 mm (range, 27-94) and a mean posterior ES depth of 6.9 +/- 4 mm (range 2-25). Skin-to-ES distance was related to BSA (r = .597, P < .0001) and weight (r = .572 P < .0001). No correlation was found between posterior ES depth and any other variable. CONCLUSIONS: The posterior ES has been found to be somewhat larger and more variable than previously described. The findings provide clinical confirmation of recent radiologic and cadaveric studies, which portray a posterior ES of variable size and complex shape. These findings have implications for cannulation and use of epidural therapy as well as for the combined catheter epidural and single-dose spinal technique.

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.

Supraventricular tachycardia associated with postpartum metoclopramide administration.

PIP: A case report is presented of supraventricular tachycardia (SVT) associated with metoclopramide administration in the early postpartum period in a 37-year-old woman. The patient was scheduled for elective laparoscopic tubal ligation 4 hours after an uncomplicated spontaneous vaginal delivery. The preoperative evaluation revealed that the patient's only significant past medical history was a total of 4 spontaneous vaginal deliveries. A review of systems was noncontributory, and the patient denied any untoward effects from drugs. Metoclopramide, 10 mg, was administered intravenously to facilitate gastric emptying and as an anti-emetic. Within 1 minute, the heart rate rose to 170 bpm. She was in no distress, being unaware of any change in her status. Arterial blood pressure remained in the 130-140 mmHg (systolic) range throughout the ensuing period. Various approaches, i.e., valsalva, carotid sinus massage, ocular pressure, were used to increase vagal tone without a decrease in the heart rate. After determining that the PR interval was grossly normal, she received 2 boluses of verapamil (10 mg intravenously) over a 10-minute period without change in heart rate. She then was given alphaprodine and droperidol for sedation. The patient then was administered Digoxin approximately 20 minutes after the administration of metoclopramide. This was followed by a gradual decrease in her heart rate to 130 bpm over the next 5 minutes. The patient was transferred to a telemetry unit for a 24-hour period, where her arterial blood pressure remained stable and her heart rate was noted to be in the 90-110 range. 12-lead EKG revealed sinus tachycardia with "nonspecific" ST changes. PR, QRS, and QTC intervals were within normal limits. Chest radiograph was without pathology. The patient was reinterviewed on several occasions and continued to deny a history of SVT, palpitations, syncope, or any other cardiac symptomatology. 2 days following the initial episode, she underwent successful laparoscopic tubal ligation under spinal anesthesia and sedation. In sum, a stable postpartum patient without history of SVT or evidence of structural heart disorder developed SVT immediately following metoclopramide administration. This may be because of the cardioactive properties of metoclopramide or to an underlying predisposition from her peripartum state, or a combination of factors.^ieng