Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 2002
Randomized Controlled Trial Clinical TrialRapid deflation of the bronchial cuff of the double-lumen tube after decreasing the concentration of inspired nitrous oxide.
Deflationary phenomena of the endotracheal tube cuff may occur after inspired nitrous oxide (N(2)O) concentrations are reduced, but deflationary phenomena of the double-lumen tube (DLT) cuff have not been investigated. In this study, tracheal and bronchial cuffs of left-sided Mallinckrodt (Athlone, Ireland) DLTs were inflated with air, 40% N(2)O, or 67% N(2)O (Air, N40, or N67 groups, respectively) in 24 patients undergoing thoracic surgery; 40 min later, O(2) was substituted for N(2)O in some of the patients in the N40 group (N40-c group). Intracuff gas volumes, N(2)O concentrations, and cuff compliance were also measured. Both tracheal and bronchial cuff pressures significantly increased in the Air group but decreased in the N67 group. Neither pressure significantly changed in the N40 group, but both decreased in the N40-c group after terminating N(2)O anesthesia; the time required for bronchial cuff pressures to decrease by half (12.0 +/- 5.5 min) was less than that for tracheal cuff pressures (31.2 +/- 11.0 min, P < 0.01). The volume change in the N40-c group was not significantly different between the tracheal and bronchial cuffs, but tracheal cuff compliance was significantly higher than bronchial compliance. Therefore, filling DLT cuffs with 40% N(2)O stabilizes cuff pressure during anesthesia with 67% N(2)O, but bronchial cuffs deflate more quickly than tracheal cuffs after cessation of N(2)O administration through smaller compliance. ⋯ We demonstrated that after cessation of nitrous oxide (N(2)O) administration, bronchial N(2)O-filled cuffs of the double-lumen tube deflate more rapidly than tracheal cuffs. To avoid insufficient separation of the lungs by the bronchial cuff, a frequent check of the cuff pressure is recommended after the inspired N(2)O concentration is decreased.
-
Anesthesia and analgesia · Jul 2002
Clinical TrialElectro-acupuncture at the Zusanli, Yanglingquan, and Kunlun points does not reduce anesthetic requirement.
We tested the hypothesis that electro-acupuncture at the Zusanli, Yanglingquan, and Kunlun acupuncture points on the legs decreases anesthetic requirement. Fourteen young, healthy volunteers were anesthetized with desflurane on two separate days. Needle electrodes were positioned at the three acupuncture points thought to produce a generalized sedative and analgesic effect. Needles were percutaneously placed on treatment days; on control days, they were insulated and taped near the insertion points. The electrodes were stimulated on the treatment day. Stimulation consisted of 2-Hz and 100-Hz currents alternated at 2-s intervals. When the end-tidal desflurane concentration of 5.5% was stable for 15 min, noxious electrical stimuli were administered via 25-gauge needles on both thighs (70 mA at 100 Hz for 10 s). Desflurane concentration was increased 0.5% when movement occurred and decreased 0.5% when it did not. An investigator, blinded to treatment, determined movement. These up-and-down sequences were continued until volunteers crossed from movement to no movement four times. A logistic regression determined the partial pressure of desflurane that produced a 50% likelihood of movement in response to noxious stimulation and consequently identified the minimum alveolar anesthetic concentration equivalent for desflurane. There was no significant difference in minimum alveolar anesthetic concentration equivalents between the electro-acupuncture (4.6% +/- 0.6%, mean +/- SD) and control (4.6% +/- 0.8%) days (P = 0.8). These data provided an 80% power for detecting a difference of 0.35 volume-percent between the groups. ⋯ Electro-stimulation of three general acupuncture points on the leg did not reduce desflurane requirements. This type of acupuncture is thus unlikely to facilitate general anesthesia or decrease the need for anesthetic drugs.
-
The use of succinylcholine in hyperkalemic patients (serum potassium >5.5 mEq/L) is often viewed as relatively contraindicated, although there are no systematic data to define what preoperative potassium level is safe. We retrospectively reviewed more than 40,000 general anesthetics administered over 70 mo in which succinylcholine was given at the induction. This search yielded 38 patients with a preoperative potassium of 5.6 mEq/L or greater. Survival of the anesthetic was 100%, and no dysrhythmias or other major morbidity were documented upon manual review of the intraoperative automated record keeper charts or the patient medical records. These data allow a 95% confidence interval assessment of maximal risk for an event of 7.9%, which is not negligible, but which almost certainly grossly overestimates the risk for patients with moderately increased potassium levels. A prospective trial to definitively assess the safety margin for succinylcholine use in hyperkalemic patients would be difficult. Therefore, these data, taken in the context of a compelling case for rapid intubating conditions without long-term paralysis, suggest safety in succinylcholine use in patients with modest hyperkalemia. ⋯ In a review of more than 40,000 general anesthetics in which succinylcholine was given at induction, 38 patients had a preoperative potassium of 5.6 mEq/L or greater. All patients survived the anesthetic with no dysrhythmias or other major morbidity documented. Succinylcholine may be appropriate and safe for use in certain patients with moderate hyperkalemia.
-
Anesthesia and analgesia · Jul 2002
Case ReportsTemporary bilateral blindness after acute lidocaine toxicity.
This case report describes an uncommon complication (blindness) occurring after an inadvertent overdosage of a frequently used local anesthetic (lidocaine) during a regional anesthetic procedure. The discussion focuses on the suspected pathophysiology of the blindness.
-
Anesthesia and analgesia · Jul 2002
The dose-related efficacy of diltiazem for enhancing diaphragmatic fatigability in dogs.
Nicardipine, a calcium channel blockade, enhances the production of diaphragmatic fatigue. We studied the dose-related effects of diltiazem, another calcium channel blockade, on diaphragmatic fatigability in dogs. Animals were divided into three groups of eight each. In each group, diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. During this fatigue-producing period, Group I received no study drug, Group II was infused with diltiazem 0.1 mg. kg(-1). h(-1), and Group III was infused with diltiazem 0.5 mg. kg(-1). h(-1). We assessed diaphragmatic contractility by transdiaphragmatic pressure (Pdi). After the fatigue-producing period, in Group I, Pdi at low-frequency (20-Hz) stimulation decreased from baseline values (P < 0.05), whereas there was no change in Pdi at high-frequency (100-Hz) stimulation. In Groups II and III, with an infusion of diltiazem, Pdi at both stimuli decreased from baseline values (P < 0.05). The decrease in Pdi to each stimulus was more in Group III than in Group II (P < 0.05). We conclude that diltiazem causes a dose-related augmentation of fatigability in the diaphragm of dogs. ⋯ Diaphragmatic muscle fatigue is implicated as a cause of respiratory failure. Diltiazem, a calcium channel blockade, enhances diaphragmatic fatigability in dogs in a dose-related manner.