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Postoperative residual paralysis and respiratory status: a comparative study of pancuronium and vecuronium.

The objective of this prospective double-blind study was to determine whether postoperative residual paralysis (PORP) after pancuronium or vecuronium results in hypoxemia and hypercapnia in the immediate admission period to the recovery ward. Eighty-three consecutive surgical patients received balanced or intravenous anesthesia with pancuronium for operations lasting longer than one hour or vecuronium for those lasting less than 60 min, both combined with neostigmine at the end of anesthesia. Standard clinical criteria assessed neuromuscular function intraoperatively. Postoperatively, we determined neuromuscular function (acceleromyography with supramaximal train-of-four (TOF) stimulation of the ulnar nerve, and a 5-s head lift) and pulmonary function (pulse oximetry: SpO2, and blood gas analysis: SaO2, PaCO2). We defined PORP as a TOF-ratio <70%, hypoxemia as a postoperative SpO2 > or =5% below the pre-anesthestic level together with a postoperative SaO2 <93%, and hypercapnia as a PaCO2 > or =46 mm Hg. Among the 49 pancuronium and 27 vecuronium patients studied, the PORP rates were 20% in the pancuronium group and 7% in the vecuronium group (p>0.05). Hypoxemia and hypercapnia occurred more often in pancuronium patients with PORP than in those without PORP namely 60% vs. 10% (p<0.05) and 30% vs. 8% (p>0.05), respectively. We conclude that PORP after pancuronium is a significant risk factor for hypoxemia.

Double-Blind Method↗

[Clinical study of perioperative changes in plasma potassium].

Forty adult patients undergoing non-cardiac major surgery were divided into 2 groups. Group A (n = 20) was anesthetized by balanced intravenous procaine anesthesia and group B (n = 20) by epidural block. Blood volume, urine output, potassium in plasma as well as urine, pH, glucose, aldosterone, cortisol and insulin were measured from 24 hours before operation to 48 hours after operation. Evident perioperative trend of hypokalemia in patients with normal renal function was most likely due to the following factors: potassium loss prior to operation, improper pre- or post-operative replacement of fluids, perioperative stress, increasing of blood insulin and urine potassium excretion. Our results run against to the general concept that it may not be necessary to supply potassium with 72 hours after operation.

Adolescent↗

Halothane effects on subendocardial oxygen supply-demand balance: estimation from intramyocardial tissue pressure and left ventricular pressure.

We evaluated the effect of halothane on the balance of subendocardial oxygen supply and demand in six dogs by estimating the endocardial viability ratio (EVR) based on the pressure generated within the subendocardium (ENDO-IMP). Concurrently, the conventional EVR based on left ventricular pressure (LVP) was estimated and compared with the EVR based on ENDO-IMP. The subendocardial oxygen supply-demand ratio based on ENDO-IMP (IMP-EVR) was significantly less than EVR based on LVP (LVP-EVR) (0.87 +/- 0.03 vs 1.07 +/- 0.06, P less than 0.05) during the control period. With 0.5% halothane administration, IMP-EVR improved significantly (1.04 +/- 0.07, P less than 0.05) while LVP-EVR remained unchanged (1.08 +/- 0.09). No further changes in EVR (either IMP-EVR or LVP-EVR) were observed with increasing halothane concentrations up to 2%. The relationship between the two indices was weak (r2 = 0.44, P less than 0.001) but statistically significant. Because an estimate of EVR based on direct measurement of subendocardial tissue pressure (IMP-EVR) would reflect more accurately the oxygen supply-demand balance of this region than the LVP-EVR, our results suggest that the oxygen balance of the subendocardium improves with halothane administration. The use of LVP-EVR as a hemodynamic index of subendocardial oxygen balance during halothane anesthesia, therefore, is questionable.

Anesthesia↗

A pharmacokinetically designed etomidate infusion regimen for hypnosis.

An etomidate infusion regimen for hypnosis as part of balanced, totally intravenous anesthesia was designed to maintain plasma etomidate concentrations above the awakening concentration of 300 ng/ml while avoiding dose-related side effects. The etomidate infusion regimen of 0.1 mg/kg/min for 3 min, 0.02 mg/kg/min for 27 min, and 0.01 mg/kg/min for the remainder of the anesthesia was used together with intravenous bolus doses of fentanyl, droperidol, and pancuronium. This was evaluated in 11 patients and the kinetics of etomidate were reexamined. The anesthetic technique seemed clinically satisfactory for the infusion periods of 30-109 min. The average time and plasma concentration at the end of the infusion was 59.5 min and 583 ng/ml, at awakening was 9.3 min and 307 ng/ml, and at alertness was 19.5 min and 227 ng/ml. The main difference between the kinetics observed in the present study and those of previous studies is in the elimination clearance. The average plasma elimination clearance of the present study was 1210 ml/min and the whole-blood clearance was estimated to be 1357 ml/min, giving an apparent hepatic extraction ratio of approximately 0.90. The negative correlation of patient mass and elimination clearance normalized for body mass suggests that the terminal infusion should not be adjusted to body mass.

Adult↗

Total intravenous anesthesia with a continuous propofol-alfentanil infusion.

A total intravenous anesthetic using propofol and alfentanil was evaluated to determine if it would provide a shorter recovery-room stay than a more traditional balanced anesthetic using isoflurane and alfentanil. Forty-three ASA I or II patients between 17 and 50 years of age undergoing major abdominal or orthopedic procedures were studied. The propofol group received alfentanil 50 mg/kg followed by propofol 1 mg/kg for anesthesia induction. Continuous propofol infusion was initiated at induction using 170 mg/kg/min for 10 minutes, followed by 130 mg/kg/min for 10 minutes, then maintained at 100 mg/kg/min until 10 minutes before the end of surgery. Ventilation was supported with an air-oxygen mixture. The group receiving balanced anesthesia received alfentanil 1 mg/kg, and anesthesia was induced with sodium thiopental 4 mg/kg. A 1% isoflurane inhalation with air-oxygen was initiated immediately upon induction. Both groups received a continuous infusion of alfentanil titrated to maintain heart rate within 10% of preinduction levels. Recovery from anesthesia was measured using a subjective pain assessment, a verbal fluency test, and a short-term memory test. No differences were detected in the rate of recovery at 30 minutes or 60 minutes postextubation. Hemodynamic stability during induction and intubation was slightly better in the propofol group than in the isoflurane group. One episode each of intraoperative awareness and delayed eye opening occurred in the propofol group. Total intravenous anesthesia using propofol and alfentanil is just as effective as a balanced inhalation anesthetic and provides equally rapid recovery. However, practitioners are cautioned to include an amnestic adjuvant when using propofol as the sole anesthetic agent.

Adolescent↗

Pulmonary hemodynamics during induction of anesthesia.

Changes in pulmonary hemodynamics and acid-base balance were recorded during induction of anesthesia using either intravenous administration of barbiturate (28 patients) or inhalation of N2O-O2-halothane (12 patients). The two types of induction resulted in equal elevations of pressures within the pulmonary circulation. The increase, proportional on the two sides of the heart, was most pronounced immediately before endotracheal intubation. Cardiac index decreased before and during intubation but subsequently increased to levels above control values. Systemic blood pressure increased more during barbiturate than during inhalation induction. Changes in acid-base balance were similar during the two types of induction: arterial blood PCO2 and PO2 increased, pH decreased, and standard bicarbonate remained unchanged. Changes in pulmonary arterial mean pressure and central venous pressure were correlated with changes in PACO2. Pulmonary capillary filtration pressure (i.e., pulmonary capillary wedge pressure minus plasma colloid osmotic pressure) was negative in every patient before anesthesia. During induction of anesthesia, filtration presures became positive in half the patients. Observed changes in circulation may have been caused by hypercapnia alone or by a combination of hypercapnia and vescular reflexes associated with instrumentation during intubation. The increased strain on the heart during induction of anesthesia may lead to cardiac failure in patients with diminished cardiac reserve.

Anesthesia, General↗

Importance of temperature and humidity in the measurement of pulmonary oxygen uptake per breath during anesthesia.

Traditionally, measurement of pulmonary O2 uptake uses mass balance of N2 to correct for differences between inspired and expired volume (V) due to temperature (T) and relative humidity (RH). Often during anesthesia, N2 balance cannot be invoked due to high inspired O2 fraction (FIO2) or nonsteady state conditions. Then, O2 uptake per breath (VO2,br) must use assumed or measured T and RH differences between inspirate and expirate. This numerical analysis study examines how errors in inspired RH and T can affect VO2,br. Equations were developed to simulate a baseline metabolic and ventilatory condition. A unit error in inspired RH of 0.5 (during constant inspired T of 22 degrees C) caused percent errors in VO2,br of 5.6% during FIO2 = 0.2% and 28.8% during FIO2 of unity. Per(-57.6 x FIO2-0.115) VO2,br was given by (change in RH) (R2 > 0.999). Errors in inspired T (during constant inspired RH of 0.5) had similar effects on percent error in VO2,br( =-8.75 x FIO2-0.093) x (change in T) (R2 = 0.999). Because inspired VO2 is larger at higher FIO2 and because VO2,br is the difference between inspired and expired VO2, VO2,br is most affected by the inspired V error at the largest FIO2 . When tissue O2 consumption decreases relative to minute ventilation, T and RH errors have a greater effect on VO2 br because the error in inspired V affects a smaller VO2,br. At lower barometric pressure, RH errors affect VO2,br more because water vapor V occupies a larger fraction of inspired V. In summary, because inspired RH and T can vary significantly during anesthesia, a fast-response humidity and T sensor, combined with flow and FO2 measurements, are needed to allow accurate determination of VO2,br x VO2,br should become an important measure of metabolism and patient wellness during anesthesia.

Anesthesia↗

[Electrolyte balance in major abdominal surgery. IV. Water diuresis under anesthesia and surgery (author's transl)].

12 patients with major laparotomies were studied during anesthesia alone, during three hours of surgery and during the first two hours of recovery. We demonstrated a decrease in plasma potassium and plasma sodium concentration starting with anesthesia and development of a moderate metabolic acidosis. Plasma osmolality was stable during anesthesia and surgery, but slightly decreased in the early postoperative period. Urine formation and osmolar clearance as well as renal sodium and potassium excretion showed a rising tendency during operation, reaching their maximal values in the recovery room. Sodium balance was positive during and after surgery, and sodium retention amounted to about 75% of sodium infused. Urine-to-plasma-osmolality-ratio was 2,0 under anesthesia alone, decreased during surgery and reached control values in the recovery room. In 5 out of 12 patient studied we demonstrated a temporary water diuresis at different points of anesthesia and laparotomy and occasionally even in the postoperative period. This could be due to low plasma levels of ADH caused by relative hypervolemia in the absence of other stimuli of ADH-secretion.

Acidosis↗

[Temperature balance and the possibility of its maintenance during general anesthesia in children].

The problems of hypothermia in the perioperative period, which are one of the most important ones in pediatric practice, in babies in particular, are solved, by using a broad spectrum of methods for preventing and correcting the patients' thermal balance. Convection heating systems exercise an on-line control over the baby's thermal regime during a surgical intervention and intensive care. The authors' own experience allows these systems to be recommended for wide practical application in the activities of anesthesiology and intensive care services.

Anesthesia, General↗

Comparing the efficacy and safety of unilateral versus bilateral spinal anesthesia: a meta-analysis and systematic review.

BACKGROUND: Unilateral spinal anesthesia has gained increasing attention in recent years. Emerging evidence suggests that it provides comparable analgesia to conventional bilateral spinal anesthesia while reducing adverse effects, and its efficacy and safety compared to bilateral spinal anesthesia remains controversial. OBJECTIVE: This systematic review and meta-analysis aims to evaluate and compare the efficacy and safety of unilateral versus bilateral spinal anesthesia. DESIGN: Systematic reviews and meta-analysis of randomized controlled trials (RCTs). DATA SOURCES: A systematic search was conducted across PubMed, EMBASE, and Cochrane Library from inception to December 10, 2024. ELIGIBILITY CRITERIA: Included studies were randomized controlled trials involving adult patients (&#x2265;18&#x2009;years) undergoing surgery under spinal anesthesia, comparing unilateral versus bilateral spinal anesthesia for efficacy and adverse effects. Studies that focused exclusively on either unilateral or bilateral spinal anesthesia were excluded. The comparator group used the same local anesthetic as the experimental group, with no restrictions on adjuncts (e.g. fentanyl, morphine). RESULTS: Nineteen randomized controlled trials including 1191 patients met the inclusion criteria. Compared with bilateral spinal anesthesia, unilateral spinal anesthesia has a longer onset of sensory blockade (MD = 2.58, 95% CI: 0.93 to 4.22, p&#x2009;=&#x2009;0.002), a shorter duration of sensory blockade (MD&#x2009;=&#x2009;-27.83, 95% CI: -39.25 to -16.42, p&#x2009;<&#x2009;0.00001). In addition, unilateral spinal anesthesia significantly reduced the incidence of hypotension (RR = 0.40, 95% CI: 0.31 to 0.52, p&#x2009;<&#x2009;0.0001), nausea and vomiting (RR = 0.20, 95% CI: 0.07 to 0.56, p&#x2009;=&#x2009;0.002), and post-dural puncture headache (RR = 0.44, 95% CI: 0.23 to 0.81, p&#x2009;=&#x2009;0.009). No statistically significant differences were observed in bradycardia and urinary retention. Collectively, these findings support unilateral spinal anesthesia as a strategy that may enhance perioperative safety while maintaining adequate anesthetic efficacy in appropriately selected patients. CONCLUSIONS: Unilateral spinal anesthesia may offer a favorable balance between anesthetic efficacy and safety compared with bilateral spinal anesthesia, although its clinical utility may depend on surgical duration and patient characteristics.

Humans↗