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PubMed1998

Postoperative nitrogen excretion after amino acid-induced thermogenesis under anesthesia.

UNLABELLED: Amino acid infusions during general anesthesia induce thermogenesis and prevent postoperative hypothermia. The effects of increased heat production during anesthesia on postoperative nitrogen balance have not been examined. Therefore, we studied the effect of perioperative amino acid infusions on postoperative nitrogen excretion in 24 patients scheduled for hysterectomy. Seven volunteers not subjected to anesthesia or surgery were used as awake controls. During isoflurane anesthesia, 8 patients received acetated Ringer's solution, and 16 patients received an IV amino acid mixture, 240 kJ/h, before and during anesthesia. Rectal temperature and energy expenditure were measured. The urinary nitrogen content was calculated from urea, creatinine, and urate the day before surgery and for 4 days postoperatively. Diets were recorded. In anesthetized control patients, postoperative nitrogen excretion was less than preoperative levels. Those patients also experienced the largest decrease in core body temperature during anesthesia (1.7+/-0.1 degrees C). All had postoperative shivering. In the amino acid-treated patients, the temperature decrease during anesthesia was less pronounced (1.0+/-0.1 degrees C; P < 0.001) and postoperative shivering disappeared. In addition, the nitrogen excretion was unchanged postoperatively, perhaps indicating an increase in protein turnover known to generate heat. In conclusion, the increase in heat production induced by amino acids reduced hypothermia, abolished shivering, and attenuated/normalized the postoperative nitrogen saving that occurred in patients who did not receive amino acids. IMPLICATIONS: We compared nitrogen excretion before and after surgery in patients who received a saline or amino acid infusion during isoflurane anesthesia. The increase in heat production induced by amino acids reduced hypothermia, abolished shivering, and attenuated/normalized the postoperative nitrogen saving that occurred in patients who did not receive amino acids.

Amino Acids↗
PubMed1988

Anesthesia with halothane and nitrous oxide alters protein and amino acid metabolism in dogs.

General anesthesia in combination with surgery is known to result in negative nitrogen balance. To determine whether general anesthesia without concomitant surgery decreases whole body protein synthesis and/or increases whole body protein breakdown, two groups of dogs were studied: Group 1 (n = 6) in the conscious state and Group 2 (n = 8) during general anesthesia employing halothane (1.5 MAC) in 50% nitrous oxide and oxygen. Changes in protein metabolism were estimated by isotope dilution techniques employing simultaneous infusions of [4,53H]leucine and alpha-[1-14C]-ketoisocaproate (KIC). Total leucine carbon flux was unchanged or slightly increased in the anesthetized animals when compared to the conscious controls, indicating only a slight increase in the rate of proteolysis. However, leucine oxidation was increased (P less than 0.001) by more than 80% in the anesthetized animals when compared with their conscious controls, whereas whole body nonoxidative leucine disappearance, an indicator of whole body protein synthesis, was decreased. The ratio of leucine oxidation to the nonoxidative rate of leucine disappearance, which provides an index of the catabolism of at least one essential amino acid in the postabsorptive state, was more than twofold increased (P less than 0.001) in the anesthetized animals regardless of the tracer employed. These studies suggest that the administration of anesthesia alone, without concomitant surgery, is associated with a decreased rate of whole body protein synthesis and increased leucine oxidation, resulting in increased leucine and protein catabolism, which may be underlying or initiating some of the protein wasting known to occur in patients undergoing surgery.

Amino Acids↗
PubMed1996

Changes in motor activity and biomechanics during balance recovery following cutaneous and muscular deafferentation.

The effects of lower limb deafferentation were examined during execution of a balance recovery step following a forward fall induced by release of an initial inclined posture. The subjects were healthy control subjects and patients with a unilateral loss of the Achilles tendon reflex following S1 radiculitis. Deafferentation of healthy subjects was obtained by unilateral leg ischemia (four subjects) and by foot anesthesia (five subjects). The balance recovery step was characterized by the surface electromyographic (EMG) activity of right and left soleus and tibialis anterior muscles and the kinetics of the center of gravity and center of foot pressure. Experimentally induced and pathological deafferentation decreased the EMG activity of the ipsilateral soleus and lowered the vertical ground reaction force. The lower limb motor activity was more affected by loss of muscle proprioceptive afferents than by loss of plantar cutaneous afferents. Patients showed early and bilateral changes in soleus and tibialis activities, whichever side was affected. The step length of patients was also shorter than that of controls, but it remained similar before and after deafferentation in the healthy subjects. The results are discussed in terms of ipsilateral and crossed pathway connections and functional adaptive strategies.

Achilles Tendon↗
PubMed2006

[Investigating the fractal characteristic of heart rate variability during anesthesia].

By use of fractal analysis indexes-correlation dimension, fractal dimension and scaling exponent, the heart rate variability signals obtained from 38 subjects' ECG during anesthesia are analyzed. The results show that there is an obvious change of fractal characteristic of heart rate variability during anesthesia. The correlation dimension (P < 0.000001) during anesthesia is evidently less than that during consciousness, while the short-range scaling exponent a (P < 0.0001) during consciousness is evidently less than that during anesthesia. These illustrate that the difference in fractal characteristic between anesthesia and well-balanced state can be detected by the fractal analysis of heart rate variability. In the end, the paper poses that the analysis of heart rate variability is fit for monitoring the depth of anesthesia by detrended fluctuation analysis.

Anesthesia↗
PubMed2004

Spinal 2-chloroprocaine: the effect of added dextrose.

UNLABELLED: Spinal 2-chloroprocaine is being investigated as an alternative short-acting spinal anesthetic to replace lidocaine for outpatient surgery. Adding dextrose increases the baricity of solutions and alters the characteristics of spinal anesthesia. In this study, we compared 2-chloroprocaine spinal anesthesia performed with or without the addition of dextrose (1.1%). Eight volunteers underwent 2 spinal anesthetics, receiving 40 mg 2-chloroprocaine (2 mL, 2%) with 0.25 mL saline with one and 0.25 mL 10% dextrose with the other in a double-blinded, randomized, balanced crossover manner. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation, and tourniquet, motor strength measurements, and time to ambulation and void were assessed. Postvoid residual bladder volume was measured via ultrasound. Spinal anesthesia was successful in all subjects and regressed within 110 (80-110) min. There was no significant difference in peak height T4 (T7-C6), time to achieve peak block height (14 +/- 6 min), time for 2-segment regression (44 +/- 9 min), regression to L1 (66 +/- 12 min), tolerance of tourniquet (43 +/- 9 min), or return of motor function (81 +/- 14 min). Mean postvoid residual volume was larger with dextrose (74 +/- 67 mL versus 16 +/- 35 mL; P = 0.02). No subject reported signs of transient neurologic symptoms (TNS). In conclusion, spinal 2-chloroprocaine provides adequate potency with reliable regression, seemingly without TNS. Adding dextrose does not significantly alter spinal block characteristics but increases residual bladder dysfunction. Therefore, the addition of glucose to 2-chloroprocaine for spinal anesthesia is not necessary. IMPLICATIONS: Spinal chloroprocaine provides adequate potency with reliable regression, seemingly without concerns of transient neurologic symptoms, and hence an appealing profile for outpatient surgery. The addition of dextrose does not alter peak block height or tolerance of thigh tourniquet, and increases the degree of residual bladder dysfunction.

Adult↗
PubMed1995

Heat flow and distribution during induction of general anesthesia.

BACKGROUND: Core hypothermia after induction of general anesthesia results from an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions of each mechanism remain unknown. The authors evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution. METHODS: Six minimally clothed male volunteers in an approximately 22 degrees C environment were evaluated for 2.5 control hours before induction of general anesthesia and for 3 subsequent hours. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. To separate the effects of redistribution and net heat loss, we multiplied the change in overall heat balance by body weight and the specific heat of humans. The resulting change in mean body temperature was subtracted from the change in distal esophageal (core) temperature, leaving the core hypothermia specifically resulting from redistribution. RESULTS: Core temperature was nearly constant during the control period but decreased 1.6 +/- 0.3 degree C in the first hour of anesthesia. Redistribution contributed 81% to this initial decrease and required transfer of 46 kcal from the trunk to the extremities. During the subsequent 2 h of anesthesia, core temperature decreased an additional 1.1 +/- 0.3 degree C, with redistribution contributing only 43%. Thus, only 17 kcal was redistributed during the second and third hours of anesthesia. Redistribution therefore contributed 65% to the entire 2.8 +/- 0.5 degree C decrease in core temperature during the 3 h of anesthesia. Proximal extremity heat content decreased slightly after induction of anesthesia, but distal heat content increased markedly. The distal extremities thus contributed most to core cooling. Although the arms constituted only a fifth of extremity mass, redistribution increased arm heat content nearly as much as leg heat content. Distal extremity heat content increased approximately 40 kcal during the first hour of anesthesia and remained elevated for the duration of the study. CONCLUSIONS: The arms and legs are both important components of the peripheral thermal compartment, but distal segments contribute most. Core hypothermia during the first hour after induction resulted largely from redistribution of body heat, and redistribution remained the major cause even after 3 h of anesthesia.

Adult↗
PubMed2005

Effect of postoperative supplemental oxygen on nausea and vomiting after cesarean birth.

Postoperative nausea and vomiting (PONV) has a significant impact on patients and health care providers. Some nonpharmacologic methods may have an effect on PONV. Administration of supplemental oxygen (80%) during and for 2 hours after surgery has been shown to reduce the incidence of PONV from 44% to 22%. However, the effect of limiting supplemental oxygen to the immediate postoperative period on PONV is unknown. The purpose of this study was to test the efficacy of postoperative supplemental oxygen in reducing the incidence of PONV. Patients (n = 106) undergoing cesarean birth were given general anesthesia with 50% oxygen balanced nitrous oxide and in the postoperative period were randomly assigned to 2 groups. Patients in the experimental group received 8 L/min oxygen by a simple face mask for 6 hours. The control group received routine care of oxygen 5 L/min in the PACU and no supplemental oxygen on the ward. Trained nurses evaluated pulse oximetry and PONV after surgery. The incidence of PONV during the first 6 postoperative hours was 28.3% in the experimental group and 24.5% in the control group ( P = .659). There was no statistically significant difference between the 2 groups. In this study, postoperative supplemental oxygen 8 L/min did not prevent PONV in patients undergoing cesarean birth.

Adult↗
PubMed1995

Heat flow and distribution during epidural anesthesia.

BACKGROUND: Core hypothermia after induction of epidural anesthesia results from both an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions of each mechanism remain unknown. The authors thus evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution. METHODS: Twelve minimally clothed male volunteers were evaluated in a approximately 22 degrees C environment for 2.5 control hours before induction of epidural anesthesia and for 3 subsequent hours. Epidural anesthesia produced a bilateral sympathetic block in only six volunteers, and only their results are reported. Shivering, when observed, was treated with intravenous meperidine. Overall heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. To separate the effects of redistribution and net heat loss, we multiplied the change in overall heat balance by body weight and the specific heat of humans. The resulting change in mean body temperature was subtracted from the change in esophageal or tympanic membrane (core) temperatures, leaving the core hypothermia specifically resulting from redistribution. RESULTS: Arm heat content decreased approximately 5 kcal/h after induction of anesthesia, but leg heat content increased markedly. Most of the increase in leg heat content was in the lower legs and feet. Core temperature increased slightly during the control period but decreased 0.8 +/- 0.3 degrees C in the 1st hour of anesthesia. Redistribution, contributing 89% to this initial decrease, required a net transfer of 20 kcal from the trunk to the extremities. During the subsequent 2 h of anesthesia, core temperature decreased an additional 0.4 +/- 0.3 degrees C, with redistribution contributing 62%. Thus, only 7 kcal were redistributed during the 2nd and 3rd hours of anesthesia. Redistribution therefore contributed 80% to the entire 1.2 +/- 0.3 degrees C decrease in core temperature during the 3 h of anesthesia. CONCLUSIONS: Core hypothermia during the 1st hour after induction of epidural anesthesia resulted largely from redistribution of body heat from the core thermal compartment to the distal legs. Even after 3 h of anesthesia, redistribution remained the major cause of core hypothermia. Despite the greater fractional contribution of redistribution during epidural anesthesia, core temperature decreased only half as much as during general anesthesia because metabolic rate was maintained and the arms remained vasoconstricted.

Adjuvants, Anesthesia↗
PubMed1975

Shortened small bowel syndrome. Mackby's operation.

Intestinal infarction is a condition with a high rate of mortality. Progress in the fields of anesthesia, maintenance of electrolyte balance, and intensive postoperative care has made survival possible in a number of patients subjected to extensive resection of the small intestine. Many of these patients, however, later succumb to the effects of malabsorption. In this paper we report on a patient who has undergone massive intestinal resection, because of venous intestinal infarction, and Mackby's operation, with favorable results twelve months postoperatively.

Adult↗
PubMed1999

Effects of pretreatment with cisatracurium, rocuronium, and d-tubocurarine on succinylcholine-induced fasciculations and myalgia: a comparison with placebo.

STUDY OBJECTIVE: To evaluate the efficacy of cisatracurium, rocuronium, and d-tubocurarine in preventing succinylcholine-induced fasciculations and postoperative myalgia in patients undergoing ambulatory surgery. DESIGN: Randomized, prospective, placebo-controlled trial SETTING: Teaching hospital. SUBJECTS: 80 ASA physical status I and II patients scheduled for elective ambulatory surgery with general anesthesia. INTERVENTION: A standardized balanced anesthetic technique was used for all patients. MEASUREMENTS AND MAIN RESULTS: Patients were randomized to receive cisatracurium 0.01 mg/kg, rocuronium 0.06 mg/kg, d-tubocurarine 0.05 mg/kg, or saline, 3 minutes prior to intravenous (i.v.) succinylcholine 1.5 mg/kg. The intensity of fasciculations and intubating conditions were assessed using a four-point rating scale. In addition, the severity of myalgia was assessed using a four-point rating scale in the postanesthesia care unit and at 24 hours postoperatively. No patient complained of any side effects after the administration of the study drug. Fasciculations were observed less frequently (p < 0.05) in the d-tubocurarine and rocuronium groups compared with the placebo and cisatracurium groups. However, there was no difference between the d-tubocurarine group and the rocuronium group (21% vs. 10%, respectively). Although fasciculations occurred less frequently in the cisatracurium group than in the placebo group (59% vs. 85%, respectively), this difference did not reach statistical significance. There was no difference among the four groups in the intubating conditions or the incidence of postoperative myalgia. CONCLUSION: Pretreatment with rocuronium and d-tubocurarine was superior to cisatracurium in preventing succinylcholine-induced fasciculations. However, pretreatment did not have any effect on the incidence of myalgia after ambulatory surgery.

Adult↗
PubMed1992

EEG-assisted titration of propofol infusion during neuroanesthesia: effect of nitrous oxide.

Total intravenous anesthesia (TIVA) with propofol is an alternative to standard techniques for neuroanesthesia. The present study compared the hemodynamic and recovery profiles of 46 neurosurgical patients randomly assigned to one of three different anesthetic treatment groups. Group 1 was anesthetized with a TIVA technique in which propofol was titrated using an EEG-assisted quantification method. Group 2 received a similar propofol-based infusion technique in combination with nitrous oxide. Group 3 (control) received a standard anesthetic technique consisting of thiopental, nitrous oxide, fentanyl, and isoflurane. Significantly less propofol was required in group 2 than in group 1 (7.4 +/- 1.9 vs. 9.0 +/- 1.0 mg/kg/h, respectively). The propofol blood concentration at the first appearance of EEG burst suppression was also higher in group 1 compared to group 2 (5.8 +/- 1.1 vs. 4.8 +/- 0.8 microg/ml). However, 25% of the patients in group 2 were treated for hypotension after induction, compared to none in groups 1 and 3. Hypertensive episodes, on the other hand, were more frequent in groups 1 (43%) and 3 (31%) than in group 2 (12%). Time to awakening was significantly shorter in the control group (6 +/- 6 min) than in groups 1 (14 +/- 10 min) or 2 (12 +/- 16 min). In conclusion, titration of propofol to achieve a burst suppressive EEG pattern resulted in a slower emergence from anesthesia than a standard "balanced" technique. Use of nitrous oxide with propofol produced more hypotension during induction; however, its use improved hemodynamic stability during the maintenance period.

Journal Article↗
PubMed2004

Ambulatory labor analgesia: what does an obstetrician need to know?

A simple statement that describes the degree of the patient's satisfaction with the pain relief from her labor epidural analgesia has often assessed the quality of labor analgesia as perceived by the patient. Many laboring parturients, midwives, obstetricians and anesthesiologists are increasingly concerned by the limitations of traditional epidural labor analgesia. In general, women dislike the inability to void, the often-dense motor block, the feeling of numbness of the lower body, the total lack of the urge to bear down, and the complete perineal anesthesia. Continuous search for balanced labor analgesia that provides relief from pain, while preserving motor function, has led to the development of an ambulatory labor analgesia technique. This article assesses the validity of various strongly advocated opinions as to whether parturients benefit from ambulation in labor and also reviews the current trends in ambulatory labor analgesia.

Analgesia, Epidural↗