No abstract available.
Resuscitation*

BACKGROUND: Atracurium is a benzylisoquinolium nondepolarizing neuromuscular blocking drug. It releases histamine upon the rapid administration of more than 2 x ED95. Cisatracurium is about three to four times more potent than atracurium, less likely to release histamine, and has weaker cardiovascular or autonomic effects. Mivacurium releases histamine to about the same degree as atracurium at the same dose. This study was undertaken to reevaluate the experimental model for the evaluation of effects on the autonomic nervous system, and to determine the neuromuscular blocking profiles and the vagolytic effects of atracurium, cisatracurium and mivacurium in cats. METHODS: Cats, either sex, anesthetized with pentobarbital, were used. Neuromuscular blocking effects were assessed using the effects on the anterior tibialis muscle twitch evoked with supramaximal stimuli (0.2 ms-duration, 0.1 Hz). Inhibition of the parasympathetic nervous system was assessed in response to bradycardia to vagal nerve stimulation with ten-second trains of square-waves (0.5 ms-duration, 20 Hz). The dose-response curves for both neuromuscular blocking and vagolytic actions were determined for each animal. The dose-response curves were constructed in cumulative fashion. The response for vagal stimuli was measured two minute after each dosing. Vagal ID50 (The doses that produced 50% inhibition of the response to vagus nerve stimulation) were determined. RESULTS: NMB ED95 and NMB ED50, respectively, were 102.0 +/- 28.3 and 143.7 +/- 40.5 microgram/kg for atracurium, 81.4 +/- 13.3 and 110.7 +/- 18.8 microgram/kg for cisatracurium, and 56.8 +/- 17.4 and 74.2 +/- 25.0 microgram/kg for mivacurium. Vagal ID50 was 2,654 +/- 1,651 microgram/kg for atracurium, 655 +/- 389 microgram/kg for cisatracurium, and 606 +/- 182 microgram/kg for mivacurium. The vagal ID50/NMB ED95 and vagal ID50/NMB ED50 were 18.5 and 26.0 for atracurium, 5.9 and 8.1 for cisatracurium, and 8.2 and 10.7 for mivacurium. CONCLUSIONS: Atracurium has a wider margin of safety only for vagal stimulation as compared with cisatracurium and mivacurium. However, we couldn't exclude that either sympathetic stimulation or histamine release might contribute to heart rate.
Animals ; Atracurium* ; Autonomic Agents ; Autonomic Nervous System ; Bradycardia ; Cats* ; Heart Rate ; Histamine ; Histamine Release ; Models, Theoretical ; Neuromuscular Blockade* ; Parasympathetic Nervous System ; Pentobarbital ; Vagus Nerve ; Vagus Nerve Stimulation

With an increase in the elderly population and an increase in the prevalence of age-related cardiovascular disease, anesthesiologists are increasingly being faced with elderly patients with known or suspected ischemic heart disease in the perioperative period. Although early reperfusion remains the best strategy to reduce ischemic injury, reperfusion may damage the myocardium. Adjuvant therapy to revascularization is therefore necessary. To develop better strategies to prevent ischemia-reperfusion injury in older patients, we need to understand the aged myocardium, which has undergone structural and functional changes relative to the normal myocardium, resulting in reduced functional capacity and vulnerability to ischemia-reperfusion injury. In addition, innate or acquired cardioprotection deteriorates with aging. These changes in the aged myocardium might explain why there is poor translation of basic research findings from young animals to older patients. In this review, I discuss changes in intracellular signaling associated with myocardial ageing that have an effect on ischemia-reperfusion injury, and I discuss the efficacy of cardioprotection afforded by ischemic and pharmacologic pre-and post-conditioning in the aged myocardium. Finally, I outline strategies to restore protection in the aged myocardium.
Aged ; Aging ; Animals ; Cardiovascular Diseases ; Diet ; Humans ; Myocardial Ischemia ; Myocardium ; Perioperative Period ; Prevalence ; Reperfusion ; Reperfusion Injury

BACKGROUND: The speed of injection of local anesthetic solutions into the subarachnoid space may influence the spread of these agents in the cerebrospinal fluid by the amount of turbulence generated, especially with large volume. To determine the proper injection speed of anesthetics in hypobaric spinal anesthesia on jack-knife position, the anesthetic level and duration were measured with the fast or slow injection speed. METHODS: Twenty patients for perianal surgery in jack-knife position under hypobaric spinal anesthesia were randomly assigned to one of two groups. Tetracaine (0.1%) in distilled water 5 ml was administered to all the patients. Group I patients received the drug with the speed of injection as 5 ml/20 sec (15 ml/min) and the others (Group II) as 5 ml/4 min (1.25 ml/min). The mean arterial pressures and heart rates at the preanesthetic period, and 5, 10, 15 and 20 min after the end of injection were measured. The anesthetic levels at 5, 10, 15 and 20 min after the injection and anesthesia duration were measured. RESULTS: There was no significant difference in mean arterial pressures, heart rates and anesthetic duration between two groups. The anesthetic level 20 min after the injection was higher in Group I than Group II, and not different at the other time sequences. CONCLUSION: At the injection speed within 1.25-15 ml/min in hypobaric spinal anesthesia on jack-knife position at 15o head-down, we acquired appropriate anesthetic level and duration for perianal surgery without any undesirable effects.
Anesthesia ; Anesthesia, Spinal* ; Anesthetics ; Arterial Pressure ; Cerebrospinal Fluid ; Head-Down Tilt* ; Heart Rate ; Humans ; Subarachnoid Space ; Tetracaine* ; Water

It is important to consider the fetal, uteroplacental, and maternal issues when choosing anesthetic technique for fetal surgery. The twin reversed arterial perfusion (TRAP) sequence, or the acardiac anomaly, occurs in 1:100 monozygous multiple pregnancies and in 1:35,000 births. The TRAP sequence is characterized by placental vascular arterio-arterial anastomosis between twin fetuses, one an acardiac/acephalic twin that receives its blood flow from the normal pumping twin, thereby endangering the normal twin by high output cardiac failure. The acardiac twin is nonviable, and perinatal mortality in the pump cotwin exceeds 50% because of cardiac failure and prematurity. This can be managed by fetal surgery. We report on a patient with a 26-wk gestation complicated by an acardiac/acephalic fetus anesthetized for surgical umbilical cord ligation.
Anesthesia* ; Female ; Fetus ; Heart Failure ; Humans ; Ligation ; Parturition ; Perfusion* ; Perinatal Mortality ; Pregnancy ; Pregnancy, Multiple ; Umbilical Cord

BACKGROUND: Lidocaine's sedative effect has not been known well. The purpose of this study was to evaluate its sedative and cardiovascular effects during induction of anesthesia. METHODS: Twenty patients were randomly allocated to group I or II, with or without lidocaine 1.5 mg/kg intravenously (IV) before induction, respectively. The BIS, blood pressure and heart rate were measured at before and 2 minutes after lidocaine IV injection, preintubation, and 1, 2, 3 and 5 minutes after tracheal intubation. The enflurane concentrations were continuously maintained at 2 volume%. RESULTS: The BIS of group I was more decreased at 1 and 2 minutes after intubation than those of group II. The systolic blood pressures of group I were less increased at 1 and 2 minutes after intubation than those of group II. The diastolic blood pressures and heart rates of group I were not different from those of group II at each stage of the procedure. CONCLUSIONS: Lidocaine reduced BIS and blunted the intubation-induced systolic hypertensive response. In addition it is thought that it has a sedative effect and is effective to maintain cardiovascular stability after tracheal intubation.
Anesthesia ; Blood Pressure ; Enflurane ; Heart Rate ; Humans ; Hypnotics and Sedatives* ; Intubation ; Intubation, Intratracheal* ; Lidocaine*

Mishaps related to valve malfunction in a self-inflating bag-valve unit can lead to fatal complications. We report a case of severe hypotension that resulted from the locking of the Laerdal valve in the inspiratory position during transport in the operating room. A 36 year old man had undergone an off-pump coronary artery bypass graft. Immediately before leaving the operating room, severe hypotension developed abruptly. But an EKG showed only a reduction of heart rate. We started closed cardiac massage with an intravenous bolus injection of epinephrine 0.5 microgram and reconnected the anesthesia breathing circuit. The patient was manually ventilated using the anesthesia reservoir bag. Vital signs immediately recovered. At that time, the patient's abdomen was distended and we suspected an expiratory abnormality. The self-inflating bag-valve unit was tested with an anesthesia reservoir bag as a test lung. Expiration did not occur. Another self-inflating bag-valve unit was substituted and normal ventilation was restored. It is essential that before use, a self-inflating bag-valve unit should be tested for proper function during both expiration and inspiration using a test lung such as, an anesthesia reservoir bag.
Abdomen ; Adult ; Anesthesia ; Coronary Artery Bypass, Off-Pump ; Electrocardiography ; Epinephrine ; Heart Massage ; Heart Rate ; Humans ; Hypotension* ; Lung ; Operating Rooms ; Respiration ; Resuscitation ; Transplants ; Ventilation ; Vital Signs

BACKGROUND: Remifentanil has been shown to be effective at treating potentially adverse hemodynamic responses to tracheal intubation even at low doses (< 1 microg/kg/min), which needs to be evaluated in patients with diverse cardiovascular conditions. METHODS: A low-dose regimen of remifentanil (continuous infusion of 0.1 microg/kg/min, preceded by 0.5 microg/kg bolus) was given before induction with bolus propofol and rocuronium, and heart rate as well as systolic, diastolic, and mean arterial pressures were measured at 1 min intervals from before induction to 5 min after tracheal intubation in normotensive patients, untreated hypertensive patients, and patients with known hypertension. RESULTS: The low-dose regimen of remifentanil resulted in parallel hemodynamic responses in all three groups, and was effective at limiting hemodynamic responses to tracheal intubation without excessive cardiovascular depression. Hemodynamic responses in our study showed a similar pattern to that reported in previous investigations, except for elevations in heart rate and arterial pressures over the baseline values immediately after intubation. CONCLUSIONS: We suggest that the low-dose regimen of remifentanil in our study could be routinely used to modify hemodynamic responses to tracheal intubation in patients with diverse hemodynamic characteristics. However, the development of supplementary regimens is still needed to control the brief, but exaggerated responses to tracheal intubation, especially in untreated hypertensive patients.
Androstanols ; Arterial Pressure ; Depression ; Heart Rate ; Hemodynamics ; Humans ; Hypertension ; Intubation ; Piperidines ; Propofol

This study was aimed to elucidate the endothelium-dependent vascular effects of halothane and sevoflurane on rabbit aortic rings at two conventional concentrations(high induction and low maintenance concentration in human). Isometric tenslon was recorded in isolated aortic rings. Preparations of rabbit thoracic aorta were suspended in Krebs' buffer and aerated with 95% O2 and 5% CO2. One set of the rings had intact endothelium and the other set of the rings had endothelium mechanically denuded. In the first experiments, the rings were precontracted with norepinephrine(NE) of 10-7 M. After tension was stabilized in 10~15 minutes following NE, halothane(1, 2%) or sevoflurane(2, 4%) was bubbled with O2/CO2 gas mixture at increasing concentrations. In the second experiment, O2/CO2 gas mixture only(control rings), halothane 2% or sevoflurane 4 % with O2/CO2, gas mixture was bubbled for 10(-7) minutes prior to and during contraction with NE of 10M. After tension was stabilized following NE, acetylcholine(10(-8)-10(-6) M) was added cumulatively. In the third experiment, the procedure was as same as the second experiment except for that acetylcholine(10(-8)-10(-6) M) was substitued for nitroglycerin (10(-9)-10(-6) M) . The present study demonstated that both of halothane and sevoflurane at high concentration caused a vasoconstriction to 110.7+/-4.2% and 122.4+/-8.4% in vascular rings with intact endothelium, and 106.1+/-1.9% and 118.3+/-3.5% in vascular rings with denuded endothelium, respectively, compared to each control value of 100%. Furthermore, halothane and sevoflurane attenuated the acetylcholine induced relaxing response in NE-precontracted vascular rings with intact endothelium, but did not affect any change of tension in vascular rings with denuded endothelium. Halothane and sevoflurane did not attenuate the nitroglycerin induced relaxing response in NE-precontracted vascular rings with both intact and denuded endothelium. In conclusion, halothane and sevoflurane at high concentration has vasoconstrictory effects on vascular smooth muscles in rabbit aortic rings regardless of presence of endothelium and also attenuated the endothelium-dependent relaxation.
Acetylcholine ; Aorta, Thoracic ; Endothelium* ; Halothane* ; Muscle, Smooth, Vascular ; Nitroglycerin ; Norepinephrine ; Relaxation ; Vasoconstriction

BACKGROUND: Cisatracurium is a nondepolarizing muscle relaxant. It less likely release histamine and has better cardiovascular stability. It presumably undergoes pH and temperature- dependent, nonenzymatic chemical process, Hofmann reaction. In vitro studies, Hofmann reaction was enhanced with increasing pH, but, in vivo the influence of acid-base imbalance is not well defined. METHODS: To evaluate the effects of acid-base imbalance on the neuromuscular blockade of cisatracurium in the cat, we induced acid-base imbalance and performed cumulative dose-response studies. RESULTS: ED50 of the cisatracurium was significantly reduced in all groups. Dose-response curves from all acid-base imbalance groups did not have significant differences in slopes. But, all showed shift-to-left when compared with control curve, showing decreased ED50. Duration of action was not affected. Recovery index was significantly changed in respiratory and metabolic alkalosis. CONCLUSIONS: It may be concluded that acid-base imbalance significantly augmented the potency of cisatracurium, but, changes of recovery index in this study may be resulted from systemic instability such as unstable hemodynamic state by the prolonged experiment.
Acid-Base Imbalance* ; Alkalosis ; Animals ; Cats* ; Chemical Processes ; Hemodynamics ; Histamine ; Hydrogen-Ion Concentration ; Neuromuscular Blockade*