Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialMyocardial ischemia and adverse cardiac outcomes in cardiac patients undergoing noncardiac surgery with sevoflurane and isoflurane. Sevoflurane Ischemia Study Group.
Sevoflurane is associated with less tachycardia and coronary vasodilation than isoflurane and thus might be associated with less myocardial ischemia. This multicenter study examined the incidence of myocardial ischemia and adverse cardiac outcomes in adults (40-87 yr) with cardiac disease having elective noncardiac surgery. Patients were randomized to receive either sevoflurane (S) (n = 106) or isoflurane (I) (n = 108) in conjunction with sodium thiopental, vecuronium, fentanyl, and 50%-70% N2O. Intraoperative hemodynamics were maintained within 20% of awake baseline with standard drugs. A Holter monitor was applied 3-24 h before surgery and maintained until 48 h after surgery. Electrocardiograms and blood samples for analysis of the MB isoenzyme fraction of creatine phosphokinase were obtained preoperatively and daily for 48 h postoperatively. Anesthetic exposure (1.79 +/- 0.15 [mean +/- SE] minimum alveolar concentration-hour) and duration of surgery (219 +/- 13 min) did not differ between groups. The incidence of ischemia in the pre-, intra- and postoperative periods, adverse cardiac outcomes (18% occurrence), intraoperative hemodynamic variations (+/-20% change from ward baseline), and administration of adjunct cardiovascular medications were similar between groups. In cardiac patients having noncardiac surgery, sevoflurane was comparable to isoflurane with respect to the incidence of intra- and postoperative myocardial ischemia and in the frequency of adverse cardiac outcomes. ⋯ Surgical patients with heart disease are at risk of heart complications, some of which could be induced by an anesthetic. We compared the incidence of cardiac complications between patients receiving sevoflurane and isoflurane. We found that the frequency of additional heart problems in cardiac patients receiving sevoflurane was not different from that associated with isoflurane.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of inhaled nitric oxide and its combination with intravenous almitrine on Pao2 during one-lung ventilation in patients undergoing thoracoscopic procedures.
The aim of this study was to assess whether hypoxemia during one-lung ventilation (OLV) can be prevented by inhaled nitric oxide (NO) (Part I) or by its combination with intravenous (IV) almitrine (Part II) in 40 patients undergoing thoracoscopic procedures. In Part I, 20 patients were divided into two groups: one received O2 (Group 1) and one received O2/NO (Group 2). In Part II, 20 patients were divided into two groups: one received O2 (Group 3) and one received O2/NO/almitrine (Group 4). In Groups 2 and 4, NO (20 ppm) was administered during the entire period of OLV, and almitrine was continuously infused (16 microg x kg(-1) x min[-1]) in Group 4. Arterial blood gases were measured during two-lung ventilation with patients in the supine position, after positioning in the lateral decubitus position, and then every 5 min for a 30-min period during OLV. During OLV, Pao2 values decreased similarly in Groups 1 and 2. After 30 min of OLV, the mean Pao2 values in Groups 1 and 2 were 132 +/- 14 mm Hg (mean +/- sem) and 149 +/- 27 mm Hg (not significant [NS]), and the Pao2 value was less than 100 mm Hg in four patients in Group 1 and five patients in Group 2. Pao2 values were greater in Group 4 than in Group 3 after 15 and 30 min of OLV. After 30 min of OLV, the mean Pao2 values were 146 +/- 16 mm Hg in Group 3 and 408 +/- 33 mm Hg in Group 4 (P < 0.001). Pao2 was less than 100 mm Hg during OLV (NS) in four patients in Group 3 and in no patient in Group 4. We conclude that NO inhalation alone has no effect on Pao2 evolution during OLV, although its combination with IV almitrine limits the decrease of Pao2 during OLV. This beneficial effect of NO/almitrine could be attributed to an improvement in ventilation-perfusion relationships. ⋯ Decrease in oxygenation during one-lung ventilation is quite common. Our study showed that inhaled nitric oxide alone did not influence Pao2 evolution. We then tried adding intravenous almitrine to nitric oxide with amazingly good results on Pao2. This nonventilatory technique should be of great use during special thoracic acts, such as thoracoscopic procedures.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialLight versus heavy sedation after cardiac surgery: myocardial ischemia and the stress response. Maritime Heart Centre and Dalhousie University.
The influence of light versus heavy sedation after coronary artery bypass graft (CABG) surgery on the development of postoperative myocardial ischemia has not been described. After uncomplicated CABG surgery, 50 patients were randomly assigned to receive LOW (n = 24; target Ramsay Sedation Score [RSS] = 2) or HIGH (n = 26; target RSS = 4) sedation with propofol. Analgesia was provided to maintain a visual analog scale (VAS) pain score <7. Myocardial ischemia was identified perioperatively using continuous 3-lead Holter monitoring. By measuring creatine kinase (CK) MB levels preoperatively, at entry to the intensive care unit (ICU), and every 12 h for 48 h; and by obtaining serial 12-lead electrocardiograms (ECG) (preoperatively; 2, 4, 12, 24, and 48 h after ICU admission, 8:00 AM the morning after surgery; and 5 min pre- and postextubation), myocardial infarction was identified. Endocrine stress response was assessed by measuring serum cortisol levels preoperatively, on admission to the ICU, and 24 h postoperatively. In a subset of patients (LOW n = 10, HIGH n = 11), plasma and urinary catecholamine levels were also measured. There were no between-group differences in demographics, operative course, hemodynamic variables, or cortisol levels while in the ICU. The VAS pain score and target RSS were achieved and sustained, and they differed between groups. There were three myocardial infarctions in each group by CKMB criteria alone. No ECG-identifiable myocardial infarction occurred. The ST segment versus time curve (LOW 187 +/- 295 versus HIGH 1071 +/- 2137 mm/min) differed between groups. Urinary and plasma catecholamine levels were similar between groups over the observation period. We conclude that the use of a reduced sedation regimen in combination with adequate analgesia did not result in an increased endocrine stress response or risk of myocardial ischemia. ⋯ This randomized study of patients after coronary artery bypass surgery examined whether light (versus heavy) sedation with propofol in the intensive care unit was associated with an increased degree of myocardial ischemia. Using techniques to detect myocardial ischemia, including Holter monitoring, electrocardiogram, and myocardial enzyme measurements, no differences were found. We conclude that light sedation does not increase the endocrine stress response or the risk of myocardial infarction.
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Anesthesia and analgesia · Nov 1997
Clinical Trial Controlled Clinical TrialThe effects of premedication on inhaled induction of anesthesia with sevoflurane.
The effects of premedication with midazolam (M), fentanyl (F), or both (B) on induction of anesthesia via a mask with sevoflurane (S) were assessed in 24 healthy volunteers who participated on three occasions, receiving either intravenous (IV) F (2.4 microg/kg), M (36 microg/kg), or B (0.6 microg/kg F, 9 microg/kg M) 5 min before three vital capacity breaths of 8% S, 66% N2O, and O2. At loss of lid-lash reflex (LLR), ventilation was manually assisted until a randomly assigned time of administration was attained, at which time laryngoscopy and tracheal intubation were attempted. The effective times for 50% of subjects (ET50) to loss of LLR were 64 s for M and B and 54 s for F (P < 0.05). The ET50 to acceptable intubating conditions were 4.3, 3.1 and 2.5 min for F, M, and B, respectively. F resulted in more airway management difficulties than M or B. Heart rate was slightly increased before intubation in M. Heart rate increases after intubation were least in F, intermediate in B, and greatest in M. The time to achieve good intubating and airway conditions up to intubation was lowest with M or B. Anesthetic adjuvants did not improve the time to achieve loss of consciousness with anesthetic induction via the face mask with sevoflurane, but they significantly decreased the time to acceptable tracheal intubating conditions. ⋯ Adults can be anesthetized with very few side effects by breathing themselves to sleep with sevoflurane. Giving patients small doses of sedatives intravenously before they inhale an anesthetic can improve the speed and quality of the process of falling asleep.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialThe effect of epidural saline injection on analgesic level during combined spinal and epidural anesthesia assessed clinically and myelographically.
An epidural injection of physiological saline solution after spinal anesthesia may produce a higher level of analgesia than spinal anesthesia alone because of a volume effect. The purpose of this study was to clarify the volume effect caused by epidural injection of saline after spinal anesthesia. Twenty patients undergoing combined spinal and epidural anesthesia for elective surgery whose analgesic levels did not reach the surgical regions 10 min after spinal anesthesia at the L4-5 interspace were randomly assigned to two groups. The control group (n = 10) received no epidural saline injection. The saline group (n = 10) received 10 mL of saline through an epidural catheter at the L2-3 or L3-4 interspace 10 min after spinal anesthesia. In the saline group, the levels of analgesia 15 and 20 min after spinal anesthesia were significantly higher than those in the control group (P < 0.05). Next, we examined the volume effect of epidural injection of saline with myelography using two adult volunteers. In both volunteers, the upper level of the contrast medium, which was injected in the lumbar subarachnoid space, began to increase concurrently with lumbar epidural injection of saline, reaching from L3 to L1 and from L2 to T12. The diameter of the subarachnoid space diminished to less than 25% after injection of saline. We conclude that lumbar epidural injection of saline increases the analgesic level 10 min after spinal anesthesia, probably because of a volume effect. ⋯ In this study, using surgical patients and volunteers, we determined that a lumbar epidural injection of physiological saline solution 10 min after spinal anesthesia produces a higher analgesic level than spinal anesthesia alone because of a volume effect.