Anesthesia and analgesia
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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 TrialThe differential effects of prostaglandin E1 and nitroglycerin on regional cerebral oxygenation in anesthetized patients.
We evaluated the effects of prostaglandin E1 (PGE1) and nitroglycerin (NTG) on regional tissue oxygenation and use in the brain using near infrared spectroscopy (NIRS). Twenty-four patients who underwent elective cardiac surgery were randomly divided into two groups. The study was performed after the induction of anesthesia and before the start of the surgical procedure. After measuring arterial and jugular venous blood gases, cardiovascular hemodynamics, and relative cerebral oxyhemoglobin (HbO2), deoxyhemoglobin, and cytochrome aa3 at the baseline, PGE1 (n = 12) or NTG (n = 12) was infused intravenously at a rate of 0.3 g/kg or 5 g/kg, respectively. Thirty minutes after the start of drug infusion, administration of the drugs was stopped. Both PGE1 and NTG reduced mean arterial pressure to approximately 70% of the baseline value 10, 20, and 30 min after start of drug infusion (P < 0.05). Internal jugular venous pressure increased significantly during NTG but not during PGE1 infusion (P < 0.05). PGE1 increased HbO2 concentration, which was sustained for 30 min after discontinuing the drug. NTG increased HbO2 concentration, but this gradually returned to the baseline level after discontinuation of the drug. Baseline value of jugular oxygen saturation was 64.5% +/- 2.1%, and there was no significant changes during the infusion of PGE1 or NTG. These results demonstrate that both NTG and PGE1 increased cerebral oxygen saturation as measured by NIRS. This may be explained by local cerebral hyperemia without major alteration in flow/metabolism coupling of brain. The onset of this increase was slower and the duration of this effect after discontinuation of the drug was more prolonged with PGE1. These phenomena occurred despite the relatively similar time course of the effect of these two drugs on systemic hemodynamic values. ⋯ The cerebrovascular effects of vasodilators used for induced hypotension are not fully understood. In this study, we used near infrared spectrometry and jugular oxygen saturation measurement to assess the effects of prostaglandin E1 and nitroglycerin on cerebral perfusion. We found that nitroglycerin and prostaglandin E1 increase cerebral oxygen saturation as measured by near infrared spectrometry, but with different time courses. This information will hopefully help anesthesiologists to better maintain adequate regional cerebral oxygenation.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialTeaching the use of fiberoptic intubation for children older than two years of age.
In 144 anesthetized children aged 2-9 yrs, the safety and feasibility of orotracheal fiberoptic intubation, with and without an airway endoscopy mask, were assessed and compared with laryngoscopic intubation. Eight anesthesia residents with experience in adult fiberoptic intubation, but who were beginners in pediatric anesthesia, participated in this study. In a randomized fashion, each resident intubated 18 children (6 in each group). The time (mean +/- SD) to achieve successful intubation was different for laryngoscopic and fiberoptic intubation (34 +/- 17 s and 80 +/- 39 s, respectively; P < 0.001). The use of the airway endoscopy mask further prolonged fiberoptic intubation (167 +/- 121 s, P < 0.001). Spo2 values remained >95% in all patients during conventional laryngoscopy and fiberoptic laryngoscopy with a mask, whereas Spo2 decreased below 95% in 2 of the 48 patients during fiberoptic intubation without a mask. Both patients promptly recovered during ventilation via a face mask. We conclude that teaching the use of fiberoptic intubation in healthy, anesthetized children aged 2-9 yrs is safe and feasible. ⋯ Fiberoptic intubation is a valuable technique of airway management. We studied the feasibility and safety of a training program that could be used for children more than 2 yrs old. This study demonstrates that fiberoptic intubation can be effectively practiced in pediatric patients without increased risk of side effects.
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialNitrous oxide enhances the level of sensory block produced by intrathecal lidocaine.
We examined the effect of nitrous oxide (N2O) administration on the level of sensory block produced by intrathecal lidocaine in patients undergoing transurethral procedures. Twenty minutes after subarachnoid injection of 100 mg (5%) hyperbaric lidocaine, the level of block to pressure sensation was assessed. After establishing the baseline sensory block, patients were randomly assigned to receive either 50% nitrogen (control group) or 50% N2O in oxygen for 10 min, and the sensory level was reassessed. All patients then received 35% oxygen for 5 min, and the level of block to pressure was assessed again. Changes were measured in centimeters and standardized by dividing those results by the height of patients (in centimeters). Ten minutes after nitrogen or N2O administration, a 3.8-cm regression of sensory block was found in the control group, and a 1.8-cm cephalad increase was found in the treatment group (P < 0.0001). Discontinuation of N2O for 5 min resulted in a rapid regression of the level of sensory block (4 cm in the N2O group versus 1.9 cm in the control group, P < 0.0001). However, 5 min after discontinuation of N2O, the overall regression of the sensory block in the control group, when measured from the baseline, was 5.7 cm versus 2.2 cm in the N2O group (P < 0.001). The differences between the two groups before standardization are consistent with those after standardization (t = 9.02 at 10 min, t = 4.24 at 15 min, and t = 3.97 for the overall change at 15 min). The results suggest that inhalation of 50% N2O enhances the level of sensory block produced by intrathecal lidocaine. ⋯ We measured the level of sensory block produced by subarachnoid anesthesia with lidocaine before and after inhalation of 50% nitrous oxide for 10 min. Nitrous oxide enhanced the level of subarachnoid anesthesia with minimal hemodynamic effects. These findings are of clinical importance when subarachnoid anesthesia subsides before the completion of surgery.
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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.