Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2001
Clinical TrialPulmonary arterial pressure can be estimated by transesophageal pulsed doppler echocardiography.
We examined whether pulmonary arterial pressure can be estimated on the basis of pulmonary arterial flow velocity determined via intraoperative pulsed Doppler transesophageal echocardiography (TEE) in 20 patients undergoing cardiac surgery. Standard pulmonary artery measurements were taken as well. Measurements were taken before sternotomy, after pericardiotomy, after cardiopulmonary bypass, and after sternum closure. ⋯ PEP/AT also showed close correlation with mPAP (r = 0.764) and log mPAP (r = 0.777). Significant agreement between sPAP and mPAP values calculated from a regression equation and values measured via pulmonary artery catheter was observed by plotting the differences against the mean values of the two measurements. We therefore conclude that noninvasive estimation of pulmonary arterial pressure is feasible via intraoperative TEE when sternotomy is not involved.
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Anesthesia and analgesia · Jun 2001
Modulations of spinal serotonin activity affect the development of morphine tolerance.
To test whether modulations of spinal serotonin (5-HT) levels would affect the development of morphine tolerance, we treated rats with either intrathecal 5-HT or 5,7-dihydroxytryptamine (5,7-DHT; a 5-HT neurotoxin) in addition to systemic infusion with morphine (2 mg x kg(-1) x h(-1)). Continuous infusion of 5-HT (10 microg x 6 microL(-1) x h(-1)) into the lumbar subarachnoid space of rats for 9 h accelerated the development of morphine tolerance. The area under the curve for the tail-flick latency test was 454.1 +/- 35.1 in the Sham Control group vs 327.6 +/- 41.0 in the 5-HT-Infused group. mu-opioid receptor binding in the lumbar spinal cord showed a decrease in the Bmax (maximal binding -46.5%), but not the binding affinity (Kd), in 5-HT-infused rats. ⋯ The binding study indicated that the affinity of lumbar micro-opioid receptors decreased 196% in 5-HT-depleted rats, whereas there was no effect on apparent binding. The infusion of 5-HT (10 microg x 6 microL(-1) x h(-1)) was not analgesic and the 5,7-DHT-induced lesion did not affect acute morphine-induced analgesia. We conclude that activity of spinal 5-HT-containing neurons plays a crucial role during the development of morphine tolerance.
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Anesthesia and analgesia · Jun 2001
Clinical TrialCardiovascular responses to scalp infiltration with different concentrations of epinephrine with or without lidocaine during craniotomy.
Intraoperative blood pressure changes alter cerebral blood flow in neurosurgical patients with impaired autoregulation. Infiltration of the scalp before craniotomy may cause hemodynamic changes that depend on the composition of the solution used. We investigated cardiovascular responses to infiltration of the scalp with five different combinations of epinephrine and lidocaine in 112 patients: Group A, lidocaine 0.5%; Group B, lidocaine 0.5% with epinephrine 1:200,000; Group C, lidocaine 0.5% with epinephrine 1:100,000; Group D, normal saline with epinephrine 1:200,000; and Group E, normal saline with epinephrine 1:100,000. ⋯ In conclusion, epinephrine 1:100,000 causes significant tachycardia. Epinephrine in concentrations of 1:100,000 and 1:200,000 causes significant hypertension. The combination of lidocaine and epinephrine attenuates the hypertension but results in a biphasic hypotensive response.
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Anesthesia and analgesia · Jun 2001
Dose-response characteristics of midazolam for reducing diaphragmatic contractility.
A sedative dose of midazolam decreases contractility of the diaphragm, but no data are available concerning the relationship between dose and diaphragmatic contractility. We studied the dose-response characteristics of midazolam for reducing the diaphragmatic contractility in dogs. Animals were divided into three groups of eight each: Group 1 received no study drug, Group 2 was infused with a sedative dose of midazolam (0.1 mg/kg initial dose plus 0.1 mg x kg(-1) x h(-1) maintenance dose), and Group 3 was infused with an anesthetic dose of midazolam (0.1 mg/kg initial dose plus 0.5 mg x kg(-1) x h(-1) maintenance dose). ⋯ Compared with Group 1, Pdi and Edi for each stimulus decreased during midazolam infusion in Groups 2 and 3 (P < 0.05). The decrease in Pdi and Edi was more in Group 3 than in Group 2 (P < 0.05). We conclude that midazolam decreases, in a dose-dependent manner, contractility of the diaphragm in dogs.