Anesthesia and analgesia
-
Anesthesia and analgesia · Aug 1997
Randomized Controlled Trial Clinical TrialEffect of dexmedetomidine on lumbar cerebrospinal fluid pressure in humans.
Dexmedetomidine's potential for analgesia without respiratory depression and its opioid- and anesthetic-sparing properties make it an attractive choice as an anesthetic adjunct for patients undergoing neurosurgery. However, the effects of dexmedetomidine on intracranial pressure are not known. We therefore studied the effect of dexmedetomidine on lumbar cerebrospinal fluid (CSF) pressure in patients after transphenoidal pituitary tumor surgery. Sixteen transphenoidal pituitary tumor surgery patients were randomized to receive placebo (n = 9) or dexmedetomidine (n = 7) for 60 min in the postanesthesia care unit. The study drug was administered by a continuous computer-controlled infusion to achieve an estimated plasma dexmedetomidine concentration of 600 pg/mL, the highest plasma concentration that has been used for clinical purposes. Patient-controlled analgesia was used to administer morphine for postoperative discomfort. Lumbar CSF pressure (via lumbar intrathecal catheter), intraarterial blood pressure, and heart rate were monitored continuously. There was no change in lumbar CSF pressure in either group. The highest values obtained were 19 mm Hg in the dexmedetomidine group and 20 mm Hg in the placebo group. During infusion, mean arterial pressure decreased from 103 +/- 10 mm Hg to 86 +/- 6 mm Hg (P < 0.05), heart rate decreased from 77 +/- 12 bpm to 64 +/- 7 bpm (P < 0.05), and cerebral perfusion pressure decreased from 95 +/- 8 mm Hg to 78 +/- 6 mm Hg (P < 0.05) in the dexmedetomidine group, but not in the placebo group. We conclude that dexmedetomidine does not have an effect on lumbar CSF pressure in patients with normal intracranial pressure who have undergone transphenoidal pituitary hypophysectomy. ⋯ The effects of dexmedetomidine (an alpha2-agonist) or placebo on lumbar cerebrospinal fluid pressure, measured via an intrathecal catheter, were studied postoperatively in 16 patients. Dexmedetomidine had no effect on lumbar cerebrospinal fluid pressure. We will continue to investigate the potential utility of dexmedetomidine for neurosurgical anesthesia.
-
Anesthesia and analgesia · Aug 1997
Randomized Controlled Trial Clinical TrialThe effect of ephedrine on the onset time of rocuronium.
-
Anesthesia and analgesia · Aug 1997
Comparative StudyLaser Doppler skin blood flow and sympathetic nervous responses to surgical incision during halothane and isoflurane anesthesia.
The aim of the present study was to evaluate whether a sudden decrease in skin blood flow measured using a laser Doppler velocimeter reflects sympathetic nervous response to surgical skin incision during halothane (n = 17) and isoflurane (n = 16) anesthesia in 33 ASA physical status I or II patients scheduled for laparotomy. Plasma norepinephrine concentrations in the responding patients who showed a sudden decrease in the skin blood flow after surgical incision increased significantly and continued to increase 1-10 min after skin incision under halothane and isoflurane anesthesia. Although plasma norepinephrine concentrations in the nonresponders did not increase after surgical incision with halothane, the concentrations increased significantly at 1 min, but not at 3 and 10 min, after skin incision with isoflurane. ⋯ Plasma epinephrine concentration increased during skin incision, but the concentrations did not differ between the patients with and without a sudden decrease in skin blood flow. Increases in systolic blood pressure and rate-pressure product on skin incision were also significantly more in patients with skin blood flow response compared with those without the response. The magnitude of changes in plasma norepinephrine concentration and hemodynamic variables with skin incision was greater with isoflurane than with halothane at the same minimum alveolar anesthetic concentration level.
-
Anesthesia and analgesia · Aug 1997
Does the platelet-activated clotting test (HemoSTATUS) predict blood loss and platelet dysfunction associated with cardiopulmonary bypass?
Platelet dysfunction is a major cause of bleeding after cardiopulmonary bypass (CPB). No timely, simple, point-of-care determinant of platelet function is available for clinical use. Adding platelet-activating factor to conventional activated clotting time methods (platelet-activated clotting test [PACT]) (HemoSTATUS; Medtronic, Inc., Parker, CO) produces rapid results (<3 min) and may yield a measure of platelet responsiveness and whole blood procoagulant activity. ⋯ The PACT had a sensitivity and specificity comparable to routine laboratory coagulation tests in predicting blood loss. The TEG maximum amplitude, however, was more predictive than both the PACT and routine coagulation tests in this respect. The PACT may be a useful indicator of platelet responsiveness or whole blood procoagulant activity, but we did not find it superior to other tests of coagulation function for predicting excessive blood loss after CPB.
-
Anesthesia and analgesia · Aug 1997
Comparative StudyRadial artery diameter decreases with increased femoral to radial arterial pressure gradient during cardiopulmonary bypass.
A clinically significant femoral to radial artery pressure gradient sometimes develops during cardiopulmonary bypass (CPB), but the mechanism responsible is not clear. We investigated when the pressure gradient developed and what mechanism could be responsible by comparing mean femoral to mean radial artery pressure and radial artery diameter in 75 male patients undergoing coronary artery bypass grafting. A pressure gradient > or =5 mm Hg (High-P) occurred in 38 patients, and the remaining 37 patients had pressure gradients <5 mm Hg (Low-P) at sternal closure. In High-P group, the pressure gradient was significantly greater (4.8 +/- 3.1 vs 1.0 +/- 3.1 mm Hg; P < 0.001) than in Low-P group, and the ratio of radial artery diameter to the diameter after induction of anesthesia was significantly decreased (0.79 +/- 0.12 vs 0.87 +/- 0.14; P = 0.006) at 5 min after aortic clamping. The pressure gradient and the arterial diameter changes persisted until sternal closure. There was a negative linear correlation between the pressure gradient (deltaP) and the radial artery diameter ratio (D) at sternal closure (D = -15.0deltaP + 16.6, r = 0.39, P < 0.001). In a subgroup of 11 High-P patients, palm temperature was significantly lower (P < 0.05) than that of 11 Low-P patients during and after CPB. We conclude that the femoral to radial artery pressure gradient develops by 5 min after aortic clamping during CPB and persists until sternal closure, and that radial artery constriction could be responsible for the pressure gradient. ⋯ A femoral to radial pressure gradient has been observed after cardiopulmonary bypass. Arterial vasodilation and vasoconstriction have been considered as causes for this gradient. We measured radial artery diameter using pulsed Doppler ultrasound and examined radial artery vasodilation versus vasoconstriction as possible mechanisms for the pressure gradient.