Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1995
Clinical Trial Controlled Clinical TrialA pharmacokinetic and pharmacodynamic evaluation of milrinone in adults undergoing cardiac surgery.
Milrinone can reverse acute postischemic myocardial dysfunction after cardiopulmonary bypass, although neither the appropriate bolus dose nor its pharmacokinetics has been established for cardiac surgical patients. Consenting patients undergoing cardiac surgery received milrinone (25, 50, or 75 micrograms/kg) in an open-label, dose-escalating study if their cardiac index was < 3 L.min-1.m-2 after separation from bypass. Heart rate, mean arterial blood pressure, pulmonary capillary wedge pressure, and cardiac index were determined before and after the administration of milrinone. ⋯ Similarly, the following clearances were estimated for the three compartments: Cl1 = 0.067 L/min, Cl2 = 1.05 L/min, and Cl3 = 0.31 L/min. The 50-micrograms/kg loading dose appeared more potent than the 25-micrograms/kg dose, and, as potent, but with possibly fewer side-effects than the 75-micrograms/kg dose. The short context-sensitive half-times of 6.7 or 10.2 min after 1- or 10-min bolus infusions underscore the need for prompt institution of a maintenance infusion when milrinone concentrations must be maintained.(ABSTRACT TRUNCATED AT 400 WORDS)
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Anesthesia and analgesia · Oct 1995
Comparative StudyNeuroanesthesia adjunct therapy (mannitol and hyperventilation) is as effective as cerebrospinal fluid drainage for prevention of paraplegia after descending thoracic aortic cross-clamping in the dog.
We compared cerebrospinal fluid (CSF) drainage (Group D; n = 8) to neuroanesthesia adjunct therapy (hyperventilation and mannitol administration; Group N; n = 8) for the prevention of paraplegia using a canine model of descending thoracic aortic cross-clamping (AXC; 2.5 mm distal to the left subclavian artery for 30 min). We expected no difference in neurologic outcome between groups. After surgical preparation and a 30-min stabilization period, dogs in Group D had CSF drained prior to application of the AXC. ⋯ At precisely 24 h after AXC, the animals were assessed for incidence and severity of paraplegia, using the Tarlov score, by an observer unaware of the experimental protocol. The animals were then killed, and the entire spinal cord was removed for histologic assessment. Multiple sections of the lumbar spinal cord were processed and stained with hematoxylin and eosin, then examined by light microscopy for nonviable neurons in the anterior spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Oct 1995
Comparative StudyComparison of isoflurane and desflurane anesthetic depth using burst suppression of the electroencephalogram in neurosurgical patients.
We compared the anesthetic effects of desflurane and isoflurane using percent burst suppression of the electroencephalogram (EEG) as an end-point in 10 neurosurgical patients. The EEG was recorded from frontal leads and processed variables were analyzed as a function of increasing isoflurane and desflurane concentration with age and baseline delta EEG power (0.5-3.75 Hz) as independent variables. Isoflurane and desflurane (0.5, 1.0, 1.5, 2.0 minimum alveolar anesthetic concentration [MAC]) were incrementally administered until the EEG was quiesecent at least 40% of the time. ⋯ Patients with baseline delta EEG power > 80% of total power produced no change in EEG frequency with increasing anesthesia but revealed a greater sensitivity to the development of burst suppression. These results show that isoflurane and desflurane produce similar EEG suppression in neurosurgical patients. If the EEG is initially slow, further slowing cannot be used to assess anesthetic depth.
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Anesthesia and analgesia · Oct 1995
The effect of midazolam on left ventricular pump performance and contractility in anesthetized patients with coronary artery disease: effect of preoperative ejection fraction.
Forty patients undergoing coronary artery bypass grafting were studied, of whom 24 had depressed global left ventricular (LV) function at preoperative catheterization, to evaluate the effects of midazolam on LV pump performance and contractility. Transesophageal echocardiography and simultaneous hemodynamic measurements were used to assess LV preload, afterload, and systolic performance during inhalation of 100% O2 and after 0.1 mg/kg of midazolam. Systolic function indices were expressed as a percent of the predicted value for observed end-systolic stress to estimate LV contractility. ⋯ As a result, systolic function decreased in relation to observed end-systolic stress, providing evidence of reduced LV contractility. Thus, midazolam administration (0.1 mg/kg) caused no change in cardiac pump performance but decreased LV contractility in the entire population. Myocardial contractility was lower at baseline and after the administration of midazolam in the depressed ejection fraction group, but the decrease in contractility was not exaggerated in the depressed ejection fraction group.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Oct 1995
The arterial to end-tidal carbon dioxide difference in neurosurgical patients during craniotomy.
PETCO2 is often used as an estimate of PaCO2, with the understanding that PaCO2 usually exceeds PETCO2. During intraoperative craniotomies, because hyperventilation is used to therapeutically lower intracranial pressure, the difference between PaCO2 and PETCO2 (P(a-ET)CO2) has therapeutic implications. The P(a-ET)CO2 was hypothesized to be stable during craniotomies with relatively short-term monitoring and controlled cardiorespiratory variables. ⋯ On comparison of subsequent measurements, 18.4% of changes in PaCO2 and PETCO2 (although sometimes small) were in opposite directions. P(a-ET)CO2 did not change with time. The PETCO2 does not provide a stable reflection of PaCO2 in many patients undergoing craniotomies.