Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1988
The temperature of bupivacaine 0.5% affects the sensory level of spinal anesthesia.
Three milliliters of plain bupivacaine 0.5% was injected intrathecally in two groups of 20 patients. Group 1 received a solution that had been equilibrated to 37 degrees C, group 2 received a solution that had been equilibrated to 4 degrees C. ⋯ The differences between segmental levels of sensory loss between groups 1 and 2 (T4 and T9, respectively) and of temperature loss (T3 and T8, respectively) 10 and 20 minutes after injection of bupivacaine were statistically significant. It is concluded that the time needed for thermal equilibration in the cerebrospinal fluid and hence temperature of the injected solution plays an important role in the sensory spread of plain bupivacaine 0.5%.
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Anesthesia and analgesia · Mar 1988
Regional hemodynamics and oxygen supply during isovolemic hemodilution alone and in combination with adenosine-induced controlled hypotension.
Studies were performed in ten pentobarbital-anesthetized, open chest dogs to evaluate regional circulatory effects of isovolemic hemodilution alone, and in combination with adenosine-induced controlled hypotension. Regional blood flow measured with 15-microns radioactive microspheres was used to calculate regional oxygen supply. Hemodilution with 5% dextran (40,000 molecular weight) reduced arterial hematocrit and oxygen content by approximately one-half and caused heterogeneous changes in regional blood flows; flow decreased in the spleen, was unchanged in the renal cortex, liver, skeletal muscle and skin, and increased in the duodenum, pancreas, brain and myocardium; however, only in the brain and myocardium were increases in flow sufficient to preserve oxygen supply. ⋯ In the myocardium, direct coronary vasodilation by adenosine caused parallel increases in blood flow and oxygen supply to levels exceeding prevailing metabolic requirements. It is concluded that 1) during isovolemic hemodilution alone, oxygen supply to the brain and myocardium is maintained at the expense of oxygen supply to less critical organs and, 2) during combined isovolemic hemodilution and adenosine-induced hypotension, oxygen is oversupplied to the myocardium but undersupplied to the brain and kidney. These latter effects suggest the need for extensive clinical monitoring of patients in whom combined isovolemic hemodilution and adenosine-induced hypotension is utilized.
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Anesthesia and analgesia · Feb 1988
Clinical TrialIonized hypocalcemia after fresh frozen plasma administration to thermally injured children: effects of infusion rate, duration, and treatment with calcium chloride.
A number of cardiac arrests and severe hypotensive episodes have been witnessed associated with the intravenous infusion of fresh frozen plasma (FFP). To clarify the possible role of hypocalcemia, 28 thermally injured anesthetized pediatric patients with massive blood loss were studied to examine the cardiovascular responses (mean arterial pressure [MAP], heart rate, ECG) to 49 infusions of FFP. Rapid, statistically significant reductions in ionized calcium ([Ca2+]) followed each of four rates (1.0, 1.5, 2.0, and 2.5 ml.kg-1.min-1 for 5 minutes) of FFP infusion (P less than 0.0001). ⋯ Adverse cardiovascular responses and reduced [Ca2+] were not significantly different between 5- and 10-minute FFP infusions. Fewer fluctuations in MAP occurred when calcium chloride (CaCl2) was administered; the least fluctuation in [Ca2+] occurred when CaCl2 was administered during the plasma infusion. It is concluded that in thermally injured children 1-17 years old: 1) Rapid infusions of FFP produce sudden but evanescent decreases in [Ca2+]; more rapid infusions result in greater reductions in [Ca2+]. 2) There is no correlation between [Ca2+] and systemic hypotension. 3) Clinically important decreases in MAP occasionally accompany the rapid infusion of FFP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Feb 1988
Randomized Controlled Trial Comparative Study Clinical TrialLaser-induced pain for evaluation of local analgesia: a comparison of topical application (EMLA) and local injection (lidocaine).
High-energy lasers are suitable for experimental pain stimulation because they selectively activate the polymodal nociceptors. Argon laser light penetrates deep into the skin and makes this laser type preferable for simulating pain arising from surgical skin incisions. Short argon laser pulses were applied to the skin and three parameters were quantified before and during analgesia; sensory threshold, pain threshold, and the pain-related cortical response (latency and amplitude). ⋯ During the next 30 minutes after removal of the cream, the thresholds increased further. The increase in analgetic effect after removal of the cream was studied using different times (15, 30, 60, 80, 100, and 120 minutes) for topical EMLA cream application. Total sensory block was reached 20 minutes after removal of application for 80 minutes or immediately after removal of the cream after it was applied for 100 or 120 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Feb 1988
ReviewThe effect of incremental positive end-expiratory pressure on right ventricular hemodynamics and ejection fraction.
The effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) function were evaluated in 36 (n = 36) ventilated patients. Positive end-expiratory pressure was increased from 0 (baseline) to 20 cm H2O in 5-cm H2O increments and RV hemodynamics and thermally derived right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVESVI) were computed. Right ventricular contractility was determined from the analysis of RV systolic pressure-volume relations. ⋯ The slope (E) of the relation of RV peak systolic pressure to RV end-systolic volume index decreased from 0.26 mm Hg.m2.ml-1 between PEEP of 0-15 cm H2O to 0.05 mm Hg.m2.m-1 at PEEP greater than 15 cm H2O. It is concluded that low levels of PEEP have a predominant preload reducing effect on the RV. Above 15 cm H2O PEEP, RV volumes increase and E decreases, consistent with increased RV afterload and a decline in RV contractility.