Anesthesia and analgesia
-
Anesthesia and analgesia · Aug 1989
Tachyphylaxis associated with repeated epidural injections of lidocaine is not related to changes in distribution or the rate of elimination from the epidural space.
The relationship between tachyphylaxis (measured as a decrease in the rate of regression of sensory levels of analgesia) during repeated epidural injections of lidocaine and both the distribution of lidocaine within the epidural space (as measured by spread of simultaneous injection of the tracer technetium-99m diethylenetriaminepentaacetate [99mTc-DTPA]) and elimination of lidocaine from the epidural space (as measured by serum concentrations of lidocaine) was investigated in 18 patients undergoing minor surgery during lumbar epidural analgesia. Twelve patients received four injections of 20 mL of 2% lidocaine at 2-hr intervals. ⋯ In another six patients 20 mL of 2% lidocaine were injected three times at 2-hr intervals before surgery, with measurements of serum concentrations of lidocaine after the first and last injections. Despite tachyphylaxis (no patient had sensory analgesia 2 hr after the third injection), there was no difference in the rate of disappearance of lidocaine from the epidural space as assessed by plasma lidocaine concentration curves during the first and third injection (0.5 +/- 0.1 and 0.3 +/- 0.04 microgram.mL-1.min-1, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
-
Anesthesia and analgesia · Aug 1989
Randomized Controlled Trial Clinical TrialNormovolemic hemodilution and lumbar epidural anesthesia.
This randomized study was designed to determine the cardiovascular effects of normovolemic hemodilution and lumbar epidural anesthesia in patients scheduled for vascular surgery. The patients were randomly assigned to three different groups: group 1 (N = 10) included patients undergoing lumbar epidural anesthesia without hemodilution; group 2 (N = 10) consisted of patients with normovolemic hemodilution without epidural anesthesia; and in group 3 (N = 10) normovolemic hemodilution was produced during lumbar epidural anesthesia. The three groups included several patients with a history of either myocardial infarction or stable mild angina or treated and controlled hypertension. ⋯ After normovolemic hemodilution, hemoglobin concentration decreased significantly (15%), whereas cardiac index increased significantly (15%) without significant changes either in mean arterial pressure or in heart rate. Systemic oxygen transport and total body oxygen consumption did not change significantly. No patient experienced chest pain or electrocardiographic evidence of myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Anesthesia and analgesia · Aug 1989
Solubility of I-653, sevoflurane, isoflurane, and halothane in plastics and rubber composing a conventional anesthetic circuit.
This study defines some characteristics of a standard anesthetic circuit that may impede anesthetic induction and recovery with I-653, sevoflurane, isoflurane, and halothane. Partition coefficients for anesthetic circuit components (masks, bellows, bags, airways, and circuit tubes) consistently ranked halothane greater than isoflurane greater than sevoflurane greater than I-653, suggesting a reverse order of washin and washout rates for an anesthetic circuit constructed from similar components. ⋯ The rates of change in I-653 concentration closely approximated the maximal possible theoretical rates. Our results suggest that absorption of I-653 by circuit components or soda lime should not hinder induction of or recovery from anesthesia.
-
Anesthesia and analgesia · Jul 1989
Randomized Controlled Trial Clinical TrialIncidence of visceral pain during cesarean section: the effect of varying doses of spinal bupivacaine.
The safety of 0.5% hyperbaric bupivacaine, as well as the incidence and severity of visceral pain, were evaluated in 36 women undergoing elective cesarean section under spinal anesthesia who, randomly divided into two groups, received different dose ranges according to height, 7.5-10 mg in group A and 10-12.5 mg in group B. When sensory block to at least the fourth thoracic dermatome was established, surgery was begun and the occurrence and severity of visceral pain recorded (visual analog scale) by an observer unaware of patient data. The level of analgesia to pinprick was determined when and if there was onset of pain intraoperatively, and supplementary medication was administered as needed. ⋯ In patients experiencing moderate to severe pain, the mean time between induction of anesthesia and onset of pain was similar in both groups, as was the amount of systemic narcotic given. Total time for regression of sensory analgesia to L5 was longer in patients in group B (243.9 versus 195.4 min), and the incidence of complete motor blockade was greater in group B. Increasing the amount of 0.5% hyperbaric bupivacaine per spinal segment reduces the occurrence of moderate to severe visceral pain during elective cesarean section without jeopardizing mother or fetus.