Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1997
Randomized Controlled Trial Clinical TrialThe effect of epidural saline injection on analgesic level during combined spinal and epidural anesthesia assessed clinically and myelographically.
An epidural injection of physiological saline solution after spinal anesthesia may produce a higher level of analgesia than spinal anesthesia alone because of a volume effect. The purpose of this study was to clarify the volume effect caused by epidural injection of saline after spinal anesthesia. Twenty patients undergoing combined spinal and epidural anesthesia for elective surgery whose analgesic levels did not reach the surgical regions 10 min after spinal anesthesia at the L4-5 interspace were randomly assigned to two groups. The control group (n = 10) received no epidural saline injection. The saline group (n = 10) received 10 mL of saline through an epidural catheter at the L2-3 or L3-4 interspace 10 min after spinal anesthesia. In the saline group, the levels of analgesia 15 and 20 min after spinal anesthesia were significantly higher than those in the control group (P < 0.05). Next, we examined the volume effect of epidural injection of saline with myelography using two adult volunteers. In both volunteers, the upper level of the contrast medium, which was injected in the lumbar subarachnoid space, began to increase concurrently with lumbar epidural injection of saline, reaching from L3 to L1 and from L2 to T12. The diameter of the subarachnoid space diminished to less than 25% after injection of saline. We conclude that lumbar epidural injection of saline increases the analgesic level 10 min after spinal anesthesia, probably because of a volume effect. ⋯ In this study, using surgical patients and volunteers, we determined that a lumbar epidural injection of physiological saline solution 10 min after spinal anesthesia produces a higher analgesic level than spinal anesthesia alone because of a volume effect.
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Anesthesia and analgesia · Nov 1997
Comparative StudyDose-related biochemical markers of renal injury after sevoflurane versus desflurane anesthesia in volunteers.
Sevoflurane (CH2F-O-CH[CF3]2) reacts with carbon dioxide absorbents to produce Compound A (CH2F-O-C[=CF2][CF3]). Because of concern about the potential nephrotoxicity of Compound A, the United States package label (but not that of several other countries) for sevoflurane recommends the use of fresh gas flow rates of 2 L/min or more. We previously demonstrated in humans that a 2-L/min flow rate delivery of 1.25 minimum alveolar anesthetic concentration (MAC) sevoflurane for 8 h can injure glomeruli (i.e., produce albuminuria) and proximal tubules (i.e., produce glucosuria and urinary excretion of alpha-glutathione-S-transferase [alpha-GST]). The present report extends this investigation to fasting volunteers given 4 h (n = 9) or 2 h (n = 7) of 1.25 MAC sevoflurane versus desflurane at 2 L/min via a standard circle absorber anesthetic system (all subjects given both anesthetics). Markers of renal injury (urinary creatinine, albumin, glucose, alpha-GST, and blood urea nitrogen) did not reveal significant injury after anesthesia with desflurane. Sevoflurane degradation with a 2-L/min fresh gas inflow rate produced average inspired concentrations of Compound A of 40 +/- 4 ppm (mean +/- SD, 8-h exposure [data from previous study]), 42 +/- 2 ppm (4 h), and 40 +/- 5 ppm (2 h). Relative to desflurane, sevoflurane given for 4 h caused statistically significant transient injury to glomeruli (slightly increased urinary albumin and serum creatinine) and to proximal tubules (increased urinary alpha-GST). Other measures of injury did not differ significantly between anesthetics. Neither anesthetic given for 2 h at 1.25 MAC produced injury. We conclude that 1.25 MAC sevoflurane plus Compound A produces dose-related glomerular and tubular injury with a threshold between 80 and 168 ppm/h of exposure to Compound A. This threshold for renal injury in normal humans approximates that found previously in normal rats. ⋯ Human (and rat) kidneys are injured by a reactive compound (Compound A) produced by degradation of the clinical inhaled anesthetic, sevoflurane. Injury increases with increasing duration of exposure to a given concentration of Compound A. The response to Compound A has several implications, as discussed in the article.
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Anesthesia and analgesia · Nov 1997
Clinical TrialAcute normovolemic hemodilution can replace preoperative autologous blood donation as a standard of care for autologous blood procurement in radical prostatectomy.
Predonation of autologous blood (PAD) is a standard of care for patients undergoing radical prostatectomy, but recent studies have shown that PAD is not cost-effective. Acute normovolemic hemodilution (ANH) is an alternative autologous blood procurement technique that is much less costly than PAD. We compared the efficacy and costs of ANH alone to ANH combined with PAD. Two hundred-fifty patients who predonated fewer than 3 units of autologous blood before radical prostatectomy underwent ANH to a target hematocrit of 28%. Perioperative hematocrit levels, transfusion outcomes and costs, and postoperative outcomes were compared for patients who predonated 0, 1, or 2 units of blood before surgery. A computer model was used to estimate the savings in red blood cells (RBC) associated with each autologous intervention. ANH alone resulted in a 21% allogeneic transfusion rate and contributed a mean net savings of 112 mL RBC in blood conservation (equivalent to 0.6 unit of blood). The addition of 1 or 2 units of PAD reduced allogeneic exposure rates to 6% or 0%, respectively. Overall, patients who predonated blood had a mean net loss of 198 mL of RBC (equivalent to 1 blood unit), due to both an absence in compensatory erythropoiesis and to the wastage of 60% of the blood units donated. Patients who underwent ANH alone had a 60% reduction in mean total transfusion costs ($103 +/- $102) compared with patients who predeposited 2 units of autologous blood in addition to ANH ($269 +/- $11, P < 0.05). We conclude that ANH can replace PAD as an autologous blood option because it is less costly and equally effective. A combination of ANH and PAD can further decrease allogeneic blood exposure, but it increases transfusion costs and wastage. ⋯ A patient's own blood can be obtained for use in surgery by predonation or acute normovolemic hemodilution on the day of surgery. Both blood collection techniques decrease the need for blood bank transfusions, but acute normovolemic hemodilution is less expensive and more convenient for patients.
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Anesthesia and analgesia · Nov 1997
Risk factors for neurologic deterioration after revascularization surgery in patients with moyamoya disease.
To investigate the risk factors for postoperative neurological deterioration in patients with moyamoya disease, we retrospectively reviewed the perioperative course of 368 cases of revascularization surgery in 216 patients with this disease. Risk factors anecdotally associated with postoperative ischemic events were analyzed by comparing groups with or without a history of such events on the operative day. Ischemic events were noted in 14 cases (3.8%), 4 of which were defined as strokes and the others as transient ischemic attack (TIA). Postoperative neurological deterioration more often developed in patients who suffered from frequent TIAs, had precipitating factors for TIA, and underwent indirect nonanastomotic revascularization. The authors conclude that the incidence of postoperative ischemic events were related more to the severity of moyamoya disease and the type of surgical procedure than to other factors, including anesthetic management. ⋯ Although preventing stroke is the major concern for patients with moyamoya disease, risk factors for perioperative cerebral ischemia have not been clarified. We retrospectively analyzed the perioperative course in 368 cases with this disease and found that the severity of the disease and type of surgical procedure were major determinants of postoperative cerebral ischemia.
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Anesthesia and analgesia · Nov 1997
A microscopic analysis of cut-bevel versus pencil-point spinal needles.
An in vitro examination of 25-gauge Quincke and 25-gauge and 27-gauge Whitacre spinal needles was performed after insertion in 210 consenting adult patients. In addition, 300 unused Quincke needles and 300 unused pencil-point needles were examined under a dissecting microscope. When the microscopic evaluation was performed on the needles after spinal blockade, burrs or blunting of the needle tip were noted in 24% of the Quincke needles compared with only 3% of the 25-gauge Whitacre needles and 10% of the 27-gauge Whitacre (P < 0.05). Bony contact with 25-gauge Quincke and 27-gauge Whitacre needles resulted in an increased incidence of microscopic tip damage (versus 25-gauge Whitacre). Needle-tip damage with the Whitacre needles was limited to blunting of the tip. The analysis of unused needles revealed significant differences among manufacturers of the cut-bevel needles with respect to stylet-to-needle length and burrs on the end of the stylet. The leading edge of the stylet protruded beyond the opening of the needle tip in 7% of the Quincke needles. However, only minor needle-tip abnormalities were noted with the pencil-point needles (i.e., variability in the side-port opening to needle tip distance, side-port opening integrity). In conclusion, bony contact produced more damage to the cut-bevel than to the pencil-point needle tips. In addition, fewer inherent manufacturing defects were noted with the pencil-point versus cut-bevel needles. ⋯ It has been suggested that damaged needle tips may contribute to a higher incidence of headaches after spinal anesthesia. A microscopic examination revealed that the pencil-point (versus cut-bevel) needles had fewer manufacturing flaws and were less susceptible to tip damage when bony contact occurred during the placement of the spinal needle.