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Biomedical subjects

S J Brull

Publications and source records attributed to S J Brull.

At least 37 records · Page 2Linked to original sources

The effect of solubility and hyperlipidemia on perioperative arterial blood gas tensions.

A case is presented to illustrate the need for technical care when handling blood gas samples. The physics of solubility are used to show hour samples changed their oxygen tension (pO2) during handling, while investigating a clinical case to show the effect of hyperlipidemia on blood gases. It appeared that inadvertent access to air allowed atmospheric oxygen to equilibrate with the sample. The physical laws predicting the effect of partial pressure and temperature on gas solubility in a liquid are illustrated by the pO2 levels measured in this case. Effects due to hyperlipidemia were not observed. The calculations are described in detail. Brief suggestions for sample handling to avoid misleading results from such cases are discussed.

Blood Gas Analysis↗

The effect of intravenous ketorolac given intraoperatively versus postoperatively on outcome from gynecologic abdominal surgery.

STUDY OBJECTIVES: To examine the effect of timing of an intravenous (i.v.) dose (intraoperative vs. postoperative) of ketorolac tromethamine on pain scores and overall outcome after total abdominal hysterectomy (TAH) and myomectomy. DESIGN: Prospective, randomized, placebo-controlled study. PATIENTS: 248 ASA physical status I and II adult female patients scheduled for elective hysterectomy or myomectomy. INTERVENTIONS: General anesthesia was administered that consisted of thiopental sodium for induction, enflurane or isoflurane in nitrous oxide-oxygen for maintenance, and small doses of fentanyl and midazolam. Patients were randomized into three groups to receive toradol/placebo on a dosing schedule of dose 1 given one-half hour prior to expected end of surgery, dose 2 given on awakening in the postanesthesia care unit, and doses 3, 4, and 5 given at 6, 12, and 18 hours, respectively, after dose 2; Group 1 patients received placebo (saline) for dose 1, ketorolac 60 mg i.v. for dose 2, and ketorolac 30 mg i.v. for doses 3, 4, and 5. Group 2 patients received ketorolac 60 mg i.v. for dose 1, placebo for dose 2, and ketorolac 30 mg i.v. for doses 3, 4, and 5. Group 3 patients received placebo for all doses. All patients were given i.v. morphine PCA postoperatively, and morphine usages, visual analog pain intensity (VAS) scores, as well as adverse events and median times to recovery milestones were recorded. MEASUREMENTS AND MAIN RESULTS: VAS scores (mean) before dose 2 were significantly lower in Group 2 than Group 1, as were at-rest evaluations at 15 minutes and one hour. Group 2 patients also had decreased morphine requirements as compared to placebo. Both ketorolac groups (Groups 1 and 2) had significantly higher values for patient and observer overall ratings, case of nursing care, and tolerability as compared to placebo (Group 3). There were no significant differences among groups in adverse events or median times to recovery milestones. CONCLUSIONS: Although it is possible to demonstrate an improvement in early postoperative pain scores with intraoperative ketorolac and better overall ratings of ketorolac both intraoperatively and postoperatively as compared with placebo, the lack of clinically significant differences in analgesic efficacy in the two active study groups indicates the need for a careful consideration by the clinician of the risks versus benefits involved in the administration of antiplatelet medication in the perioperative period.

Adult↗

Patient awareness during general anesthesia: a shocking outcome.

Patient awareness under minimal anesthesia may include the painful impulses of a nerve stimulator used for the monitoring of muscle relaxation. We present a case where discomfort from nerve stimulation was greater than that caused by the surgical incision or the endotracheal tube.

Abscess↗

The effect of intradermal administration of lidocaine and morphine on the response to thermal stimulation.

Opioids appear to exert a peripheral effect by gaining access to peripheral opioid receptors. It has been proposed that inflammatory processes and highly osmotic substances could alter the perineural barrier, thereby allowing easy access to opioid receptors. Although local anesthetics do not have osmotic activity, they are highly active on neural tissue and appear to work synergistically with opioids when administered for major conduction blockade. We therefore evaluated, in a double-blind fashion, the combination of lidocaine plus morphine in an attempt to provide a scientific basis for the use of a combination of morphine plus local anesthetics in the periphery. Seven thermal stimuli in 2 degrees C increments (range 40-52 degrees C) were delivered in a random sequence by a computer-controlled thermistor to one of three pretreated sites on 10 volunteers' forearms: reference site (no injection), lidocaine site (0.1-mL intradermal injection of lidocaine 0.5%), or lidocaine plus morphine site (0.1 mL of 0.5 mg of morphine plus lidocaine 1%). Pain responses to the thermal stimuli were rated by the volunteers using the method of magnitude estimation. Pain scores indicated that the combination of lidocaine plus morphine was not more effective than lidocaine alone in attenuating the heat-induced pain. Twenty and 120 min after injection, scores at the lidocaine plus morphine site were 37% and 20% greater than those at the lidocaine site. The addition of morphine to lidocaine did not result in an improvement in the analgesic efficacy and actually had an antianalgesic effect.

Adult↗

Early neuromuscular recovery characteristics following administration of mivacurium plus vecuronium.

PURPOSE: This study was designed to describe the early recovery characteristics, as well as the speed of onset of neuromuscular block, after a combination of mivacurium and vecuronium. METHODS: In this controlled, randomized study, 30 consenting ASA I-III patients were assigned to three treatment groups. The "2M2V" group received twice the dose necessary to cause 95% depression of the evoked twitch response (2 x ED95) of mivacurium (0.15 mg.kg-1) plus 2 x ED95 of vecuronium (0.1 mg.kg-1); the "2V" group received 2 x ED95 of vecuronium; and the "4V" group received 4 x ED95 of vecuronium. Evoked neuromuscular responses of the adductor pollicis were assessed with an adductor pollicis force transducer. The time until maximum block and times to 10% and 25% recovery (T10 and T25) in each group were expressed as mean +/- standard deviation and compared using ANOVA. RESULTS: Onset of block in the 2M2V group was 27% faster than in the 2V group (2.0 +/- 0.6 vs. 2.7 +/- 0.8 min respectively, P < 0.05) and was similar to the 4V group (1.95 +/- 0.3 min, P = NS). The times until 10% recovery were similar in the 2M2V and 4V groups (59.9 +/- 12 vs 68.2 +/- 25 min, P = NS) and were slower than in the 2V groups (37.2 +/- 9 min, P < 0.05). Between T10 and T25 recovery after 2M2V resembled that after 2V (6.7 +/- 3 vs 5.7 +/- 1 min, P = NS) and was faster than after 4V (10.9 +/- 7 min, P < 0.05). CONCLUSIONS: When 2 x ED95 of mivacurium is added to 2 x ED95 of an intermediate or long-acting relaxant, recovery after T10 will proceed as if one had administered the longer-acting agent alone.

Humans↗

Efficacy and safety of divided dose administration of mivacurium for a 90-second tracheal intubation.

STUDY OBJECTIVE: To compare the safety and effectiveness of 0.25 mg divided doses of mivacurium chloride to succinylcholine for a 90-second tracheal intubation. DESIGN: Randomized, double-blind, multicenter study in two groups. SETTING: Operating rooms at four university medical centers. PATIENTS: 200 healthy ASA status I and II adult patients scheduled for elective surgery with general anesthesia and endotracheal intubation. INTERVENTIONS: Patients were premedicated with 1 to 2 mg midazolam and 2 micrograms/kg fentanyl. Anesthesia was induced with 2 mg/kg propofol. Group A received 0.25 mg/kg mivacurium given as a divided dose (0.15 mg/kg followed in 30 seconds with 0.1 mg/kg). Group B (control) received 1.5 mg/kg succinylcholine (SCh) preceded two minutes earlier by 50 micrograms/kg d-tubocurarine (dtc). MEASUREMENTS AND MAIN RESULTS: Tracheal intubation grading, train-of-four response of the adductor pollicis, heart rate (HR), and mean arterial blood pressure (MAP) were measured and evaluated. Chi-square analysis was performed for comparison between Group A and Group B with respect to the frequency distribution of intubation using the scores excellent, good, and poor and not possible (combined). Group B had a significantly higher excellent score of intubation than Group A, 84% versus 56% (p < 0.0001). No significant difference was found between the two groups when the scores excellent and good were combined (Fisher's Exact test, p = 0.28). The changes in MAP and HR were similar for the two groups. CONCLUSIONS: When Sch is not desirable, mivacurium 0.25 mg/kg given as a divided dose provides good to excellent intubation conditions 90 seconds after the initial dose without significant changes in MAP or HR. It can be an appropriate alternative for short surgical procedures. It must be emphasized that this conclusion does not apply to rapid-sequence induction-intubation.

Adolescent↗

Lidocaine plasma levels following two techniques of obturator nerve block.

STUDY OBJECTIVES: To assess plasma levels and the potential toxicity of lidocaine following two different approaches to the obtruator nerve. DESIGN: Prospective, randomized, clinical trial. SETTING: Operating rooms of a university hospital. PATIENTS: 45 ASA physical status I, II and III patients over 40 years of age, and undergoing transurethral resection of urinary bladder tumors. INTERVENTIONS: A prospective study compared lidocaine plasma levels following direct and indirect (3-in-1) obturator nerve block using lidocaine 1.5% plus 1:200,000 epinephrine. Patients with unilateral urinary bladder tumors were randomized to receive direct obturator nerve block with 15 ml of lidocaine (Group A, n = 20), while those with bilateral tumors received a bilateral direct obturator nerve block with 30 ml (2 x 15 ml) of lidocaine (Group B, n = 12). A third group of patients with unilateral bladder tumors received 3-in-1 indirect) obturator nerve block with 40 ml of lidocaine (Group C, n = 17). Plasma lidocaine concentration was determined every 5 minutes for 30 minutes, and at 45, 60, and 90 minutes after the block. MEASUREMENTS AND MAIN RESULTS: In Group A, mean (+/- SD) peak plasma lidocaine level of 1.35 +/- 0.5 micrograms/ml (range 0.61 to 2.41 micrograms/ml) occurred 45 minutes after injection. In Group B, a peak of 3.63 +/- 2.07 micrograms/ml (0.75 to 7.21 micrograms/ml) occurred 15 minutes after injection. Mean peak level in Group C of 2.08 +/- 0.77 micrograms/ml (0.84 to 3.21 micrograms/ml) occurred 60 minutes after injection Lidocaine concentrations were significantly higher in Groups B and C than in Group A, and they were higher in Group B than in Group C. No patient had any signs of symptoms of local anesthetic toxicity. CONCLUSIONS: Despite a lower total dose of lidocaine administered (450 mg), higher mean and peak plasma levels were reached sooner with bilateral direct obturator nerve block compared with the indirect obturator nerve block (600 mg), indicating a faster blood absorption of lidocaine following direct block. Both types of obturator nerve block prevented adductor muscle contraction in a large percentage of cases.

Absorption↗

Subcutaneous cysts: another cause of "failed" spinal anesthesia?

Spinal anesthesia continues to be one of the major techniques in the arsenal of the modern anesthesiologist. Inadequate anesthesia may follow a spinal anesthetic for a variety of reasons. We report a case in which entry of a spinal needle into a subcutaneous cyst mimicked the free flow of cerebrospinal fluid seen with dural puncture. This was confirmed by microscopic examination of the fluid, which was consistent with the contents of a subcutaneous cyst. This represents an unusual cause for failure of spinal anesthesia. Such a possibility should be borne in mind, especially when "clear fluid" return occurs through a spinal needle placed at a relatively superficial depth.

Adult↗

Compound motor action potential recording distinguishes differential onset of motor block of the obturator nerve in response to etidocaine or bupivacaine.

The purpose of this investigation was to establish an objective (quantitative) method for determining onset time of motor block induced by different local anesthetics. Twenty-four consenting patients undergoing transurethral surgery during spinal anesthesia were randomized to receive direct obturator nerve block with 10 mL of plain bupivacaine 0.5% (n = 12) or 10 mL of plain etidocaine 1% (n = 12). Another 14 patients (control group) received obturator nerve "block" with saline. After identification of the obturator nerve, patients underwent testing of nerve conduction by recording compound motor action potentials (CMAPs) of thigh adductor muscles in response to stimulation provided by a nerve stimulator at 0.2 to 0.5-mA currents. Testing ended when CMAP amplitudes had returned to their baseline values (control group) or when motor blockade was 90% complete (local anesthetic groups). In all 38 patients, the amplitude of the thigh CMAPs decreased immediately after injection of saline or local anesthetic. While CMAP amplitudes in the control group returned to their initial (baseline) values after 3-6 min, the patients receiving etidocaine or bupivacaine achieved > or = 90% motor blockade after 6 and 13 min, respectively. In the present report, the time to > or = 90% block was significantly faster in patients given etidocaine compared with those given bupivacaine. We conclude that electromyographic recording of CMAPs can be used to compare the ability of different local anesthetics to induce motor block.

Adult↗

Reduction of postburn hyperalgesia after local injection of ketorolac in healthy volunteers.

BACKGROUND: Nonsteroidal antiinflammatory drugs may be particularly effective against prostaglandin-mediated, post-injury hyperalgesia and related inflammatory pain. However, their usefulness may be limited by their systemic side effects. The current study determined if local effectiveness can be achieved by low-dose intradermal nonsteroidal antiinflamatory drug administration. METHODS: Ten healthy volunteers were asked to make magnitude estimations of the pain induced by a contact thermal stimulator at 1 degree C increments between 43 and 51 degrees C at three 1 x 1 cm study sites on each forearm during three study phases:(1) baseline; (2) after pretreatment with 10 microl 0.9% saline (n=1 site on each forearm), 0.3 mg ketorolac (n=1 on each forearm), or nothing (n=1 on each forearm); and (3) after "injury" by a mild burn at the ketorolac- and saline-treated sites on one arm or by injection of 10 nmol bradykinin at all three sites on the other arm. The effects of pretreatment on the pain induced by thermal testing were assessed using repeated-measures analysis of variance. RESULTS: Pretreatment with ketorolac had a selective effect on the postburn injury hyperalgesia, reducing the increase in pain intensity (P<0.05) but not the decline in pain threshold. It had no effect on the responses to thermal stimuli before injury or on the pain of burning, which were similar at ketorolac- and saline-treated sites. The effect of pretreatment with ketorolac on bradykinin-induced hyperalgesia was not achieved after bradykinin injection at sites pretreated with saline as well as ketorolac.

Anti-Inflammatory Agents, Non-Steroidal↗

Recovery of train-of-four after mivacurium.

The present study was designed to determine the time-course of recovery of the train-of-four (TOF) ratio during spontaneous recovery from mivacurium-induced block. Fifteen patients, free of neuromuscular disease, undergoing general endotracheal anaesthesia with isoflurane were studied. After anaesthetic induction, patients received a bolus dose of mivacurium 0.15 mg.kg-1. The TOF was then recorded continuously every 12 sec with a mechanogram (adductor pollicis monitor). When the TOF ratio recovered spontaneously to 0.9, an additional 0.05 mg.kg-1 of mivacurium was given. The durations required for recovery from a TOF ratio of 0.3 to 0.7 (DUR0.3-0.7) and from a TOF ratio of 0.3 to 0.9 (DUR0.3-0.9) were determined. The DUR0.3-0.7 averaged 7.0 +/- 2.5 min (range 3.4-12.2 min). The DUR0.3-0.9 averaged 11.8 +/- 3.9 min (range 6.0-20.2 min). There was no evidence of prolongation of recovery times (cumulation) following repeated dosing. The present data indicate that, in patients with normal cholinesterase activity (clinical duration 7-25 min), waiting 20 min beyond the time when fade is no longer apparent by visual or tactile evaluation is sufficient to attain a TOF ratio greater than 0.7-0.9 during spontaneous recovery from mivacurium, and may enable anaesthetists to avoid antagonism of mivacurium-induced block.

Adolescent↗

Effects of single-dose oral ranitidine and sodium citrate on gastric pH during and after general anaesthesia.

The effects on gastric pH of the H2-receptor antagonist ranitidine (R) with 0.3 molar (M) sodium citrate (SC) as an oral effervescent and those of plain SC were studied in 25 patients scheduled for elective surgery. Following induction of general anaesthesia, the gastric contents were evacuated via a nasogastric tube, and a pH electrode was placed in the stomach. Then, eight patients received R 300 mg plus SC dose (Group R300), ten received R 150 mg plus SC dose (Group R150), and seven received 50 ml SC alone (Group SC). The drugs were administered orally in a double-blind fashion, and the gastric pH was recorded continuously over a period of 24 hr. Mean (range) baseline pH values were 1.2 (0.8-1.8), 1.3 (1.0-1.8), and 1.2 (0.9-1.6) in the R300, R150, and SC groups, respectively (P = NS among groups). These values increased to 7.0 (6.2-7.5), 6.9 (6.3-7.3), and 4.9 (1.9-7.3), respectively, at emergence from anaesthesia (P < 0.05 for R300 vs SC and R150 vs SC). Two minutes after administration of R300 and R150, a mean (range) gastric pH of 6.8 (5.8-7.5), and 5.6 (1.2-7.0), respectively, was reached, and remained above 2.5 for 14 hr (P = NS). Plain SC increased the gastric pH within two minutes to a mean of 6.8 (6.7-7.0), and maintained it above 2.5 for six hours (P < 0.05 for R300 vs SC at 8, 10, 12, and 14 hr after induction).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

The cost of modern technology.

Continuous infusion of intravenous (i.v.) drugs is increasing in popularity, as technological advances in equipment (such as "smart" pumps) and pharmacologic improvements of drugs (such as ultra-short acting drugs) are introduced into clinical anesthesia practice. Such new technology, however, also introduces potential new complications. We report one such complication associated with the improper manufacturing of a proprietary i.v. tubing and cassette system.

Anesthesia, Intravenous↗

Laparoscopic pelvic lymphadenectomy during epidural anesthesia.

This report describes the perioperative management of a 70-year-old man undergoing bilateral pelvic lymphadenectomy. Because of concerns regarding this patient's high risk for myocardial ischemia, the four-hour surgical procedure, which included the formation of pneumoperitoneum, was performed during epidural anesthesia with minimal sedation. The anesthetic implications of pneumoperitoneum during regional anesthesia are discussed.

Aged↗

Real time versus slow-motion train-of-four monitoring: a theory to explain the inaccuracy of visual assessment.

The present study was undertaken to determine why visual assessment of thumb adduction in response to train-of-four (TOF) stimulation of the ulnar nerve commonly overestimates the ratio that is obtained mechanographically. In patients undergoing general endotracheal anesthesia plus vecuronium for relaxation, 73 data sets were collected at different depths of neuromuscular block in response to supramaximal TOF stimulation. Each data set consisted of: (i) visual estimation of the TOF ratio by an experienced observer; (ii) mechanographic measurement of the TOF ratio with an adductor pollicis force transducer; and (iii) determination of the TOF ratio by measuring the slow-motion thumb displacement recorded on videotape. The last 23 data sets also included visual assessment and videotape recording of evoked responses at low stimulating current (30 mA). Visual inspection at 60 mA overestimated the mechanographic ratio by 0.20 units (48%). Videotape review provided a ratio that was 0.23 units (56%) greater than that determined mechanographically. However, after the first three twitches (T1-3), the thumb did not return to the same resting position as the (original) baseline prior to the first twitch. When the change in thumb position as a result of T1-3 was taken into account, the measured height of T4 was 40% less than it was when measured from the original baseline, and the T4/T1 ratio was identical to that obtained mechanographically. For the 23 data sets obtained at low current visual assessment overestimated the mechanographic value to a lesser degree than when obtained at high current. Again, correction for the T1-3 baseline shift improved the accuracy of videotape analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗

The time course of gastric pH changes induced by omeprazole and ranitidine: a 24-hour dose-response study.

The time-course of the effects of single-dose acid-reducing therapy in surgical patients is not known. Therefore, a prospective, randomized trial compared the effects of single-dose administration of omeprazole or ranitidine on gastric pH in 52 patients undergoing lower abdominal surgery. The two drugs were administered intravenously in random fashion after placement of a gastric electrode for continuous 24-h pH monitoring In patients receiving omeprazole 20 mg (n = 13) and 40 mg (n = 13), gastric pH > or = 2.5 was achieved after a median of 80 (range 15-269) min and 40 (6-102) min (P = not significant [NS]), whereas in those receiving ranitidine 25 mg (n = 13) and 50 mg (n = 13), this pH was reached after a median of 32 (15-82) and 44 (16-84) min, respectively (P = NS). Over the first 24 h postoperatively, gastric pH remained less than 2.5 for a significantly longer time (1060 min vs 611 min), and more than 4.0 for a significantly shorter time (240 min vs 780 min) after omeprazole 20 mg than after ranitidine 50 mg. There were no other significant differences among treatment groups regarding the duration of gastric pH less than 2.5, between 2.5 and 4.0, and more than 4.0. In all treatment groups, the gastric pH returned to the baseline value of < 2.0 within 18 h. We conclude that when it is desired that gastric pH be more than 4.0 for at least 3 h, a single dose of ranitidine 25 mg or 50 mg should be administered 30-45 min prior to induction of anesthesia.

Abdomen↗

Electromyographic comparison of obturator nerve block to three-in-one block.

Obturator nerve block during spinal, epidural, or general anesthesia without muscle relaxants has been recommended for transurethral surgery to prevent thigh adductor muscle contractions during operative electrocautery. We investigated the effectiveness of direct obturator and 3-in-1 nerve motor blocks in 44 patients undergoing transurethral surgery during spinal anesthesia with isobaric bupivacaine. Patients were randomly assigned to receive 3-in-1 block with 40 mL (n = 13) or 50 mL (n = 11) of 1.5% lidocaine plus epinephrine, or direct obturator nerve block with 10 mL of 2% lidocaine plus epinephrine (n = 20). After both direct obturator and 3-in-1 blocks, compound muscle action potential (CMAP) testing of the obturator nerve was performed at 1-10-s intervals for 10 min. In patients given direct obturator nerve block (n = 20), CMAP amplitude decreased by 88.8 +/- 21% (mean +/- SD) from baseline. In contrast, 3-in-1 block reduced the evoked CMAP amplitude by 7.4 +/- 19% (P < 0.05). Peak lidocaine plasma levels of 1.6 +/- 0.2 micrograms/mL (range 1.0-2.8 micrograms/mL) were reached 60-90 min after the block in those patients receiving 50 mL of local anesthetic. The 3-in-1 technique fails to predictably result in effective motor block of the obturator nerve and thus may not prevent inadvertent thigh adductor muscle contractions during transurethral surgery. A direct approach to the obturator nerve is significantly more effective in producing motor block, and even when given in larger than recommended dosages it results in subtoxic peak plasma lidocaine concentrations.

Action Potentials↗