Showing papers in "Anesthesia & Analgesia in 1993"
1,583 citations
TL;DR: The existing knowledge concerning the efficacy of analgesic combination therapy from postoperative pain studies is summarized and primary emphasis will be placed on moderate and severe pain and the use of and need for combined analgesic regimens.
Abstract: reatment of postoperative pain is provided for humanitarian reasons and to alleviate nocicepT tion-induced responses, such as the endocrine metabolic response to surgery, autonomic reflexes with adverse effects on organ function, reflexes leading to muscle spasm, and other undesirable results (1). During the last decade there has been a virtual explosion in our knowledge of basic pain physiology (2,3), but the implications for clinical practice have been less substantial. The explanation for the discrepancy between the fast progress in basic pain pathophysiology and the rather slow advances in providing optimal postoperative pain treatment may be several, but one important factor may be that more than 95% of the literature on postoperative pain treatment has considered unimodal treatment. We have emphasized previously that total or optimal pain relief allowing normal function can not be achieved by a single drug or method without major strain on equipment and surveillance systems or without significant side effects (4). Therefore, we have recommended combined analgesic regimens (balanced analgesia) or a multimodal approach to the treatment of postoperative pain (4). The rationale for this strategy is achievement of sufficient analgesia due to additive or synergistic effects between different analgesics, with concomitant reduction of side effects, due to resulting lower doses of analgesics and differences in side-effect profiles. We summarize here the existing knowledge concerning the efficacy of analgesic combination therapy from postoperative pain studies. The effects on postoperative outcome are not included, because of lack of sufficient studies. We also exclude obstetric and pediatric pain, which may represent special pain entities and solutions for treatment, although they obviously share many of the problems of general postoperative pain. Primary emphasis will be placed on moderate and severe pain and the use of and need for
1,298 citations
TL;DR: Recently, evidence has begun to accumulate that opioid antinociception can be initiated by activation of opioid receptors located outside the central nervous system (CNS) as discussed by the authors, which is the earliest evidence that opioids exert analgesic effects through actions outside the CNS.
Abstract: Traditionally, opioids exert analgesic effects through actions within the central nervous system (CNS) exclusively (1) Recently, however, evidence has begun to accumulate that opioid antinociception can be initiated by activation of opioid receptors located outside the CNS One of the earliest repo
603 citations
TL;DR: Remifentanil appears to have a pharmacologic profile similar to other potent μ agonists, but with exceptionally short-lasting pharmacokinetics, which is likely to make it a very useful opioid for clinical practice.
Abstract: Remifentanil is a newly synthesized 4-anilidopiperidine with an ester side chain susceptible to esterase metabolism. We evaluated the safety, analgesic efficacy, and pharmacokinetics of remifentanil in 48 male volunteers. Volunteers were randomized to receive increasing doses of remifentanil, alfent
535 citations
TL;DR: It is demonstrated that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.
Abstract: Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maint
490 citations
TL;DR: Observations indicate that positional stretching of the cauda equina may contribute to enhanced and selective vulnerability of a subset of nerve fibers exposed to a hyperbaric solution of 5% lidocaine administered in a dose that is recommended for a single subarachnoid injection.
Abstract: idocaine has been used for subarachnoid anesthesia for more than half a century and has had L a remarkable safety record. However, postanesthetic sequelae manifesting as peripheral nerve symptoms such as motor weakness, hypesthesia, or paresthesia have been observed in the past in a very small number of patients. Moreover, nerve root involvement resulting in persistent peripheral neuropathy has been linked to the anesthetic (1). According to another follow-up study, adverse neurologic effects such as numbness, tingling, heaviness, or burning sensations have been noted in patients following subarachnoid administration of procaine-tetracaine and other local anesthetics (2). In most cases, these symptoms were restricted to the lumbar and sacral dermatomes and had disappeared within 6 mo. In the present report, we describe signs of transient neurologic impairment in four patients following bolus injection of hyperbaric 5% lidocaine into the subarachnoid space for surgery performed in the lithotomy position. Our observations indicate that positional stretching of the cauda equina may contribute to enhanced and selective vulnerability of a subset of nerve fibers exposed to a hyperbaric solution of 5% lidocaine administered in a dose that is recommended for a single subarachnoid injection.
412 citations
Journal Article•
248 citations
TL;DR: The hypothesis that forced-air warming preserves core temperature better than circulating-water mattresses was tested in 16 adults undergoing major maxillofacial surgery, including radical node resection and flap reconstruction and 10 young children undergoing pelvic or femoral osteotomies.
Abstract: The hypothesis that forced-air warming preserves core temperature better than circulating-water mattresses was tested in: (a) 16 adults undergoing major maxillofacial surgery, including radical node resection and flap reconstruction; (b) 53 adults undergoing hip arthroplasty, having approximately 25% of their body surface area available for warming; (c) 20 infants undergoing minor maxillofacial surgery; and (d) 10 young children undergoing pelvic or femoral osteotomies. Patients having each type of surgery were randomly assigned to forced-air warming (approximately 40 degrees C) or conductive warming using a full-length circulating-water mattress at 40 degrees C. Forced-air warming was applied to the legs of the adults undergoing maxillofacial surgery and to one arm, the shoulders, and the neck in the adults undergoing hip arthroplasty; a U-shaped, tubular forced-air cover was positioned around the pediatric patients. Core temperatures increased in all patients given forced-air warming and decreased or remained constant in those without active warming. Furthermore, we needed to decrease the temperature of the warmer from high to medium (approximately 37 degrees C) in most patients assigned to forced-air warming to prevent hyperthermia. After 15 h of anesthesia, rectal temperatures in the adults undergoing maxillofacial surgery were 3.4 degrees C higher in the forced-air group (P < 0.01). After 4 h of anesthesia, esophageal temperatures had increased 0.8 +/- 0.5 degrees C in the patients warmed with forced-air and decreased 0.8 +/- 0.3 degrees C in those warmed by circulating-water mattresses (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
245 citations
TL;DR: Almost 70% of women receiving epidural analgesia with fentanyl or ultra low-dose bupivacaine, epinephrine, and fentanyl may ambulate safely during labor, and half of patients delivering during administration of only their study drug did not need higher doses of local anesthetics.
Abstract: The effectiveness of two epidural analgesic regimens on the ability to ambulate was compared in women in labor by a prospective, randomized, double-blind design. One group of patients received epidural fentanyl, a 75-micrograms bolus and an infusion of fentanyl 2.5 micrograms/mL at 15 mL/h (FENT, n = 53). A second group received ultra low-dose bupivacaine (0.04%), epinephrine (1.7 micrograms/mL), and fentanyl (1.7 micrograms/mL) (BEF, n = 77), a 15-mL bolus followed by an infusion at 15 mL/h. Adequate analgesia was rapidly obtained in 90.6% of patients in the FENT group and 92.2% of patients in the BEF group (P = 0.89). Seventy percent of patients in the FENT group ambulated versus 68% in the other group. The BEF mixture provided analgesia of longer duration (287 +/- 171 min versus 156 +/- 72 min, P = 0.0001). The number of patients delivering during administration of only their study drug (without needing higher doses of local anesthetics) was 52% for BEF and 21% for FENT (P = 0.0005). Hip flexion weakness precluding ambulation occurred in 17% (P = 0.002) of BEF patients and orthostatic hypotension in 9% (P = 0.08). Neither problem occurred in FENT patients. Neonatal outcome was similar in both groups. Approximately 70% of women receiving epidural analgesia with fentanyl or ultra low-dose bupivacaine, epinephrine, and fentanyl may ambulate safely during labor.
244 citations
Journal Article•
TL;DR: The incidence of hypotension was significantly higher for the elderly, females, Caucasians, those undergoing abdominal and integumentary procedures, and those given propofol with opioids, benzodiazepines, or propranolol, while Bradycardia was significantly more common when prop ofol was combined with opioids or chronically taken beta-adrenergic receptor-blocking drugs.
Abstract: To investigate clinically important hypotension and bradycardia after induction of anesthesia with propofol, we analyzed data from a Phase IV stepwise study involving 25,981 patients, 1722 institutions, and 1819 anesthesiologists. In Step 1, propofol was used for induction only. In Step 2, propofol was used for induction and then maintenance by intermittent injection. In Step 3, an induction dose was followed by a maintenance infusion. Participants were to be 18-80 yr of age and ASA physical status I-III; they could not have a continuing pregnancy or prior adverse anesthetic experience. Detailed data on demographic, perioperative, and outcome variables were recorded on data collection forms. The overall incidence of hypotension (systolic blood pressure < 90 mm Hg) was 15.7%; 77% of the episodes were recorded within 10 min of induction of anesthesia with propofol. Bradycardia (heart rate < 50 beats/min) occurred in 4.8% of patients, with 42% of the episodes in the first 10 min. Only 1.3% of patients had both hypotension and bradycardia. The incidence of hypotension was significantly higher for the elderly, females, Caucasians, those undergoing abdominal and integumentary procedures, and those given propofol with opioids, benzodiazepines, or propranolol. Bradycardia was significantly more common when propofol was combined with opioids or chronically taken beta-adrenergic receptor-blocking drugs. Bradycardia and hypotension were not commonly associated. Giving this new drug by protocol, even inexperienced anesthesiologists incurred few adverse hemodynamic changes. Hemodynamic changes were transient and rarely (< 0.2%) required drug therapy. Cardiovascular changes and drug interactions were predictable and manageable based on knowledge of the pharmacology of propofol.
240 citations
TL;DR: It is indicated that postoperative pain can be decreased when ketamine in low doses is added to general anesthesia before surgical stimulation.
Abstract: In a randomized, double-blind study, postoperative pain was assessed in 22 patients undergoing elective open cholecystectomy with two types of anesthesia: standardized general anesthesia (control group), and low-dose ketamine as an addition to the same method of general anesthesia, before surgical incision (ketamine group) After the operation we found that the time from the end of surgery to the first request for analgesic was longer in the ketamine group Postoperatively, patients in both groups were treated with patient-controlled analgesia (PCA) in exactly the same way The major difference in the study was the reduced dose requirement of morphine in the ketamine group compared with the control group after the operation The mean dose of morphine given in patients of the control group during the first 24 h was 487 mg vs 295 mg in the ketamine group Mean visual analog scale (VAS) and verbal rating scale (VRS) were higher in patients in the control group during the first 5 h after surgery (P 005) Our results indicate that postoperative pain can be decreased when ketamine in low doses is added to general anesthesia before surgical stimulation
TL;DR: It is concluded that CO2 diffusion into the body is more marked during extraperitoneal than during intra peritoneal CO2 insufflation but is not influenced markedly by the duration of intraperitoneAL insufflated.
Abstract: We examined end-tidal CO2 tension (PETCO2) and pulmonary CO2 elimination of CO2 (VECO2) during CO2 insufflation under general anesthesia for three surgical procedures: gynecologic laparoscopy (intraperitoneal CO2 insufflation for 43 +/- 4 min), laparoscopic cholecystectomy (intraperitoneal CO2 insufflation for 125 +/- 14 min), and pelviscopy (extraperitoneal CO2 insufflation for 45 +/- 3 min). All patients (10 in each group) underwent controlled mechanical ventilation. Oxygen consumption (VO2) and VECO2 were measured at 2-min intervals by a system using a mass spectrometer. For the three surgical procedures, VO2 remained stable, whereas VECO2 and PETCO2 increased in parallel from the 8th to the 10th min after the start of CO2 insufflation. A plateau was reached 10 min later in patients having intraperitoneal insufflation, whereas VECO2 and PETCO2 continued to increase slowly throughout CO2 insufflation during pelviscopy. During pelviscopy, the maximum increase in VECO2 and PETCO2 (76 +/- 5% and 71 +/- 7%) was significantly more pronounced than that observed during cholecystectomy (25 +/- 4% and 25 +/- 4%) and gynecologic laparoscopy (15 +/- 3% and 12 +/- 2%). The authors conclude that CO2 diffusion into the body is more marked during extraperitoneal than during intraperitoneal CO2 insufflation but is not influenced markedly by the duration of intraperitoneal insufflation.
Journal Article•
TL;DR: It is concluded that clonidine and guanfacine, unlike traditional local anesthetics, demonstrate a tendency toward steady‐state differential nerve block wherein C fibers are blocked to a greater extent than A&agr; fibers.
Abstract: To determine whether α2-adrenergic agonists inhibit impulse conduction, clonidine and guanfacine were applied to rat sciatic nerve fibers studied in vitro Clonidine and guanfacine produced concentration-dependent, tonic inhibition of compound action potentials in large, myelinated Aα fibers The 50
TL;DR: The authors conclude that the S(-)-bupivacaine exerts less detrimental effects on the isolated heart of the rabbit perfused at a constant coronary flow with protein-free buffer.
Abstract: The enantiomers of a racemic drug generally differ in their pharmacokinetic and/or pharmacodynamic properties. Because bupivacaine is a mixture of two optical isomers known to exert different toxic properties on isolated nerve preparations, we decided to use an isolated rabbit heart model with const
Journal Article•
TL;DR: It is concluded that intraarticular morphine significantly reduces postoperative pain following knee arthroscopy and that there is no advantage of combining bupivacaine with morphine.
Abstract: A randomized, double-blind, controlled study was conducted in patients undergoing elective knee arthroscopy to assess the analgesic effect of intraarticular morphine and bupivacaine, alone and in combination. Patients in group 1 (n = 10) received 5 mg of morphine in 25 mL of saline; patients in group 2 (n = 10) received 25 mL of 0.25% bupivacaine (62.5 mg); patients in group 3 (n = 10) received a combination of 5 mg of morphine and 62.5 mg of bupivacaine in 25 mL dilution; and patients in group 4 (n = 10) received 25 mL of saline. All the drugs were injected intraarticularly. Postoperative pain was assessed using the visual analogue scale at 1, 2, 4, 8, and 24 h after the intraarticular injection. The need for supplemental analgesia was recorded. Results showed that there was no significant difference in the pain scores or analgesic requirements between groups 1 and 3. Patients in groups 1 and 3 had significantly lower pain scores than those in groups 2 and 4. These low pain scores were associated with lower requirements of supplementary analgesics. The patients in group 4 showed the highest pain scores and analgesic requirements. We conclude that intraarticular morphine significantly reduces postoperative pain following knee arthroscopy and that there is no advantage of combining bupivacaine with morphine.
TL;DR: The synchronous decrease in the shivering and vasoconstriction thresholds during spinal anesthesia is consistent with thermoregulatory impairment resulting from altered afferent thermal input.
Abstract: Reportedly, during spinal anesthesia, the shivering threshold is reduced approximately 1 degree C but the vasoconstriction threshold remains normal. Such divergence between the shivering and vasoconstriction thresholds is an unusual pattern of thermoregulatory impairment and suggests that the mechanisms of impairment during regional anesthesia may be especially complex. Accordingly, we sought to define the pattern of thermoregulatory impairment during spinal anesthesia by measuring response thresholds. Seven healthy women volunteered to participate on two study days. On one day, we evaluated thermoregulatory responses to hypothermia and hyperthermia during spinal anesthesia; on the other day, responses were evaluated without anesthesia. Upper body skin temperature was kept constant throughout the study. The volunteers were warmed via the lower body and cooled by central venous infusion of cold fluid. The core temperatures triggering a sweating rate of 40 g.m-2 x h-1, a finger flow of 0.1 mL/min, and a marked and sustained increase in oxygen consumption were considered the thermoregulatory thresholds for sweating, vasoconstriction, and shivering, respectively. Spinal anesthesia significantly decreased the thresholds for vasoconstriction and shivering, and the decrease in each was approximately 0.5 degree C. The range of temperatures not triggering thermoregulatory responses (those between sweating and vasoconstriction) was 0.9 +/- 0.6 degree C during spinal anesthesia. The synchronous decrease in the shivering and vasoconstriction thresholds during spinal anesthesia is consistent with thermoregulatory impairment resulting from altered afferent thermal input.
TL;DR: Laparoscopic cholecystectomy is a relatively new surgical procedure, enjoying ever-increasing popularity and presenting new anesthetic challenges, but anesthesiologists should be prepared to recommend conversion to an open procedure if hemodynamic, oxygenation, or ventilation difficulties occur during the procedure.
Abstract: Laparoscopic cholecystectomy is a relatively new surgical procedure, enjoying ever-increasing popularity and presenting new anesthetic challenges. The advantages of shorter hospital stay and more rapid return to normal activities are combined with less pain associated with the small limited incisions and less postoperative ileus compared with the traditional open cholecystectomy. Complications are mostly due to traumatic injuries sustained during blind trocar insertion, and physiologic changes associated with patient positioning and pneumoperitoneum creation. The choice of anesthetic technique for laparoscopic cholecystectomy is limited most frequently to general anesthesia. Controlled ventilation avoids hypercarbia, and an anesthetic technique incorporating antiemetics and nonsteroidal antiinflammatory agents has reduced postoperative nausea and vomiting. The use of nitrous oxide and narcotics during laparoscopic cholecystectomy is controversial. Laparoscopic cholecystectomy is a major advance in the management of patients with symptomatic gallbladder disease. However, in the present era of cost containment, older and sicker patients may present for this procedure on the day of surgery without adequate preoperative evaluation. Anesthesiologists thus should be prepared to recommend conversion to an open procedure if hemodynamic, oxygenation, or ventilation difficulties occur during the procedure.
TL;DR: A graphical method using CIs is proposed that allows ready interpretation of VAS data that allows a visual assessment of whether a particular technique would produce clinically important effects in the population at large.
Abstract: Visual analog scales (VAS) ranging from 0 cm (no pain) to 10 cm (worst imaginable pain) are used widely for pain measurement, but various investigators have not treated these data consistently. Conventional statistical tests of such data, although evaluating the "statistical significance" may obscure the clinical value of a treatment. On the other hand, confidence intervals (CIs) can illuminate both statistical and clinical importance. CIs give a range of values based on the observed data which contain, with a specified probability, a true but unknown variable typifying a population. We reviewed 112 articles published recently in anesthesia journals for statistical reporting of VAS data. Of the 112 articles, only two used CIs to report mean pain scores and one used CIs to report differences in median pain scores between the study groups. Only two articles presented 95% CI for the mean pain scores graphically. Analgesic techniques that produce VAS values in the range of 0-3 have been reported to represent adequate analgesia. A graphical method using CIs is proposed that allows ready interpretation of VAS data. With this approach, one evaluates whether the 95% CI for the mean pain score in a group during a particular period lies entirely within the zone defined as "analgesic success" (0-3). Such an analysis allows a visual assessment of whether a particular technique would produce clinically important effects in the population at large. This approach seems to provide more information than the use of conventional hypothesis testing in the interpretation of VAS data for pain measurement.
TL;DR: This study evaluated intrathecal (IT) sufentanil for labor analgesia with respect to sensory changes, side effects, and fetal heart rate (FHR) changes to find out whether these changes were associated with adverse neonatal outcome or not.
Abstract: This study was designed to evaluate intrathecal (IT) sufentanil for labor analgesia with respect to sensory changes, side effects, and fetal heart rate (FHR) changes. In Phase I of the study, data regarding duration of analgesia and hemodynamic changes were obtained retrospectively from the labor and anesthetic records of 90 patients who had received IT sufentanil, 10 micrograms in 1 mL of saline, during active labor. In Phase II, an additional 18 parturients who received similar treatment were studied prospectively to document sensory, motor, and hemodynamic changes, as well as the incidence of side effects. In Phase I, analgesia occurred rapidly and lasted 124 +/- 68 min (SD); 19% of patients required no further analgesia before delivery. In Phase II, median time to onset of analgesia was 3 min (range 1-6 min) and mean duration of analgesia was 96 +/- 36 min. Decreased sensation to pinprick and cold occurred within 6 min extending from T4 to L4 (upper and lower median levels) in the majority of patients. All subjects requested additional analgesia within approximately 30 min of recession of sensory changes. Motor strength remained normal throughout. Hypotension (systolic blood pressure [BP] 20% decrease in systolic BP) occurred in 14% and 11% of patients in Phase I and II, respectively. Perineal itching preceded analgesia in 95% of patients and all subjects experienced mild sedation. FHR changes occurred in 15% of cases but were not associated with adverse neonatal outcome.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this article, the respiratory effects of intravenous morphine infusions in 30 patients (2 to 570 days old, mean 155 days) after cardiac surgery were evaluated, and the results showed that morphine levels more than 15 ng/mL resulted in hypercarbia in 46% of patients, whereas levels less than 15 n/mL were associated with hyper carbia in 13% (P = 0.05).
Abstract: We evaluated the respiratory effects of intravenous morphine infusions in 30 patients (2 to 570 days old, mean 155 days) after cardiac surgery. PaCO2 during spontaneous breathing and CO2 response curves during rebreathing were obtained on morphine infusions at drug steady state and during drug washout. Steady state morphine serum levels > 20 ng/mL resulted in hypercarbia (PaCO2 > 55 mm Hg) and depressed CO2 response curve slopes (< 10 mL.min-1.mm Hg ETCO2(-1).kg-1) in 67% and 70% of patients, respectively (P < 0.05, compared to those with levels < 20 ng/mL). During washout, morphine levels more than 15 ng/mL resulted in hypercarbia in 46%, whereas levels less than 15 ng/mL were associated with hypercarbia in 13% (P = 0.025). No age-related differences in respiratory effect were seen in these studies at the same serum morphine level. Careful observation of any patient receiving morphine remains necessary, but neonates and young infants seem to have the same respiratory response to morphine infusions as older infants and children at the same blood level.
TL;DR: A better understanding of CBF, CMRO2, autoregulation and mechanism(s) of cerebral injury during CPB has lead to a scientific basis for many of the decisions made regarding extracorporeal perfusion.
Abstract: Although much has been learned about cerebral physiology during CPB in the past decade, the role of alterations in CBF and CMRO2 during CPB and the unfortunately common occurrence of neuropsychologic injury still is understood incompletely. It is apparent that during CPB temperature, anesthetic depth, CMRO2, and PaCO2 are the major factors that effect CBF. The systemic pressure, pump flow, and flow character (pulsatile versus nonpulsatile) have little influence on CBF within the bounds of usual clinical practice. Although cerebral autoregulation is characteristically preserved during CPB, untreated hypertension, profound hypothermia, pH-stat blood gas management, diabetes, and certain neurologic disorders may impair this important link between cerebral blood flow nutrient supply and metabolic demand (Figure 5). During stable moderate hypothermic CPB with alpha-stat management of arterial blood gases, hypothermia is the most important factor altering cerebral metabolic parameters. Autoregulation is intact and CBF follows cerebral metabolism. Despite wide variations in perfusion flow and systemic arterial pressure, CBF is unchanged. Populations of patients have been identified with altered cerebral autoregulation. To what degree the impairment of cerebral autoregulation contributes to postoperative neuropsychologic dysfunction is unknown. It must be emphasized that not the absolute level of CBF, but the appropriateness of oxygen delivery to demand is paramount. However, the assumption that the control of cerebral oxygen and nutrient supply and demand will prevent neurologic injury during CPB is simplistic. A better understanding of CBF, CMRO2, autoregulation and mechanism(s) of cerebral injury during CPB has lead to a scientific basis for many of the decisions made regarding extracorporeal perfusion.
TL;DR: Whether head trauma alters the integrity of the blood-brain barrier (BBB), the role of the BBB in edema formation and neurologic outcome, and the effect of MK-801 (a noncompetitive N-methyl-D-aspartate receptor antagonist) on BBB permeability are determined.
Abstract: We previously described the time course of changes in neurologic status (as indicated by neurologic severity score [NSS]) and cerebral edema (as indicated by brain tissue specific gravity and water content) after closed head trauma in rats. The present study was designed to determine whether head trauma alters the integrity of the blood-brain barrier (BBB), the role of the BBB in edema formation and neurologic outcome, and the effect of MK-801 (a noncompetitive N-methyl-D-aspartate receptor antagonist) on BBB permeability. Rats in which cranial impact was delivered during ether anesthesia (n = 106) were killed at 15 min, 1, 2, 4, 10, and 24 h, and 2, 4, and 7 days. Control rats (n = 12) received no cranial impact. Subsets of head-injured rats killed at 4 and 24 h received MK-801 (3 mg/kg intraperitoneally) 1 h after injury. BBB permeability was assessed with intravenous injection of Evans Blue dye, cerebral edema was assessed by determining brain tissue specific gravity and water content, and neurologic status was assessed using NSS. Tissue extravasation of Evans Blue was maximal in the injured hemisphere 4 h after injury, but a residual BBB permeability defect was still evident as long as 4 days after the insult. In MK-801-treated rats, extravasation of Evans Blue in the injured hemisphere was not significantly different from that in the noninjured hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Investigating the epidemiology of MH, its association with various drugs, and mortality rates finds case fatality rates have decreased with time to 10% since 1985, partly and independently due to dantrolene therapy, as well as to better vigilance and awareness on the part of the anesthetic community.
Abstract: Malignant hyperthermia (MH) is triggered by many anesthetics. This study investigates the epidemiology of MH, its association with various drugs, and mortality rates. Five hundred three cases of MH were reported. MH patients were demographically similar worldwide. Pediatric (52.1%, age < 15 yr) and male (65.8%) MH patients exceed the general surgical population. Congenital defects and musculoskeletal surgical procedures were associated clearly with MH. Previous uneventful anesthesia (20.9%) and absence of positive family history (75.9%) were common. Case fatality rates have decreased with time to 10% since 1985. This decline is partly and independently due to dantrolene therapy, as well as to better vigilance and awareness on the part of the anesthetic community.
TL;DR: The parasagittal anatomy important to the modified technique of supraclavicular nerve block designed to decrease the incidence of pneumothorax and to determ infection is defined.
Abstract: Supraclavicular nerve blocks are technically easy to perform, but may be associated with pneumothorax. The objective of this study is to define the parasagittal anatomy important to our modified technique of supraclavicular nerve block designed to decrease the incidence of pneumothorax and to determine whether this technique is anatomically sound. Two cadaver specimens were studied. One embalmed specimen was dissected to establish the relationship of the brachial plexus to our modified needle entry site. The neck and upper thorax of an unembalmed cadaver were frozen, and parasagittal serial sections were made to establish the relationship of the brachial plexus to surface features and the chest cavity. Additionally, 12 volunteers underwent magnetic resonance (MR) imaging and anatomic measurements of their supraclavicular anatomy important to our modified block. MR imaging showed that in no instance using our modified technique was the lung contacted by the simulated needle before entering either the subclavian artery or contacting the brachial plexus. Our technique has been used in more than 110 patients without pneumothorax. The combination of our cadaver and magnetic resonance data suggests that our plumb-bob technique of supraclavicular nerve block is anatomically sound and may minimize the development of pneumothorax during supraclavicular block.
TL;DR: Perioperative management of anxiety, perceptions, and expectations may prove valuable in improving pain control and satisfaction with IV-PCA.
Abstract: Despite intravenous patient-controlled analgesia's (IV-PCA) increasing popularity, the psychological and pharmacological factors upon which patient satisfaction with IV-PCA are based are unknown. Sixty-eight women scheduled for abdominal hysterectomy completed a series of questionnaires measuring emotional distress, locus of control, perceived support, and optimism before their surgery. Postoperative ratings of pain intensity, emotional distress, anticipated recovery time, nightmares, and satisfaction with IV-PCA were taken 1 and 3 days after surgery. A nurse observer rated perceived anxiety, estimated recovery, and satisfaction with IV-PCA. Cumulative and hourly IV-PCA use and dose/demand ratio were obtained. Degree of dissatisfaction with IV-PCA was significantly correlated with pain intensity, nightmares, patient's perceptions of support, expectations of recovery, preoperative anxiety, and postoperative depression. Dose/demand ratio and hourly analgesic usage were significantly related to pre- and postoperative emotional distress factors. Perioperative management of anxiety, perceptions, and expectations may prove valuable in improving pain control and satisfaction with IV-PCA.
TL;DR: It is concluded that vasopressin improves vital organ perfusion during ventricular fibrillation and cardiopulmonary resuscitation and seems to be at least as effective as epinephrine in this pig model of ventricularfibrillation.
Abstract: Based upon the hypothesis that vasopressin (antidiuretic hormone) may increase vascular resistance during ventricular fibrillation, the effects of this potent vasoconstrictor were studied in a porcine model of ventricular fibrillation. Vasopressin therapy was compared to epinephrine by randomly allocating 14 pigs to receive either 0.045 mg/kg of epinephrine (n = 7) or 0.8 U/kg of vasopressin (n = 7) after 4 min of ventricular fibrillation and 3 min of open-chest cardiopulmonary resuscitation. During cardiopulmonary resuscitation, myocardial blood flow before and 90 s and 5 min after drug administration was 57 +/- 11, 84 +/- 11, and 59 +/- 9 mL.min-1 x 100 g-1 (mean +/- SEM) in the epinephrine group, and 61 +/- 5, 148 +/- 26, and 122 +/- 22 mL.min-1 x 100 g-1 in the vasopressin group (P < 0.05 at 90 s and 5 min). At the same times, mean cardiac index was not significantly different between the groups. After drug administration, coronary venous PCO2 was significantly higher and coronary venous pH was significantly lower in the epinephrine as compared to the vasopressin group. All pigs in both groups were resuscitated and survived the 2-h observation period. We conclude that vasopressin improves vital organ perfusion during ventricular fibrillation and cardiopulmonary resuscitation. Vasopressin seems to be at least as effective as epinephrine in this pig model of ventricular fibrillation.
TL;DR: Perhaps caution should be exercised when administering etomidate to patients with a history of seizures as the myoclonic activity is associated with seizure activity, and the incidence of excitatory movements after administration of propofol is very low.
Abstract: Excitatory movements have been observed during induction of anesthesia with etomidate, thiopental, methohexital, and propofol. We studied the frequency of these excitatory effects and correlated movements with electroencephalographic (EEG) findings in 67 unpremedicated patients (mean age 66.1 yr, range 45-82 yr). Excitatory effects, including myoclonus, tremor, and dystonic posturing, occurred in 86.6% of patients receiving etomidate; 69.2% of the patient responses were myoclonic. Multiple spikes appeared on the EEG in 22.2% of the etomidate patients. The frequency of excitatory effects was 16.6% after thiopental, 12.5% after methohexital, and 5.5% after propofol. None of the patients receiving thiopental, methohexital, or propofol developed myoclonic or seizure activity. In most patients, the excitatory movements were coincident with the early slow phase of the EEG which corresponds to the beginning of deep anesthesia. We conclude that perhaps caution should be exercised when administering etomidate to patients with a history of seizures as the myoclonic activity is associated with seizure activity. The incidence of excitatory movements after administration of propofol is very low.
TL;DR: It is concluded that vasodilation produced by propofol is not endothelium-dependent but is likely due to blockade of voltage-gated influx of extracellular Ca2+.
Abstract: The mechanism of vasodilation induced by propofol was investigated using isolated rat thoracic aortic rings. Aortic rings were precontracted with potassium chloride (KCl) (40 mM) or phenylephrine (PE) (3 x 10(-8) to 3 x 10(-7) M) in the presence and absence of intact endothelium. Propofol produced similar concentration-dependent relaxation in aortic rings with and without endothelium regardless of whether they were precontracted with KCl or PE. The relaxation response to propofol was significantly greater in KCl-contracted aortic rings than in PE-contracted aortic rings. The propofol concentration producing 50% relaxation from the contracted state (RC50) was lower in aortic rings contracted with KCl than with PE, both with (5 +/- 0.6 x 10(-5) M vs 8.3 +/- 5.7 x 10(-4) M, P < 0.001) and without intact endothelium (3.9 +/- 0.5 x 10(-5) M vs 7.2 +/- 3.8 x 10(-4) M, P < 0.001). Propofol inhibited the Ca(2+)-induced contractions of aortic rings exposed to Ca(2+)-free media and depolarized with KCl (40 mM, 100 mM) in a dose-dependent manner. These effects are similar to those produced by verapamil. Propofol (5 x 10(-5) M) had minimal effect on the intracellular Ca2+ release elicited by PE (10(-5) M). We conclude that vasodilation produced by propofol is not endothelium-dependent but is likely due to blockade of voltage-gated influx of extracellular Ca2+.
TL;DR: Although rats that received both particulate and acidic material had a much more severe lung injury than with either of these substances alone, particulate injury also induced chronic inflammation with the formation of early granuloma at 48 h postaspiration, suggesting a critical and interactive role for both acid and small particulate components in the pathogenesis of gastric aspiration pneumonitis.
Abstract: Experimental aspiration pneumonitis studies in general have focused on the pathogenesis of the acidic component of the lung injury, although the injury produced by the particulate component of gastric contents largely has been ignored. The present study compares the inflammatory potential of small g