Showing papers in "Anesthesia & Analgesia in 2000"

Sedative, amnestic, and analgesic properties of small-dose dexmedetomidine infusions.

Abstract: This research determined the safety and efficacy of two small-dose infusions of dexmedetomidine by evaluating sedation, analgesia, cognition, and cardiorespiratory function. Seven healthy young volunteers provided informed consent and participated on three occasions with random assignment to drug or placebo. Heart rate, blood pressure, respiratory rate, ETCO(2), O(2) saturation, and processed electroencephalogram (bispectral analysis) were monitored. Baseline hemodynamic measurements were acquired, and psychometric tests were performed (visual analog scale for sedation; observer's assessment of alertness/sedation scale; digit symbol substitution test; and memory). The pain from a 1-min cold pressor test was quantified with a visual analog scale. After a 10-min initial dose of saline or 6 microg. kg(-1). h(-1) dexmedetomidine, volunteers received 50-min IV infusions of saline, or 0.2 or 0.6 microg. kg(-1). h(-1) dexmedetomidine. Measurements were repeated at the end of infusion and during recovery. The two dexmedetomidine infusions resulted in similar and significant sedation (30%-60%), impairment of memory (approximately 50%), and psychomotor performance (28%-41%). Hemodynamics, oxygen saturation, ETCO(2), and respiratory rate were well preserved throughout the infusion and recovery periods. Pain to the cold pressor test was reduced by 30% during dexmedetomidine infusion. Small-dose dexmedetomidine provided sedation, analgesia, and memory and cognitive impairment. These properties might prove useful in a postoperative or intensive care unit setting. IMPLICATIPNS: The alpha(2) agonist, dexmedetomidine, has sedation and analgesic properties. This study quantified these effects, as well as cardiorespiratory, memory and psychomotor effects, in healthy volunteers. Dexmedetomidine infusions resulted in reversible sedation, mild analgesia, and memory impairment without cardiorespiratory compromise.

Dexamethasone for the prevention of postoperative nausea and vomiting: a quantitative systematic review.

Abstract: The role of dexamethasone in the prevention of postoperative nausea and vomiting (PONV) is unclear. We reviewed efficacy and safety data of dexamethasone for prevention of PONV. A systematic search (MEDLINE, EMBASE, Cochrane Library, hand searching, bibliographies, all languages, up to April 1999) w

The visual analog scale allows effective measurement of preoperative anxiety and detection of patients' anesthetic concerns.

Abstract: The advent of managed care, reduction of costs, and advances in medical technology place increasing demands on anesthesiologists. Preoperative anxiety may go unnoticed in an environment that stresses increased productivity. The present study compares different methods for measuring preoperative anxiety, identifies certain patient characteristics that predispose to high anxiety, and describes the quantity and quality of anxiety that patients experience preoperatively. Seven hundred thirty-four patients participated in the study. We assessed aspects of anxiety by means of visual analog scales (VAS) and the State Anxiety Score of the Spielberger State-Trait Anxiety Inventory (STAI). The mean STAI anxiety score was 39 6 1( n 5 486) and the mean VAS for fear of anesthesia was 29 6 1( n 5 539). Patients feared surgery significantly more than anesthesia (P , 0.001). The VAS measuring fear of anesthesia correlated well with the STAI score (r 5 0.55; P , 0.01). Young patients, female patients, and patients with no previous anesthetic experience or a previous negative anesthetic experience had higher anxiety scores. Patients worried most about the waiting period preceding surgery and were least concerned about possible awareness intraoperatively. Factor analysis of various anxiety items showed three distinct dimensions of fear: 1) the fear of the unknown 2) the fear of feeling ill, and 3) the fear for one’s life. Among these dimensions, fear of the unknown correlated highest with the anxiety measuring techniques STAI and VAS. The simple VAS proved to be a useful and valid measure of preoperative anxiety. Implications: The study of qualitative aspects of anxiety reveals three distinct dimensions of preoperative fear: fear of the unknown, fear of feeling ill, and fear for one’s life. Groups of patients with a higher degree of preoperative anxiety and their specific anesthetic concerns can be identified using the visual analog scale.

A prospective, randomized study of goal-oriented hemodynamic therapy in cardiac surgical patients.

Abstract: Organ dysfunction and multiple organ failure are the main causes of prolonged hospital stay after cardiac surgery, which increases resource use and health care costs. Increased levels of oxygen delivery and consumption are associated with improved outcome in different groups of postoperative patients. Cardiac surgical patients are at risk of inadequate perioperative oxygen delivery caused by extracorporeal circulation and limited cardiovascular reserves. The purpose of our study was to test whether increasing oxygen delivery immediately after cardiac surgery would shorten hospital and intensive care unit (ICU) stay. Four hundred three elective cardiac surgical patients were enrolled in the study and randomly assigned to either the control or the protocol group. Goals of the protocol group were to maintain Svo 2 >70% and lactate concentration <=2.0 mmol/L from admission to the ICU and up to 8 h thereafter. Hemodynamics, oxygen transport data, and organ dysfunctions were recorded. The median hos-pital stay was shorter in the protocol group (6 vs 7 days, P < 0.05), and patients were discharged faster from the hospital than those in the control group (P < 0.05). Discharge from the ICU was similar between groups (P = 0.8). Morbidity was less frequent at the time of hospital discharge in the protocol group (1.1% vs 6.1%, P < 0.01). Increasing oxygen delivery to achieve normal Svo 2 values and lactate concentration during the immediate postoperative period after cardiac surgery can shorten the length of hospital stay. Implications: Health care economics has challenged clinicians to reduce costs and improve resource use in cardiac surgery and anesthesia in a patient population increasing in age and in severity of disease. Optimizing cardiovascular function to maintain adequate oxygen delivery during the immediate postoperative period after cardiac surgery can decrease morbidity and reduce length of hospital stay.

Prevention of pain on injection with propofol: a quantitative systematic review.

Abstract: The best intervention to prevent pain on injection with propofol is unknown. We conducted a systematic literature search (Medline, Embase, Cochrane Library, bibliographies, hand searching, any language, up to September 1999) for full reports of randomized comparisons of analgesic interventions with placebo to prevent that pain. We analyzed data from 6264 patients (mostly adults) of 56 reports. On average, 70% of the patients reported pain on injection. Fifteen drugs, 12 physical measurements, and combinations were tested. With IV lidocaine 40 mg, given with a tourniquet 30 to 120 s before the injection of propofol, the number of patients needed to be treated (NNT) to prevent pain in one who would have had pain had they received placebo was 1.6. The closest to this came meperidine 40 mg with tourniquet (NNT 1.9) and metoclopramide 10 mg with tourniquet (NNT 2.2). With lidocaine mixed with propofol, the best NNT was 2.4; with IV alfentanil or fentanyl, it was 3 to 4. IV lidocaine before the injection of propofol was less analgesic. Temperature had no significant effect. There was a lack of data for all other interventions to allow meaningful conclusions. The diameter of venous catheters and speed of injection had no impact on pain. Implications IV lidocaine (0.5 mg/kg) should be given with a rubber tourniquet on the forearm, 30 to 120 s before the injection of propofol; lidocaine will prevent pain in approximately 60% of the patients treated in this manner.

The Effect of Remifentanil on the Bispectral Index Change and Hemodynamic Responses After Orotracheal Intubation

Abstract: In order to examine whether changes in the bispectral index (BIS) may be an adequate monitor for the analgesic component of anesthesia, we evaluated the effect of remifentanil on the BIS change and hemodynamic responses to laryngoscopy and tracheal intubation. Fifty ASA physical status I patients we

Textbook of Pain

Abstract: The fourth edition of the Textbook of Pain reflects the evolution of Pain Medicine over the years. As in other editions of this landmark book, the editors have brought together an erudite commentary of 102 authors in addressing the science and philosophy of pain. The authorship is clearly international and multispecialty. This registration of thought gives an invaluable view of pain that knows no geographic boundaries and lacks the bias that can occur when one specialist tries to write as if a member of another basic science or clinical discipline. Indeed, the editors acknowledge that they have made no attempt to homogenize the writing style nor, more importantly, the opinions or comments in the individual chapters by such a diverse group of knowledgeable individuals. Many authors are recognized authorities in the field and/or on the topic on which they have written. Anesthesiologists will be well served by this book as it will widen their knowledge base about “pain” and do so without the distraction of the regional anesthesia/analgesia focus so prevalent in other texts. The editors have consolidated some of the topics, offering a reduced number of chapters (68), yet there is still adequate coverage of pain overall (the page total is increased). The text remains comprehensive and contemporary in content. The reader’s understanding is enhanced by the chapter architecture, the organizational style of the text, and the use of summary statements in most of the chapters. Twenty-five percent of the text is devoted to basic science and physical and psychosocial mechanism considerations. The realistic interdigitation of physical and psychological realms of “pain” is consistently emphasized. The series of chapters on pain measurement are a valuable subsection of the text, as this aspect of pain medicine continues to be one of the most difficult to realize in clinical practice. This pertinent section is expanded from recent editions, and the chapter on pain studies in humans is crucial material for all clinicians. The Clinical States midportion (almost 50% of the pages) addresses the necessary disease states and sources of pain that are encountered in clinical practice. Anesthesiologists commonly see patients with chronic low back pain, cancer pain, and chronic regional pain syndrome, each of which is addressed with a chapter devoted to the topic. The editors are to be credited with including updated material on such new-age topics as chronic pelvic pain, spinal cord injury pain, gender differences in pain, and pain associated with end-of-life issues. The therapeutics section, again, deals with the expected modalities for pain management in a forthright manner. The chapter on spinal cord and brain stimulation techniques is of high quality, as is the one on the placebo response, and both appropriately emphasize the necessary selection of patients. Anesthesiologists will find this textbook lacking in extensive discussions about therapeutic regional anesthesia and analgesia techniques, but multiple other sources of such information are available to those needing that material. The chapter on therapeutic trials contains fundamental material that will be of interest to most clinicians and helps to elevate one’s appreciation of how hard it is to conduct scientifically honest research that results in valid outcomes. Pain management is a distinct and growing aspect of clinical anesthesia practice. The clinician needs access to educational resources that encompass the many components of pain medicine. Textbook of Pain fulfills such a need in assimilating the individual interpretations of a diverse collection of reputable authors into a well organized and useful text. The page total has been increased appropriately, yet there is a economy given that the writing is not wordy. The tables and illustrations are supplementary to the text, and not mere restatements. There is a small color plate section, and the chapter on the imaging techniques for pain is very interesting. The bibliography for most chapters is thorough (superb in some cases) and generally up to date. The enduring emphasis on pain being viewed at all times in the evaluation and treatment phases as a biopsychosocial disease is consistently presented and maintains the appropriate contemporary focus.

Preoperative anxiety and intraoperative anesthetic requirements.

Abstract: The purpose of this study was to determine whether larger doses of anesthetics are required in the anxious patient to establish and maintain a clinically sufficient hypnotic component of the anesthetic state. Fifty-seven women undergoing bilateral laparoscopic tubal ligation with a propofol-based an

The effects of tramadol and morphine on immune responses and pain after surgery in cancer patients.

Abstract: There has been growing interest in determining the possible immune consequences of opioid administration for the management of postoperative pain. We studied the effects of morphine and tramadol on pain and immune function during the postoperative period in 30 patients undergoing abdominal surgery for uterine carcinoma. Phytohemoagglutinin-induced T lymphocyte proliferation and natural killer cell activity were evaluated immediately before and after surgery, and 2 h after the acute administration of either 10 mg of morphine IM or 100 mg tramadol IM for pain. In all patients, phytohemagglutinin-induced lymphoproliferation was significantly depressed by surgical stress. However, in the morphine-treated group, proliferative values remained lower than basal levels for 2 h after treatment, whereas in tramadol-administered patients proliferative values returned to basal levels. Natural killer cell activity was not significantly affected by surgery nor by morphine administration, whereas tramadol significantly enhanced the activity of natural killer cells. Both drugs produced a comparable reduction in postoperative pain. We conclude that, as previously observed in the experimental animal, tramadol and morphine, when administered in analgesic doses, induce different immune effects. (Anesth Analg 2000;90:1411‐4)

Thoracic paravertebral block for breast surgery.

Abstract: Cosmetic and reconstructive breast augmentation is a frequently performed surgical procedure. Despite advances in medical treatment, surgical intervention is often associated with postoperative pain, nausea, and vomiting. Paravertebral nerve block (PVB) has the potential to offer long-lasting pain r

Pediatric evaluation of the bispectral index (BIS) monitor and correlation of BIS with end-tidal sevoflurane concentration in infants and children.

Abstract: The bispectral index (BIS) has been developed in adults and correlates well with clinical hypnotic effects of anesthetics. We investigated whether BIS reflects clinical markers of hypnosis and demonstrates agent dose-responsiveness in infants and children. In an observational arm of this study, BIS

The Hemodynamic and Adrenergic Effects of Perioperative Dexmedetomidine Infusion after Vascular Surgery

Abstract: UNLABELLED: We tested dexmedetomidine, an alpha(2) agonist that decreases heart rate, blood pressure, and plasma norepinephrine concentration, for its ability to attenuate stress responses during emergence from anesthesia after major vascular operations. Patients scheduled for vascular surgery received either dexmedetomidine (n = 22) or placebo (n = 19) IV beginning 20 min before the induction of anesthesia and continuing until 48 h after the end of surgery. All patients received standardized anesthesia. Heart rate and arterial blood pressure were kept within predetermined limits by varying anesthetic level and using vasoactive medications. Heart rate, arterial blood pressure, and inhaled anesthetic concentration were monitored continuously; additional measurements included plasma and urine catecholamines. During emergence from anesthesia, heart rate was slower with dexmedetomidine (73 +/- 11 bpm) than placebo (83 +/- 20 bpm) (P = 0.006), and the percentage of time the heart rate was within the predetermined hemodynamic limits was more frequent with dexmedetomidine (P < 0.05). Plasma norepinephrine levels increased only in the placebo group and were significantly lower for the dexmedetomidine group during the immediate postoperative period (P = 0.0002). We conclude that dexmedetomidine attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia. IMPLICATIONS: The alpha(2) agonist, dexmedetomidine, attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia in vascular surgery patients.

Postoperative analgesic effects of celecoxib or rofecoxib after spinal fusion surgery.

Abstract: UNLABELLED Nonsteroidal antiinflammatory drugs are recommended for the multimodal management of postoperative pain and may have a significant opioid-sparing effect after major surgery. The analgesic efficacy of the cyclooxygenase-2 nonsteroidal antiinflammatory drugs, celecoxib and rofecoxib, have not been evaluated after major orthopedic surgery. This study was designed to determine whether the administration of a preoperative dose of celecoxib or rofecoxib to patients who have undergone spinal stabilization would decrease patient-controlled analgesia (PCA) morphine use and/or enhance analgesia. We evaluated 60 inpatients undergoing spine stabilization by one surgeon. All patients received PCA morphine. The patients were divided into three groups. Preoperatively, they were given oral celecoxib 200 mg, rofecoxib 50 mg, or placebo. The outcome measures included pain scores and 24-h morphine use at six times during the first 24 postoperative h. The total dose of morphine and the cumulative doses for each of the six time periods were significantly more in the placebo group than in the other two groups. The morphine dose was significantly less in five of the six time intervals in the rofecoxib group compared with the celecoxib group. The pain scores were significantly less in the rofecoxib group than in the other two groups at two of the six intervals, and less than the placebo group in an additional interval. Although both rofecoxib and celecoxib produce similar analgesic effects in the first 4 h after surgery, rofecoxib demonstrated an extended analgesic effect that lasted throughout the 24-h study. We thus recommend that rofecoxib be used as a preoperative component of pain management that includes PCA morphine in patients undergoing spine stabilization surgery. IMPLICATIONS The cyclooxygenase-2-specific nonsteroidal antiinflammatory drugs, celecoxib and rofecoxib, both demonstrate an opioid-sparing effect after spinal fusion surgery. Celecoxib resulted in decreased morphine use for the first 8 h after surgery, whereas rofecoxib demonstrated less morphine use throughout the 24-h study period.

Recovery profiles and costs of anesthesia for outpatient unilateral inguinal herniorrhaphy.

Abstract: The use of an ilioinguinal-hypogastric nerve block (IHNB) as part of a monitored anesthesia care (MAC) technique has been associated with a rapid recovery profile for outpatients undergoing inguinal herniorrhaphy procedures. This study was designed to compare the cost-effectiveness of an IHNB-MAC technique with standardized general and spinal anesthetics techniques for inguinal herniorrhaphy in the ambulatory setting. We randomly assigned 81 consenting outpatients to receive IHNB-MAC, general anesthesia, or spinal anesthesia. We evaluated recovery times, 24-h postoperative side effects and associated incremental costs. Compared with general and spinal anesthesia, patients receiving IHNB-MAC had the shortest time-to-home readiness (133+/-68 min vs. 171+/-40 and 280+/-83 min), lowest pain score at discharge (15+/-14 mm vs. 39+/-28 and 34+/-32 mm), and highest satisfaction at 24-h follow-up (75% vs. 36% and 64%). The total anesthetic costs were also the least in the IHNB-MAC group ($132.73+/-33.80 vs. $172.67+/-29.82 and $164.97+/-31.03). We concluded that IHNB-MAC is the most cost-effective anesthetic technique for outpatients undergoing unilateral inguinal herniorrhaphy with respect to speed of recovery, patient comfort, and associated incremental costs.

Levosimendan, a new positive inotropic drug, decreases myocardial infarct size via activation of K(ATP) channels.

Abstract: We tested the hypothesis that levosimendan, a new positive inotropic drug that activates adenosine triphosphate-regulated potassium (KATP) channels in vitro, decreases myocardial infarct size in vivo. Myocardial infarct size was measured after a 60-min left anterior descending coronary artery occlus

Emergence agitation after sevoflurane versus propofol in pediatric patients.

Abstract: Sevoflurane may be associated with a high incidence of emergence agitation in preschool children. We tested the hypothesis that maintenance of anesthesia with propofol after sevoflurane induction would reduce the incidence of this excitatory behavior compared with continuing sevoflurane for maintena

Gabapentin enhances the analgesic effect of morphine in healthy volunteers.

Abstract: The most effective group of drugs for the treatment of severe pain is opioid analgesics. Their use, however, is limited by decreased effects in neuropathic and chronic pain as a result of increased pain and development of tolerance. Gabapentin (GBP) is effective in both experimental models of chroni

Aggressive warming reduces blood loss during hip arthroplasty.

Abstract: We evaluated the effects of aggressive warming and maintenance of normothermia on surgical blood loss and allogeneic transfusion requirement. We randomly assigned 150 patients undergoing total hip arthroplasty with spinal anesthesia to aggressive warming (to maintain a tympanic membrane temperature

Multimodal antiemetic management prevents early postoperative vomiting after outpatient laparoscopy.

Abstract: Because no completely effective antiemetic exists for the prevention of postoperative nausea and vomiting (PONV), we hypothesize that a multimodal approach to management of PONV may reduce both vomiting and the need for rescue antiemetics in high-risk patients. After IRB approval, women undergoing outpatient laparoscopy were randomized to one of three groups. Group I (n = 60) was managed by using a predefined multimodal clinical care algorithm. Patients undergoing the same surgical procedure who received a standard balanced outpatient anesthetic with ondansetron 4 mg (Group II, n = 42) or placebo (Group III, n = 37) prophylaxis were chosen to establish baseline incidence of nausea and vomiting. None of the Group I patients vomited before discharge, compared with 7% in Group II (P = 0.07) and 22% in Group III (P = 0.0003). However, one patient (2%) in Group I required treatment for symptoms in the postanesthesia care unit, compared with 24% in Group II (P<0.0001) and 41% in Group III (P< 0.0001). Time to discharge-ready was significantly shorter in Group I (128, 118-139 min; mean, 95% confidence interval) versus Group II (162, 145-181 min; P = 0.0015) and Group III (192, 166-222 min; P = 0.0001). Patient satisfaction with control of PONV was not different between Group I and Group II. Return to normal daily activity and overall satisfaction were not different among groups. Multimodal management resulted in a 98% complete response rate and a 0% incidence of vomiting before discharge; however, this improvement did not result in an increased level of patient satisfaction when compared with routine monotherapy prophylaxis. We conclude that both multimodal management and routine monotherapy antiemetic prophylaxis resulted in an increased level of patient satisfaction than symptomatic treatment in this high-risk population.

Comparing methods of clinical measurement: reporting standards for bland and altman analysis.

Abstract: In this era of medical technology assessment and evidence-based medicine, evaluating new methods to measure physiologic variables is facilitated by standardization of reporting results. It has been proposed that assessing repeatability be followed by assessing agreement with an established technique. If the “limits of agreement” (mean bias 6 2sd) are not clinically important, then one could use two measurements interchangeably. Generalizability to larger populations is facilitated by reporting confidence intervals. We identified 44 studies that compared methods of clinical measurement published during 1996 to 1998 in seven anesthesia journals. Although 42 of 44 (95.4%) used the limits of agreement methodology for analysis, several inadequacies and inconsistencies in reporting the results were noted. Limits of agreement were defined a priori in 7.1%, repeatability was evaluated in 21.4%, and relationship (pattern) between difference and average was evaluated in 7.1%. Only one of the articles reported confidence intervals. A computer macro for the Minitab statistical package (State College, PA) is described to facilitate reporting of Bland and Altman analysis with confidence intervals. We propose standardization of nomenclature in clinical measurement comparison studies. Implications: A literature review of anesthesia journals revealed several inadequacies and inconsistencies in statistical reports of results of comparison studies with regard to interchangeability of measurement methods. We encourage journal editors to evaluate submissions on this subject carefully to ensure that their readers can draw valid conclusions about the value of new technologies.

The effect of timing of dexamethasone administration on its efficacy as a prophylactic antiemetic for postoperative nausea and vomiting

Abstract: We evaluated the timing effect of a 10-mg IV administration of dexamethasone on its efficacy as a prophylactic antiemetic on postoperative nausea and vomiting (PONV). One hundred twenty women (n = 40 in each of three groups) undergoing abdominal total hysterectomy under general anesthesia were enrol

A dose-response study of prophylactic intravenous ephedrine for the prevention of hypotension during spinal anesthesia for cesarean delivery.

Abstract: UNLABELLED We performed a randomized, double-blinded dose-finding study of IV ephedrine for prophylaxis for hypotension in 80 women who received an IV crystalloid preload and spinal anesthesia for elective cesarean delivery. One minute after the intrathecal injection, patients were given saline control or ephedrine 10, 20, or 30 mg IV for 30 s. Systolic arterial pressure (SAP) in the first 12 min after the spinal injection was greater in the 30-mg group compared with other groups (P < 0.05). Hypotension occurred in 7 patients (35%) in the 30-mg group compared with 19 (95%), 17 (85%), and 16 (80%) patients in the control and 10- and 20-mg groups, respectively (P < 0.0001). Maximum decrease in SAP was smaller in the 30-mg group (mean lowest SAP 87% of baseline, range 58%-105%) compared with other groups (P < 0.01). Reactive hypertension occurred in 9 patients (45%) in the 30-mg group (mean highest SAP 120% of baseline, range 104%-143%) compared with 2 (10%), 1 (5%), and 5 (25%) patients in the other groups (P = 0.009). Heart rate changes, total ephedrine requirement, incidence of nausea and vomiting, and neonatal outcome were similar among groups. The proportion of patients with umbilical arterial pH < 7.2 was 10.5%, 25%, 42%, and 22% in the control, 10-, 20-, and 30-mg groups, respectively (P = 0. 12). We conclude that the smallest effective dose of ephedrine to reduce the incidence of hypotension was 30 mg. However, this dose did not completely eliminate hypotension, nausea and vomiting, and fetal acidosis, and it caused reactive hypertension in some patients. IMPLICATIONS We investigated different doses of IV ephedrine as prophylaxis for hypotension during spinal anesthesia for cesarean delivery and found that the smallest effective dose was 30 mg. However, this dose did not completely eliminate hypotension, caused reactive hypertension in some patients, and did not improve neonatal outcome.

A comparison of the electrocardiographic cardiotoxic effects of racemic bupivacaine, levobupivacaine, and ropivacaine in anesthetized swine.

Abstract: We sought, in this observer-blinded study, to determine the lethal dose for each of the local anesthetics levobupivacaine (L), racemic bupivacaine (B), and ropivacaine (R), and to compare their respective effects on the QRS interval of the precordial electrocardiograph after intracoronary injection.

Interscalene brachial plexus block with a continuous catheter insertion system and a disposable infusion pump.

Abstract: Continuous interscalene brachial plexus blockade traditionally requires a hospital stay for local anesthetic infusion, and achieving consistent catheter insertion may be difficult. Incorporating long-acting pain relief from a continuous peripheral nerve block, with a reliable method of catheter insertion, and a self-contained infusion system would be a valuable asset for short-stay care. We compared the efficacy of single injection interscalene brachial plexus blockade to a continuous peripheral nerve block, with an insulated Tuohy system and a disposable infusion pump. Forty adult patients scheduled for open rotator cuff repair were entered in this randomized, double-blinded, placebo-controlled study. Patients received an interscalene brachial plexus blockade and a continuous peripheral nerve catheter as their primary anesthetic and then, were assigned to receive one of two different postoperative infusions: either 0.2% ropivacaine at 10 mL/h via a disposable infusion pump or normal saline at 10 mL/h via a disposable infusion pump (n = 18-20 per group). Visual analog pain scores and postoperative morphine consumption were measured for 24 h. The ropivacaine group showed less pain than the placebo group (P: = 0.0001) between 12 and 24 h after the initial injection of local anesthetic. In addition, initial interscalene blockade was successful in all patients and all redosed catheters were functional after 24 h with the continuous catheter insertion system. We conclude that it is possible to achieve a high rate of successful catheter placement and analgesia by using the continuous catheter insertion system and a disposable infusion pump in the ambulatory setting. This method of analgesia may offer improved pain relief after outpatient rotator cuff repair.

Does the ProSeal Laryngeal Mask Airway Prevent Aspiration of Regurgitated Fluid

Abstract: In this randomized, cross-over cadaver study, we determined whether a new airway device, the ProSeal laryngeal mask airway (PLMA; Laryngeal Mask Company, Henley-on-Thames, UK), prevents aspiration of regurgitated fluid. We studied five male and five female cadavers (6-24 h postmortem). The infusion set of a pressure-controlled, continuous flow pump was inserted into the upper esophagus and ligated into place. Esophageal pressure (EP) was increased in 2-cm H(2)O increments. This was performed without an airway device (control) and over a range of cuff volumes (0-40 mL) for the classic laryngeal mask airway (LMA), the PLMA with the drainage tube clamped (PLMA clamped) and unclamped (PLMA unclamped). The EP at which fluid was first seen with a fiberoptic scope in the hypopharynx (control), above or below the cuff, or in the drainage tube, was noted. Mean EP at which fluid was seen without any airway device was 9 (range 8-10) cm H(2)O. EP at which fluid was seen was always higher for the PLMA clamped and LMA compared with the control (all, P<0.0001). The mean EP at which fluid was seen for the PLMA unclamped was similar to the control at 10 (range 8-13) cm H(2)O. For the PLMA unclamped, fluid appeared from the drainage tube in all cadavers at 10-40 mL cuff volume and in 8 of 10 cadavers at zero cuff volume. Mean EP at which fluid was seen above the cuff was similar for the PLMA clamped and LMA at 0-30 mL cuff volume, but was higher for PLMA clamped at 40-mL cuff volume (81 vs 48 cm H(2)O, P = 0.006). Mean EP at which fluid was seen below the cuff was similar at 0-10 mL cuff volume, but was higher for the PLMA clamped at 20, 30, and 40 mL cuff volume (62, 68, 73 vs. 46, 46, 46 cm H(2)O, respectively, P<0.04). For the PLMA clamped and the LMA, fluid appeared simultaneously above and below the cuff at all cuff volumes. We concluded that in the cadaver model, the correctly placed PLMA allows fluid in the esophagus to bypass the pharynx and mouth when the drainage tube is open. Both the LMA, and PLMA with a closed drainage tube, attenuate liquid flow between the esophagus and pharynx. This may have implications for airway protection in unconscious patients.

Postdural puncture headache: a randomized comparison of five spinal needles in obstetric patients.

Abstract: This prospective, blinded, randomized study compares the incidence of postdural puncture headache (PDPH) and the epidural blood patch (EBP) rate for five spinal needles when used in obstetric patients. One thousand two women undergoing elective cesarean delivery under spinal anesthesia were recruited. We used two cutting needles: 26-gauge Atraucan and 25-gauge Quincke, and three pencil-point needles: 24-gauge Gertie Marx (GM), 24-gauge Sprotte, and 25-gauge Whitacre. The needle for each weekday was chosen randomly. Cutting needles were inserted parallel to the dural fibers. The incidences of PDPH were, respectively, 5%, 8.7%, 4%, 2.8%, and 3.1% for Atraucan, Quincke, GM, Sprotte, and Whitacre needles (P = 0.04, chi(2) analysis), and the corresponding EBP rates in those with PDPH were 55%, 66%, 12.5%, 0%, and 0% (P = 0.000). The Quincke needle had a more frequent PDPH rate than the Sprotte or the Whitacre needle (P = 0.02) and a more frequent EBP rate than the GM, Sprotte, or the Whitacre needle (P = 0.01). The Atraucan needle had a more frequent EBP rate than the Sprotte or Whitacre needle (P = 0.05). Neither the PDPH rate nor the EBP rates differed among the pencil-point needles. The cost of EBP must be taken into consideration when choosing a spinal needle. We conclude that pencil-point spinal needles should be used for subarachnoid anesthesia in obstetric patients.

The benefits of intraoperative small-dose ketamine on postoperative pain after anterior cruciate ligament repair.

Abstract: In a randomized, double-blinded study with three parallel groups, we assessed the analgesic effect of intraoperative ketamine administration in 45 ASA physical status I or II patients undergoing elective arthroscopic anterior ligament repair under general anesthesia. The patients received either IV

The efficacy of intrathecal morphine and clonidine in the treatment of pain after spinal cord injury.

Abstract: We performed a double-blinded, randomized, controlled trial in 15 patients to determine the efficacy of intrathecal morphine or clonidine, alone or combined, in the treatment of neuropathic pain after spinal cord injury. The combination of morphine and clonidine produced significantly more pain relief than placebo 4 h after administration; either morphine or clonidine alone did not produce as much pain relief. In addition, lumbar and cervical cerebrospinal fluid (CSF) concentrations, sampled at these levels at different times after administration were examined for a relationship between pain relief and CSF drug concentration. Lumbar CSF drug concentrations were initially several orders of magnitude larger than those in cervical CSF. After 1-2 h, the concentrations of morphine in cervical CSF markedly exceeded those of clonidine. The concentration of morphine in the cervical CSF and the degree of pain relief correlated significantly. We conclude that intrathecal administration of a mixture of clonidine and morphine is more effective than either drug administered alone and is related to the CSF-borne drug concentration above the level of spinal cord injury. If there is pathology that may restrict CSF flow, consideration should be given to intrathecal administration above the level of spinal cord damage to provide an adequate drug concentration in this region.

Novel analgesic adjuncts for brachial plexus block: a systematic review.

Abstract: This article reviews current evidence for the efficacy of adding novel analgesic adjuncts to brachial plexus block, the goal of which is to prolong analgesic effect without the disadvantage of systemic side effects or prolonged motor block. It may also allow for a reduction in the total dose of local anesthetic used. Novel adjuncts studied to date include opioids, clonidine, neostigmine, and tramadol. Twenty-four studies were reviewed and assessed by using specific inclusion criteria, and only those studies satisfying these criteria were included in the final assessment. Satisfactory studies were then assessed for inclusion of a systemic control group to determine peripheral effect, as opposed to possible systemic effect, of an adjunct administered peripherally. Evidence regarding the analgesic benefit of opioid adjuncts remains equivocal and more evidence is required before their routine use can be recommended. Clonidine appears to have significant analgesic benefit and to cause minimal adverse effects when used in doses up to 150 microg. Data regarding other drugs, such as tramadol and neostigmine, are not sufficient to allow for any recommendations, and further studies are required.

The effect of ketamine on opioid-induced acute tolerance : can it explain reduction of opioid consumption with ketamine-opioid analgesic combinations?

Abstract: UNLABELLED Ketamine administered intraoperatively in very small doses reduces postoperative opioid consumption. We suggest that this effect is the result of attenuation of acute tolerance to the analgesic effect of opioids. We sought to demonstrate that acute tolerance induced by alfentanil infusion can be attenuated by a dose of ketamine that is too small to produce a direct antinociceptive effect. The experiments were conducted in rats with the use of an infusion algorithm designed to maintain a constant plasma level of the opioid for 4 h. The degree of acute tolerance was determined on the basis of decline in the level of analgesia measured with a tail compression test. Ketamine (10 mg/kg) did not change the baseline pain threshold and did not increase the peak of alfentanil-induced analgesia. At the same time, it attenuated the development of acute tolerance to analgesia during alfentanil infusion and suppressed rebound hyperalgesia observed the day after the infusion. These effects were similar to those observed with dizocilpine (0.1 mg/kg). The development of acute tolerance to analgesia induced by the infusion of an opioid can be attenuated by ketamine administered in doses that are not large enough to provide a direct antinociceptive effect. Therefore, ketamine has the potential to reduce opioid consumption even in subanalgesic doses. IMPLICATIONS Ketamine attenuated the development of acute tolerance to analgesia during alfentanil infusion and suppressed rebound hyperalgesia observed the day after the infusion.