David C. Abramson

Thromboelastography with heparinase in orthotopic liver transplantation

OBJECTIVE To investigate the role of heparin in the postreperfusion coagulopathy during liver transplantation with heparinase-guided thromboelastography. DESIGN A prospective, interventional study. SETTING A university-affiliated hospital. PARTICIPANTS Twenty-six patients undergoing orthotopic liver transplantation (OLT). INTERVENTIONS Blood drawn at five intervals for thromboelastography assessment with native (12 patients) or celite blood (14 patients) compared with simultaneous thromboelastography traces with added heparinase. MAIN RESULTS In the native samples, the prolonged R (reaction) and K (coagulation) time and decreased alpha angle were corrected in heparinase thromboelastograph traces immediately before reperfusion and 10 minutes postreperfusion. In the celite-accelerated samples, the heparinase traces showed correction of the R and K times and alpha angle only at the 10-minute postreperfusion stage. In seven patients who had thromboelastography performed after protamine administration, there were no differences between celite and heparinase-celite traces. CONCLUSIONS Heparinase-treated thromboelastography offered compelling evidence for the presence of heparin-like activity after liver graft reperfusion. The objective evidence provided by this modification of thromboelastography-guided protamine administration and was useful in identifying one of the many potential causes of postreperfusion bleeding in patients undergoing OLT.

Demonstration of dose-dependent global and regional cocaine-induced reductions in brain blood flow using a novel approach to quantitative single photon emission computerized tomography

Ischemic stroke is a common cause of morbidity and mortality in cocaine addicts. Because the previous semiquantitative single photon emission computerized tomography (SPECT) method for measuring brain blood flow does not quantify blood flow, the magnitude and specificity of cocaines effects during drug taking has not been well established. Here, using a novel quantitative approach to SPECT, we established that intravenous cocaine administration to nine recently abstinent cocaine-dependent subjects was associated with significant decreases in global and regional brain blood flow to dopamine-rich areas such as the prefrontal, frontal, temporal, and subcortical gray matter. Establishing the utility of this relatively new quantitative SPECT technique provides an important tool for the management of vascular disorders of the brain. Additionally, identifying the site-specific effects of cocaine provides targets for the development of putative therapeutic medications to attenuate or minimize ischemic stroke in cocaine addicts.

Anaesthesia for magnetoencephalography in children with intractable seizures

Background Magnetoencephalography (MEG), a noninvasive technique for evaluation of epileptic patients, records magnetic fields during neuronal electrical activity within the brain. Anaesthesia experience for MEG has not yet been reported.

Isradipine prevents global and regional cocaine-induced changes in brain blood flow: A preliminary study

Abstract The L-type calcium channel antagonist, isradipine, reduces brain ischemia in animal models of ischemic stroke. These effects of isradipine appear more pronounced in dopamine (DA) rich brain regions. These same DA-rich brain regions have also been shown to be the areas most affected by cocaine-induced ischemic changes. Using a novel quantified approach to single photon emission computerized tomography, we demonstrated that isradipine pre-treatment prevented cocaine-induced ischemic changes, especially in these DA-rich brain regions. This is the first demonstration that any medication, including isradipine, can prevent the ischemic effects of cocaine on brain blood flow. Isradipine may, therefore, be a useful therapeutic agent for the prevention of brain ischemia in cocaine addicts.

Effects of acute intravenous cocaine on cardiovascular function, human learning, and performance in cocaine addicts.

Continuous non-invasive cardiovascular monitoring in eight healthy cocaine addicts receiving intravenous cocaine (0.325 mg/kg or 0.650 mg/kg) or placebo in double-blind, randomized, cross-over fashion demonstrated significant dose-dependent increases in pulse and mean arterial pressure following cocaine. Pulse and mean arterial pressure peaked 5 min post-cocaine injection and maximal response was sustained for a further 15 min and 35 min afterwards, respectively. Cocaine administration had no significant effect on peripheral oxygen saturation, and no clinically significant abnormalities of rhythm or conduction were seen on the electrocardiogram. These doses and method of single-dose intravenous cocaine administration, and our procedures for cardiovascular monitoring, appear relatively safe for laboratory studies of healthy cocaine addicts with no pre-existing cardiovascular disease. In addition, cocaine-taking (0.325 mg/kg i.v. and 0.650 mg/kg i.v.) was associated with enhanced attention (i.e. increased numbers of correct responses on the Rapid Visual Information Processing Task), but the trend towards reduced reaction time did not achieve statistical significance. Cocaine-taking resulted in a small but statistically insignificant improvement in learning on the Digit Symbol Substitution Task. These results suggest that cocaine-taking in rested subjects is associated with some cognitive enhancement.

Celite-activated thrombelastography in children

STUDY OBJECTIVE To quantify global coagulation and establish normal ranges for the celite-activated thrombelastograph (TEG) in healthy pediatric patients. DESIGN Prospective observational study. SETTING Operating suite of a university-based hospital. PATIENTS 110 healthy pediatric patients in four age groups and 25 healthy adult patients. INTERVENTIONS Blood sampling for the celite-activated TEG was carried out after anesthetic induction. MEASUREMENTS TEG indices: R time (reflecting time to fibrin formation), K time and alpha angle (fibrinogen-platelet interaction), maximum amplitude (reflecting maximal clot strength, platelet and fibrinogen function), TEG index (mathematical incorporation of the prior four measurements), and percent fibrinolysis at 30 minutes, were all recorded. MAIN RESULTS Statistically significant differences between <12-month group in angle (compared to 25-48 month group) and % fibrinolysis (compared to all other pediatric groups). Significant differences in angle between two pediatric groups and adult group, and in the TEG index between three pediatric groups and adult group (all differences p < 0.05). CONCLUSIONS These data identify changes of small magnitude in three celite-TEG parameters in healthy children compared to adults, without implication of abnormal coagulation between groups. Changes do not seem to be consistently related to age and will be useful for clinicians using the TEG to monitor (ab) normal coagulation in pediatric patients.

Sudden unexpected sneezing during the insertion of peribulbar block under propofol sedation

The author presents a case report where, following propofol sedation for a peribulbar block, sneezing was induced once the local anaesthetic needle was placed in the orbital cavity. The physiology of sneezing is discussed, as well as the pathophysiology of the ACHOO (Autosomal Dominant Compelling Helio-Ophthalmic Outburst) syndrome, an autosomal dominant condition, present in approximately 25% of the population, where sneezing is provoked upon exposure to bright light. It is suggested that the anaesthesia induced by propofol may have sensitized patients with this condition to sneeze, since there appeared to be no other excitatory sequelae which have previously been described with propofol.RésuméCette observation décrit un épisode d’étemuements survenu pendant une sédation au propofol exécutée pour un bloc péribulbaire. Les étemuements surviennent lorsque l’aiguille pénètre la cavité orbitale. La physiologie de l’étemuement est discutée ainsi que la physiopathologie du syndrome d’accès d’étemuements provoqués par la lumière intense, affection autosome dominante, présente dans 25% de la population. On suggère que l’anesthésie induite au propofol pourrait provoquer des êternuements chez les patients souffrants de cette condition bien qu’il ne semble pas que le propofol ait tendance à provoquer de l’excitation.

Sonoclot analysis in healthy children.

Although use of the Sonoclot device (Sienco, Inc., Morrison, CO) has been reported in isolated pediatric cases and in small reports in neonates, there are no published data for normal pediatric patients. As the device is used in situations of abnormal coagulation, such as cardiac and liver transplantation surgery, our aim was to determine normal data ranges in healthy pediatric surgical patients. Blood was withdrawn after anesthetic induction, and the Sonoclot activated clotting time, rate of clot formation, time to peak amplitude, and peak amplitude was compared among four pediatric groups (<12 mo, 13–24 mo, 25–48 mo, 49 mo–9 yr) and an adult group. The Sonoclot activated clotting time in the <12-mo and the Adult groups were shorter than the oldest group of children (P < 0.05), although all were within the anticipated normal range, and there were no significant differences in clot rate, peak amplitude, and time to peak amplitude among groups without apparent trends with increasing age. These Sonoclot variables quantify adequate global clot formation in pediatric patients and will facilitate clinical coagulation management with appropriate pediatric normal ranges, avoiding the application of extrapolated adult data to children.

Effects of isradipine on intravenous cocaine‐induced cardiovascular response: a pilot study

We examined the effects of isradipine, a dihydropyridine‐class calcium channel antagonist, and effective antihypertensive medication on the pressor effects of cocaine on cardiac function. Using continuous non‐invasive cardiovascular monitoring of heart rate, blood pressure, electrocardiographic recordings, and peripheral oxygen saturation, six healthy cocaine addicts received the following treatments in blinded, crossover fashion: (a) placebo; (b) intravenous cocaine (0·325 mg/kg iv), and (c) isradipine (10 mg p.o.)+cocaine. While cocaine‐taking was associated with a small increase in blood pressure, this effect was not significantly affected by isradipine. Isradipine pretreatment was, however, associated with a significant reflex rise in heart rate following cocaine. Cocaine administration with or without isradipine produced no clinically significant abnormalities of rhythm or conduction on the electrocardiogram and on peripheral oxygen saturation. While these results should be considered preliminary, they do suggest that this isradipine dose and/or dosing strategy does not have a clinically significant cardioprotective effect during cocaine‐taking. Copyright

Ketorolac and platelet function.

We appreciate the comments by Dr. Arron regarding our survey (1). Dr. Arron suggests that Question 27 of our survey may have resulted in an underreporting of the degree to which anesthesiologists clean laryngoscope blades appropriately. His point is well taken in that we did not distinguish between high and low levels of disinfection as recommended by the Centers for Disease Control (CDC). As Dr. Arron suggests, this may have resulted in an underreporting of compliance with respect to the practice of cleaning laryngoscope blades. However, if indeed this was true, then it further highlights the need for stricter adherence to the CDC’s guidelines. Although we concur that this particular question may not have been definitive, we disagree with Dr. Arron’s suggestion that the questionnaire as a whole was therefore misleading. Dr. Arron makes some important points with respect to the expectation of anesthesiologists to meet at least the minimum standards of care regarding perioperative control of infection. In a previous report which represented the first phase of this study, 88% of anesthesiologists reported that they always complied with the CDC guidelines for the prevention of occupational transmission of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) when presented with a known HIVor HBV-infected patient, but only 24.7% adhered to the guidelines when the patient was considered low risk (2). Despite the fact that there is no convincing evidence to support a direct cause and effect relationship between anesthesia practice and infection, anesthesiologists can ill afford to become complacent and, as Dr. Arron points out, we should strive to adhere to the recommended guidelines until we can be persuaded that less stringent measures can be adopted safely.