Neurological and histological outcomes after subarachnoid injection of a liposomal bupivacaine suspension in pigs: a pilot study.

BACKGROUND: An injectable liposomal bupivacaine suspension (EXPAREL™) is approved by the US Food and Drug Administration for analgesia by tissue infiltration and interscalene brachial plexus, but not for use in the neuraxial space. This pilot study describes neurological and histological outcomes of escalating doses of this extended-release formulation of bupivacaine after subarachnoid administration. METHODS: Twenty-five pigs (Sus scrofa domesticus) weighing 36.2 (4.4) kg were randomly assigned to one of five groups to receive a subarachnoid injection of sodium chloride 0.9%, 3 ml (negative control), preservative-free bupivacaine hydrochloride 0.5%, 3 ml (positive control), or one of three doses of liposomal bupivacaine suspension 1.33%: 1.5, 3, or 5 ml. After recovering from general anaesthesia, neurological outcomes were assessed by blinded observers. Three weeks later, the animals were sacrificed for histological evaluations of neurotoxicity. RESULTS: Animals that received sodium chloride 0.9%, bupivacaine hydrochloride, or liposomal bupivacaine 1.5 ml recovered within 2, 5, or 4 h, respectively. Animals that received liposomal bupivacaine 3 or 5 ml exhibited signs of neuraxial block (decreased nociception and proprioception) up to 32 h after injection. No histological evidence of neurotoxicity was found in any of the groups. CONCLUSIONS: Subarachnoid administration of liposomal bupivacaine in pigs exhibited a dose-response effect, and resulted in longer duration of neuraxial block than bupivacaine hydrochloride without histological evidence of neurotoxicity. Our study contributes preliminary data to inform further toxicological assessments and regulatory approval before subarachnoid administration in humans.

The effect of force applied to the left paratracheal oesophagus on air entry into the gastric antrum during positive-pressure ventilation using a facemask.

Cricoid force is widely applied to decrease the risk of pulmonary aspiration and gastric antral insufflation of air during positive-pressure ventilation, yet its efficacy remains controversial. We compared manual oesophageal compression at the low left paratracheal and cricoid levels for the prevention of gastric antral air insufflation during positive-pressure ventilation by facemask in patients scheduled for elective surgery under general anaesthesia. After gaining written consent, participants were randomly allocated by sealed envelope to one of three groups: oesophageal compression by 30 N paratracheal force (paratracheal group); oesophageal compression by 30 N cricoid force (cricoid group); or no oesophageal compression (control group). Gastric insufflation of air was assessed before and after positive-pressure ventilation by ultrasound measurement of the antral cross-sectional area and/or presence of air artefacts in the antrum. The primary outcome measure was the proportion of participants with ultrasound evidence of gastric insufflation. We recruited 30 patients into each group. Before facemask ventilation, no air artefacts were visible in the antrum in any of the participants. After facemask ventilation of the participant's lungs, no air artefacts were seen in the paratracheal group, compared with six subjects in the cricoid group and eight subjects in the control group (p = 0.012). Our results suggest that oesophageal compression can be achieved by the application of manual force at the low left paratracheal level and that this is more effective than cricoid force in preventing air entry into the gastric antrum during positive-pressure ventilation by facemask.

The ontogeny of partial seizures in infants and young children.

PURPOSE: To describe the clinical manifestations of partial seizures in the pediatric population as a function of age. METHODS: Using the database of the pediatric epilepsy monitoring unit (Children's Hospital of New York), clinical and EEG characteristics of partial seizures were distributed by age groups 0-2, 2-6, and 6+ years for 123 patients who had at least one such seizure with a clear EEG correlate during their admission. chi2 tests for trend were used to examine clinical and EEG features as a function of age. RESULTS: The frequency of aura, limb automatisms, dystonic posturing, secondary generalization, and unresponsiveness increased with age, whereas asymmetric clonus and symmetric tonic posturing decreased with age. There were no clear changes in the types of EEG ictal patterns observed with age; however, partial seizures emanating from the anterior regions of the brain tended to increase with age, whereas those from the posterior regions tended to decrease with age. CONCLUSIONS: Important differences exist in the clinical expression of seizures between young children and adults. These findings will contribute to a better understanding of ictal ontogeny that will promote more accurate classification of seizures and of the epilepsies in young patients. Such efforts can be used to identify young patients for focal epilepsy surgery and to select appropriate anticonvulsive medications.

The effect of intrathecal analgesia on the success of external cephalic version.

UNLABELLED: External cephalic version (ECV), the procedure whereby a fetus in the breech position is converted to vertex, is often performed to avoid an operative delivery. Potential benefits of epidural and spinal anesthesia for this procedure are controversial. Several previous studies have evaluated the use of epidural anesthesia with varying results. We sought to determine whether analgesia produced by subarachnoid sufentanil would safely improve the success of ECV. Patients who received subarachnoid analgesia (n = 20) were compared with those who did not (n = 15) in regard to success of ECV, level of pain during ECV, and satisfaction. ECV was successful in 21 patients (60%), with more frequent success in women who received spinal analgesia as compared with those who did not (80% vs 33%, respectively; P = 0.005). Patients who received spinals also reported smaller pain scores and were more satisfied with ECV. None of the women who received spinal analgesia developed a postdural puncture headache, and the only case of fetal bradycardia occurred in a patient who did not receive spinal analgesia. More profound patient comfort after spinal analgesia may have permitted greater manipulation of the abdomen during ECV, thus improving success rates of ECV without increasing risk. IMPLICATIONS: The success of external cephalic version (ECV) was compared in women who received spinal analgesia and those who did not. Successful ECV occurred more frequently in those women who received spinal analgesia. Because term singleton pregnancies associated with breech position usually require cesarean delivery, an increase in success of ECV may decrease the number of cesarean deliveries performed.

Experience with the ketogenic diet in infants.

OBJECTIVE: To evaluate the effectiveness, tolerability, and adverse effects of the ketogenic diet in infants with refractory epilepsy. METHODS: A retrospective review of 32 infants who had been treated with the ketogenic diet at a large metropolitan institution. RESULTS: Most infants (71%) were able to maintain strong ketosis. The overall effectiveness of the diet in infants was similar to that reported in the literature for older children; 19.4% became seizure-free, and an additional 35.5% had >50% reduction in seizure frequency. The diet was particularly effective for patients with infantile spasms/myoclonic seizures. There were concomitant reductions in antiepileptic medications. The majority of parents reported improvements in seizure frequency and in their child's behavior and function, particularly with respect to attention/alertness, activity level, and socialization. The diet generally was well-tolerated, and 96.4% maintained appropriate growth parameters. Adverse events, all reversible and occurring in one patient each, included renal stone, gastritis, ulcerative colitis, alteration of mentation, and hyperlipidemia. CONCLUSION: The ketogenic diet should be considered safe and effective treatment for infants with intractable seizures.

Use of atraumatic spinal needles among neurologists in the United States.

OBJECTIVE: To evaluate atraumatic spinal needle use among US neurologists. BACKGROUND: Postdural puncture headache following lumbar puncture may be dramatically reduced through the use of atraumatic pencil-point spinal needles. It was hypothesized that atraumatic spinal needles are rarely used by members of specialties outside of anesthesiology. To determine the extent to which atraumatic spinal needles are currently being used for lumbar puncture in the United States, American neurologists (one group of physicians who regularly perform lumbar punctures) were surveyed. METHODS: A questionnaire was mailed to all 7798 members of the American Academy of Neurology listed in the membership directory. The questionnaire included items pertaining to age, practice setting, knowledge of pencil-point (atraumatic) spinal needles, and lumbar puncture practices. RESULTS: Only a fraction (2%) of the neurologists surveyed routinely use atraumatic spinal needles. Almost half of the responding neurologists reported having no knowledge of pencil-point spinal needles. Among those who did have knowledge of these new spinal needles, the most common reasons given for not using them were nonavailability and expense. CONCLUSIONS: Atraumatic spinal needles for lumbar puncture have been shown to dramatically decrease the risk of postdural puncture headache. Although the use of these needles is standard practice among anesthesiologists, they have not been adopted by other medical specialties. This may lead to unnecessary morbidity among patients undergoing lumbar puncture.

The interaction of temperature with thiopental and etomidate on extracellular dopamine and glutamate levels in Wistar-Kyoto rats subjected to forebrain ischemia.

BACKGROUND: Many studies demonstrate an association between brain damage and the extracellular release of catecholamines and amino acids during cerebral ischemia. While the clinical value of hypothermia during periods of compromised cerebral blood flow and oxygen delivery is well established, the role of anesthetic agents is less clear. Furthermore, the interaction between these agents and hypothermia remains to be elucidated. The purpose of this study was to examine the interactive effects of temperature, sodium thiopental (STP) and etomidate (ETOM) on extracellular neurotransmitter accumulation in the rat corpus striatum during cerebral ischemia. METHODS: Animals were randomly assigned to one of six subgroups: normal saline (NS-norm, pericranial t approximately equal to 37 degrees C, and NS-hypo, t=30 degrees C), etomidate (ETOM-norm and ETOM-hypo), and sodium thiopental (STP-norm and STP-hypo). Microdialysis probes were inserted into the corpus striatum. Dopamine (DA), glutamate, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels were measured. At zero minutes, animals received a 10-min infusion of STP (3 mg x kg(-1) x min(-1)), ETOM (0.6 mg x kg(-1) x min(-1)), or NS. Prior to ischemia, animals were given either intravenous STP (10 mg x kg(-1)), ETOM (3 mg x kg(-1)), or NS in bolus form. Each animal was then subjected to 10 min of forebrain ischemia (Is1) followed by a reperfusion interval (Rep1). The entire sequence was then repeated. RESULTS: There were significant interactions between temperature and drug for DA (Is1, P=0.006, Is2, P=0.032) and its metabolites (DOPAC, Is1 P=0.01, HVA, Is1 P=0.03), and for glutamate (Is1, P=0.03, Is2 P=0.06). The nature of this interaction differed for DA and glutamate. The reduction in DA accumulation seen during hypothermia was offset by the addition of either STP or ETOM, whereas the addition of these drugs did not affect the reduced glutamate levels seen with hypothermia. During normothermia, STP and ETOM resulted in diminished DA accumulation compared to controls, yet they increased the accumulation of extracellular glutamate. CONCLUSIONS: Consistent with other studies, hypothermia was associated with diminished extracellular DA concentrations during forebrain ischemia. However, depending on the temperature condition, the addition of STP or ETOM in our forebrain ischemia model led to unexpected findings. The administration of these agents during normothermia diminished ischemia-induced DA accumulation yet resulted in significantly higher concentrations of extracellular glutamate. In contrast, STP and ETOM during hypothermia were noted to significantly offset the DA-reducing effects of hypothermia.

The practice of peripheral nerve blocks in the United States: a national survey [p2e comments].

BACKGROUND AND OBJECTIVES: A nationwide survey was conducted in order to describe practice patterns surrounding the use of peripheral nerve blocks (PNBs). METHODS: Questionnaires were mailed to 805 anesthesiologists selected systematically from the 1995 ASA and ASRA membership directories. Responses from 409 attending anesthesiologists (response rate 56.5%) were analyzed. RESULTS: While almost all respondents (97.8%) regularly use at least some regional anesthesia techniques in their practices, significantly fewer use PNBs, with most anesthesiologists (59.7%) performing less than five PNBs monthly. Peripheral nerve blocks of the lower extremity (femoral 32 %, sciatic 22 %, popliteal 11%) were less frequently used than PNB of the upper extremity (axillary 88%, interscalene 61%) (McNemar chi-square test = 215.2; P < .001). Anesthesiologists who rated their training in PNBs as adequate (50.8%) devoted a larger percentage of their practice to PNBs than anesthesiologists who rated their training as inadequate (P = .02). Despite the infrequent use of PNBs, 176 respondents (42.6%) predicted that their use of PNBs would increase in the future. CONCLUSIONS: Although this survey indicates that regional anesthesia is frequently practiced in the United States, PNBs and particularly PNBs of the lower extremities remain underutilized.

Does metoclopramide supplement postoperative analgesia using patient-controlled analgesia with morphine in patients undergoing elective cesarean delivery?

BACKGROUND AND OBJECTIVES: Recent studies have shown that metoclopramide may decrease postoperative narcotic requirements in patients undergoing second-trimester induced abortions or prosthetic hip surgery. It is often used to decrease the incidence of nausea and vomiting in the patient undergoing cesarean delivery under regional anesthesia. If metoclopramide were found to be an analgesic adjunct in these patients, it would offer an additional impetus for its routine use. METHODS: After elective cesarean delivery under spinal anesthesia, 32 patients were monitored for initial and 24-hour postoperative morphine requirements via intravenous patient-controlled analgesia. These patients were divided into two groups. Prior to spinal block, group 1 (n = 17) received 10 mg intravenous metoclopramide, and group 2 (n = 15) received an intravenous saline placebo. RESULTS: No differences were found between groups in the time from spinal placement to the time of pain onset, the amount of morphine necessary to initially achieve comfort, or 24-hour postoperative morphine requirements. (P > .05). CONCLUSIONS: This study demonstrates that metoclopramide decreases intraoperative nausea but does not supplement analgesia in patients undergoing elective cesarean delivery.

The association between Doppler transmitral flow variables measured by transesophageal echocardiography and pulmonary capillary wedge pressure.

The association between Doppler transmitral flow variables, measured by transesophageal echocardiography (TEE), and pulmonary capillary wedge pressure (PCWP) was studied in 88 patients undergoing coronary artery surgery. The Doppler flow variables and PCWP were measured after sternotomy by blinded investigators. In the first part of the study, patients were divided into two groups according to left ventricular (LV) ejection fraction (EF): Group A, EF > 35% (n = 38) and Group B, EF < or = 35% (n = 34). In Group B, significant correlations were found between deceleration time of early filling (DCT-E) and PCWP (r2 = 0.899) and deceleration slope of early filling and PCWP (r2 = 0.692), (P < 0.001 for both). When the relationship between DCT-E and PCWP was tested prospectively in a third group of patients [Group C; EF < or = 35% (n = 16)], a close agreement between the calculated and measured PCWP (bias = -0.55 +/- 3.87 mm Hg) was noted. The sensitivity, specificity, and positive predictive value of DCT-E > or = 150 ms for PCWP < 10 mm Hg were 93.3%, 100%, and 100%, respectively. In summary, patients with decreased left ventricular systolic function undergoing coronary artery surgery demonstrated high, statistically significant, correlations between PCWP and the deceleration time or deceleration slope of early diastolic filling as measured by transesophageal Doppler echocardiography.

Acupressure versus intravenous metoclopramide to prevent nausea and vomiting during spinal anesthesia for cesarean section.

Nausea and vomiting occur frequently during cesarean section under spinal anesthesia. Metoclopramide reduces intraoperative nausea and vomiting, but not without potential side effects. Acupressure, a noninvasive variation of acupuncture that involves constant pressure on the wrist, has been suggested as an alternative method to prevent nausea and vomiting. The aim of this study was to compare acupressure and intravenous (IV) metoclopramide for the prevention of nausea and vomiting during elective cesarean section under spinal anesthesia. Seventy-five patients were studied in a randomized, prospective, double-blind comparative trial. Group I patients received acupressure bands + 2 mLIV saline, Group II patients received placebo wrist bands + 10 mg IV metoclopramide, and Group III patients received placebo wrist bands + 2 mL IV saline. Patients who received either acupressure or metoclopramide prior to initiation of spinal anesthesia for cesarean section had much less nausea than patients in the placebo group. Acupressure is an effective, non-pharmacologic method to reduce intraoperative nausea during elective cesarean section in the awake patient.

Comparison of questionnaire-derived and tumour registry-derived smoking histories.

Information on cigarette smoking, an exposure of great epidemiological interest, is occasionally obtained from tumour registry data. We compared smoking histories from a hospital tumour registry with those from a questionnaire administered to 94 lung cancer patients. Reliability of tumour registry data was good for classifying individuals as ever-smokers and non-smokers (sensitivity 0.96, specificity 0.86). There was higher discrepancy in classifying smokers as current or former smokers. Current smokers had lower reliability for amount of smoking than former smokers, whereas both groups had high reliability for duration of smoking. These results suggest that tumour registry derived data on smoking must be used with caution.