Utility of CT head in the acute setting: value of contrast and non-contrast studies.

INTRODUCTION: To examine the added diagnostic value of emergent contrast enhanced CT head (CECTH) in patients who present to the emergency department (ED) with acute non-traumatic symptoms referable to the brain, and to assess the financial implications of CECTH in the emergent setting. MATERIALS AND METHODS: We queried healthcare data for head CTs ordered by our ED between January 2008 and December 2010. Those who presented to the ED with non-traumatic neurologic disturbances were included. All traumatic head injury cases were excluded. Two board certified radiologists with fellowship training who were blinded to patient history and physical findings, independently reviewed all non-contrast computed tomography of the head (NCTH) and CECTH images. CECTH's were read following abnormal NCTH's, and findings were recorded as normal or abnormal. RESULTS: In our investigation, 379 patients-210 (55 %) females and 169 (45 %) males-met the inclusion criteria. Common indications for head CT included: headache 183 (48 %); dizziness 73 (19 %); altered mental status 49 (13 %); and seizure 38 (10 %). The mean age of study subjects was 47 (±29) years. Two hundred sixty-one (69 %) of all patients scanned showed no abnormality. One hundred eighteen (31 %) of 379 patients had abnormal scans. We encountered 1 abnormal CECTH on which NCTH was normal. Cost of CECTH was $465 and NCTH was $385. CONCLUSION: Head CT in ED non-traumatic neurological presentations with CECTH is not generally indicated and represents a calculable cost savings in the management of these patients.

Changes in cerebral oximetry during peritoneal insufflation for laparoscopic procedures.

BACKGROUND: Changes in cardiac output may occur during insufflation for laparoscopic procedures. However, there are limited data regarding its potential effects on cerebral oxygenation. MATERIALS AND METHODS: Cerebral oxygenation (ScO(2)), end tidal CO(2), heart rate, blood pressure and oxygen saturation by pulse oximetry were recorded every 5 minutes prior to insufflation, during insufflation and after desufflation. Minute ventilation was increased to maintain normocapnia and the depth of anesthesia was adjusted or fluids/phenylephrine administered to maintain the blood pressure within 20% of the baseline. RESULTS: The cohort for the study included 70 adults for laparoscopic herniorrhaphy, gastric bypass or cholecystectomy. A total of 1004 ScO(2) values were obtained during laparoscopy. The ScO(2) decreased from the baseline in 758 of the 1004 data points. The ScO(2) was 0-9 less than the baseline in 47.8% of the values, 10-19 less than the baseline in 24.9% of the values and 20-29 less than the baseline in 26 values (2.6%). Eighty-two (8.2%) of the values were less than 80% of the baseline value, while 25 values (2.5%) were less than 75% of the baseline value. Twelve patients had at least one ScO(2) value that was less than 80% of the baseline and 6 had at least one ScO(2) value that was less than 75% of the baseline. Four patients of the cohort had ScO(2) values less than 80% of the baseline for more than 50% of the laparoscopic procedure. CONCLUSIONS: Although relatively uncommon, significant changes in cerebral oxygenation do occur in some patients during insufflation for laparoscopic surgery.

Comparison of end-tidal and transcutaneous measures of carbon dioxide during general anaesthesia in severely obese adults.

BACKGROUND: Patients with severe obesity (body mass index (BMI) greater than 35 kg x m(-2)) present difficulties for end-tidal carbon dioxide (FE'(CO(2))) monitoring. Previous studies suggest that transcutaneous (TC) carbon dioxide measurements could be valuable, so we compared FE' and TC measures with Pa(CO(2)) in severely obese patients during anaesthesia. METHODS: We studied patients with severe obesity (BMI >or=40 kg x m(-2)) undergoing gastric bypass surgery. Carbon dioxide was measured with both FE' and TC devices. The difference between each measure (FE'(CO(2)) and TC-CO(2)) and the Pa(CO(2)) was averaged for each patient to provide one value, and data compared with a non-paired, two-way t-test, Fisher's exact test. RESULTS: We studied 30 adults (aged 18-54 yr, mean 41, SD 8.0 yr; weight: 115-267 kg, mean 162, SD 35 kg). The absolute difference between the TC-CO(2) and Pa(CO(2)) was 0.2 (0.2) (mean, SD) kPa while the absolute difference between the FE'(CO(2)) and Pa(CO(2)) was 0.7 (0.4) kPa (P<0.0001). The bias and precision were +0.1 (0.3) kPa for TC vs arterial carbon dioxide and -0.7 (0.4) kPa for FE' vs arterial carbon dioxide. CONCLUSIONS: Transcutaneous carbon dioxide monitoring provides a better estimate of Pa(CO(2)) than FE'(CO(2)) in patients with severe obesity.

Effects of rapacuronium on respiratory function during general anesthesia: a comparison with cis-atracurium.

BACKGROUND: With its introduction for widespread clinical use, there has been an increase in reports of bronchospasm related to the administration of rapacuronium. As it is commonly used for rapid sequence intubation, it has been suggested that these effects may be related to an inadequate depth of anesthesia. The current study examines the airway effects of rapacuronium in tracheally intubated, anesthetized adults. METHODS: Endotracheal intubation was accomplished without the use of neuromuscular blocking agents. Dynamic compliance, tidal volume, peak inspiratory flow rate, peak expiratory flow rate, and peak inflating pressure were measured after administration of either rapacuronium (1.5 mg/kg) or cis-atracurium (0.2 mg/kg) to 20 adult patients (10 received rapacuronium and 10 received cis-atracurium) anesthetized with propofol-remifentanil. RESULTS: Statistically significant increases in peak inflating pressure (22 +/- 6 to 28 +/- 9 cm H2O, P = 0.0012) and decreases in dynamic compliance (108 +/- 43 to 77 +/- 41 ml/cm H2O, P = 0.0001), peak inspiratory flow rate (0.43 +/- 0.11 to 0.39 +/- 0.09 l/s, P = 0.0062), peak expiratory flow rate (0.67 +/- 0.10 to 0.59 +/- 0.09 l/s, P = 0.0015), and tidal volume (744 +/- 152 to 647 +/- 135 ml, P = 0.0293) occurred after administration of rapacuronium. No changes were seen after administration of cis-atracurium. CONCLUSION: These data demonstrate that rapacuronium, but not cis-atracurium, has significant airway effects in intubated, mechanically ventilated adults.

Venous air embolism during endoscopic strip craniectomy for repair of craniosynostosis in infants.

BACKGROUND: Various studies have reported an incidence of venous air embolism (VAE) as high as 82.6% during surgical procedures for craniosynostosis. There has been an increase in the use of minimally invasive, endoseopie surgical procedures, including applications for endoscopic strip craniectomy. The current study prospectively evaluated the incidence of VAF during endoscopic strip craniectomy. METHODS: Continuous, intraoperative monitoring for VAE was performed using precordial Doppler monitoring. A recording was made of the Doppler tones and later reviewed to verify its accuracy. RESULTS: The cohort for the study included 50 consecutive neonates and infants ranging in age from 3.5 to 36 weeks and ranging in weight from 3 to 9 kg. Surgical time varied from 31 to 95 min for a total of 2,701 mm of operating time, during which precordial Doppler tones were auscultated. In 46 patients, there was no evidence of VAE. In four patients, there was a single episode of VAE. Two of the episodes of VAE were grade I (change in Doppler tones), and two were grade H (change in Doppler tones and decrease in end-tidal carbon dioxide). No grade III (decrease in systolic blood pressure by 20% from baseline) VAF was noted. CONCLUSION: In addition to previously reported benefits of decreased blood loss, decreased surgical time, and improved postoperative recovery time, the authors noted a low incidence of VAF during endoscopic strip craniectomy in neonates and infants.

Rapacuronium administration to patients receiving phenytoin or carbamazepine.

Patients receiving anticonvulsants such as phenytoin or carbamazepine may be resistant to neuromuscular blocking agents. The authors report the response to rapacuronium bromide (1.5 mg/kg) in two adult patients; one receiving phenytoin and the other receiving carbamazepine. In both patients, there was a delay in achieving maximum blockade; 100% depression of the first twitch was never achieved in the patient receiving phenytoin. Recovery of neuromuscular function was rapid. In the patient receiving phenytoin and carbamazepine respectively, the clinical duration (time to return of T1% to 25% of baseline) was 5 and 9 minutes, the recovery index (T1 25%-75%) was 4 minutes and 3 minutes, and the time to return of T4/T1 to greater than 0.7 was 15 minutes and 18 minutes 40 seconds. As has been reported with other neuromuscular blocking agents of the aminosteroid class, the clinical duration and the recovery index of rapacuronium are shortened in patients receiving either phenytoin or carbamazepine.

Impact of the initial doses of rocuronium and pancuronium on subsequent maintenance for neuromuscular block.

PURPOSE: To determine the impact of the neuromuscular blocking agent given for intubation on the duration of effect of multiple maintenance doses of pancuronium and rocuronium. METHODS: Seventy-eight subjects were randomly assigned to receive one of four dosing combinations for intubation and neuromuscular maintenance: rocuronium for intubation and maintenance, rocuronium for intubation and pancuronium for maintenance, pancuronium for intubation and rocuronium for maintenance, or pancuronium for both. Each time that the first twitch response returned to 25% of the baseline value, the duration of the dose was determined and another maintenance dose was administered. The duration of action of the maintenance doses was compared between the groups. RESULTS: Twitch suppression from the first maintenance dose was shorter for subjects who received rocuronium for both doses (Group RR) compared with that for subjects that received pancuronium (Groups PR & PP) as their intubation dose (17.6 vs 34 & 59.8 min, respectively, P < 0.05). Subjects who received rocuronium followed by pancuronium (Group RP) showed a shorter duration of twitch suppression after the first maintenance dose than the group that received pancuronium for both doses (Group PP) (21.3 vs 59.8 min, P < 0.05). By the third maintenance dose, the influence of the intubating dose on the maintenance dose duration had essentially diminished. CONCLUSIONS: For combinations of rocuronium and pancuronium, the duration of twitch suppression after a maintenance dose is only dependent on the first agent given for the first two maintenance doses administered.

Rapacuronium administration to two children with Duchenne's muscular dystrophy.

Children with Duchenne's muscular dystrophy should not be exposed to succinylcholine because of the risk of hyperkalemic cardiac arrest and rhabdomyolysis. This report describes the response to rapacuronium bromide in two patients with Duchenne's muscular dystrophy. Both patients had a recovery index 2 times longer than that reported in children with normal neuromuscular function.

Gene therapy for prostate cancer.

Prostate cancer remains one of the most significant challenges in clinical oncology, yet present therapies provide incomplete treatment in many cases. Innovative and practical gene therapy-based approaches will prove invaluable in filling the gaps that now exist in the treatment of localized and distant disease. Although multiple potential strategies have been developed, early clinical trials in prostate cancer gene therapy are now in the phase I/II stage of development. Novel preclinical and early clinical data should be considered optimistically, yet cautiously, as this field emerges from its infancy.

Early experience and learning curve associated with laparoscopic Nissen fundoplication.

BACKGROUND: Laparoscopic approach for hiatal hernia repair is relatively new. Information on the learning curve is limited. METHODS: From January 1994 to September 1996, 280 patients underwent antireflux surgery at our institution. A laparoscopic repair was attempted in 60 patients (21.4%). There were 38 men and 22 women. Median age was 49 years (range 21 to 78 years). Indications for operation were gastroesophageal reflux in 59 patients and a large paraesophageal hernia in one. A Nissen fundoplication was performed in all patients; 53 (88.3%) had concomitant hiatal hernia repair. RESULTS: In eight patients (13.3%) the operation was converted to an open procedure. Median operative time for the 52 patients who had laparoscopic repair was 215 minutes (range 104 to 320 minutes). There were no deaths. Complications occurred in five patients (9.6%). Median hospitalization was 2 days (range 1 to 5 days). Median operative time and median hospitalization were significantly longer in the first 26 patients than in the subsequent 25 patients (248 vs 203 minutes and 2 days vs 1 day, respectively; p = 0.03). Seven of the first 30 patients (23.3%) required laparotomy as compared with two of the second 30 (6.7%) (p = 0.07). Follow-up in the 51 patients who had laparoscopic fundoplication for reflux was complete in 50 (98.0%) and ranged from 7 to 38 months (median 13 months). Functional results were classified as excellent in 34 patients (68.0%), good in 6 (12.0%), fair in 7 (14.0%), and poor in 3 (6.0%). Three patients were reoperated on for recurrent reflux symptoms at 5, 5, and 11 months. CONCLUSIONS: We conclude that laparoscopic Nissen fundoplication can be performed safely. The operative time, hospitalization, and conversion rate to laparotomy are higher during the early part of the experience, but all are reduced after the learning curve.

Fuzzy logic for model adaptation of a pharmacokinetic-based closed loop delivery system for pancuronium.

In this paper, we investigate the ability of fuzzy to adapt the parameters of a pharmacokinetic and pharmacodynamic model-based controller for the delivery of the muscle relaxant pancuronium. The system uses the model to control the rate of drug delivery and uses feedback from a sensor which measures muscle relaxation level to adapt the model using fuzzy logic. The control strategy administers mini-bolus doses of pancuronium and modulates the magnitude and time interval between the bolus doses to maintain a patient's muscle relaxation within an allowable range specified by the user. Before each new dose is given, the fuzzy logic adaptation scheme uses the error between the predicted patient response and the measured response to adapt the model. The system was tested using computer simulation by varying the parameters of the model by 50% from their nominal values. It was also evaluated in a clinical trial of five patients undergoing surgical procedures lasting 5 h or longer.

Intracranial pressure, middle cerebral artery flow velocity, and plasma inorganic fluoride concentrations in neurosurgical patients receiving sevoflurane or isoflurane.

UNLABELLED: This study examined the concentration-related effects of sevoflurane and isoflurane on cerebral physiology and plasma inorganic fluoride concentrations. Middle cerebral artery flow velocity (Vmca), intracranial pressure (ICP), electroencephalogram (EEG) activity, and jugular bulb venous oxygen saturation were measured, and cerebral perfusion pressure (CPP) and estimated cerebral vascular resistance (CVRe) were calculated at baseline and at 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane (n = 8) or isoflurane (n = 6). Mannitol 0.5-0.75 g/kg was given before dural incision, and blood was sampled for plasma inorganic fluoride during surgery and for up to 72 h postoperatively. Both sevoflurane and isoflurane decreased Vmca (to 31 +/- 12 - 36 +/- 14 cm/s, mean +/- SD), did not significantly alter ICP (13 +/- 9 - 15 +/- 11 mm Hg), and did not cause epileptiform EEG activity. With sevoflurane, decreased Vmca was accompanied by decreased CPP and unchanged CVRe at 0.5 MAC, and unchanged CPP and increased CVRe at 1.0 and 1.5 MAC. Plasma inorganic fluoride was 39.0 +/- 12.9 microM at the end of anesthesia (3.2 +/- 2.0 MAC hours) with sevoflurane, similar to the value (36.2 +/- 3.9 microM) for 3.7 +/- 0.1 MAC hours sevoflurane in patients not receiving mannitol. Decreased Vmca during sevoflurane presumably results from decreased cerebral metabolic rate, with CVRe changing secondarily in accord with CPP. Plasma inorganic fluoride does not seem to be altered by mannitol-induced diuresis. IMPLICATIONS: In neurosurgical patients, sevoflurane decreased middle cerebral artery flow velocity and caused no epileptiform electroencephalogram activity and no increase of intracranial pressure or plasma inorganic fluoride. These effects are suitable for neurosurgery. Two other possible effects of sevoflurane, i.e., increased cerebrospinal fluid volume and/or intracranial elastance, may not be suitable for neurosurgery and warrant further study.

Clinical analysis of the flexor hallucis brevis as an alternative site for monitoring neuromuscular block from mivacurium.

STUDY OBJECTIVES: To compare the flexor hallucis brevis, which is responsible for flexion of the great toe, to the adductor pollicis as a site for monitoring the onset and recovery from neuromuscular block after an intubating dose of mivacurium chloride. DESIGN: Prospective patient-controlled study. SETTING: University teaching hospital. PATIENTS: 10 ASA physical status I and II adults (age 18 to 55 years, 6 women, 4 men) scheduled for elective procedures requiring muscle relaxation for tracheal intubation. MEASUREMENTS AND MAIN RESULTS: Patients were monitored at the adductor pollicis and the flexor hallucis brevis during the onset and recovery of neuromuscular block, which was administered to facilitate tracheal intubation. All subjects were given mivacurium 0.2 mg/kg over 30 seconds. Their train-of-four (TOF) response was continually monitored at both sites until the patient recovered from the intubating dose to a TOF ratio of 0.75. The time to onset of neuromuscular block, recovery of the first TOF response, and recovery to a TOF ratio of 0.75 were compared between the two monitoring sites using the Wilcoxon signed rank test. Following administration of the intubating dose of mivacurium, the loss of all twitch response occurred 1.2 minutes sooner at the adductor pollicis than at the flexor hallucis brevis (p < 0.02). Reappearance of the first twitch occurred 0.49 minutes slower at the adductor pollicis, although this difference was not statistically significant. The time to recovery to a TOF ratio of 0.75 at the adductor pollicis was slower by 2.83 minutes (p = 0.046). CONCLUSIONS: Due to its lag behind the adductor pollicis, the flexor hallucis brevis is not a good indicator of when to intubate the trachea during the onset of neuromuscular block; however, its faster recovery may make it useful for monitoring deep neuromuscular block intraoperatively or during recovery when the adductor pollicis TOF response still shows complete blockade.

Long-term results after reoperation for failed antireflux procedures.

From January 1960 to June 1995, 185 patients underwent reoperation without esophageal resection for symptoms of recurrent gastroesophageal reflux disease. There were 102 men and 83 women. Median age was 58 years (range 20 to 84 years). A single previous antireflux operation had been performed in 147 patients, two in 33, and three in 5. The median interval between the reoperation and the previous operation was 36 months (range 1 to 291 months). Indications for reoperation were symptoms in 184 patients and a large paraesophageal hernia in one patients. The surgical approach was by means of a thoracotomy in 133 patients (71.9%), laparotomy in 27 (14.6%), and a thoracoabdominal incision in 25 (13.5%). A Nissen fundoplication was performed in 107 patients (57.8%), Belsey fundoplication in 47 (25.4%), truncal vagotomy and antrectomy with Roux-en-Y reconstruction in 17 (9.2%), anatomic hernia repair in 12 (6.5%), and Hill gastropexy in 2 (1.1%). A Collis gastroplasty was added to the fundoplication in 116 patients (62.7%), and a pyloroplasty was performed in 17 (9.2%). There was one operative death (0.5%). Complications occurred in 47 patients (25.4%). Median postoperative hospitalization was 9 days (range 5 to 58 days). Follow-up was complete in 156 patients (84.3%) and ranged from 3 to 283 months (median 44 months). Improvement occurred in 137 patients (87.8%). Functional results were classified as excellent in 65 patients (41.6%), good in 29 (18.6%), fair in 43 (27.6%), and poor in 19 (12.2%). No single operative approach or procedure proved to be functionally superior. We conclude that reoperation with esophageal preservation after a failed antireflux procedure will result in significant functional benefit and can be performed with low mortality and acceptable morbidity. The type of repair should be tailored to the individual patient.

A comparison of dynamic and isometric force sensors for train-of-four measurement using submaximal stimulation current.

OBJECTIVE: We studied the accuracy and repeatability of train-of-four (TOF) ratio measurements made from a dynamic piezoelectric sensor that records movement of the thumb in response to ulnar nerve stimulation compared with an isometric mechanomyogram that measures force of contraction of the adductor pollicis. METHODS: The study involved 10 patients whose level of neuromuscular block was held constant with an intravenous (IV) infusion of vecuronium bromide (0.4 to 1.0 micrograms/kg/min) (Organon, West Orange, NJ). The sensors were attached to opposite arms of each patient and simultaneous measurements of TOF ratio were taken at stimulation current levels of 50, 30, and 20 mA. RESULTS: In comparison to the TOF ratio measured at the maximal stimulation current (50 mA), the TOF ratio from the piezo sensor showed a bias and standard deviation of -0.13 +/- 0.24 when the stimulation current was reduced to 30 mA. At 20 mA, the bias and standard deviation was -0.24 +/- 0.28. The TOF ratio from the mechanomyogram showed a bias and standard deviation of 0.01 +/- 0.07 at 30 mA and 0.0 +/- 0.20 at 20 mA when compared with measurements made when the stimulation current was 50 mA. CONCLUSIONS: Both sensors showed diminished repeatability in TOF measurement with decreasing stimulation current. The data indicate that neither sensor is reliable for general monitoring of neuromuscular block at submaximal current levels. However, the individual patient results showed that some patients could be monitored accurately with both sensors, even at the lowest stimulation current levels.