Hari H. Dash

Effect of intraoperative dexmedetomidine on postoperative recovery profile of children undergoing surgery for spinal dysraphism.

Background: Smooth recovery from anesthesia is desirable in children undergoing surgery for spinal dysraphism who are nursed in prone position during the postoperative period. Dexmedetomidine may be beneficial in these children owing to its sedative, anxiolytic, and opioid-sparing properties with minimal respiratory depression. Methods: Thirty-six children with spinal dysraphism at lumbosacral area, aged 8 to 12 years, undergoing corrective surgery were randomized to receive either dexmedetomidine or volume-matched saline (placebo) after positioned prone until beginning of skin closure. Inspired concentration of sevoflurane was changed to keep the bispectral index score between 45 and 55. Perioperative hemodynamics, intraoperative fentanyl and sevoflurane consumption, and postoperative recovery profile and fentanyl consumption was observed by blinded observers. Postoperative pain, emergence agitation (EA), and discharge readiness from postanesthesia care unit was evaluated using the modified objective pain score, agitation Cole score, and modified Aldrete score, respectively. Fentanyl 0.5-1 µg/kg was administered for pain (objective pain score ≥4) or severe EA (agitation Cole score ≥4) lasting for >5 minutes. Results: The 2 groups did not differ significantly with respect to demographics, duration of anesthesia, emergence, and extubation times. The intraoperative consumption of sevoflurane and fentanyl was significantly less in dexmedetomidine group (0.2±0.1 vs. 0.3±0.1 mL/min, P<0.0001 and 2.3±0.5 vs. 3.1±0.6 &mgr;g/kg, P=0.0001, respectively), along with a lower mean heart rate (P<0.001). The mean systolic blood pressure (P=0.98) and incidence of bradycardia and hypotension was comparable in between the 2 groups. Postoperatively, the children in dexmedetomidine group had significantly lower pain scores (P<0.0001), agitation scores (P<0.0001), and time to achieve full modified Aldrete score [0 (0 to 10) vs. 10 (0 to 20) min, P=0.001]. The postoperative consumption of fentanyl was significantly less in dexmedetomidine group [0 (0 to 1.04) vs. 0.88 (0 to 3) µg/kg, P=0.003], along with a longer time of first analgesic requirement [600 (5 to 2100) vs. 5 (5 to 185) min, P=0.0001]. The mean heart rate and systolic blood pressure were higher in placebo group (P<0.001), whereas no difference was observed in respiratory rate (P=0.73) and arterial oxygen saturation (P=0.36). The number of patients with postoperative nausea and vomiting was significantly lower in dexmedetomidine group [2 (11.1%) vs. 9 (50%), P=0.03]. Conclusions: Intraoperative use of dexmedetomidine in children undergoing spinal surgery results in a favorable recovery profile with reduced postoperative pain and EA, without adverse perioperative hemodynamic effects.

Planning for early emergence in neurosurgical patients: a randomized prospective trial of low-dose anesthetics.

BACKGROUND: For early detection of a cerebral complication, rapid awakening from anesthesia is essential after craniotomy. Systemic hypertension is a major drawback associated with fast tracking, which may predispose to formation of intracranial hematoma. Although various drugs have been widely evaluated, there are limited data with regards to use of anesthetics to blunt emergence hypertension. We hypothesized that use of low-dose anesthetics during craniotomy closure facilitates early emergence with a decrease in hemodynamic consequences. METHODS: Three emergent techniques were evaluated in 150 normotensive adult patients operated for supratentorial tumors under standard isoflurane anesthesia. At the time of dural closure, the patients were randomized to receive low-dose propofol (3 mg · kg−1 · h−1), fentanyl (1.5 &mgr;g · kg−1 · h−1) or isoflurane (end-tidal concentration of 0.2%) until the beginning of skin closure. Nitrous oxide was discontinued after head dressing. RESULTS: Median time to emergence was 6 min with propofol, 4 min with fentanyl, and 5 min with isoflurane (P = 0.008). More patients had hypertension in the pre-extubation compared with extubation or postextubation phase (P = 0.009). Comparing the three groups, fewer patients required esmolol with fentanyl use overall, and in the pre-extubation phase (P = 0.01). Significant midline shift in the preoperative cerebral imaging scans was found to be an independent risk factor for emergence hypertension. CONCLUSIONS: Pain during surgical closure may be an important cause of sympathetic stimulation leading to emergence hypertension. The use of low-doses of fentanyl during craniotomy closure is more advantageous than propofol or isoflurane for early emergence in neurosurgical patients and is the most effective technique for preventing early postoperative hypertension.

Perioperative management of children with encephalocele: an institutional experience.

Background Encephaloceles are neural tube defects that are characterized by protrusion of the brain and meninges through a defect in the cranium. The inherent implications of pediatric anesthesia and difficult airway make surgical correction challenging for anesthesiologists Methods Available medical records of 118 children who underwent excision and repair of encephalocele over a period of 10 years were analyzed retrospectively. Data on associated anomalies, anesthetic management, perioperative complications, and outcome at discharge were reviewed. Results The average age of presentation was 1 year and 6 months. The most common site of lesion was the occiput (67%). Encephaloceles were giant (size of sac larger than the head) in 15.3% of children. Hydrocephalus was the most common complication (45.8%) and was predominantly associated in children with occipital encephaloceles (P=0.00). Difficult mask ventilation and intubation were encountered in 5.9% and 19.5% of children, respectively. In children with occipital encephalocele, the trachea was intubated commonly by direct laryngoscopy in the lateral position (47.5%). The average blood loss was 69.6±13.2 mL, and 56 children required transfusion, the average being 13.2±9.6 mL/kg. Intraoperative hemodynamic disturbances and respiratory complications were observed in 21.1% and 13.5% of children, respectively. The mean intensive care unit and hospital stay were 1.8±2.1 and 8.6±4.9 days, respectively. The stays were prolonged significantly whenever the children developed hydrocephalus, meningitis, and respiratory infection, predisposing to poor outcome. Conclusions Difficult airway is not the only concern in children with encephalocele, but associated congenital malformations, hydrocephalus, large size of sac, and hemodynamic disturbances all require careful consideration.

A randomized, double-blinded comparison of ondansetron, granisetron, and placebo for prevention of postoperative nausea and vomiting after supratentorial craniotomy.

Postoperative nausea and vomiting (PONV) are frequent and distressing complications after neurosurgical procedures. We evaluated the efficacy of ondansetron and granisetron to prevent PONV after supratentorial craniotomy. In a randomized double-blind, placebo controlled trial, 90 adult American Society of Anesthesiologists I, II patients were included in the study. A standard anesthesia technique was followed. Patients were divided into 3 groups to receive either placebo (saline), ondansetron 4 mg, or granisetron 1 mg intravenously at the time of dural closure. After extubation, episodes of nausea and vomiting were noted for 24 hours postoperatively. Statistical analysis was performed using χ2 test and 1-way analysis of variance. Demographic data, duration of surgery, intraoperative fluids and analgesic requirement, and postoperative pain (visual analog scale) scores were comparable in all 3 groups. It was observed that the incidence of vomiting in 24 hours, severe emetic episodes, and requirement of rescue antiemetics were less in ondansetron and granisetron groups as compared with placebo (P<0.001). Both the study drugs had comparable effect on vomiting. However, the incidence of nausea was comparable in all 3 groups (P=0.46). A favorable influence on the patient satisfaction scores, and number needed to prevent emesis was seen in the 2 drug groups. No significant correlation was found between neurosurgical factors (presence of midline shift, mass effect, pathologic diagnosis of tumor, site of tumor) and the occurrence of PONV. We conclude that ondansetron 4 mg and granisetron 1 mg are comparably effective at preventing emesis after supratentorial craniotomy. However, neither drugs prevented nausea effectively.

Comparative evaluation of percutaneous retrogasserian glycerol rhizolysis and radiofrequency thermocoagulation techniques in the management of trigeminal neuralgia.

BACKGROUND: Among the percutaneous procedures for the treatment of trigeminal neuralgia, percutaneous anhydrous glycerol rhizolysis (PRGR) and radiofrequency (RF) ablation of trigeminal neuralgia have stood the test of time. OBJECTIVE: A prospective study was conducted to compare PRGR and RF ablation techniques in patients with trigeminal neuralgia in terms of (1) efficacy of pain relief, (2) duration of pain relief and (3) side effects. METHODS: All patients presenting to our pain clinic for the first time for the treatment of trigeminal neuralgia were enrolled to receive either PRGR or RF ablation; the treatment was chosen by the patient. Demographic data, magnetic resonance imaging scan, relevant medical disease, amount of anhydrous glycerol, lesion temperature, and total duration of RF were noted. The presence or absence of cerebrospinal fluid egress, immediate pain relief, duration of pain-free period, need for repeat injection or additional peripheral nerve block, and recurrence of pain were also noted. The degree of pain relief was recorded every 3 months. Any complications during the procedure and side effects were also recorded. RESULTS: Seventy-nine patients underwent either PRGR (n = 40) or RF thermocoagulation (n = 39). A total of 23 patients (58.9%) in the PRGR group and 33 patients (84.6%) in the RF group experienced excellent pain relief. The mean duration of excellent pain relief in the PRGR and RF groups was comparable. By the end of the study period, 39.1% patients in the PRGR group and 51.5% patients in the RF group experienced recurrence of pain. CONCLUSION: Both PRGR and RF techniques can achieve acceptable pain relief with minimal side effects.

Bispectral index-guided administration of anesthesia for transsphenoidal resection of pituitary tumors: a comparison of 3 anesthetic techniques.

The main aims of anesthesia for pituitary surgery include maintenance of hemodynamic stability, provision of conditions that facilitate surgical exposure, and a smooth emergence to facilitate a prompt neurologic assessment. The primary aim of our study was to compare the effects of 3 anesthetic regimens on hemodynamics and recovery characteristics of the patients. Ninety patients undergoing transsphenoidal surgery were enrolled in the study. Standard anesthesia technique was followed for induction. Patients were randomly divided to receive propofol, isoflurane, or sevoflurane for maintenance of anesthesia. The bispectral index target range during maintenance was 40 to 60. The hemodynamic variables (heart rate and mean arterial pressure) and bispectral index were noted during the various stages of the surgery. The time to emergence and extubation was noted. We evaluated cognitive function at 5 and 10 minutes posttracheal extubation. The 3 study groups were comparable with respect to age, sex, weight, and duration of surgery. We observed an increase in heart rate and blood pressure during intubation, nasal packing, and insertion of self-retaining nasal speculum. After tracheal intubation, the rise in blood pressure was more in sevoflurane group than propofol. During emergence, hypertensive response was seen in all patients. Emergence and extubation times were significantly shorter with propofol and sevoflurane. Patients who received propofol had better cognition scores. Aldrete scores were better with propofol and sevoflurane than isoflurane. The pressor response after intubation and emergence hypertension was significantly less with propofol. Better recovery profile was seen in sevoflurane and propofol groups and a better cognition in patients receiving propofol. Propofol plus nitrous oxide anesthesia could be the technique of choice in patients undergoing transnasal transsphenoidal pituitary surgery.

Cerebral autoregulation and CO2 reactivity before and after elective supratentorial tumor resection

Background The effect of surgical decompression of tumor on autoregulation and CO2 reactivity is not known. We examined the effect of elective tumor resection on cerebral autoregulation and CO2 reactivity. Methods Patients with supratentorial tumors undergoing elective craniotomy for tumor resection under standard anesthesia underwent cerebral autoregulation and CO2 reactivity testing immediately before and between 6 and 24 hours after surgery. Transient hyperemic response of the middle cerebral artery after the release of 10 second compression of the ipsilateral common carotid artery was used to calculate the transient hyperemic response ratio (THRR). THRR>1.1 defined the normal autoregulation. Voluntary hyperventilation was titrated to reduce the ETCO2 by 10 mm Hg below baseline and CO2 reactivity was calculated. Results Thirty-five patients (26 male and 9 female) were studied. Overall, cerebral autoregulation was intact before and after tumor resection for the cohort (THRR 1.27±0.10 and 1.30±0.12, P=0.11). However, cerebral autoregulation was impaired preoperatively in 7 (20%) patients and remained impaired in all 7 patients after tumor resection. Larger tumor size (P=0.002), and midline shift more than 5 mm (P<0.001) were associated with impaired cerebral autoregulation. Twenty-eight (80%) patients who had intact preoperative cerebral autoregulation maintained autoregulation postoperatively. CO2 reactivity was within normal limits before and after surgery in all patients and did not change between the 2 periods (3.41±0.46/mm Hg and 3.60±0.63%/mm Hg, P=0.07). Conclusion Preoperative cerebral autoregulation was impaired in a significant number of patients with large supratentorial tumor size and midline shift more than 5 mm and was associated with postoperative impaired cerebral autoregulation during the first 24 hours after the surgery.

EEG entropy values during isoflurane, sevoflurane and halothane anesthesia with and without nitrous oxide.

We hypothesized that like bispectral index, entropy may be anesthetic agent specific. We carried out a study to assess the entropy values of different anesthetics at equi-minimal alveolar concentrations (MACs) with air and nitrous oxide as carrier gases. Thirty adult patients undergoing spine surgery were randomized to receive halothane, isoflurane, or sevoflurane, in 2 stages, (a) with air/oxygen mixture (2:1) and (b) in nitrous oxide/oxygen (2:1). Heart rate, mean arterial blood pressure, response entropy (RE), and state entropy (SE) were noted at 1.0 and 1.5 MACs for each agent. Statistical analysis was done using the 2-way analysis of variance followed by Bonferroni correction and Student t test for paired data. P value of less than 0.05 were considered significant. The demographics and baseline values of heart rate, mean arterial blood pressure, RE, and SE were comparable. Changing from air/oxygen as carrier gas to 66% nitrous oxide in oxygen resulted in significant increase in both RE and SE at 1.0 MAC for all the agents (P<0.05). Among the agents, it was found that both RE and SE values were significantly higher during halothane anesthesia as compared with sevoflurane and isoflurane (P<0.05). At 1.5 MAC for all agents, after addition of nitrous oxide, there was an insignificant reduction in both RE and SE (P>0.05). Again the values of RE and SE remained high for halothane as compared with isoflurane and sevoflurane. In conclusion, our data suggest a possibility of misinterpretation of anesthetic hypnosis when entropy values increase with addition of nitrous oxide to 1 MAC isoflurane and sevoflurane.

Sevoflurane provides better recovery as compared with isoflurane in children undergoing spinal surgery.

Rapid recovery is desirable in pediatric neurosurgical patients to obtain an early neurologic assessment. We compared the recovery characteristics of 2 commonly used anesthetic agents, sevoflurane and isoflurane, under bispectral index-guided anesthesia in children undergoing spinal surgery. Eighty children who underwent surgery for occult spinal dysraphism at the lumbar and sacral level were randomized to anesthesia with sevoflurane or isoflurane in oxygen and nitrous oxide. Anesthesia depth was guided by a bispectral index monitor kept between 40 and 60. In addition to time at emergence, extubation and discharge, recovery (modified Aldrete) score, and hemodynamics were compared. The 2 groups did not differ significantly with respect to demographics, duration of surgery and anesthesia, and intraoperative hemodynamic changes. Extubation (6.4±3.3 vs. 10.7±4.6) and emergence (7.8±3.4 vs. 12.8±5.6) times (minutes) were significantly shorter with sevoflurane (P<0.001). Time (minutes) to achieve full Aldrete (modified) scores was less with sevoflurane (13.9±5.3 vs. 20.3±6.5) than isoflurane (P<0.001). However, the time (minutes) to achieve discharge criteria from postanesthesia care unit (140.7±49.3 vs. 146±43.3) and first dose of postoperative analgesic (60±24.1 vs. 72±33.4) in addition to incidence of postoperative agitation were similar in both groups (P>0.05). Sevoflurane results in an earlier recovery and assessment of modified Aldrete score when compared with isoflurane.

Anesthetic concerns and perioperative complications in repair of myelomeningocele: a retrospective review of 135 cases.

Myelomeningocele (MMC) a complex congenital spinal anomaly, results from neural tube defect during first 4 weeks of gestation. Medical records of 135 children who underwent excision and repair of MMC from January 2003 to December 2006 were analyzed, retrospectively. Data on associated illnesses, anesthetic management, perioperative complications, and outcome were recorded. The patient population consisted of older infants with unrepaired MMC. The average age of presentation was 1 year and 8 months. The commonest site of presentation was lumbar (39.3%). Leaking MMC was present in 19.3% of cases, most had associated electrolyte imbalance. Hydrocephalus was the commonest association (67.4%) followed by Chiari-II malformation (58.4%). Renal abnormality was present in 9% of cases and 24.4% of children had scoliosis. Two infants (1.5%) presented with inspiratory stridor. Intraoperative cardiac and respiratory problems were observed in 15.6% and 11.1%, of cases, respectively. Two children (1.5%) suffered cardiac arrest; both had associated Chiari-II malformation and hydrocephalus. Postoperative ventilation was required in 8.9% of children, primarily due to inadequate reversal from neuromuscular blockade. Infection, cerebrospinal fluid leak, and pseudomeningocele were common surgical complications. Improvement of motor, sensory, and sphincteric function was observed in 30.5%, 22.9%, and 14.1%, respectively. To conclude, surgical repair of MMC may at times pose life-threatening complications mostly because of associated anomalies. Children with associated Chiari malformation and/or hydrocephalus need special attention during perioperative period.