Anesthesia and Perioperative Medicine

Hemodynamic derangements have been reported after surgery involving upper cervical spine. Similar observations, however, are rare during a lumbar spine surgery. We share our experience in a patient who had 2 episodes of bradycardia leading to transient asystole while undergoing lumbar discectomy for prolapsed intervertebral disc. The risk of life-threatening hemodynamic disturbances during seemingly uncomplicated surgery in prone position has been emphasized.

To the Editor: Dexmedetomidine has been used to treat agitation and delirium in the intensive care units (ICUs). 1 However, there is very little literature reporting agitation following use of dexmedetomidine. A 45-year-old male weighing 72 kg presented to our pain clinic with sharp and lancinating pain on the right side of face and forehead for one year. The pain was not relieved by different medications and remained within the distribution of V1 and V2 divisions of the trigeminal nerve. His past history and physical examination were unremarkable. Radiofrequency ablation of the respective divisions under sedation was planned. In the operating, routine monitors such as ECG, noninvasive blood pressure (BP), SpO 2 , EtCO 2 (via nasal prongs) were attached, baseline vitals recorded, and an intravenous (IV) access was secured. Oxygen was administered via nasal prongs at 2 L/minute and a loading dose of dexmedetomidine (1 lg/kg over 10 minutes) was started with an infusion pump. Five minutes later (35 lg dexmedetomidine infused), the patient displayed signs of agitation, disorientation, flailing of arms, and irritable behavior. His heart rate was 96/min, BP 130/84 mmHg, and SpO 2 100%. Dexmedetomidine was presumed to be the possible cause of agitation, and hence, the infusion was stopped; the patient was kept under observation. His behavior became normal after 15 minutes, and he had no recall of the event. Although the patient requested to proceed with the procedure, it was decided to postpone it to a later date. A week later, he underwent the procedure, uneventfully, under sedation with midazolam 2 mg and fentanyl 100 lg IV; there was no sign of agitation. The pain relief was complete, and there was no recurrence of agitation at 1-month follow-up. Dexmedetomidine is known to reduce emergence agitation during the postoperative period. 1 It is also used to reduce agitation and delirium in ICU as it has sedative and analgesic properties without respiratory depression. 2 These effects are attributed to selective central presynaptic a-2 agonist properties, which inhibits the action of norepinephrine and epinephrine centrally and peripherally by inhibiting presynaptic as well as postsynaptic a-2 receptors. 3 The reduction in central sympathetic activity which inhibits nociception is mainly responsible for reducing agitation. 4 However, the presence of agitation during infusion in this case points toward the possibility of increase in central sympathetic activities. Agitation has been reported with the use of dexmedetomidine for prolonged ICU sedation (more than 24 hours), with an incidence of 2%. 5 However, this is the first report of agitation with infusion of dexmedetomidine during procedural sedation, observed at a small dose of 0.5 lg/kg. We believe that dexmedetomidine may have some degree of unknown central postsynaptic a-receptor activity increasing sympathetic surge which may result in agitation. Caution must therefore be exercised, and possible occurrence of agitation may be anticipated during infusion of dexmedetomidine for procedural sedation.

Object Cerebral vasospasm following subarachnoid hemorrhage (SAH) causes significant morbidity in a delayed fashion. The authors recently published a new scale that grades the maximum thickness of SAH on axial CT and is predictive of vasospasm incidence. In this study, the authors further investigate whether different aneurysm locations result in different SAH clot burdens and whether any concurrent differences in ruptured aneurysm location and maximum SAH clot burden affect vasospasm incidence. Methods Two hundred fifty patients who were part of a prospective randomized controlled trial were reviewed. Most outcome and demographic variables were included as part of the prospective randomized controlled trial. Additional variables were also collected at a later time, including vasospasm data and maximum clot thickness. Results Aneurysms were categorized into 1 of 6 groups: intradural internal carotid artery aneurysms, vertebral artery (VA) aneurysms (including the posterior inferior ...

IMPORTANCE The present study is the largest on the use and effect of intracranial pressure (ICP) monitoring in pediatric trauma patients. OBJECTIVE To determine the effect of ICP monitoring on survival in pediatric patients with severe head injuries using the National Trauma Data Bank. DESIGN, SETTING, AND PARTICIPANTS The National Trauma Data Bank was queried (version 6.2, 2001-2006) for information on patients younger than 17 years admitted to an intensive care unit with blunt traumatic brain injury (TBI), Injury Severity Score (ISS) greater than 9, and Glasgow Coma Scale (GCS) score less than 9. Patients with incomplete medical records and those with intensive care unit length of stay of less than 24 hours were excluded from the study. MAIN OUTCOMES AND MEASURES Parametric comparisons (t tests and χ 2 as appropriate) were performed to compare patients who received ICP monitoring with those who did not. Stepwise logistic regression methods were used to assess whether ICP monitoring in the presence of other variables (age, sex, ISS, Revised Trauma Score, and GCS score) was associated with survival. RESULTS Monitoring of ICP was performed in only 7.7% of patients who met the monitoring criteria recommended by the Brain Trauma Foundation. There were no significant differences in age, sex, or GCS score. After adjustment for admission GCS score, age group, sex, Revised Trauma Score, and injury ISS, ICP monitoring was associated with a reduction in mortality only for patients with a GCS score of 3 (odds ratio, 0.64; 95% CI, 0.43-1.00). Comparison between the 2 groups showed that the ICP monitoring group had a longer hospital length of stay (21.0 days vs 10.4 days; P < .001), longer intensive care unit stay (12.6 vs 6.3 days; P < .001), and more ventilator days (9.2 vs 4.7; P < .001). CONCLUSIONS AND RELEVANCE Despite current Brain Trauma Foundation guidelines, ICP monitoring is used infrequently in the pediatric population. The data suggest that there is a small, yet statistically significant, survival advantage in patients who have ICP monitors and a GCS score of 3. However, all patients with ICP monitors experienced longer hospital length of stay, longer intensive care unit stay, and more ventilator days compared with those without ICP monitors. A prospective observational study would be helpful to accurately define the population for whom ICP monitoring is advantageous.

Background: There are conflicting opinions on the effect of dexmedetomidine on cerebral autoregulation. This study assessed its effect on dynamic cerebral autoregulation (dCA) using a transcranial Doppler (TCD). Methods: Thirty American Society of Anesthesiologists physical status I and II patients between 18 and 60 years, who underwent lumbar spine surgery, received infusions of dexmedetomidine (Group D) or normal saline (Group C), followed by anesthesia with propofol and fentanyl, and maintenance with oxygen, nitrous oxide and sevoflurane. After five minutes of normocapnic ventilation and stable bispectral index value (BIS) of 40-50, the right middle cerebral artery flow velocity (MCA FV) was recorded with TCD. The transient hyperemic response (THR) test was performed by compressing the right common carotid artery for 5-7 seconds. The lungs were hyperventilated to test carbon dioxide (CO 2) reactivity. Hemodynamic parameters, arterial CO 2 tension, pulse oximetry (SpO 2), MCA FV and BIS were measured before and after hyperventilation. Dexmedetomidine infusion was discontinued ten minutes before skin-closure. Time to recovery and extubation, modified Aldrete score, and emergence agitation were recorded. Results: Demographic parameters, durations of surgery and anesthesia, THR ratio (Group D: 1.26 ± 0.11 vs. Group C: 1.23 ± 0.04; P = 0.357), relative CO 2 reactivity (Group D: 1.19 ± 0.34 %/mmHg vs. Group C: 1.23 ± 0.25 %/mmHg; P = 0.547), blood pressure, SpO 2 , BIS, MCA FV , time to recovery, time to extubation and modified Aldrete scores were comparable. Conclusions: Dexmedetomidine administration does not impair dCA and CO 2 reactivity in patients undergoing spine surgery under sevoflurane anesthesia.