Zhaoxing Pan

The Hemodynamic Response to Dexmedetomidine Loading Dose in Children With and Without Pulmonary Hypertension

BACKGROUND:Dexmedetomidine, an &agr;-2 receptor agonist, is widely used in children with cardiac disease. Significant hemodynamic responses, including systemic and pulmonary vasoconstriction, have been reported after dexmedetomidine administration. Our primary goal of this prospective, observational study was to quantify the effects of dexmedetomidine initial loading doses on mean pulmonary artery pressure (PAP) in children with and without pulmonary hypertension. METHODS:Subjects were children undergoing cardiac catheterization for either routine surveillance after cardiac transplantation (n = 21) or pulmonary hypertension studies (n = 21). After anesthetic induction with sevoflurane and tracheal intubation, sevoflurane was discontinued and anesthesia was maintained with midazolam 0.1 mg/kg IV (or 0.5 mg/kg orally preoperatively) and remifentanil IV infusion 0.5 to 0.8 &mgr;g/kg/min. Ventilation was mechanically controlled to maintain PCO2 35 to 40 mm Hg. When end-tidal sevoflurane was 0% and fraction of inspired oxygen (FIO2) was 0.21, baseline heart rate, mean arterial blood pressure, PAP, right atrial pressure, pulmonary artery occlusion pressure, right ventricular end-diastolic pressure, cardiac output, and arterial blood gases were measured, and indexed systemic vascular resistance, indexed pulmonary vascular resistance, and cardiac index were calculated. Each subject then received a 10-minute infusion of dexmedetomidine of 1 &mgr;g/kg, 0.75 &mgr;g/kg, or 0.5 &mgr;g/kg. Measurements and calculations were repeated at the conclusion of the infusion. RESULTS:Most hemodynamic responses were similar in children with and without pulmonary hypertension. Heart rate decreased significantly, and mean arterial blood pressure and indexed systemic vascular resistance increased significantly. Cardiac index did not change. A small, statistically significant increase in PAP was observed in transplant patients but not in subjects with pulmonary hypertension. Changes in indexed pulmonary vascular resistance were not significant. CONCLUSION:Dexmedetomidine initial loading doses were associated with significant systemic vasoconstriction and hypertension, but a similar response was not observed in the pulmonary vasculature, even in children with pulmonary hypertension. Dexmedetomidine does not appear to be contraindicated in children with pulmonary hypertension.

Video assessment of supraglottic airway orientation through the perilaryngeal airway in pediatric patients.

The COBRA perilaryngeal airway (PLA) is a new supraglottic airway device available for use in children. We studied the orientation of the larynx as viewed through the PLA using video obtained with a fiberoptic bronchoscope in 45 infants and children. Laryngeal view was scored, and position of the grill bars of the PLA and the epiglottis was assessed. An acceptable airway was obtained in all subjects, but the laryngeal view was nearly or completely obstructed in 76.9% of the patients 10 kg and less, with the epiglottis folded over the glottic opening. This was uncommon in larger children. The grill bars of the PLA were closely opposed to the epiglottis and supraglottic structures in nearly all subjects. We conclude that 1) the PLA provides an acceptable airway in infants and children, but infolding of the epiglottis with obstruction of the view of the glottic opening is common in infants, 2) extra vigilance for airway obstruction in this age group is necessary, and 3) the PLAs close opposition to the supraglottic structures suggests that removal in a deeper plane of anesthesia might minimize laryngeal stimulation.

Positive Intravascular Test Dose Criteria in Children During Total Intravenous Anesthesia with Propofol and Remifentanil Are Different than During Inhaled Anesthesia

BACKGROUND: The use of local anesthetic test doses is standard practice when performing regional anesthesia. When an intravascular test dose is administered during inhaled anesthesia, the heart rate does not increase in about 25% of children; altered T-wave amplitude is a better indicator. No studies have examined the criteria for a positive result during total IV anesthesia (TIVA) in children. METHODS: We studied the effect of a simulated positive test dose on heart rate, arterial blood pressure, and T-wave amplitude in 17 ASA physical status I or II children receiving TIVA with propofol and remifentanil. Bupivacaine 0.25% 0.1 mL/kg with epinephrine 1:200,000 was injected IV, and vital signs and electrocardiogram were continuously monitored. Increases of heart rate and arterial blood pressure >10% and T-wave amplitude >25% of baseline were considered clinically significant changes. RESULTS: All subjects had increased systolic and diastolic blood pressure (30.3% ± 11.7% and 49.3% ± 16.7%), which peaked within 120 s. Heart rate increases >10% of baseline occurred in 73% of subjects. T-wave amplitude increased in 33.3%, was unchanged in 25%, and decreased in 41.7% of subjects. CONCLUSIONS: A positive test dose during TIVA is best detected by increased arterial blood pressure. Twenty-seven percent of intravascular injections were missed using heart rate criteria. T-wave amplitude is not a reliable indicator of intravascular injection during TIVA. This is in marked distinction to what is seen during inhaled anesthesia.

Hemodynamic response to ketamine in children with pulmonary hypertension

The safety of ketamine in children with pulmonary hypertension has been debated because of conflicting results of prior studies in which changes in mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) have been widely variable. The goal of this prospective study was to quantitate the effects of ketamine on pulmonary hemodynamics in a cohort of children with pulmonary hypertension under conditions in which variables such as airway/ventilatory management, FiO2, and use of vasodilating anesthetics were controlled.

Screening by pulse CO‐oximetry for environmental tobacco smoke exposure in preanesthetic children

Objective:u2002 The purpose of this study was to evaluate the ability of multiple wavelength pulse CO‐oximetry (SpCO) to screen for environmental tobacco smoke (ETS) exposure in children.

Intrathecal Morphine Versus Extended-release Epidural Morphine for Postoperative Pain Control in Pediatric Patients Undergoing Posterior Spinal Fusion

BACKGROUND: Posterior spinal fusion for scoliosis is one of the most painful elective pediatric surgeries. Good postoperative pain control allows early ambulation and return of ability to tolerate oral intake. Options for analgesia in this patient population are suboptimal. We hypothesized that extended-release epidural morphine (EREM) would provide better pain control and less adverse effects compared to intrathecal (IT) morphine. METHODS: The primary outcome was total IV morphine consumption during 0–48 hours postoperatively. Secondary outcomes included time until first patient-controlled analgesia (PCA) demand, pain scores, and adverse opioid effects. After institutional review board approval, 71 subjects undergoing posterior spinal fusion for idiopathic scoliosis completed the study. The subjects were randomly allocated to 7.5 &mgr;g/kg IT morphine or 150 &mgr;g/kg EREM. The final IT morphine and EREM groups contained 37 and 34 subjects, respectively. Postoperative pain was treated with morphine PCA, ketorolac, oral oxycodone, and acetaminophen. Morphine consumption, pain scores, nausea and vomiting, pruritus, and respiratory depression were measured every 4 hours. Parents completed a caregiver questionnaire about their child’s pain control regimen after the first postoperative day. RESULTS: There was no difference in total morphine consumption over the first 48 hours between subjects in the EREM and IT morphine groups: median (range) 42.2 (5.5–123.0) and 34.0 (4.5–128.8) mg, respectively (P = .27). EREM and IT morphine groups had no difference in time until first PCA demand. Pain scores were no different between the groups from 8 to 24 hours after surgery. Compared to IT morphine, EREM subjects had lower pain scores from 28 to 36 hours after surgery. The reported incidence of pruritus was lower in the EREM subjects. CONCLUSIONS: There was no difference in total morphine consumption or time until first PCA demand between the EREM and IT morphine groups. EREM provides a longer duration of analgesia after posterior spinal fusion for scoliosis and may be associated with less opioid-induced pruritus.

Exhaled carbon monoxide screening for environmental tobacco smoke exposure in preanesthetic children

Objective:u2002 Exposure to environmental tobacco smoke (ETS) is associated with an increased risk of perioperative adverse events in children. The purpose of this study was to evaluate exhaled carbon monoxide (CO) as a preoperative ETS screening tool in children.

Continuous local bupivacaine wound infusion with neuraxial morphine reduces opioid consumption after cesarean delivery

Abstract Background: As a part of a quality improvement program, maternal postoperative opioid use and pain scores were compared between those receiving continuous infusion of bupivacaine for local incisional pain control with multimodal pain management and neuraxial morphine versus multimodal pain management with neuraxial morphine alone. Objective: We compared postoperative opioid use and pain scores between the multimodal pain management group with neuraxial morphine and the group receiving multimodal pain management, neuraxial morphine, and continuous infusion of bupivacaine for local incisional pain control. Study design: A retrospective cohort analysis of cesarean deliveries from January of 2015 through March of 2016 was undertaken. Deliveries were grouped by utilization of continuous infusion of bupivacaine for local incisional pain control. For each postoperative day, the average daily opioid use, antiemetic use and pain scores were determined. Patients received 1–2 tablets oxycodone–acetaminophen (5–325u2009mg) every 4u2009h as needed with oxycodone 5–10u2009mg immediate release tablets every 4u2009h as needed for breakthrough pain in addition to acetaminophen and ibuprofen. Total dose of narcotic, antiemetic use, and pain scores was compared between groups utilizing t-test for continuous variables and chi square for categorical data. A linear mixed model with unstructured covariance was utilized to analyze the daily dose of narcotic and pain scores from postoperative day 1 through day 4. Results: Patients in the standard multimodal group with neuraxial morphine used more opioids versus those receiving continuous wound infusion of bupivacaine in total postoperative dosing (122.79u2009±u200961.92u2009mg versus 89.88u2009±u200951.38u2009mg, pu2009=u2009.0063). There was a statistically significant difference between the standard group and local infusion of bupivacaine group on postoperative days 1 and 2 (32.79u2009±u200915.56u2009mg versus 22.13u2009±u200915.73u2009mg, pu2009=u2009.0011 and 40.25u2009±u200919.84u2009mg versus 29.13u2009±u200914.58u2009mg, pu2009=u2009.0018, respectively). There was no difference in narcotic use for postoperative days 3 and 4. There was a higher mean number of antiemetic doses in the standard group (0.31u2009±u20090.70 versus 0.10u2009±u20090.30, pu2009=u2009.0396). Pain scores did not differ between groups, although there was a correlation between opioid dosing and pain scores. The standard group received more IV ketorolac (87.72u2009±u200942.01u2009mg versus 64.50u2009±u200953.3u2009mg, pu2009=u2009.0165) and more IV acetaminophen (634.89u2009±u2009706.42u2009mg versus 375.0u2009±u2009490.29u2009mg, p =u2009.0315) within the first 24u2009h postoperatively. In addition, the standard group received more oral acetaminophen (6969.67u2009±u20093230.14u2009mg versus 5248.75u2009±u20092711.71u2009mg, pu2009=u2009.0064). No difference was seen in regard to ibuprofen between groups. These results remained constant when adjusted for differences in gestational age, variation in intraoperative opioid dosing, as well as differences in uterine incision type. Conclusion: We found a significant reduction in postoperative opioid use when continuous infusion of bupivacaine for local incisional pain control was added to our standard pain management with neuraxial morphine after cesarean delivery. As a result of this quality improvement initiative, we have implemented this intervention universally as a part of our multimodal postoperative pain management strategy.

Laryngeal view and temperature measurements while using the perilaryngeal airway (Cobra-PLUS™) in children

The Cobra‐PLUS™ perilaryngeal airway (CP) is a modification of the Cobra perilaryngeal airway. It has a distal curve for easier placement and a thermistor on the pharyngeal cuff. We assessed the orientation of the larynx to the CP and compared temperatures measured using CP to temporal arterial (TA) and infrared tympanic (T) thermometers.