Diurnal variations in recovery times after general anaesthesia in children.

BACKGROUND: Circadian rhythms coordinate almost all physiological functions and are implicated in major disease development. Even though circadian rhythms have a major impact on human health, little is known about how they affect general anaesthesia. The purpose of this study was to understand if the time of day affects the length of time a child needs to achieve readiness for discharge after general anaesthesia for brain MRI. METHODS: A retrospective analysis over a 3 yr period (2013-5) on the length of stay in the postanaesthesia care unit (PACU) before discharge was performed for children (age <18 yr) undergoing brain magnetic resonance imaging as outpatients. PACU duration was correlated to either morning vs afternoon or to time clusters for discharge times (<9 AM, >9 AM <12 PM, >12 PM <3 PM, >3 PM <6 PM, >6 PM). RESULTS: Data from 2340 procedures in children, with median age [inter-quartile range (range)] of 4.7 [2.3-7.25 (0.5-17.8)] yr were available for analysis. The length of stay in the PACU significantly increased over the course of the day with an observed maximum increase of 18 or 19 min (<9 AM vs >6 PM) in children older than 3 or 5 yr, respectively. Subgroup analysis suggested time of day dependent PACU time increase was independent of sex, co-medications, or obstructive sleep apnoea. CONCLUSION: The time of day significantly affects PACU recovery times in children of both genders having brain imaging under general anaesthesia. Children younger than 3 yr might not be affected. Further validation of these findings may guide future strategies to reduce discharge times.

Differences in Blood Pressure in Infants After General Anesthesia Compared to Awake Regional Anesthesia (GAS Study-A Prospective Randomized Trial).

BACKGROUND: The General Anesthesia compared to Spinal anesthesia (GAS) study is a prospective randomized, controlled, multisite, trial designed to assess the influence of general anesthesia (GA) on neurodevelopment at 5 years of age. A secondary aim obtained from the blood pressure data of the GAS trial is to compare rates of intraoperative hypotension after anesthesia and to identify risk factors for intraoperative hypotension. METHODS: A total of 722 infants ≤60 weeks postmenstrual age undergoing inguinal herniorrhaphy were randomized to either bupivacaine regional anesthesia (RA) or sevoflurane GA. Exclusion criteria included risk factors for adverse neurodevelopmental outcome and infants born at <26 weeks of gestation. Moderate hypotension was defined as mean arterial pressure measurement of <35 mm Hg. Any hypotension was defined as mean arterial pressure of <45 mm Hg. Epochs were defined as 5-minute measurement periods. The primary outcome was any measured hypotension <35 mm Hg from start of anesthesia to leaving the operating room. This analysis is reported primarily as intention to treat (ITT) and secondarily as per protocol. RESULTS: The relative risk of GA compared with RA predicting any measured hypotension of <35 mm Hg from the start of anesthesia to leaving the operating room was 2.8 (confidence interval [CI], 2.0-4.1; P < .001) by ITT analysis and 4.5 (CI, 2.7-7.4, P < .001) as per protocol analysis. In the GA group, 87% and 49%, and in the RA group, 41% and 16%, exhibited any or moderate hypotension by ITT, respectively. In multivariable modeling, group assignment (GA versus RA), weight at the time of surgery, and minimal intraoperative temperature were risk factors for hypotension. Interventions for hypotension occurred more commonly in the GA group compared with the RA group (relative risk, 2.8, 95% CI, 1.7-4.4 by ITT). CONCLUSIONS: RA reduces the incidence of hypotension and the chance of intervention to treat it compared with sevoflurane anesthesia in young infants undergoing inguinal hernia repair.

Peripheral nerve catheters in children: an analysis of safety and practice patterns from the pediatric regional anesthesia network (PRAN).

BACKGROUND: Peripheral nerve catheters (PNCs) are used with increasing frequency in children. Although adult studies have demonstrated safety with this technique, there have been few safety studies in children. The main objective of the current investigation was to examine the incidence of PNC complications in children undergoing surgery. METHODS: This is an observational, multi-institutional study using the Pediatric Regional Anesthesia Network (PRAN) database. Data pertaining to PNCs were entered prospectively into a secure, online database by each participating centre. Patient characteristics, anatomic location, localization techniques, medications used, and complications were recorded for each catheter. All complications and any sequelae were followed until resolution. RESULTS: There were 2074 PNCs included in the study. 251 adverse events and complications were recorded, resulting in an overall incidence (95% CI) of complications of 12.1% (10.7-13.5%). The most common complications were catheter malfunction, block failure, infection, and vascular puncture. There were no reports of persistent neurologic problems, serious infection, or local anaesthetic systemic toxicity, resulting in an estimated incidence (95% CI) of 0.04% (0.001-0.2%). Patients who developed an infection had used the catheters for a greater number of days, median (IQR) of 4.5 (3-7) days compared with 3 (1-3) days in the patients who did not develop an infection, P<0.0001. CONCLUSIONS: Our data support the safety of placing PNCs in children, with adverse event rates similar to adult studies. Catheter problems are common, yet minor, in severity.

Sedation-analgesia in the pediatric intensive care unit.

The provision of sedation and analgesia is an integral aspect of the care of PICU patients. A careful systems approach to the provision of sedation and analgesia can minimize complications and maximize benefit to patients. Vigilance in monitoring and adherence to published guidelines are important for safety. Physicians must define the goals in clearly devising a plan and tailor the prescription to those goals rather than use a regimented protocol for all patients.

Guidelines for the pediatric perioperative anesthesia environment. American Academy of Pediatrics. Section on Anesthesiology.

The American Academy of Pediatrics proposes the following guidelines for the pediatric perioperative anesthesia environment. Essential components are identified that make the perioperative environment satisfactory for the anesthesia care of infants and children. Such an environment promotes the safety and wellbeing of infants and children by reducing the risk for adverse events.

Diaphragmatic shortening after thoracic surgery in humans. Effects of mechanical ventilation and thoracic epidural anesthesia.

BACKGROUND: Diaphragmatic function is believed to be inhibited after thoracic surgery and may be improved by thoracic epidural anesthesia. METHODS: Diaphragmatic function after a thoracotomy was monitored by implanting one pair of sonomicrometry crystals and two electromyogram (EMG) electrodes on the costal diaphragm of six patients undergoing an elective pulmonary resection. Crystals and EMG electrodes remained in place for 12-24 h. RESULTS: During mechanical ventilation, costal diaphragmatic length (as a percent of rest length; %LFRC) decreased passively as tidal volume (VT) increased (%LFRC = 2.81 + 1.12 x 10(-2) VT (ml), r = 0.99). During spontaneous ventilation, the costal shortening (2.1 +/- 2.3 %LFRC) was less than during mechanical ventilation (7.9 +/- 3.0 %LFRC, P < 0.05) at the same VT. Comparing spontaneous ventilation before and 30 min after thoracic epidural anesthesia, there were increases of VT (390 +/- 78 to 555 +/- 75 ml), vital capacity (1.37 +/- 0.16 to 1.68 +/- 0.21 l), and esophageal (-8.5 +/- 1.5 to -10.6 +/- 1.7 cmH2O), gastric (-0.7 +/- 0.8 to +0.8 +/- 0.8 cmH2O), and transdiaphragmatic (7.7 +/- 1.5 to 11.5 +/- 1.9 cmH2O) pressures, but diaphragmatic EMG and shortening fraction remained constant. In three of six patients, epidural anesthesia produced paradoxical segment lengthening upon inspiration. CONCLUSIONS: Thoracotomy and pulmonary resection produce a marked reduction of active diaphragmatic shortening, which is not reversed by thoracic epidural anesthesia despite improvement of other indices of respiratory function.

Thoracic epidural anesthesia increases diaphragmatic shortening after thoracotomy in the awake lamb.

BACKGROUND: Prolonged inhibition of diaphragmatic function occurs after thoracic and upper abdominal surgery. It was hypothesized that thoracic epidural anesthesia on the day after a thoracotomy could block inhibitory neural pathways and increase the shortening of costal and crural diaphragmatic segments. METHODS: Pairs of sonomicrometer crystals were implanted into the costal and crural regions of the diaphragm through a right lateral thoracotomy in 14 30-kg, 4-5-month-old lambs. One day after surgery, a thoracic epidural catheter was placed at the T8-T9 level. Regional diaphragmatic shortening normalized to end-expiratory length (%LFRC), was measured by sonomicrometry in these awake lambs. Changes in gastric (delta Pgas), esophageal (delta Pes), and transdiaphragmatic (delta Pdi) pressures were measured with transnasal balloon catheters. End-tidal carbon dioxide (FETCO2), costal and crural electromyogram (Edi), and tidal volume (VT) were measured. Inductance plethysmography was used in four lambs to assess relative contributions of the rib cage and abdomen to VT. Control values were obtained during quiet breathing and while rebreathing at up to 10% FETCO2. To block thoracic dermatomes, 1% or 2% lidocaine was injected through the epidural catheter. Measurements were repeated after each lidocaine injection. RESULTS: There was no change of resting length with 1% lidocaine; costal resting length increased by 22% with 2% lidocaine. After 2% lidocaine, costal %LFRC increased from control both during quiet breathing (8.7 +/- 0.7 to 18.1 +/- 1, mean +/- SEM%) and at FETCO2 10% (22.1 +/- 2 to 33.7 +/- 3%). VT during quiet breathing was unchanged after 1% lidocaine but increased from 235 +/- 16 to 283 +/- 28 ml after 2% lidocaine. At 10% FETCO2, delta Pdi was unchanged after 1% lidocaine and decreased from 36.5 +/- 4.3 to 26.3 +/- 4.9 cmH2O after 2% lidocaine. Regional delta Edi was unchanged with both 1% and 2% lidocaine at rest and during carbon dioxide rebreathing. Plethysmography in three lambs showed a reduction in rib cage contribution to tidal volume with 2% lidocaine during quiet breathing. CONCLUSIONS: Improved postoperative tidal volume and diaphragmatic shortening after thoracic epidural blockade may be due to changes of chest wall conformation and resting length and a shift of the workload of breathing from the rib cage to the diaphragm caused by intercostal muscle paralysis.

Inhaled nitric oxide in persistent pulmonary hypertension of the newborn.

Nitric oxide (NO) has vasodilatory effects on the pulmonary vasculature in adults and animals. We examined the effects on systemic oxygenation and blood pressure of inhaling up to 80 parts per million by volume of NO at FiO2 0.9 for up to 30 minutes by 6 infants with persistent pulmonary hypertension of the newborn (PPHN). In all infants this treatment rapidly and significantly increased preductal oxygen saturation (SpO2); in 5 infants postductal SpO2 and oxygen tensions also increased. Inhalation of NO did not cause systemic hypotension or raise methaemoglobin. These data suggest that low levels of inhaled NO have an important role in the reversal of hypoxaemia due to PPHN.

Effects of aminophylline on regional diaphragmatic shortening after thoracotomy in the awake lamb.

Aminophylline has been reported to augment diaphragmatic contraction, although this remains a controversial finding. We studied the effect of aminophylline on regional diaphragmatic shortening, changes in transdiaphragmatic pressure (delta Pdi), and integrated regional electromyographic (EMG) activity of the diaphragm (Edi) after a right thoracotomy in nine lambs using sonomicrometry, esophageal and gastric balloons, and EMG. Sonomicrometer crystals and EMG leads were implanted into the costal and crural regions of the diaphragm through a right thoracotomy, and a tracheostomy was performed. The animals were studied while awake within 4 days after surgery. Fractional costal and crural diaphragmatic shortening was measured using the sonomicrometer; delta Pdi was calculated from esophageal and gastric pressures. Respiratory variables were measured through the tracheostomy. Data were collected during quiet breathing and during CO2 rebreathing. After control measurements, aminophylline (10 mg/kg) was administered intravenously, producing a serum concentration of 17.7 +/- 1.5 micrograms/ml. Aminophylline did not augment shortening, increase delta Pdi, or overcome postoperative diaphragmatic inhibition acutely in the awake sheep after a right lateral thoracotomy. A small decrease of end-tidal CO2, from 5.2% to 4.9%, was measured at rest during aminophylline infusion, but Edi was unchanged. Although during CO2 rebreathing diaphragmatic shortening increased, the addition of aminophylline did not further augment shortening. Our data in awake lambs suggest that aminophylline does not improve diaphragmatic contraction in the acute postoperative period.

Continuous oxygen saturation monitoring following rectal methohexitone induction in paediatric patients.

Rectal methohexitone has been used to induce anaesthesia in paediatric patients for a number of years. This study was conducted in order to confirm the safety of this method of induction for uncomplicated routine paediatric patients. Children between the ages of six months and six years were considered candidates for induction with methohexitone (10%, 25-30 mg.kg-1). Patients were monitored with a continuous oxygen saturation recording. Forty-nine patients participated in this study and anaesthesia was induced successfully in 44. The mean age of the patients was 2.7 +/- 1.6 yr. The mean weight was 13.8 +/- 4.3 kg and the mean dose of methohexitone for successful induction was 27.0 +/- 3.0 mg.kg-1. Continuous oximeter recordings were available in 31 of the 42 patients who allowed oximeter placement prior to administration of methohexitone. No major desaturation events were noted in any patient. Two brief episodes of desaturation occurred. One with a nadir of 90% which lasted for 45 sec and another with a nadir of 86% which lasted for 26 sec. Both children had their heads flexed over their parents' shoulders at the time of the event resulting in partial airway obstruction. Both of these episodes were the result of upper airway obstruction which was clinically diagnosed by the anesthetist and readily corrected by repositioning the head. This study confirms the efficacy and safety of rectal methohexitone for induction of general anaesthesia in children. Mechanical obstruction of the airway following induction seems to be the most likely cause for oxygen desaturation. Monitoring of pulse oximetry does not appear necessary provided the child is carefully observed for adequacy of air exchange.