Journal Review

British Journal of Anaesthesia Highlights

By Elizabeth S. Yun, MD
University of Wisconsin School of Medicine
Madison, WI

In 2014, the British Journal of Anaesthesia published articles on various pediatric anesthesia topics.  This review highlights some of these articles. Several articles covered topics concerning pediatric cardiac anesthesia.

Guzzetta et al studied the effects of recombinant factor VIIa and three-factor prothrombin complex concentrate (3F-PCC) on thrombin generation, a critical step in the coagulation pathway.  They compared the effects of both factor concentrates on a computer simulated thrombin generation model and on neonates undergoing cardiac surgery with cardiopulmonary bypass.  Their data showed that 3F-PCC was more effective in restoring TG and had improved procoagulant activity in the neonate (1). The authors proposed that more research is needed to determine the safety and efficacy of this factor. 

Savan et al suggested a model for predicting postoperative blood loss in patients undergoing cardiopulmonary bypass.  They did a retrospective analysis of prospective data on 182 children undergoing congenital heart surgery.  They defined significant bleeding as blood loss greater than 10% of total blood volume in the first 6 postoperative hours.  After analyzing the data, they determined that preoperative body weight, cyanotic heart disease and wound closure duration had a significant relationship with bleeding. The authors felt that a combination of these factors could be used to estimate the probability of postoperative blood loss (2). 

Arenas-Lopez et al noted that clonidine has analgesic, sedative and hemodynamic profiles that make it useful in critically ill infants.  In this study they characterized the absorption profile after an enteral dose of clonidine.  They gave clonidine via a nasogastric tube to16 infants undergoing congenital heart surgery.  They found the patients had stable hemodynamic profiles and sustained therapeutic plasma clonidine levels.  However, they also saw slow and erratic absorption of the clonidine and concluded that the parenteral route might be preferred if rapid onset is needed (3).

There were also articles on pediatric regional anesthesia.  Lundblad et al had previously described a finding where patients receiving a high dose caudal block (1.5 ml/kg) had a bidirectional cerebrospinal fluid flow leading to a cranial spread of local anesthetic that they called CSF rebound mechanism.  Based on this hypothesis, they speculated that the increase of CSF from the spinal canal to the intracranial space would cause significant changes in cerebral blood flow and cerebral oxygenation.  They used Doppler ultrasound in an observational study of infants receiving high dose caudal blocks.  They measured changes in cerebral blood flow velocity (CBFV) and mean flow velocity to follow changes in cerebral blood flow and cerebral oxygen in these patients.  They found significant changes in CBFV immediately and 5 minutes after a high dose caudal injection as well as changes in cerebral oxygen level.  The authors conclude that these observations lend support to their hypothesis and highlighted a possible safety issue of doing high dose caudal blocks in patients with intracranial pathology (4). 

Kim et al performed a prospective randomized double blind study to determine if a caudal injection of ropivacaine and dexamethasone had better analgesia than ropivacaine alone.  They randomized 80 patients having outpatient orchiopexy surgery to receive either ropivacaine caudal blocks or ropivacaine and dexamethasone caudal blocks. Postoperative pain scores, rescue analgesic dose and adverse effects were recorded at 6 and 24 hours after surgery.  The ropivacaine and dexamethasone group had lower pain scores, longer time to first analgesic dose and remained pain free at 48 hours.  Adverse effects were the same in both groups.  The authors concluded that adding dexamethasone could significantly improve analgesia in caudal blocks (5)

Other articles covered a wide range of topics.  Chen et al compared remifentanil versus Dexmedetomidine for maintaining spontaneous ventilation for removal of airway foreign body.  They randomized 77 patients undergoing rigid bronchoscopy to either a remifentanil-TIVA or dexmedetomidine-TIVA.  They measured heart rate, arterial pressure, oxygen saturation respiratory rate, end-tidal CO2 and induction time in both groups. Results indicated that dexmedetomidine-TIVA patients had a more stable hemodynamic and respiratory course but had a prolonged recovery time (6). 

Souza-Neto et al studied the anatomic relationships of the internal jugular (IJC), subclavian (SCV) and femoral veins (FV) in children using 2D ultrasound.  They enrolled 142 patients scheduled for elective neurosurgical procedures under general anesthesia. After induction of anesthesia, patients were positioned and images of the veins were obtained.  Parameters measured were diameter of adjacent artery and vein, the distance between them and position of the vein in relation to the artery.  They found a 7.7% variation in the IJV, 9.8% variation in the FV and 7.4% in the SCV.  The authors concluded that these findings support a systematic ultrasound screening before attempting to access these veins for central venous access (7). 

Edjo Nkillly et al performed a single center observational study on the effect of perioperative use of hypotonic fluids on postoperative sodium levels.  They looked at 34 newborns having abdominal or thoracic surgery and collected data on type and duration of surgery, calculated IV free water intake and pre and postoperative sodium levels.  Patients who received hypotonic and free water intake of greater than 6.5 ml/kg had a significant decrease in plasma sodium of >4mM.  These results questioned the routine use of hypotonic solutions in neonatal surgery (8).

Van de Putte and Perlas reviewed the use of bedside ultrasound to measure gastric content and volume as a means for assessing a patient’s risk for aspirations.  They noted that for many patients, the risk of aspiration is based on fasting times.  However, there are many situations where accurate fasting times are not obtainable (ex. emergency situations, medical issues with gastric emptying). Reviewing current literature on this topic, the authors found ten articles that examined the use of ultrasound to determine the nature of the gastric contents.  Nine articles used ultrasound to estimate the volume of gastric volume by reporting a correlation between the ultrasound determined antral cross sectional area and the total gastric fluid volume.  Based on this review the authors proposed a possible clinical algorithm for gastric ultrasound use for assessing aspiration risk.  However they noted that the data published only applied to adults and there was no defined minimum training requirements established for using this tool (9).

Two meta-analyses were published in 2014.  Bellis et al reviewed the literature to determine if children undergoing tonsillectomy who got dexamethasone or dexamethasone with an NSAID, had a greater incidence of post tonsillectomy hemorrhage.  They defined post tonsillectomy hemorrhage as any bleeding that required a change in postoperative management (ex. readmission, reoperation).  Because of the rarity of this finding, they included nonrandomized studies as well as randomized controlled studies in their meta-analysis.  Based on their review they did not find any evidence that dexamethasone increased the risk of hemorrhage.  There was insufficient data to determine what additional impact the use of NSAIDs had on that risk.  The authors stated that large studies specifically designed to follow hemorrhage rate are needed (10). 

Pickard et al conducted a systematic review to examine the effects of alpha 2 adrenergic agonists on postoperative behavioral disturbances.  They looked at full text reports of randomized controlled trials (RCT) on children receiving either IV clonidine or IV dexmedetomidine.  After a selection process, they found twelve articles that met their inclusion criteria.  After reviewing these articles and analyzing their data, they found evidence that intravenous alpha 2 adrenergic agonists reduced the incidence of emergence delirium in children. There was evidence that these agents had no adverse hemodynamic effects but prolonged time in the recovery room.  There was no data on the effects of these drugs on post hospitalization behavioral changes, an area that provides opportunity for further research (11)

References

1. Guzzetta NA, Szlam F, Kiser AS, Fernandez JD, Szlam SD, Leong T, Tanaka KA. Augmentation of thrombin generation in neonates undergoing cardiopulmonary bypass.  British Journal of Anaesthesia 2014; 112 (2): 319-27.
2. Savan V, Willems A, Faraoni D, Van der Linden P.  Multivariate model for predicting postoperative blood loss in children undergoing cardiac surgery: a preliminary study.  British Journal of Anaesthesia 2014; 112 (4): 708-14.
3. Arenas-Lopez S, Mulla H, Manna S, Durward A, Murdoch IA, Tibby SM.  Enteral absorption and hemodynamic response of clonidine in infants post-cardiac surgery.  British Journal of Anaesthesia 2014; 113 (6): 964-69.
4. Lunblad M, Forestier J, Marhofer D, Eksborg S, Winberg P, Lonnqvist PA.  Reduction of cerebral mean blood flow velocity and oxygenation after high volume (1.5 ml kg-1) caudal block.  British Journal of Anaesthesia 2014; 113 (4): 688-94.
5. Kim EM, Lee JR, Koo BN, Im YJ, Oh HJ, Lee JH.  Analgesic efficacy of caudal dexamethasone combined with ropivacaine in children undergoing orchiopexy.  British Journal of Anaesthesia 2014; 112 (5): 885-91.
6. Chen KZ, Ye M, Hu CB, Shen X.  Dexmedetomidine vs remifentanil intravenous anaesthesia and spontaneous ventilation for airway foreign body removal in children. British Journal of Anaesthesia 2014; 112 (5): 892-97.
7. Souza-Neto EP, Groussan S, Duflo F, Tahan F, Mottolese C, Dailler F.  Ultrasonographic anatomic variations of the major veins in pediatric patients.  British Journal of Anaesthesia 2014; 112 (5): 879-84.
8. Edjo Nkillly G, Michelet D, Hilly J, Diallo T, Greff B, Mangalsuren N, Lira E, Bounadja I, Brasher C, Bonnard A, Malbezin S, Nivoche Y, Dahmani S.  Postoperative decrease in plasma sodium concentration after infusion of hypotonic intravenous solutions in neonatal surgery.  British Journal of Anaesthesia 2014; 112 (3): 540-45.
9. Van de Putte P, Perlas A.  Ultrasound assessment of gastric content and volume.  British Journal of Anaesthesia 2014; 113 (1): 12-22.
10. Bellis JR, Pirmohamed M, Nunn AJ, Loke YK, De S, Golder S, Kirkham JJ. Dexamethasone and hemorrhage risk in pediatric tonsillectomy: a systematic review and meta-analysis.  British Journal of Anaesthesia 2014; 113 (1): 23-42.
11. Pickard A, Davies P, Birnie K, Beringer R.  Systematic review and meta-analysis of the effect of intraoperative α2 adrenergic agonists on postoperative behavior in children.  British Journal of Anaesthesia 2014; 112 (6): 982-90.