1. Effect of dexamethasone in combination with caudal analgesia on postoperative pain control in day-case paediatric orchiopexy. JY Hong, SW Han, WO Kim, EJ Kim, JK Kil. British Journal of Anaesthesia 105 (4): 506 -10. 2010.
This is a randomized double-blinded placebo controlled trial looking at the effects of a single dose of intravenous dexamethasone on postoperative analgesia in children undergoing day case orchidopexy. 77 children underwent general anaesthesia and a caudal block. They were randomised to receive dexamethasone, 0.5 mg/kg IV, or an equivalent volume of saline. Significantly fewer children in the dexamethasone group needed rescue analgesia in PACU than in the control group (7.0 % vs. 38.5 %). Significantly fewer patients in the dexamethasone group required oral paracetamol in the first 24 hours after surgery (23.7 % vs. 64.1 %). The time to first analgesia was significantly longer in the control group (646 min vs. 420 min). Post-operative pain scores were lower in the dexamethasone group. The study was adequately powered to show a 20 % difference in time to first analgesia at p = 0.05. There was no difference in the incidence of adverse effects between the two groups (vomiting, sedation, shivering). The incidence of vomiting was very low in this study and may be attributed to avoidance of opiates.
The mechanism by which dexamethasone enhances analgesia is not fully understood. It has powerful anti-inflammatory effect and may act by interrupting bradykinin release and cyclo-oxygenase formation. The elimination half life of dexamethasone is short (6 hrs) but because it has its effects by changing DNA transcription, its clinical effects can be prolonged. The authors state that the risk of a single dose of dexamethasone appears to be minimal. Indeed the use of dexamethasone as an ant-emetic in the peri-operative setting is widespread and accepted. However a single dose of dexamethasone may not be completely harmless. The July issue of Anaesthesia and Intensive Care contains an editorial that discusses this issue. Two studies looking at anti-emetic dexamethasone and post-operative infection and one looking at anti-emetic dexamethasone and serum cortisol levels are published in this issue. The dose of dexamethasone used for anti-emetic prophylaxis is generally much lower than the dose used in this study.
2. Dexmedetomidine Infusion for Analgesia and Prevention of Emergence Agitation in Children with Obstructive Sleep Apnea Syndrome Undergoing Tonsillectomy and Adenoidectomy. A Patel, M Davidson, MCF Tran et al. Anesthesia and Analgesia 2010 vol 111 (4) 1004 – 1010.
This is a prospective randomized, blinded and controlled study which looks at the effect of an infusion of dexmedetomidine compared to a fentanyl bolus on pain and emergence agitation. The study was adequately powered to show a 50 % reduction in emergence agitation and a 50 % reduction in the number of patients requiring intra-operative rescue fentanyl and rescue morphine in PACU. Children in both groups received fentanyl 1mcg/kg. Children in the dexmedetomidine group received 2mcg/kg via infusion over 10 minutes followed by an infusion of 0.7 mcg/kg/hr. A significantly greater number of children in the fentanyl group required intra-operative rescue fentanyl. Objective pain scores were higher in the fentanyl group. Post operative morphine requirements were significantly lower in the dexmedetomidine group. The frequency of severe emergence agitation at 3 different time points was lower in the dexmedetomidine group. The duration of severe emergence agitation was also reduced in the dexmedetomidine group. Sevoflurane was adjusted to maintain BIS below 60. It was found that MAC values were statistically lower in the dexmedetomidine group. Time to awakening and time to extubation were also statistically lower in the dexmedetomidine group.
Dexmedetomidine is an alpha 2 agonist which has sedative, analgesic and anxiolytic properties. Dexmedetomidine acts as an opiate sparing agent, lowers BP and may reduce the incidence and duration of emergence agitation. Unlike clonidine, it does not produce prolonged sedation and may have a MAC sparing effect. It therefore may be useful for children with obstructive sleep apnoea undergoing adenotonsillectomy, a population at risk for emergence agitation as well as opiate sensitivity and postoperative airway obstruction
3. Emergence delirium and postoperative pain in children undergoing adenotonsillectomy: a comparison of propofol vs. sevoflurane anesthesia. BJ Pieters, E Penn, P Niclaus et al. Pediatric Anesthesia 2010; 20: 944 – 950.
This is a randomized, prospective double-blind study which aims to evaluate the effect of sevoflurane versus propofol on the quality of recovery. The study uses the validated Paediatric Anesthesia Emergence Delirium (PAED) scale to assess delirium and the Children’s Hospital of Eastern Ontario Scale (CHEOPS) to assess pain. The study found that propofol maintenance did not influence agitation as measured by the PAED scale. The study found that propofol was associated with less analgesia requirement during recovery. There was also a lower incidence of PONV.
The main confounding factor in assessing emergence delirium is pain. Although the PAED scale has been validated as a measure of post anaesthesia agitation, the authors acknowledge that the independence of the PAED scale from pain scales has not been looked at. In fact the authors found a significant correlation between the PAED score and the CHEOP score. Other studies that have looked at the effects of emergence delirium have tried to eliminate pain as a confounder. This is done by either selecting procedures not associated with pain or procedures where a regional anaesthetic or local anaesthetic can be used for pain. This study looks at a particularly painful procedure and excludes the use of local anaesthetic. Patients who received propofol maintenance took longer to be ready for awake-extubation but PACU stay was not prolonged. However, as depth of anaesthesia was not controlled the significance of this finding is unclear. Patients who received propofol also had less fentanyl in recovery. There is no indication as to whether this is a result of reduced pain or reduced emergence delirium as the two were not significantly different between the two groups. In addition, Fentanyl was given to treat both pain (high CHEOPS, patient request or crying) and emergence delirium (high PAED score). The difference in the use of fentanyl between the two groups may have had an impact on the incidence of PONV between the two groups. There was no significant difference in sedation as measured by the Aldrete score. The study may or may not have been adequately powered to show a difference in sedation.
Take Home Message
This paper highlights a common problem in paediatric anaesthesia, the definition and measurement of emergence delirium in association with pain. I do not feel that any strong conclusion can be drawn about the effects of propofol versus sevoflurane from this paper because it fails to adequately control for pain as a confounding factor.
4. Ipsilateral Transversus Abdominis Plane Block Provides Effective Analgesia After Appendectomy in Children: A Randomized Controlled Trial. J Carney, O Finnerty, J Raug et al. Anaesthesia and Analgesia Oct 2010; 111 (4) 998 – 1003.
In this study, 42 children were randomized to receive a Transversus Abdominis Plane (TAP) block with 2.5 mg /kg of ropivacaine (max 150 mg) or placebo for open appendicectomy. The TAP block was performed using a land mark technique after induction of anaesthesia and prior to surgical incision. General anaesthesia and intra-operative analgesia was standardized. The children then received standard postoperative analgesia with IV morphine and regular diclofenac and paracetamol. Children older than 8 years received analgesia via PCA. Children younger than 8 years received nurse-administered intravenous morphine on demand. The primary outcome measure was 48 hour morphine consumption. Secondary outcome measures were time to first morphine request, VAS and side effects associated with morphine. The median time to first morphine requirement was significantly greater in the TAP group (55 min v 16 min). The total amount of morphine received in the first 48 hours was significantly less in the TAP group (10.3mg v 22.3 mg). There was no significant difference in the rates of nausea and vomiting or sedation. There were no complications associated with the TAP block.
Take home Message
TAP block is an effective addition to post-operative analgesic regime for children having open appendicectomy. I wonder whether superior analgesia is achieved using TAP block versus local infiltration by the surgeon, a much less time consuming method. TAP block is more easily and reliably achieved using ultrasound. It would be interesting to see what results would be achieved using this technique.
5. The Anesthetic Considerations of Tracheobronchial Foreign Bodies in Children: A literature Review of 12 979 Cases. CW Fidkowski, H Zheng, PG Firth. Anaesthesia and Analgesia; 111 (4) 1016 - 1025 October 2010.
This paper gives a useful review of the epidemiology of foreign body aspiration. It also looks at diagnosis both clinical and radiological. Plain X-ray, CT and Virtual bronchoscopy are described. Anaesthetic management for bronchoscopy is reviewed. Maintaining spontaneous ventilation is the most common technique. The disadvantages and merits of a relaxant technique are also discussed. There is no consensus as to the most optimal technique and each case needs to be assessed individually.
See also Journal Watch October 2009, 6.
6. Does ultrasound guidance improve the efficacy of dorsal penile nerve block in children? D Faraoni, A Gilbeau, P Lingier et al. Pediatric Anesthesia 2010. 20: 931 – 936.
This study compares the efficacy of penile nerve block by the landmark technique to penile nerve block by the ultrasound guided technique. Forty boys were randomised to receive a standard dose of ropivacaine with or without ultrasound guidance. General anaesthesia was standardised. The study found no difference in the failure rate between the two groups. The efficacy of the block, as measured by objective pain scores on arrival in PACU, and at 30 minutes as well as time to first paracetamol, was greater with the ultrasound guided technique. The ultrasound guided technique increased the duration of the procedure (induction of anaesthesia to end of surgery) by 10 minutes. The very low incidence of complications with this block means that this study was not adequately powered to show a difference in complication rates between the two techniques.
Take Home Message
Dorsal penile block is an effective means of providing analgesia for circumcision. The efficacy of the block can be improved by the use of ultrasound. This is at the expense of a significant increase in the duration of the procedure. This study was not able to show an improvement in safety of the block. Some of the complications of this block are potentially catastrophic and so the risk benefit may favour the use of ultrasound in particular if the time taken to perform the block using ultrasound could be reduced.
Reasonable attempts are made to include articles representative of recent publications, but no attempt is made to include every important article. The commentaries and take-home messages are only some of many possible opinions/interpretations from the anaesthesia literature.
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