Paediatric JW August 2010

 

 

1.    Study to assess the laryngeal and pharyngeal spread of topical local anesthetic administered orally during general anesthesia in children.  R Beringer. N Skeahan, S Sheppard, P Ragg, N Martin, I McKenzie, A Davidson.  Pediatric Anesthesia 20: 757 – 762; 2010.

This study is a prospective, randomized, blinded, observational study.  It looks at the spread of topical local anaesthetic after blind oral instillation in children.  Children were randomized to receive one of two different volumes of lignocaine stained with methylene blue.  They were also randomized to receive: no additional manoeuvre, laryngeal dunk or a head lift.  A blinded observer performed laryngoscopy and assessed the staining of the vocal cords, epiglottis, vallecula and piriform fossae.  53 out of 63 had complete staining of all four structures, the primary outcome measure.  The secondary outcome measure was the frequency of adverse events (cough, laryngospasm, and desaturation).  Coughing was more likely in children with incomplete staining, low volume of lignocaine and with a head lift. The authors acknowledge the potential for diminished protective airway reflexes post extubation.

Take Home Message

Blind oral instillation of local anaesthetic achieves good coverage of laryngeal structures. It does not necessarily follow that adequate anaesthesia levels will be reached.  Blind oral instillation may facilitate the practice of intubation without muscle relaxation, by attenuating the effects of laryngoscopy such as coughing, laryngospasm, regurgitation and sympathetic nervous system stimulation.  These complications are also related to the depth of anaesthesia at the time of instrumentation of the airway.  As this was not controlled, it may act as a confounder in the secondary outcome.

 

 

2.    Topical lidocaine reduces the risk of perioperative airway complications in children with upper respiratory tract infections.  K Schebesta, E Guloglu, A Chiari, N Mayer, O Kimberger.  Canadian Journal of Anesthesia 57: 745 – 750, 2010.

A randomized double-blind controlled trial that compared the effect of topical lignocaine gel on the incidence of air way complications in children with URTI (current mild symptoms, or symptoms in the past 6 weeks) vs. children without URTI.  In the lignocaine group, a LMA with a lignocaine containing lubricant gel was inserted.  In the placebo group plain lubricant was used. Anaesthesia induction and airway management were standardized.  The LMA was removed, without prior suctioning of the airway, whilst patients were in a deep plane of anaesthesia and without deflating the cuff.  In the URTI group, lignocaine gel reduced the incidence of postoperative coughing significantly and reduced the overall incidence of respiratory complications.  There was no difference in intraoperative coughing, laryngospasm, desaturation and bronchospasm. In the non URTI group, there was no significant reduction in airway complications.  Overall, complications occurred less frequently in the non URTI group than in the URTI group.

Take Home Message

Current or recent symptoms of URTI are known to increase the risk of respiratory complications associated with general anaesthesia. This increased risk can persist for up to six weeks. It follows that in order to minimise this risk, we would need to wait six weeks after URTI symptoms have resolved prior to anaesthesia for elective surgery.  Because children suffer multiple URTI s a year, this is impractical.  Many children with recent URTI or current mild URTI undergo general anaesthesia at a time when their upper airway remains reactive.  Strategies to minimise the risk for these children are of value.  Lignocaine has been applied to the airway by various methods to facilitate intubation and to reduce coughing, laryngospasm and other respiratory complications.  The method described in this paper is simple and combines the benefits of avoiding intubation in these patients with topical anaesthesia.  It would be interesting to see what structures come into contact with the lignocaine after this technique.

 

 

3.    A comparison of emergence delirium scales following general anesthesia in children.  S A Bakwa. D Costi, A Cyna.  Pediatric Anestehsia 20: 704 – 711; 2010.

This paper compares 3 different scales used to measure emergence delirium. The Pediatric Anaesthesia Emergence Delirium (PAED) scale, the Wathcha scale and the Cravero scale.  They found that the 3 scales correlated well with each other.  They found that the Watcha scale was a simple tool for practical clinical use.  It also had greater sensitivity and specificity than the other scales.  The PAED scale, which is better known, had a greater sensitivity and specificity with scores greater than or equal to 12 than with scores greater than or equal to 10.  An experienced observer also assessed all patients for emergence delirium.  The experienced observer diagnosed delirium in far fewer cases than any of the scales.  However, all the patients the experienced observer classified as having emergence delirium scored highly on all three scales.  It is not clear that whether the subjective experienced observer was more discerning whilst the delirium scales were diagnosing delirium when it was not present or vice versa.

Take Home Message

Emergence delirium refers to behavioural disturbance that occurs following general anaesthesia. There are multiple confounding factors.  The most important of these is pain with many of the features that occur in emergence delirium also attributable to pain.  Emergence delirium is variably defined, variably characterised and very difficult to measure. As a result, the literature on this phenomenon becomes difficult to interpret. In particular when comparing studies or pooling results.  A simple-to-use scale that can reliably assess for the presence or absence of emergence delirium would facilitate both clinical practice and research.

 

 

4.   Sevoflurane for central catheter placement in neonatal intensive care:  a randomized trial.  F Micel, R Vialet, S Hassid et al.  Pediatric Anesthesia 20: 712- 719; 2010.

This study compares the use of sevoflurane deep sedation with glucose and non nutritive sucking (GNNS) for insertion of PICC lines in NICU.  The study is a randomised controlled trial looking at efficacy in reducing duration of procedure and preventing pain.  It also compared safety.  The study was not able to be blinded.  The authors did not measure pain scores directly. They used indirect measures of pain including HR, MAP and movement.  They found no significant difference in the duration of the procedure in spite of greater immobility in the sevoflurane group.  They concluded that sevoflurane did not make catheter placement easier but that it did prevent pain-related symptoms.

Take Home Message

In paediatrics, general anaesthesia for PICC line placement is accepted practice.  However, this does not extend to the neonate. PICC placement in neonates is difficult and often requires multiple attempts.  There is the potential for significant stress to the neonate and simple techniques such as local anaesthetic and glucose non-nutritive sucking may be insufficient at relieving pain. The authors put forth that pain in preterm neonates is associated with poorer cognitive function and motor development at 8 and 18 months.  Sensitisation and hyperalgesia has been shown to occur in babies with repeated painful stimuli.  Their efforts to find an alternative are valid.  The authors chose to look at sevoflurane because it is predictable and short acting. It avoids the unpredictable pharmacokinetics and pharmacodynamics of opiods and benzodiazepines in the neonate.  There is a real risk of sevoflurane use by untrained providers in what is effectively under monitored general anaesthesia.  There is the potential for unnecessary and repeated exposure of the neonate to volatile anaesthetic agents which may have deleterious effects on the developing brain.  There is also the potential for generalised pollution of the NICU environment with anaesthetic gases.  The benefit of sevoflurane use for this indication is questionable if it does not make the procedure easier to perform and safer with fewer attempts and a shorter duration.

 

 

5.   Pharmacokinetic-Pharmacodynamic Modeling of Propofol in Children.  A Rigouzzo, F Servin, I Constant. Anesthesiology 113: 343 – 52, 2010.

This study compares the performance of different models for propofol TCI in prepubertal children down to age 6.   BIS has now been well studied in the paediatric population and is used in this study to provide pharmacodynamic feedback allowing comparison of different PK-PD models for propofol.  The relationship between BIS and predicted concentrations were analysed using Kataria, Marsh, Schuttler and Schnider models in children and using Schnider model in the adults.  Actual venous propofol blood concentrations were taken and compared to that predicted by each model for that time.  The measured BIS and predicted BIS were compared using the Kataria and Schnider models.  In the children, they found that the adult Schnider model provided the best fit for the predicted concentration to effect (BIS) relationship.

Take Home Message

The use of propofol TCI in adult anaesthesia is commonplace. In spite of the widely accepted benefits of propofol based anaesthesia, the use of this technique in paediatric anaesthesia remains infrequent.  Pharmacokinetic and pharmacodynamic modelling does not extend to the paediatric population, with most algorithms for TCI tested down to age 16.  This reflects the practical and ethical challenges of research in paediatrics.  This paper is difficult to follow.  However, it adds to the literature and provides some evidence for the rational use of Propofol TCI in children down to age 6.  Further research into the pharmacokinetics and pharmacodynamics of propofol in this population and in children 5 years old and under is required before the benefits of propofol TCI can be delivered with ease to children.

 

 

6.   Pediatric anesthesia in developing countries:  experience in the two main university hospitals of Benin in West Africa.  Zoumenou E, Gbenou S, Assouto P et al.  Pediatric Anesthesia 20: 741 – 747; 2010.

This paper gives an overview of the quality of Paediatric anaesthesia services in Benin, a country in sub-Saharan West Africa.  

Points of interest:

  •          Pancuronium is the only non-depolarizing muscle relaxant available.
  •          Succinylcholine is not generally available.
  •          Halothane is becoming difficult to obtain and sevoflurane is not available.
  •          There was no use of mechanical ventilation.
  •          No device considered essential monitor for anaesthesia was used regularly (pulse oximeter  73 %  NIBP   54 %, precordial stethoscope 20 %)
  •          Capnography, ECG, temperature and neuromuscular monitoring were not available.
  •          After surgery 93 % of patients were transferred straight to a ward.  1% went to recovery and 6% to ICU.
  •          Cardiac arrest incidence is 156 per 10 000 (compared to 1.4 per 10 000 in USA).  Mortality was 97 per 10 000, with neonates having highest rate (10%).  Hypoxia following respiratory complications was the commonest cause of cardiac arrest.  Difficult intubation, laryngospasm and bronchospsasm were the main causes of cardiac arrest at all stages of anaesthesia.

The level of care is well below what would be considered minimum safe practice in the developed world. The authors conclude that hypoxia is the main risk factor for children presenting for anaesthesia.  They hope that access to the WHO global pulse oximeter project may present an opportunity to improve practice.

 

 

Disclaimer:

1              Reasonable attempts are made to include articles representative of recent publications, but no attempt is made to include every important article.

2             The commentaries and take-home messages are only some of many possible opinions/interpretations in the anaesthesia literature.

 

 

For other months of Paediatric Journal Watch click here

 

 

Refresh