1. Serious hazards of transfusion in children (SHOT) Review Article. E Harrison, P Bolton. Pediatric Anesthesia, 21: 10 -13; 2011.
This is the UK national audit of transfusion practice in children. Initially, the system was voluntary. It has now become mandatory. It therefore provides valuable data on adverse effects related to transfusion in children and can be used to improve practice. The following are the major findings of the latest review of the data as presented in this paper.
· 4.2 % of RBC transfused to children under 18 years, with 18 adverse events per 100, 000.
· 1.7 % of RBC transfused to children under 1 year, with 37 adverse events per 100, 000.
The most common cause of incompatible transfusion was laboratory error. This is probably because transfusion in the neonatal age group is complex. Inappropriate transfusion (usually overtransfusion) also occurs commonly. The authors stress the importance of standardized methods of prescribing blood and using 'mls' and not units of blood. Administrative errors may occur more frequently in neonates who may not have been named or have a name change and in any children who can not confirm their identity. Other common errors include failure to use leukocyte depleted blood, or CMV negative blood in children under 1. Acute transfusion reactions are the most common non-error related complications in the overall paediatric population. However, acute transfusion reactions rarely occur in the neonatal age group. The authors list relative immune suppression and unrecognized reactions as possible reasons for this. Transfusion transmitted infections are extremely rare. TRALI is rare in children.
Take Home Message
Children have a much higher incidence of adverse events. The adult rate is 13 : 100 000. Safe transfusion in this population requires an understanding of the specific requirements of neonates and infants, standardized prescription methods and strict methods of checking and cross checking to avoid administrative errors.
2. Neonatal transfusion review. Review Article. S R. Sloan. Pediatric Anesthesia, 21: 25 -30; 2011.
Neonates do not make antibodies to minor RBC antigens but their plasma may contain maternal antibodies to ABO antigens. Infants do not make antibodies to RBC antigens until 3 or 4 months of age in response to bacterial colonisation of the intestine. Therefore, blood transfusion in this age group uses blood that is compatible with the infant’s blood type (ABO, Rhesus) and with any maternal antibodies that may be present. Repeated blood typing to check for newly formed antibodies is not required in the first 3 - 4 months of life so long as strict guidelines are followed (including continuous admission and no name change). In immune compromised patients such as premature infants, blood components need to be irradiated to prevent transfusion-associated graft-versus-host disease which occurs when transfused lymphocytes proliferate. Electrolyte disturbance leading to arrhythmia is a real risk for neonates and infants. Irradiation increases potassium leak out of stored red cells. Hypocalcaemia occurs in response to citrated plasma. Neonates have a reduced ability to metabolize citrate, they have lower ionized calcium stores and have a myocardium that is more dependent on ionized calcium for its function. Hypothermia from rapid transfusion of cold blood also increases the risk of arrhythmia. Dilutional coagulopathy and toxicity from additives are important risks in infants and neonates. ABO compatible FFP, cryoprecipitate and platelets should be used as incompatible units may contain sufficient antibodies to cause significant haemolysis of RBC both circulating and developing.
Take Home Message
This review article provides a summary of the transfusion requirements and risks for neonates. The Australasian Society for Blood transfusion (ASBT) has a protocol based on Australian Guidelines for transfusion in neonates and infants.
3. Blood transfusion risks and alternative strategies in pediatric patients. Review Article. J Lavoie. Pediatric Anesthesia, 21: 14 - 24; 2011.
This review outlines the risks of blood transfusion in paediatric patients. It also covers techniques for minimizing blood loss as they apply to paediatric patients. These include intraoperative blood salvage, preoperative autologous donation, deliberate hypotension, hypervolaemic haemodilution, acute normovolaemic haemodilution and antifibrinolytic use. These methods can be used safely in paediatric patients but the author stresses that combined techniques of blood conservation are more effective than any single method. The author also stresses that transfusion algorithms should be evidence based.
4. Quantitative analysis of continuous intravenous infusions in pediatric anesthesia: safety implications of dead volume, flow rates, and fluid delivery. H Ma, M A. Lovich, R A Peterfreund. Pediatric Anesthesia 21: 78 - 86; 2011.
In small patients, dead space volume and transient changes in infusion rates (such as occurs when elevating and lowering infusion pumps) can lead to clinically significant and undesirable bolus dosing or changes in rate. This paper looks at two drugs commonly given by infusion, propofol and remifentanil. It examines the effect of patient weight, infusion system dead volume, drug flow rate and carrier fluid flow rates on the actual delivery of these drugs into the circulation. The effect of drug concentration was also examined. As expected, the drug available for bolus in the infusion system dead space is more significant in smaller children and may exceed the expected loading dose. The overall mass of drug is dependent not only on the volume of the dead space but also on the concentration of the drug in the line and on the flow rate. In Infants who have lower carrier infusion flow rates, the time to achieve steady state delivery is increased. (? still takes 3 - 5 time constants, but time constants are increased). Infusion of drugs necessitates the delivery of a volume of fluid that is dependent on the drug dose and the concentration used. This volume may be a significant percentage of maintenance fluid volumes. Reducing the concentration, to allow faster flow rate and therefore more rapid achievement of steady state, results in an increase in the volume of fluid delivered.
Take Home Message
This paper is heavy to read and includes lots of mathematics and graphs. Essentially the take home message is: If inadvertent bolus dosing of a given drug is likely to be clinically significant, then a dedicated line for fluid, blood and other drug boluses is essential and becomes more important the smaller the child.
5. Randomized controlled trial comparing morphine or clonidine with bupivacaine for caudal analgesia in children undergoing upper abdominal surgery. R. Singh, N. Kumar, P. Singh. British Journal of Anaesthesia 106 (1): 96–100 (2011).
This is a randomized double-blind controlled study comparing morphine and clonidine used to prolong caudal analgesia after upper abdominal surgery. 50 patients undergoing upper abdominal surgery were randomized to receive 2 mcg / kg of clonidine in 1.25 ml / kg of 0.2 % bupivacaine or 30 mcg / kg in morphine in 1.25 ml / kg of 0.2 % bupivacaine. The study found that clonidine prolonged analgesia significantly more than morphine. However, sedation was significantly prolonged in the clonidine group. More vomiting occurred in the morphine group than in the clonidine group. However this difference was not statistically significant. Itch occurred significantly more in the morphine group. There were no reports of hypotension, respiratory depression and bradycardia in either group.
Take Home Message
There are many studies looking at caudal analgesia and additives for lower abdominal surgery, lower limb and urogenital surgery in children. This study shows that analgesia for upper abdominal surgery (intestinal obstruction, resection anastamosis, hepatico jejunostomy) can be achieved using a single shot caudal technique prolonged with either morphine or clonidine.
6. Incidence of perioperative adverse events in obese children undergoing elective general surgery. S. El-Metainy, T. Ghoneim, E. Aridae, M. A Wahab. British Journal of Anaesthesia. Advance Access published Dec 10, 2010. doi:10.1093/bja/aeq368
This study looked at children between 2 and 16 years of age undergoing general surgery over a two year period in a paediatric operating theatre. BMI was calculated and children identified as overweight or obese based on age specific charts. The study then looked at co-morbidities and respiratory complications during the perioperative period. These included significant desaturation (< 90 %), upper airway obstruction, difficult mask ventilation, difficult laryngoscopy and bronchospasm. 10.5 % of the children in the study were overweight and 15.2 % were obese. The patients were stratified according to age into four groups and comparisons were made between matched groups. Obese children were found to have a significantly higher incidence of co-morbidities in particular asthma and sleep apnoea. Mallampati III classification was significantly more common in the obese groups. The study found a significantly higher incidence of desaturation , difficult mask ventilation and airway obstruction in the obese groups than the non-obese, particularly in the younger groups.
Take Home Message
We all recognise that obese adult patients
present particular challenges for anaesthetists. Obesity
among children is becoming more common. There is some
evidence that obese children are at risk for complications.
This study, whilst not ground breaking, adds to that
evidence. It shows that in a cohort of children in Egypt
undergoing general surgery, there was an increase in the incidence
of adverse respiratory events in obese children and in particular
at younger ages.
See Journal Watch September 2009.
7. Early childhood general anaesthesia exposure and neurocognitive development
L. Sun. British Journal of Anaesthesia. 105 (Suppl 1): 161 - 168; 2010. doi: 10.1093/bja/aeq302
There is animal evidence that agents commonly used in general anaesthesia may be neurotoxic to the developing brain. This paper summarises the evidence from pre-clinical studies with regards to exposure to anaesthetic agents and neuronal apoptosis and neurodegeneration at critical stages of cellular development. The critical stage was different for rats and non human primates and seemed to correspond with periods of rapid synaptogenesis. The paper also summarises 5 clinical studies, all of them retrospective cohorts, which looked at neurobehavioural outcomes. This paper also summarises two large multi-centre clinical trials currently underway that are examining anaesthetic neurotoxicity in children. The GAS study is looking at 600 infants undergoing either general anaesthesia or regional anaesthesia for inguinal hernia repair. Neurodevelopmental evaluation will occur in these children at age 2 and 5. The PANDA (Paediatric Anesthesia and Neuro Develoment Assessment) study is a sibling matched cohort study. Children included are those who have undergone a single episode of general anaesthesia for inguinal hernia repair before 36 months of age.
Take Home Message
Studies in the area of neurocognitive development present many challenges. These include the definition of adverse neurodevelopmental outcome, and the measurement of neurocognitive function across multiple domains. Non-standardised definitions and measurement tools or methods make research in this area difficult to interpret and to compare. Defining the period of risk in the developing human brain is also difficult. Although animal evidence suggests that periods of rapid synaptogenesis constitute at risk periods, cross species variability means that animal results can not be extrapolated to humans. Moreover, within the human developing brain, peak synaptogenesis occurs in different areas of the brain at different times. This means that the potential period of vulnerability to neurotoxicity may extend up to 36 months. Generalisability of results is also limited.
8. Perioperative opioid requirements are decreased in hypoxic children living at altitude. J A. Rabbits, C B. Groenwald, N M Dietz et al. Pediatric Anesthesia 20: 1078–1083 ; 2010 doi:10.1111/j.1460-9592.2010.03453.x.
This paper aims to investigate the effect of altitude on analgesic requirements by measuring the fentanyl usage of children undergoing surgery at sea level compared to those undergoing surgery at altitude. The study was a retrospective chart review of the opioid requirements of children who underwent cleft lip and cleft palate surgery in Peru over a 2 year period. Children with significant co morbidities were excluded. The patients who had surgery at altitude had a significantly lower baseline saturations compared to those at altitude. Those who received surgery at altitude received significantly less fentanyl in the perioperative period compared to those at sea levels.
Take Home Message
As mentioned by the authors, there is some evidence for reduced opioid requirement /increased sensitivity in children with obstructive sleep apnoea undergoing adenotonsillectomy and in animal models for intermittent hypoxia. This study is relevant because it may have implications for disease states associated with chronic hypoxia. However, this study has a number of limitations that are common to retrospective studies including missing data, non-standardised care and non-standardised end points.
Disclaimer
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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