PRINCIPLESN OF PEDIATRIC ANAESTHESIAЗавантажити презентацію
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1.One of the most important differences between paediatric and adult patients is oxygen consumption which, in infants may exceed 6ml/kg/min, twice that of adults. 2.The cardiac index (defined as the cardiac output related to the body surface area to allow a comparison between different sizes of patients) is increased by 30-60 percent in neonates and infants to help meet the increased oxygen consumption 3.Stroke volume is therefore relatively fixed and the only way of increasing cardiac output is by increasing heart rate. 4.The sympathetic nervous system is not well developed predisposing the neonatal heart to bradycardia.
.Respiratory 1.The head is relatively large with a prominent occiput, the neck is short and the tongue is large. The airway is prone to obstruction because of these differences. 2.The epiglottis is large, floppy and U shaped. The trachea is short (approximately 4-9cm) 3.The glottic opening (laryngeal opening) is more anterior and the narrowest part of the airway is at the cricoid ring. (In the adult airway the narrowest point is the vocal cords). 4.An uncuffed endotracheal tube which has an air leak around it when positive pressure is applied to it should be used in children under 10 years of age. An uncuffed tube provides a larger internal diameter compared with a cuffed tube. 5.(Age / 2) + 12 6. Increased alveolar ventilation is achieved by an increase in respiratory rate
Temperature regulation 1.infants have a large surface area to volume ratio and therefore a greater area for heat loss, especially from the head. 2.There is an increased metabolic rate but insufficient body fat for insulation and heat is lost more rapidly. 3.It is important to maintain a warm environment to minimise heat loss.
1.Fluid requirements can be considered as maintenance fluids and replacement fluids. 2.Maintenance fluid requirements are calculated on an hourly basis depending on the body weight. A suitable way of working this out is as follows: 4 ml/kg for the first 10 kg, adding 2 ml/kg for the second 10 kg and 1 ml/kg for each kg over 20 kg. A regimen with 30% of the fluid as normal saline and 70% as dextrose 5% is suitable for this purpose. 3.Replacement fluids.replaced by balanced salt solutions such as Hartmanns solution. Colloid solutions are sometimes used when losses are heavy.In general abdominal surgery will need extra fluid to replace these third space losses at around 10 mls/kg/hour for each hour of surgery
.Preoperative Assessment 1.Every patient should be visited by the anaesthetist prior to surgery, preferably in the presence of the parents in order to obtain a history, perform a physical examination and evaluate laboratory data in addition to estimating the patient's response to hospitalisation. 2.Fasting. Newborn to 12 months: No formula or breast milk 4 hours before surgery Clear liquids up to 2 hours before surgery Over 1 year: No formula, milk or solid food 6 hours before surgery Clear liquids up to 2 hours before surgery
Pre-medication 1.should be prescribed according to the needs of the patient. 2.Sedatives should be reserved for those who are unduly anxious. Oral midazolam 0.75 mg/kg administered 30 minutes prior to induction is very suitable. 3.Atropine or glycopyrrolate can be administered orally (or intramuscularly) preoperatively or given iv on induction of anaesthesia.Vagolytic dose of atropine (0.03 mg/kg) provides complete protection against vagal cardiac slowing or other cardiac arrhythmias.
Basic Anaesthetic Technique 1.Since children can deteriorate rapidly during anaesthesia it is especially important to check that all drugs and apparatus are ready prior to induction. 2.induction.Induction of anaesthesia is generally by intravenous or inhalational methods 3.Occasionally the anaesthetist is confronted by an unruly and hysterical child who will not co-operate with either of the above methods of induction. While an IM injection of ketamine (3-5 mg/kg) is possible