Presentation on theme: "ANAESTHETIC IMPLICATIONS IN PEDIATRIC PATIENTS"— Presentation transcript:
1ANAESTHETIC IMPLICATIONS IN PEDIATRIC PATIENTS Dr Vishawjeet SinghModerator Dr Jyoti Pathania
2PREOPERATIVE PREPARATION A– In addition to routine pre- anaesthetic evaluation, the following points should be stressed:1- gestational age at birth- extent of prematurity.2- congenital anomalies3- assessment of airway (cleft lip, micrognathia )4- severity of coexistent disease-eg sepsis , resp. failure.5- degree of birth asphyxia, apneic spells.
3B- CHILD---Psychological preparation is very important.1- Children over 2-6 years are over 5 times more likely to have significant preoperative anxiety.2- parental anxieties concerning the surgical procedures may be profound and can be transmitted to the child.3- anaesthesiologist should formulate the plan for smooth induction, explain the possibilities regarding induction and help soothe the family members.4- chidren are principally worried about pain and separation from parents.
4Presurgical prep. programmes such as brochures, videos or tour can be helpful. Reassurances to parent and children is helpful.In hospitals with appropriate facilities, separation anxiety can be avoided by inviting a parent to accompany the child at induction of anaesthesia.
5ANAESTHETIC ASSESSMENT Previous illness and operationH/o allergyh/o apnoeic spells- more likely to develop apnoea following anaesthesia and should not be accepted for day care procedres until they are atleast 50 wks gestation.WEIGHT- influence the selection of anaesthetic eqipments.Upto 12 yrs wt= (age + 3) 5/2 or age x 2 +9h/o respiratory tract infectionsURTI– H/O RTI within 4 wks of operation , or who have symtoms of URTI preoperatively are at increased risk of respiratory complications such as --- laryngospasmbronchospasmatelectasishypoxemiait is usual to postpone elective srgery for 4-6 wks, which may not be always practical.
6URTI- If decision is taken to proceed with the surgery endotracheal tube should be used to control the airways.Postoperatively the pt needs supplemental oxygen and careful monitoring.
7ExaminationHead and neck– forloose deciduous teethsigns of potentially difficultintubationlimited mouth openingmicrognathialarge tonguenoisey breathingA precordial murmur , circulatory instability or cyanosis point to a CHD in neonate.Preoperative cough, fever, malaise and audible chest signs suggests lower respiratory tract infections. Elective anaesthesia should be postponed for 4-6 wks.
8INVESTIGATIONSNeonates scheduled for elective minor surgery--- CBCS. GlucoseNeonates with chronic illness and congenital defects– CBC, glucose, albumin, clotting profile, platelet count.In a healthy child scheduled for minor surgery – no investigations needed.Hb estimation– in pts of chronic diseases , hemoglobinopathies, anaemia.Hb and cross matching- if significant blood loss anticipated.Other investigations should be indicated only when clinically indicated.
9PREOPERATIVE FASTINGmilk clear fluids<6mths6-36mths>36 mthsPreoperative fasting times for different types of liquid and solidsclear breast cow/formula solidmilk milk< 3 mths> 3 mths
10Infants and young children become dehydrated easily than adults. Preoperative fasting is required to minimize residual gastric volume at induction of anaesthesia and reduce the risk of pulmonary aspiration of gastric contents.Gastric emptying time with breast milk and cow milk is more and thus more chances of aspiration.
11PREMEDICATIONNo premedication is required for < 6 mthsThe need for premedication should be individualized according to-underlying medical conditionlength of surgerydesired induction of anaesthesiapsychological make up of child and family.
12Drugs for premedication MIDAZOLAM-Oral mg/kgNasal mg/kgRectal – 0.5 mg/kgIm – 0.15 mg/kgIt takes 20 minutes for oral midazolam to be effectve.KETAMINE—IM mg/kg- in highly uncooperative ptsOral mg/kgNasal 3 mg/kgORAL TRANSMUCOSAL FENTANYL CITRATE(OTFC)mg/kg onset – 30 minduration mindisadvantages nausea, vomiting, pruritis, occasional desaturation.advantages decreases intra and post operatine analgesic requirements.
13SUFENTANILNasal – 3 microgm/kgOnset minAdv dec analgesic requireementsearly discharge from hospitalDisadv burning sensation in the nosedec in chest wall complianceand oxygen saturation.
14H2 BLOCKERSTo decrease the potential for aspiration of gastric contents.ANTICHOLINERGICSglycopyrrolate 5mic/kgatropine mic/ kg-- lessen incidence of bradycardia-- reduces incidence of hypotension duringinduction in neonates and infants-- prevent accumulation of secretions for pts wiyh URTI,and those given ketamine.
15INDUCTION OF ANAESTHESIA Choice of agent and technique must be based on the needs of the individual patient.Method/ technique of induction is determined by-- medical condition of the patient-- surgical procedure-- level of anxiety of the child-- whether able to cooperate, communicate.-- presence or absence of full stomach.
16A- INHALATION INDUCTION -Reduced requirement-incd incidence of bradycardia, hypotension and cardiac arrest To attenuate this, HR maintained and preload optimized.Iv atropine 0.02 mg/kg.BSS or albumin 10-20ml/kg before induction**Most dangerous time during inhalation induction as the child loses consciousness- depress the heartSo once anesthesia is induced, dec halothane or sevoflurane conc. till iv line is securedDon’t proceed to deeper planes of anesthesia without iv line in place.2nd most dangerous point- immediately after tracheal intubation If vaporizernot closed before laryngoscopy-overdose of inhaled anestheticsDISCONTINUE ALL ANESTHETICS UNTIL LARYNGOSCOPY AND ET INTUBATION ACCOMPLISHED
17TECHNIQUESNEONATES AND INFANTSholding the end of anaesthesia circuit in a cupped hand over the infants face, the other hand can adjust the conc of anaesthetic .Allowing the neonate or infant to suck on a rubber nipple or on a finger generally prevents crying during induction.As the infant loses consciousness, the anaesthesia mask is added to improve delivery and to decrease operating room pollution.
18PEDIATRIC PATIENTS1- BLOW UP THE BALLON2- HYPNOTIC SUGGESTIONSanesthesia mask- aeroplane pilots masksmell of halothane- aviation fuelThe use of constant conversation and 0.25 – 0.5% increase in inspired concentration for 3 – 4 breaths.If child holds breath, avoid assisted respiration as it can cause laryngospasm, coughing.3- FLAVOURED MASK4- SINGLE BREATH TECHNIQUESChild is asked to take a full inspiration followed by a full expiration. Placement of mask at the end of expiration, another full inspiration held as long as possible and then normal breathing.Prior to inductioin– circuit is filled with 55 halothane in 60% n2o.Takes < 1 min for induction
19HALOTHANEStandard agentSweat, non pungent, allows smooth induction and maintenance.early onset and recovery.Lower MAC in neonates d/tA- immaturity of CNS.B- attenuation of pain response d/t high levels of plasma peptides.Higher MAC in infants d/t increase in brain water content.In view of profound cvs effects of halothane in infants an incremental technique of induction is employed.
20Incremental technique- Following the administration of 70% N2O in oxygen, halothane concentration is increased in 0.5% increments every 3-5 breaths.Consciousness is usually lost after 1-2 min. this incremental technique may occasionally be associated with An exaggerated excitement phase.
21ISOFLURANELess myocardial depressantPreservation of heart rateGreater reduction of CMRO2Noxious smell and thus greater incidence of airway related problems.DESFLURANEUnsuitable for inhalational induction as it has a pungent etheral odour.
22SEVOFLURANEDOC for inhalational induction in many centres becoz of its minimal pungency---Relatively low BG solubility- rapid induction and recovery.A combinatioin of N20 70% in oxygen is given initially to obtund the child. At this stage, 8% sevoflurane can be introduced without any reaction from the patient and unconsciousness will be produced after 4-6 breaths. In addition to increasing the speed of induction, the use of 8% sevoflurane results in less excitation than an incremental technique.
23Disadvantages sevoflurane relatively higher rate of metabolismfluoride ioncompound A .
24NITROUS OXIDESweet smelling, non irritant, non inflammable.Occasionally premature and sick neonates may not tolerate cvs effects of nitrous in which case air may be substituted as a carrier gas for oxygen.Main contraindication is h/o air pockets within the body and the need for high inspired oxygen concentration.
25INTRAVENOUS INDUCTION Important when induction with mask is contraindicated- full stomach, reflux esophagitisi/v access.Cannulation of tiny pediatric patient can be difficult.Use of EMLA crème.All air bubbles should be removed from the i/v line since high incidence of patent foramen ovale increases the risk of paradoxical air embolism.In emergency situations where iv access is impossible fluids can be effectively infused through an18 G needle inserted into the medullary sinusoids within the tibial bone. This intraosseous infusion can be used for all medications normally given iv with rapid result.
261- THIOPENTONE SODIUMLower dose in neonates than in infantsNeonates- 4-5 mg/kgInfants mg/kgdecreased dosage in neonates is due to-- immature brain-- decreased plasma protein binding-- more permeable BBB.INCREASED REQUIREMENT in infants d/tincreased cardiac output as this would be expected to reduce the first pass concentration of thiopentone arriving at the brain.
27PropofolDose required is higher in children< 2 yrs – 2.9 mg/kg6-12 yrs – 2.2 mg/kgKETAMINEAS an induction agent in neonates especially those with cyanotic heart disease.
28RECTAL INDUCTIONChild falls asleep in parents armsMethohexital- 10% mg / kgInduction within 8-10 minutes.THIOPENTONE30mg/kgKetamine 10 mg/kgMidfazolam 1mg/kg max 20 mg
30RAPID SEQUENCE INDUCTION WITH CRICOID PRESURE In full stomach patientsRapid desaturationmay occur in child because- oxygen consumption highchild may refuse preoxygenationAtropine 0.02 mg/kg is given iv to prevent reflux induced/ sch induced bradycardia.
31Prep. of intubating equipment and suction Preoxygenation of lungsRapid induction using STP, propofol or ketamineApplication of cricoid pressureRapid onset of paralysis with sch, roc
32MUSCLE RELAXANTSSUCCINYL CHOLINE1-- Highly water soluble, therefore increased dose requirement inpaediatric patients.2 – effective when given intramuscular.Infants – 5 mg/kgchildren 4 mg/kgonset 3-4 minduration of relaxation 20 minIn an emergency situation scholine can be given intralingually. 2 mg/ kg in midline to avoid hematoma formation.
333– Children are more susceptible than adults to cardiac arrhythmias, hyperkalemia, and malignant hyperthermia after Sch administration due to underlying unrecognized muscle dystrophy. So it should be best avoided for routine elective surgery in children.4– atropine should be given just prior to the first dose of scholine in all children including teenagers.
34NON DEPOLARIZING MUSCLE RELAXANTS Immaturity of neuromuscular junctiontends to increase senstivity.Disproportionately large extracellular compartment results in dilution of drug.Greater volume of distribution in neonates result inslower rate of excretion and prolongation of effect.Drugs such as vecuronium which has hepatic metabolism has increased duration of effect.Hoffman degradation of atracurium makes it useful but histamine release can be a problem.
35MIVACURIUM0.2 – 0.3 mg/kg dose causes adequate relaxation within 2 minutes and thus is ideal for constant infusion.ROCURONIUM0.6 mg/kg for routine induction0.9 – 1.2 mg/kg- rapid sequence induction but prolonged duration min should be expected.It offers the advantage that it could be given intramuscularly in deltoid. It produces intubating conditions in 3 – 4 minutes.im- 1mg/kg infants1.8 mg/kg children > 1 yr
36Because of the extreme variability in response, the doses of long acting muscle relaxants should be titrated carefully starting from half to third of the usual dose.The effect of the incremental doses of ms relaxants should be monitored with a peripheral nerve stimulator.
37ANTAGONISM OF MS RELAXANTS IT is recommended in all neonates and infants even if they have recovered clinically becoz any increase in the work of breathing may cause fatigue and respiratory failure. Useful signs of reversal are the ability of infant to lift the legs and arms.
38PEDIATRIC AIRWAY MANAGEMENT INTUBATIONFollowing inhalational induction, N20 and vaporizers should be discontinued prior to intubation so that that the lungs contain high inspiratory concentration of oxygen to combat apnoea.Correct head positionApplication of the external pressure at the level of cricoid cartilage to push the larynx into view.
39LARYNGOSCOPE BLADEINFANTS- flat blades are more suitable as it flattens out the curvature of the epiglottis and can be used to lift it forward to expose the larynx.> 1 yr– medium sized curved badeswith the tip placed in the vallecula.Gentle insertion, avoid trapping the lips between teeth and blade . Not to lever on upper tooth.
40Tube sizeUncuffed tubes < 8 yrs of age.Decreased incidence of post intubation croupProvide a leak tominimize the risk of accidental barotauma. Allow a leak when cm of water pressure is applied.Size- < 6yrs – age/3 +3.5>6 yrs – age/neonate 3 kg – 3 mmid< 3kg – 2.5 mmid
41Tube lengthLength of the tube should be such that the tip of the tube lies in midtrachea while 2-3 cm protrudes from the mouth.Length in cm = ID X 3> 2 yr = age/2 + 13Neonate = 10 cm1 yr = 12 cm
42ANESTHESIA CIRCUITS FOR PEDIATRICS A- dead space should be minimalB- weight and size be suitableC- no valves to cause undue obstructionD- humidified gases be usedE- reservoir bag should be smaller to monitor respiratory movements.F- facemask must fit well to contour of face.G- work of breathing should be less while preventing rebreathing.
43NON REBREATHING CIRCUITS 1- provide minimal WOB becoz they have no valves to be opened up by patients respiratory efforts.2- rate of induction is rapid becoz- volume of non rebreathing circuit is less- no equilibrium with CO2 absorber is required- anaesthetic gases are delivered immediately in the airway.3- as the volume of nonrebreathing circuit is small as compared to that of circle system,the compression and compliance volumes are significantly less. This improves the ability to observe respiratory efforts as reflected by movement of anaesthesia bag as well as the ability to estimate pulmonary compliance.
44T – piece systemOriginal T- piece ( Ayres) system consists of light metal T tube with a main lumen of 1cm diameter and of smaller side tube at right angle to the main lumen through which anaesthetic gas mixture was introduced. A length of rubber tubing attached to open end of T piece act as reservoir for anaesthetic gases.
45Jackson Rees modification Attached open tailed bag to the reservoir tube in order to facilitate controlled ventilation.ADV- simplicityconveniencecompact sizeT Piece system rely on adequate FGF to eliminate CO2During spontaneous vent- FGF > 2 MVControlled vent FGF = MV
46CIRCLE SYSTEMConsists of –afferent and efferent breathing tubesReservoir bagChemical absorberOne way flow d/t unidirectional valvesADV-Economical use of anaesthetic gasesConservation of heat and humidity
47Provided ventilation is controlled in neonates and either controlled or assisted in infants , a standard adult circle system fitted with low dead space connectors , a small bore tubing and a reduced capacity reservoir bag is suitable for maintenance of anaesthesia for pts of all ages.
48MAINTENANCE OF ANAESTHESIA The goals-Provision for adequate anesthesia and operating conditionsMaintaining physiological hemostasisAdequate fluid replacementInfants are poor candidates for anaesthesia with spontaneous ventilation becoz of poor pulmonary mechanics and increased susceptibility to cardiovascular depressant effects of volatile anaesthetic agents.Combination of tracheal intubation and balanced anaesthesia with full dose of muscle relaxants , controlled ventilation, minimum concentration of volatile anaesthetics and reduced dose of opioids is optimum.
49MONITORING Pulse – temporal/ radial artery easily accessible. Precordial/ esophageal stethoscope auscu;ltationECG monitoringRespiratory monitoring by visual movements of chest wallPulse oximetryETCo2 for assessment of ventilation and confirmation of ETT placement and early warning of MH.Temperature monitoringUrine outputFluidsGlucose monitoringNIBP monitoringInvasive monitoring
50POST OPERATIVE CARE Attention to the airways Provision of oxygen therapyMonitoring of pulse, respiration and blood pressureCompletion of post anaesthetic recovery chartsRecovery nurses should be trained to detect early changes in respiration and circulation and should be able to initiate treatment while the anaesthesiologist is summoned.Once the child is awake , one of the patients parent can come in the recovery.
51PROBLEMS DURING RECOVERY -- Hypoxemia – oxygen administered routinely toall pts-- Post operative apnea-- Nausea and vomiting –perinormemeset mg/kg-- Post intubation croup-- Post operative pain relief-oral pcm= 15 mg/kg0.5 mg/ kg-- Postoperative fluids