Neonat~1
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1. Neonatal surgical emergencies are common in developing countries due to factors like high birth rate, consanguinity, and infections during pregnancy. 2. Anesthetizing neonates requires special considerations due to their underdeveloped organ systems and immature physiology. Their cardiovascular, respiratory, renal and thermoregulatory systems are particularly vulnerable. 3. Close monitoring of vital signs, oxygenation, hydration and glucose levels is essential during anesthesia and in the post-operative period when apnea and cardiac arrest risks are high. Maintaining normal temperature is also critical for neonates.
Neonat~1
- 1. NEONATAL SURGICAL EMERGENCIES & ANAESTHETIC MANAGEMENT Dr.Narasimha Reddy, M.D.,DA Professor & H.O.D, Dept. of Anaesthesiology, Kurnool Medical College , Kurnool
- 2. PART I PHYSIOLOGICAL CONSIDERATIONS & ANAESTHETIC IMPLICATIONS
- 3. • Neonatal surgical emergencies are common in developing countries. – High birth rate – Consanguinity – Infections during pregnancy – Multiple pregnancies – malnutrition
- 4. Some terminologies: • Fetus: intrauterine period • Newborn: upto 12 hrs after birth • Neonate: upto 30 days after birth • Infant: first 12 months of age. • Gestational age:time from conception to birth • Post-natal age:time from birth to present time • Post-conceptual age:from conception to present age (G.A+post natal age)
- 5. CNS • Gets 1/3rd of CO • Autoregulation present, but not effective • Myelination incomplete, senses are active • Can feel pain , can smell & hear • Blood – brain barrier – Immature,hydrophilic & lipophilic cross the barrier – Autonomic regulation good – Parasympathetic domination – Less number of receptors & variant protein binding
- 6. CNS….. • InterVentricular hemorrhage: – Surgical stimulation, – inadequate analgesia, – Airway instrumentation, – Excessive transfusion, prematures are more prone, stressed neonate lacks autoregulation, Fluctuations in CPP
- 7. CVS • Heart contractile mass 30%, • Ventricles less compliant, • CO 350- 400ml/kg/mt. • CO depends on heart rate & SV • O2 consumption is 7 ml/kg/mt. • Bradycardia is due to hypoxia, low CO, vagal stimulation in anesthesia
- 8. AUTONOMIC NERVOUS SYSTEM • Baroreceptors are immature & sensitive to anesthetics • Sympathectomy due to spinal or epidural- no fall in B.P.(as sympathetic system is immature). • Fall of BP & HR due to sympathetic blockade is offset by inhibition or withdrawal of cardiac vagal activity.
- 9. RESPIRATORY SYSTEM • Neonate has a large head, small weak neck,obligate nose breather, large tongue, U-shaped epiglottis, funnel shaped larynx, Subglottic portion is the narrowest larynx is anterior & cephalad cricoid is complete ring, tracheal length is 2-5 cms.
- 10. • Respiratory centre is immature & sensitive to depressant drugs • More in prematures, apnoeic episodes are common • Lung volumes – Tidal volume is small, 6 ml/kg 15 ml/kg – O2 consumption is 7-9 ml/kg – Resp.rate & alveolar vent. 2-3 times adult. – FRC/VA ratio in neonates is 0.23, – Changes in FiO2 causes rapid changes in oxygenation, – MV/FRC is 5:1 – Less number of underdeveloped alveoli, surfactant less – Ventilation is better controlled in infants < 3/12 of age
- 11. BLOOD • Hb 18-19 gm/dl. • PCV 60% • Fetal Hb 70-90% • ODC shifted to left • Blood volume 80 ml/kg • Cardiac index ,i.e CO/BSA is more
- 12. KIDNEYS 1. Decreased renal blood flow& decreased GFR Days 6-24 mths Urine vol. 1.5 2.4 ml/kg/hr Osmolality 40-900 50-1400 EC vol.(%B.W) 42 34 Body fluid vol./ 82-107 70-75 ml/kg Higher BSA & immature skin-evaporative losses
- 13. Metabolism & Thermal Homeostasis • O2 consumption is 7 ml/kg/mt – 7th day • Temperature control is the most imp. Consideration in pediatric anesthesia • Metabolism drives MV & CO by increasing rate. • Resting energy requirements is double that of older child. • Glucose is primay substrate for heart & brain
- 14. Metabolism & Thermal Homeostasis…… • Neonate has core temp. of 370C – Increasing metabolic demands, – Decreased stored carbohydrates, – Decreased liver function, – Increasing tendency to hypoglycemia – Heat production by non shivering mech.
- 15. Metabolism & Thermal Homeostasis….. • Neutral thermal state: minimal O2 consumption when the difference of core & skin temp.is < 2-40C. • Hypothermia leads to- – catecholamines- O2 consumption – pulmonary & peripheral vasoconstriction – metabolic acidosis, resp.depression – depressed conscious state, delayed recovery – prolonged action of drugs,reduced surfactant – dysarrythmias & cardiac depression
- 16. Fluid & Electrolyte Balance • Initial fluid replacement must be low • Overhydration can cause pulmonary edema • Neonate requires Na: 2-3 meq/kg/day • K : 2-3meq/kg/day • Hypocalcemia is common in premature, sick & acidotic • Daily maintenance of Ca 500mg/kg/day • Hypoglycemia is common in prematures < 20mgs/dl
- 17. PAC & OPTIMISATION • Keep in mind – Neonatal problems – Surgical problems – Associated congenital problems • Maintain – Clear airway – O2 therapy to achieve PaO2 of 50-70mm.Hg – Stomach decompression – Keep the baby warm at 370 C. – I.V.line – Correct acidosis if pH is < 7.3 with soda bicarb. 1-2meq/kg, slow infusion over 10-30 mts.
- 18. PAC & OPTIMISATION….. – Ventilate if PaCO2 is > 50mm.Hg. – Correct dehydration ( crystalloids), • Insensible loss • GI losses • Others – Correct hypovolemia ( colloids) • Albumin, plasma, RBC, & whole blood if necessary. – Arterial line in critically ill patients.
- 19. MONITORING • Precordial stethoscope or esophageal steth. • ECG lead II • BP cuff, oscillometer, arterial cath • CVP – int.jugular, cubital vein • Temp., thermister probe – rectal,esophageal or nasopharyngeal
- 20. MONITORING….. • Ventilation – Airway pr.monitoring, – O2 analyser – Mass spectrography – Infra red capnograph • Blood gases- – SPO2, ETCO2, blood glucose & electrolytes
- 21. MONITORING….. • Blood loss – Small vol.suction traps, – Swab weighing, – Serial Hct estimation • Urine volume – Urinary catheter & collecting bag • Above all, trained anesthesiologists eyes , hands & ears are indispensible.
- 22. ANESTHESIA • Major decision is whether or not the neonate needs post-op ventilation & resuscitation. • If post-op ventilation is needed, anesthesia technique is of little importance, any tech. which maintains BP & oxygenation is acceptable. • If extubation is planned, anesthesia tech. is very crucial. • GA + Regional tech. with epidural Bupivacaine 0.25 %, 1 ml./kg with adrenaline is good.
- 23. ANESTHESIA…. • Regional block reduces doses of muscle relaxants, narcotics & recovery will be good. • Post-op pain relief can be planned • All new borns must be intubated unless it is a very minor procedure • Consider them always ‘full stomach’ • Rapid sequence induction- no need of priming with NDMR before DM. No fasciculations, no rise of pressure with DMR.
- 24. INDUCTION • It is to eliminate stress, • CVS stability, • To secure airway & ventilation, • To prevent aspiration. • Gastric pH at birth is 6.0; after 6 hrs. it is 2.5
- 25. INTUBATION • It can be awake, or anesthetised. • Indications for awake intubation: – Very sick patients – Anesthesiologist inexperienced in pediatric anesthesia – H/o apnoea or respiratory distress, – Full stomach.
- 26. INTUBATION….. • Complications of awake intubation: – Arterial hypertension, – IVH – Apnoea, – Obstruction to breathing, – Desaturation & bradycardia • Deep inhalational induction & 2% xylocaine spray followed by intubation • Intubation after paralysing with SUXA 2mg/kg (controversial) , or NMDR & cricoid pressure.
- 27. INTUBATION….. • Preoxygenation for 2 mts.is a must, uncuffed ET , 20-40 cm/H2O pressure, no pillow under the head & head extended. • MAINTENANCE: • Good oxygenation, prevention of stress due to pain by short acting narcotics, intermittent inhalational & muscle relaxants.
- 28. Maintenance… – Intra – op fluid therapy: • 0.2 % saline with 5% dextrose closely resembles the obligatory fluid of neonate • 4 ml/kg/hr. ( hyponatremia if given more) • Better to use 0.45 % saline c 5% Dx. • RL for 3rd space losses • More 5% Dx causes hyperglycemia which leads to IVH due to diuresis, cell dehydration & severe hyperosmolality. • 5% Dx should not exceed 15-20ml/kg • Serial estimation of glucose is necessary.
- 29. Maintenance… • 3rd space losses in NEC, Omphalocele & gastroschisis can exceed patients blood volume. • CDH , congenital heart patients may not tolerate larger vol. • Interstitial edema develops • Serial estimation of Hct , proteins , osmolality , electrolytes & urine output help in accurate replacement of fluids. • Neonate can tolerate 10% of blood loss • Transfusion reactions like coagulation defects, temp. changes, metabolic problems occur early in neonates
- 30. RECOVERY • Recovery is quick , • Extubation without good recovery causes laryngeal spasm, • Rx with IPPV , head extension , mandible thrust. • If desaturation occurs ( < 85% ) IV suxa & intubation. • Don’t wait for cyanosis & bradycardia! • Strong inspiratory efforts c obstruction causes pul. edema, • NMJ block must be reversed fully until active movements of all 4 limbs occur • Temp. must be > 35 0 C before reversal.
- 31. POST-OP PERIOD • Most vulnerable period , hypoxia , laryngospasm & cardiac arrest are common. • Respiratory depression: Due to – Apnoea • Prematurity , narcotics , anesthetics , incomplete reversal , hypothermia , concomitant antibiotics & hypermagnesemia –(PIH) apnoea is more common below 41 weeks of PCA upto 4th mth.
- 32. POST-OP PERIOD… Hypoxemia due to – Hypothermia , sepsis & acidosis. • Rx: FiO2 for 1st 24 hrs., monitor SaO2 • In conditions c reduced FRC like peritonitis, int.obstruction, massive transfusions, correction of omphalocele & gastroschisis- minimum of CPAP should be provided
- 33. POST-OP PERIOD… • Pre-op lung problems like RDS , pulmonary dysplasia needs active ventilation. • NMJ transmission impairment • Hypotension may be due to hypovolemia or residual inhalational agents • Metabolic complications: hypocalcemia, hypo & hyperglycemia.
- 34. Keep your eyes wide open …