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Anesthesia During the First Year of Life Hany El-Zahaby, MD Dept. of Anesthesia, Ain Shams University “Safe and effective anesthesia for neonates & infants undergoing surgery is one of the most challenging tasks presented to anesthesiologist.” Knowledge Manual skills Continuous practice + Adequate monitoring ↓ Outcome Anesthetic Considerations for surgeries during the first year of life Age-specific considerations Case-specific considerations Age-specific considerations Airway differences –Infant Vs Adult Big head, small body Tongue/Epiglottis relatively larger Glottis more superior, at level of C3 (vs C4 or 5) Cricoid ring narrower than vocal cord aperture Age-specific considerations Fast desaturation • Low FRC, high closing volume, highly compliant airways► atelectasis • High oxygen consumption + can’t do forced inspiration ► increase R.R. ►high work of breathing • Diaphragmatic breathing► easily fatigue (less type I muscle fibers)►fast desaturation Age-specific considerations • Cardiac output is rate dependent (can’t increase stroke volume) • Immature baroreceptor reflex and limited ability to compensate for hypotension by increasing heart rate. They are more susceptible, therefore, to the cardiac depressant effects of volatile anesthetics (parasympathetic predominance) • Immature hepatic function (drug dosing intervals &maintenance) • Immature renal function (poor toleration of fluid restriction/overload) Age-specific considerations • High volume of distribution of drugs • Temperature control (easily loose heat under GA) due to high surface area to body weight ratio, no shivering • Competent nociceptive system (nonanalgesic practice is no longer accepted) Premedication Atropine (10-20µ/kg IV, minimum 100µ) to counteract parasympathetic reflexes. Pain (increments of morphine 10-20µ/kg IV up to 100µ/kg) Monitoring FiO2, ECG, NIBP, ETCO2, Pulse oximetry, Temperature Direct BP (accurate, intravascular volume status e.g. undulations with ventilation and reduced upstroke of the BP curve in case of hypovolemia) CVP (vasoactive drugs) Urine output (1 ml/kg/h) How Long Pre-oxygenation? 60 seconds 6L/min (gives 80-90 seconds before desaturation) (Morrison JE et al: Pediatric Anaesthesia1998:8;293) Inhalation VS Intravenous Induction? IV access + hemodynamically stable→ STP 4-8mg/kg (prolonged emergence & postoperative apnea)- Propofol 3-3.5mg/kg IV access + hemodynamically unstable → Ketamine 1.5-3mg/kg Difficult IV access or compromised airway → Sevoflurane or halothane Combined technique → (opioid + nondepolarizing MR + inhalation agent) LMA VS ETT? LMA: less than 30-45 min Size 1 ( 50% misplacement, NGT, small dose of MR, large dead space & hypercapnea, helpful for ex-premis with BPD) ETT: longer surgeries No awake intubation (very stressful/painful stimulus with suboptimal conditions) Relaxation? Succinyl choline (RSI) (higher doses than adults), large ECF volume Nondepolarizing MR (similar doses as adults), sensitivity offset by large ECF Deep inhalation anesthesia, disadvantages? Technique? •Oral Vs nasal? (lateral/prone/limited head access) •Straight blade- go deeper then withdraw •Level: term neonate (9cm oral/11cm nasal), 1 year 11-12cm •Leak pressure? 20-25cmH2O, affected by head position& MR •50% decrease in flow from size 3.5 to 3 •Non-cuffed/cuffed: 8y (upper abdominal & thoracic surgery, poor lung compliance) •After intubation → VCM (40cmH2O/15 sec) or TRIM (30cmH2O/10 sec) Spontaneous Vs controlled? -Spontaneous: more than 6 mos, less than 30 min Pressure Vs volume control? -Pressure control: First few days, premature, respiratory distress or lung pathology -Volume control: surgical manipulations interfere with ventilation -Peep 3-5 is routine “ Whatever the technique, an expired tidal volume & PIP should be tailored to the desired levels” Maintenance: • Halothane/sevoflurane/isoflurane all depress baroreceptor reflex • Halothane depress the myocardium more • Halothane decrease the heart rate more (Hypotension is treated by atropine & lowering halothane) • Sevo/Isoflurane decrease PVR more (treated by 5-10ml/kg fluid bolus) • Nitrous oxide 60% decreases MAC of halothane, isoflurane & sevoflurane by 60%, 40% & 25% respectively • Narcotics: -Fentanyl 1-2µ/kg if regional block was done -Fentanyl based anesthesia for prolonged major surgery with postoperative ventilation “The use of light general volatile anesthetic with a central or peripheral nerve block has proved to be of great benefit in neonatal surgery” Bosenberg AT et al, Pediatr Surg Int, 1992:7, 289 Larsson BA et al, Anesth Analg 1997:84, 501 Intraoperative Volume Replacement Hypovolemia with blood loss accounts for 12% of causes of cardiac arrest in OR with almost half of it due to under estimation of blood loss.* *Anesthesia-Related Cardiac Arrest in Children: Update from the Pediatric Perioperative Cardiac Arrest Registry Bananker et al, Anesthesia & Analgesia, August 2007 Assessment of dehydration Wt loss% Behavior Thirst Mucous memb. Tears Anterior fontanel Skin turgor Urine output Mild (50ml/kg) Moderate (100ml/kg) Severe (150ml/kg) 5 Normal Slight Normal Normal Flat Normal <2ml/kg/hr 10 Irritable Moderate Dry + + + <1ml/kg/hr 15 ++irrit/lethargic Intense Parched Absent Sunken Increased <0.5ml/kg/hr Fluid & blood loss Type of fluid? Dextrose? BSS? Weighing swabs before it dries. Intraoperative blood loss should be replaced with balanced salt solution (1:3), or colloid (1:1) Estimated maximum allowable blood loss = EBV x (Hctstarting – Hctacceptable) Hctstarting Prevention of Heat Loss Radiation Evaporation Convection Conduction Prevention of Heat Loss Room temp.: 76-78 F Avoid unnecessary exposure & cover cotton wraps as much as possible HME (active or passive) IVF: warm Active warming mattress Cover exposed viscera with warm wet towels Incubator: keep plugged Emergence Reversal of MR after spontaneous movement even with adequate time after last dose Extubation: Regular spontaneous breathing Vigorous movements of all limbs Gagging Eye opening or pronounced grimacing Stable hemodynamics & good oxygen saturation Absence of significant hypothermia Case-specific considerations Hydrocephalus • Burr hole over a dural venous sinus • Bowel injury (re-do) • Perforation of chest wall/neck vessels/occipital bone • Hemodynamic instability/arrhythmias (acute decompression) Craniosynostosis Premature fusion of cranial suture → lack of growth perpendicularly & compensated overgrowth in normal areas affecting mental development &vision due to intracranial hypertension Difficult airway if syndrome Positioning (Supine → RAE or reinforced, Prone → nasal T. sutured to nasal septum with 4-0 nylon) Blood loss (Donation, coag. Profile, 2 Ivs, A line) Prolonged surgery & hypothermia Venous air embolism Raised ICP Encephalocele Neural tube defect with variable neural dysfunction + Hydrocephalus + Arnold Chiari type II Wet/soft covering Avoid pressure Antibiotics Prone (nasal intubation) Blood loss Hypothermia Latex – free procedure Document spontaneous breathing postoperatively Myelomeningocele Neural tube defect with variable neural dysfunction + Hydrocephalus + Arnold Chiari type II Wet covering Avoid pressure Antibiotics Prone (nasal intubation) Blood loss Hypothermia Latex – free procedure Neonatal Conditions Requiring Surgeries Airway Obstruction Inspiratory stridor with jugular &intercostal/subcostal retractions -Bilateral choanal atresia -Laryngomalacia -Supraglottic papillomatosis -Subglottic hemangioma -Cystic hygroma -The Pierre Robin Syndrome Choanal atresia CHARGE Syndrome (Coloboma-Heart –Atresia-RetardedGenital-Ear) OGT Laryngomalacia Supraglottic Papillomatosis Subglottic Hemangioma Cystic Hygroma ↑ Cystic Hygroma( Recurrence) The Pierre Robin Syndrome Typical Anesthestic Management of a Neonate Presenting with Stridor: ABG, chest x-ray IV access, atropine, preoxygenation Inhalation induction (deep) CPAP Smaller ETT or inhaled gases through side port of bronchoscope Hydrocortisone 1-2 mg/kg ICU or high dependency area for 12-24 h Neonatal Conditions Requiring Surgeries Airway Obstruction Cleft Lip/Palate Echocardiography Blood? Atropine 10µ/kg Difficult intubation RAE tubes Throat pack Infra-orbital N. block Extubation Thoracic Surgeries Esophageal Atresia/TEF 1cm Thoracic Surgeries Esophageal Atresia/TEF 1:3000 M:F 25:3 First fed chocking, cyanosis CHD, VACTERL association 13% Thoracic Surgeries Esophageal Atresia/TEF Management: Head up Continuous low suction on blind pouch Echocardiography Antibiotics Vit K Next day surgery Thoracic Surgeries Congenital Lobar Emphysema Unilateral disease due to bronchomalacia, vascular anomaly, bronchial obstruction) Present with respiratory distress & cyanosis with mediastinal shift Coexisting CHD in 35% Anesthesia: Spontaneous ventilation should be maintained with 100% oxygen + Ketamine + Inotropes Expand lungs before closure Intercostal block Extubate (spontaneous breathing) Thoracic Surgeries Patent Ductus Arteriosus A disease of Prematurity with Lt to Rt shunt resulting in: 1- Pulmonary over-circulation, high load on lt side, high output cardiac failure 2- In severe cases, reversal of diastolic aortic blood flow in the descending aorta resulting in splanchnic hypoperfusion and NEC Treatment: Fluid restriction/diuretics (hypovolemia + hypokalemia) Endomethacin (transient renal dysfunction, platelet dysfunction) Ligation Thoracic Surgeries Patent Ductus Arteriosus Preoperative: Echo (ht failure, hypovolemia) Head ultrasound (intracranial pathology) Routine labs (hypokalemia) 1 unit PRBCs, 1 unit plasma Last 24h urine output Anesthesia: Atropine Low dose Sevoflurane + opioids + relaxant If not intubated, nasal intubation is preferred Tolerate desaturation for progress of surgery (limit is bradycardia) Treat hypotension with plasma expander + inotrope Intercostal block by surgeon No immediate extubation Abdominal Surgeries Congenital Diaphragmatic Hernia 1:5000 M:F 1:1.8 Resp. distress Scaphoid abdomen Shifted heart sounds Bil. Pulmonary hypoplasia Hypoxia, hypercarbia Pulmonary HTN, shunting Abdominal Surgeries Congenital Diaphragmatic Hernia Management: Gentle ventilation: Limiting PIP, Oscillator ( preductal SpO2> 90%) Delayed repair (>100h) until medical stabilization Reversal of duct shunting Oxygenation Index < 40 PaCO2 < 40 Stable hemodynamics Poor Predictors: Overall survival 63% Polyhydramnios Immediate need for ventilation Immature RBCs (intrauterine ↓COP) Abdominal Surgeries Congenital Diaphragmatic Hernia Anesthesia: Working NGT 2 pulse oximeters Atropine Inhalation/ slow opioid Treat hypotension with fluids/inotropes Treat pneumothorax on the other side immediately Treat the increased Rt to Lt shunt with fentanyl, higher FiO2, hyperventilation, correction of acidosis, Nitric oxide Omphlocele 1:5000 Hernial sac CHD 30-40% Blood loss Hypothermia High abdominal pressure RSI Insensible water loss 10ml/kg/h UOP > 30 mmHg (Ventilation ) Gastroschisis Midline above umbilicus Other abnormalities are rare No hernial sac Coverage Heating I.V fluids Abdominal pressure Gastrointestinal Obstruction Pyloric Stenosis Forceful projectile vomiting 4-6 weeks of age, palpable olive-like mass in epigastrium Loss of hydrogen, chloride & potassium Dehydration, electrolyte imbalance & acid-base disorder Hypochloremic, hypokalemic alkalosis Rehydration (do not accept base excess > +2) Functioning NGT RSI No narcotics, local wound infiltration Gastrointestinal Obstruction & Malrotation Rehydration Functioning NGT Cross match PRBCs, FFP RSI (ketamine) If hypotension, give boluses of FFP, albumin 5% or PRBCs + dopamine Untwisting malrotated gut releases vasoactive substances & lactic acid causing hypotension Inguinal Hernial Repair Hydrocele Undescended Testis Wiener ES et al: Hernia survey of the Section on Surgery of the American Academy of Pediatrics. J Pediatr Surg 1996:31, 1166 70% GA (face mask or LMA) + Caudal epidural or spinal An. 15% Spinal anesthesia alone 11% Caudal anesthesia alone Necrotizing Enterocolitis It’s a disease of prematurity due to intestinal ischemia with secondary bacterial overgrowth → abdominal distention, increasing gastric aspirate, gastrointestinal bleeding & generalized sepsis. Antibiotics TPN Volume replacement (Albumin 5%, FFP, PRBCs) Functioning NGT Check coagulation profile Ecchocardiography Chest x-ray for BPD Inotropes (do not interrupt) Maintain UOP (volume, Lasix 0.5 mg/kg) Bladder Extrophy Wet covering Antibiotics Blood loss Hypothermia Latex – free procedure Postoperative immobility Surgery on the NICU Graduate First group: Uneventful prematurity → straight forward anesthesia Second group: Ventilatory support-sepsis-PDA-IVH-NEC-multiple medications-BPD/chronic lung disease of the newborn-extubated with great difficulty. The main concern is postoperative apnea until 6-12 Mon. Goals: Avoid intubation/ventilation Avoid postoperative apnea Common surgeries: 1- Laser/cryosurgery for ROP → Face mask/LMA, avoid IV drugs in general 2- Inguinal hernia repair → awake caudal without any drug supplementation or combined with inhalation anesthesia via LMA 3- Circumcision → face mask with penile block