Anesthesia During the First Year of Life Hany El-Zahaby, MD Dept. of Anesthesia, Ain Shams...
-
Upload
melanie-adkins -
Category
Documents
-
view
222 -
download
4
Transcript of Anesthesia During the First Year of Life Hany El-Zahaby, MD Dept. of Anesthesia, Ain Shams...
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
Age-specific considerations Airway differences –Infant Vs Adult
Big head, small bodyTongue/Epiglottis relatively largerGlottis 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)
• 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)
Age-specific considerations
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
Mild
(50ml/kg)
Moderate
(100ml/kg)
Severe
(150ml/kg)
Wt loss%
Behavior
Thirst
Mucous memb.
Tears
Anterior fontanel
Skin turgor
Urine output
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
Conduction
Convection
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
Wet/soft covering
Avoid pressure
Antibiotics
Prone (nasal intubation)
Blood loss
Hypothermia
Latex – free procedure
Document spontaneous breathing postoperatively
Neural tube defect with variable neural dysfunction + Hydrocephalus + Arnold Chiari type II
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 SurgeriesAirway Obstruction
Inspiratory stridor with jugular &intercostal/subcostal retractions
-Bilateral choanal atresia
-Laryngomalacia
-Supraglottic papillomatosis
-Subglottic hemangioma
-Cystic hygroma
-The Pierre Robin Syndrome
Choanal atresia
OGTCHARGE Syndrome(Coloboma-Heart –Atresia-Retarded-Genital-Ear)
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 SurgeriesAirway ObstructionCleft Lip/Palate
Echocardiography
Blood?
Atropine 10µ/kg
Difficult intubation
RAE tubes
Throat pack
Infra-orbital N. block
Extubation
Thoracic SurgeriesEsophageal Atresia/TEF
1cm
Thoracic SurgeriesEsophageal Atresia/TEF
1:3000M:F 25:3First fed chocking, cyanosisCHD, VACTERL association 13%
Thoracic SurgeriesEsophageal Atresia/TEF
Management:
Head up
Continuous low suction on blind pouch
Echocardiography
Antibiotics
Vit K
Next day surgery
Thoracic SurgeriesCongenital 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 + InotropesExpand lungs before closureIntercostal blockExtubate (spontaneous breathing)
Thoracic SurgeriesPatent 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 SurgeriesPatent Ductus Arteriosus
Preoperative: Echo (ht failure, hypovolemia)Head ultrasound (intracranial pathology)Routine labs (hypokalemia)1 unit PRBCs, 1 unit plasmaLast 24h urine output
Anesthesia:AtropineLow dose Sevoflurane + opioids + relaxantIf not intubated, nasal intubation is preferredTolerate desaturation for progress of surgery (limit is bradycardia)Treat hypotension with plasma expander + inotropeIntercostal block by surgeonNo immediate extubation
Abdominal Surgeries Congenital Diaphragmatic Hernia
1:5000M:F1:1.8
Resp. distressScaphoid abdomenShifted heart sounds
Bil. Pulmonary hypoplasiaHypoxia, hypercarbiaPulmonary 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
1:5000Hernial sac
CHD 30-40%Blood loss
HypothermiaHigh abdominal pressure
RSIInsensible water loss 10ml/kg/h
UOP
> 30 mmHg (Ventilation )
GastroschisisMidline above umbilicusMidline above umbilicusOther abnormalities are rareOther abnormalities are rareNo hernial sacNo hernial sacCoverage Coverage Heating Heating I.V fluidsI.V fluidsAbdominal pressureAbdominal pressure
Gastrointestinal ObstructionPyloric 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 RepairHydroceleUndescended 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