Transcript Neonatal Anesthesia

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