Neonatal anaesthesia different from adult

1. Anaesthetic implication in
neonatal anaesthesia

2.  NEONATES :LESS THAN 28DAYS
 INFANTS : UPTO 1 YEAR
 TODDLERS : 1-3 YEARS

3. Children are not MINI
adults

4. • Children are different from adults in various
aspects
• Body weight
• Airway
• Drug behavior
• Fluid requirements
• Blood loss
• Thermo-regulation
• Respiratory system
• Cardio-vascular system
• Renal system etc.,
Children are different

5. NEONATES / INFANTS AIRWAY VS ADULT
AIRWAY
FEATURES NEONATES/INFANTS ADULT
NARES NARROW WIDE
TONGUE LARGE SMALLER
EPIGLOTTIS LARGE ,FLOPPY,Ώ
SHAPED
THINNER
POSITION OF LARYNX NEONATES C3
INFANTS C4-5
C5-6
LARYNX MORE ANTERIOR
AND CEPHALHEAD
LOWER
VOCAL CORDS ANTERIOR SLANTING NOT SO
SUBMUCOSAL TISSUE MORE – INCREASED
CHANCE OF EDEMA
LESS

8. FEATURE NEONATES /
INFANTS
ADULT
CARTILAGES SOFT,COLLAPSE
EASILY- REDUCE
CRICOID PRESSURE
HARDER AND
STABLE
SUBGLOTTIS FUNNEL SHAPED NO FUNNELING
ANGULATION OF
BRONCHI
MORE HORIZONTAL LESS
SUBGLOTTIS NARROWEST PART
TRACHEA LENGTH SHORT MORE
RIBS HORIZONTAL SLANTED
ALVEOLI LESSER (20-50
MILLION)
MORE(300 MILLION)

9. • Narrowest at
cricoid rather
than vocal cords
• Tube may be
small enough to
pass through
cords but not
cricoid

10. . The airway is funnel shaped & narrowest at level of
cricoid cartilage
– Epithelium loosely bound to underlying tissue
– Trauma to airway results in edema
– 1 mm of edema narrow baby’s airway by 60%
. Neonates – Obligatory nose breathers
– Narrow nasal passage easily blocked by
secretions
RESPIRATORY SYSTEM

11. •
• Neonates & infants have limited respiratory reserve
• FEWER AND SMALLER ALVEOLI,REDUCING LUNG
COMPLIANCE
• CARTILAGENOUS RIB CAGE MAKES THEIR CHEST WALL VERY
COMPLAINT
• SO CHEST WALL COLLAPSE DURING INSPIRATION AND
LOW RESIDUAL LUNG VOLUME AT EXPIRATION
• RESULTING DECREASE IN FRC LIMITS OXYGEN RESERVES DURING
PERIODS OF APNOEA.
• PREDISPOSE THEM TO ATELECTASIS AND HYPOXEMIA
RESPIRATORY SYSTEM

12. RESPIRATORY SYSTEM
 RESPIRATORY RATE IS INCREASED
 PRESENCE OF FEWER AND SMALLER AIRWAY – INCREASED
AIRWAY RESISTANCE
 WORK OF BREATHING INCREASED
 RESPIRATORY MUSCLES EASILY FATIGUE
 HYPOXIC AND HYPERCAPNIC VENTILATORY DRIVES ARE NOT
FULLY DEVELOPED

13. CARDIOVASCULAR
SYSTEM
. In neonates:
– Myocardium less contractile
– Limits the size of stroke volume
–Cardiac output therefore rate dependent
–Ventricles less compliant
–Vagal parasympathetic tone high = prone
for bradycardia
– Prophylactically atropine is given IV 0.01
mg/kg
– Diluted atropine ready

14. CARDIOVASCULAR SYSTEM
 HIGHER HEART RATE :100-170
 BP IS LOWER( 50-65mm Hg)
 : SYSTOLIC BP IS GOOD INDICATOR FOR BLOOD VOLUME
 THEY ARE LESS ABLE TO RESPOND TO HYPOVOLEMIA WITH
COMPENSATORY VASOCONSTRICTION
 HYPOVOLEMIA SIGNALED BY HYPOTENSION WITHOUT
TACHYCARDIA

15. TEMPERATURE REGULATION
 GREATER HEAT LOSS
 THIN SKIN
 LOW FAT CONTENT
 HIGH SURFACE AREA/ WEIGHT RATIO
 NO SHIVERING UNTIL 1 YEAR
 THERMOGENESIS BY BROWN FAT
 MORE PRONE TO IATROGENIC HYPO /HYPERTHERMIA
 ESPECIALLY PRETERM AND SICK BABIES

16.  OPTIMAL AMBIENT TEMPERATURE TO PREVENT HEAT LOSS
 PREMATURE INFANT : 34*c
 NEONATES :32 *C

17. Temperature
control
. Effect of hypothermia:
• Delayed awakening from
anaesthesia
– Causes respiratory depression
– Acidosis
– Decreased cardiac output
– Increases duration of action of drugs
– Decrease platelet function
– Increases risk of infection

18. Infant kidneys : Immature at birth:
.↓ GFR/ Renal blood flow
– Till 2 years hence high renal vascular resistance
.↓ Concentrating capacity
– Urine output is 1-2mls/kg/hour
.↓ Na reabsorption
– Tubular function is immature till 8 months, so infants are
unable to excrete a large sodium load. Dextrose with ½ or ¼
Normal saline used
.↓HCO3/H exchange
RENAL SYSTEM

19. . Dehydration:
– Poorly tolerated
– Premature infants ↑insensible losses = large surface
area relative to weight
– Higher proportion of ECF in children (40% BW as
compared to 20% in adult)
. Conclusion:
– Newborn kidneys has limited capacity to compensate
for Volume EXCESS or Volume DEPLETION
RENAL SYSTEM

20. • Immature liver function with decreased function of
hepatic enzymes
• Barbiturates & opioids have a longer duration of
action due to slower metabolism
HEPATIC SYSTEM

21. GLUCOSE
METABOLISM
• Hypoglycaemia is common in stressed neonate
glucose level should be monitored regularly
• Hypoglycemia <35mg /dl
• Glycogen stores are located in the liver &
myocardium

22. HAEMATOLOG
Y
. At birth 70-90% of haemoglobin = HbF
– < 3 months, levels ↓ 5% & HbA 95%
– Hb in newbown = 18-20g/dL , HCT ~ 0.6
– 3-6 months: 9-12 g/dl as the increase in circulating volume
increases more rapidly than bone marrow function
. Fetal Haemoglobin:
. less 2,3-DPG
. ODC shifted to right
. Tighter bond with Oxygen

23. HAEMATOLOGY
•Vit K dependant clotting factor (II, VII, IX, X) function are deficient in
first few months
•Transfusion recommended when 15% of the circulating volume has
been lost.

24. CENTRAL NERVOUS
SYSTEM
. Blood brain barrier(BBB) poorly formed
– Drugs (barbiturates, opioids, antibiotics, bilirubin cross
BBB = prolong & variable duration of action
. Cerebral vessels in preterm infant are thin walled &
fragile
– Prone to Intra-ventricular haemmorage
– Risk increased with hypoxia, hypercarbia, awake airway
manipulation, rapid bicarbonate administration

25.  SMALL BRAIN : LOWERS MAC BY 25%
 SPINAL CORD ENDS AT L3 :SPINAL ANESTHESIA GIVEN AT LOWER LEVEL
 THIN UNMYELINATED NEURONS : FASTER ONSET OF NEURAXIAL BLOCK

26. PHARMACOLOGICAL DIFFERENCES
 TOTAL BODY WATER CONTENT INCREASED (70-75%)
 LARGE VOLUME OF DISTRIBUTION FOR WATER SOLUBLE MEDICINES
 INCREASED DOSE/Kg
 IMMATURE HEPATIC METABOLIC FUNCTIONS
 DECREASED PROTEIN BINDING
 SMALLER MUSCLE MASS IN NEONATES :
 TERMINATION OF ACTION BY REDISTRIBUTION IS PROLONGED

27. Practical application in pediatric anesthesia

28. TO SUMMARISE

29. . HYPOXIA is the most common cause of pediatric
perioperative cardiac arrest.
– Infants turn blue fast. upper airway obstruction
during anesthesia (particularly at induction and
emergence)
Laryngospasm is common
. Infants and young children are not small adults.
What makes Pediatric Anesthesia
different?
Airway!! Airway!!! Airway!!!

30. PRE-OPERATIVE
. Evaluate: VISIT
– Medical conditions of the child
– The needs of planned surgical procedure
– Physiological makeup of patient & family
. Weight -drugs calculated according to weight
. Investigations - Hb: Large expected blood loss, premature infant,
systemic disorder, congenital heart disease
– Electrolytes: Renal or metabolic disease, IV Fluid, dehydration
. Discuss regarding post op pain management:
– Suppository medications Explain to parents
– Nerve blocks for pain relief

31. • Children get URTI at least 7-9 infections per year
• Mostly viral infection (rota virus)
• Increased incidence of peri-operative airway complications
(within 4 weeks)
• Anesthesiologist will decide to postpone for 2-3 weeks or take
up the child for anesthesia
• Based on severity of symptoms
• Urgency of surgery
• Presence of other co-existing diseases.
URTI & ANESTHESIA

32. • Awareness of risk factors will guide the anesthetist in deciding
whether to proceed, and to tailor the anesthetic to optimize the
child’s condition.
• Minimize secretions
• Limit stimulation of airway
• LMA preferred over ETT
• Anti cholinergic to dry secretions
• Bronchodilators – Salbutomol
• Extubation under deeper planes of anesthesia
• Informed consent, good clinical judgment and experience are
crucial factors in the decision-making process
URTI & ANESTHESIA

33. PREMEDICATIONS
PRE-OPERATIVE FASTING
Solids 6 Hours
Formula milk 4-6 hours
Breast milk 3-4 hours
Clear fluids 2 hours
Sedations Analgesics
Midazolam Paracetamol
Chloral hydrate Codeine
Ketamine Fentanyl
PRE-OPERATIVE

34. BASIC SET UP
AIRWAY ACCESS
EQUIPMENT
SUCTION
ANESTHESIA
WORKSTATION
PEDIATRIC CIRCUIT
DRUGS IN PROPER
DILUTION
MONITORS
ROUTINE +
TEMPERATURE
TABLE
WARMER
IV ACCESS

38. Tube Size:
ID (mm) = Age (years) / 3 + 3.5 (Age < 6 years)
ID (mm) = Age (years) / 4 + 4.5 (Age > 6 years)
Length :
For oral = Age/2 + 12 cm
For nasal = Age/2 + 15 cm
The ideal position for the tip of the tube is mid-trachea
Auscultation on both sides to make sure both lungs are ventilated
Uncuffed tubes used till 8 years to prevent post extubation
edema
Leak around the ET tube is deliberate
One size above &below is kept as standby
Endotracheal tubes

39. Age Weight in kgs Internal
diameter
External
diameter
Premature
infants
< than 2.5 2.5 12
Neonates 2.5 – 5 3 14
6 months 5 - 8 3.5 16
1 year 8 - 10 4 18
2-3 years 10 15 4.5 20
3-5 years 15 - 20 5 22
Endotracheal tubes
The rule of thumb is tube should be as large as the small finger of
child

40. Laryngoscope
MILLER LARYNGOSCOPE MACINTOSH LARYNGOSCOPE

41. Breathing Circuits
• For children less than 20 kgs = Jackson Ree’s
modification of Ayre’s T piece is used
•Minimal dead space
•Minimal resistance
•Light weight
•Fresh gas flow = 3 times the
minute volume

42. Breathing circuit for older children (circle system)

43. Induction of anesthesia

44. INDUCTION:
1.IV Induction
2.Gas
induction
High cardiac
output to vessels
rich organ (eg:
Brain)
Reduced tissue
blood
solubility
EFFECT OF FAST INDUCTION
Greater alveolar
to FRC ratio

45. Ideal maneuvre is
combination of jaw thrust
& chin lift, keeping the
mouth open

47. • Administration: Volumetric chambers/Infusion Pump
• Warm fluid/blood/blood product
• Perioperative fluid management is divided into three phases
–Fluid Deficit
–Maintenance
–Replacement of losses (3rd
space loss)
FLUID MANAGMENT

48. • Calculated and replaced based on duration of fasting, presence
of associated conditions like
•Fever,
•Vomiting, diahorrea
•Surgical problem likely to affect fluid status (bowel
obstruction, peritonitis)
For eg; in an infant 5kg weight, not received oral/ iv fluid for 4
hrs fasting :
A deficit of 80ml ( ie; 5 x 4ml/kg/hr X 4hr)
FLUID DEFECIT MANAGMENT

49. MAINTAINANCE FLUID
MANAGMENT

50. 1
Type of surgery
Intra-abdominal surgery
ml/kg/hour
6-10 mls/kg/hr
2 Intra-thoracic surgery 4-7 mls/kg/hr
3 Neurosurgery 1-2 mls/kg/hr
4 Eye surgery --------
5 Superficial surgery --------
3rd SPACE FLUID MANAGMENT

51. BLOOD MANAGMENT
ESTIMATED BLOOD VOLUME (EBV)
Premature Neonate 90-100mls/kg
Term neonate 80-90mls/kg
3mo – 1yr 75-80mls/kg
3-6 yrs 70-75mls/kg
>6 yrs 65-70 mls/kg
Allowable blood loss
ABL = WEIGHT x EBV X (H₀ - H₁)/H。
H₀ = Starting Hematocrit
H₁ = Lowest acceptable hematocrit

52. • Intraoperative blood loss replacement is done with
Ringer’s lactate 3 ml per 1ml of blood loss
• 1 ml of colloid solution for each ml of blood loss
• 0.5 ml of red cell concentrates for each ml of blood loss
Allowable blood loss
ABL = WEIGHT x EBV X (H₀ - H₁)/H。
H₀ = Starting Hematocrit
H₁ = Lowest acceptable hematocrit
BLOOD MANAGMENT

53. THANK YOU