A short presentation covering most important anatomical differences along with physiological difference of pediatric population from adult. Also covers important aspects of anaesthesia consideration in pediatric patients.
I specifically made this presentation by using morgan and miller books.
2. CONTENTS
Anatomical Changes In Peads Patients
Physiological Changes In Of Peads Patient
Thermoregulation
Age-related Changes In Vital Signs
Approximate MAC 1 Values For Pediatric Patients
Fluid Management In Peads Patient
Fasting Recommendations
Blood In Different Age Groups
How To Calculate Appropriate Ett Size In Peads Pateint
Case study
5. Airway
Head size is greater in relation to the body
Angle of the jaws greater
Dimension of the upper airway are effectively narrowed by large
tongue
Epiglottis in infant is longer, stiffer and U shaped
Larynx is higher: C3/4 (C5/6 in adults)
Larynx lies more anteriorly
Cricoid ring is the narrowest part
Trachea is short 4-5cm and narrow
7. Cardiopulmonary System
In the CVS system the capacity of the heart to increase
cardiac output by increasing stroke volume is limited.
Cardiac output increases predominantly by increasing
heart rate
The limbs are smaller in relation to the body
This means that there is less blood volume to mobilize
from the periphery in response to hypovolemia.
Infants have less reserves.
8. Surface area to body ratio
A large surface area to body ratio is associated with increased heat loss.
All infants are at a greater risk than adults or larger children of hypothermia
The need to maintain body temperature via heat production results in a higher
metabolic rate and higher tissue oxygen demand. Desaturation occurs quicker
The higher BMR is associated with higher resting heart rate and respiratory rate.
9.
10. Thermoregulation
Children are very prone for hypothermia because of their decreased ability to
produce and conserve heat and increased heat loss due to large body surface area.
The only mechanism for heat production is metabolism of brown fat which is
special fat present in posterior neck, interscapular and vertebral areas and around
kidneys and adrenal glands.
To prevent hypothermia the operation theater temperature should be maintained at
28°C (usually maintained at 21°c for adu lts).
13. Fluid Management In Peads Patient
Maintenance:
requirements for pediatric patients can be determined by the “4:2:1 rule”:
4 mL/kg/h for the first 10 kg of weight,
2 mL/kg/h for the second 10 kg,
1 mL/kg/h for each remaining kilogram.
A solution such as D 5 ½ NS with 20 mEq/L of potassium chloride provides
adequate dextrose and electrolytes at these maintenance infusion rates.
D 5 and N/S may be a better choice in neonates because of their limited ability to
handle sodium loads. Children up to the age of 8 years require 6 mg/kg/min of
glucose to maintain euglycemia (40–125 mg/dL)
prematureneonates require 6–8 mg/kg/min.
14. Fluid Management In Peads Patient
Deficits
In addition to a maintenance infusion, any preoperative fluid deficits must be replaced. For
example:
5-kg infant has not received oral or intravenous fluids for 4 h prior to surgery, a deficit of 80 mL has
accrued
(5 kg × 4 mL/kg/h × 4 h). In contrast to adults, infants
respond to dehydration with decreased blood pressure and without increased heart rate.
Preoperative fluid deficits are often administered with hourly maintenance requirements in
aliquots of 50% in the first hour and 25% in the second and third hours. In
the example above, a total of 60 mL would be given
in the first hour (80/2 + 20) and 40 mL in the second
and third hours (80/4 + 20). Bolus administration of dextrose-containing solutions is avoided to
prevent hyperglycemia.
16. Blood In Different Age Groups
Blood volume of premature neonates (100 mL/kg)
full-term neonates (85–90mL/kg)
infants (80 mL/kg) is proportionately larger than that of adults (65–75 mL/kg).
An initial hematocrit of 55% in the healthy full-term neonate gradually falls to as
low as 30% in the 3-month-old infant before rising to 35% by 6 months.
Hemoglobin (Hb) type is also changing during this period: from a 75%
concentration of HbF (greater oxygen affinity, reduced Pa o 2 , poor tissue
unloading) at birth to almost 100% HbA (reduced oxygen affi nity, high Pa o 2 ,
good tissue unloading) by 6 months.
17. How To Calculate Appropriate ETT Size
In Peads Patient
12 + Age/2 = Length of tube (in cm)
4 + Age/4 = Tube diameter (in mm)
For example, a 4-year-old child would be predicted to require a 5-mm tube. This
formula provides only a rough guideline, however.
Exceptions include:
premature neonates (2.5–3 mm tube)
full-term neonates (3–3.5 mm tube).
newborn takes a 2.5- or 3-mm tube.
5-year-old takes a 5-mm tube. It
20. Diaphragmatic Hernia
Diaphragmatic Hernia:
It results from incomplete closure of diaphragm
leading to herniation of abdominal contents in thorax resulting in:
pulmonary hypoplasia,
pulmonary hypertension,
hypoplasia of left ventricle,
Prognosis is very poor.
21. Anesthetic Management
After pre oxygenation awake intubation is done.
Bag and mask ventilation is contraindicated (as it will increase the distension of
bowels leading to more compression of lung).
Positive pressure ventilation should be done with airway pressure< 20 cm H20
otherwise
pneumothorax can occur in hypoplastic lung.
If available then ventilate with high frequency oscillatory ventilation.
Anesthesia is maintained on oxygen and low dose volatile anesthetics or opioids
like fentanyl.
Nitrous oxide is contraindicated as it can diffuse into gut loop causing their
distension and further compression of the lung.
Postoperative elective ventilation is often required.
23. Tracheosophageal Fistula
Anesthetic Management
Rule out associated abnormalities like atrial septa defect (ASD), ventricular septal
Defect (VSD), tetralogy of Falot, coarctation of aona.
Nurse the baby in propped up position to
minimize gastric regurgitation.
Aspirate the upper blind pouch of esophagus to remove secretion from it.
Ventilation with bag and mask is contraindicated
as air can reach stomach through
fistula causing gastric distension and aspiration.
Intubation can be awake or after intravenous anesthetic.
The position of tube is most important; it should be below the fistula but above the
carina.
These patients are very vulnerable for hypoxia as there occur significant V I Q
mismatchin lateral position.
24. Pyloric Stenosis (Intestinal
Obstruction)
Due to repeated vomiting the patients with pyloric stenosis are
dehydrated with hypokalemic, hypochloremic alkalosis
therefore, metabolic, fluid and electrolyte correction must be done before
taking them patient for surgery.
Either awake intubation or rapid sequence
intubation (crash intubation with Sellick's maneuver) is performed.
Ventilation with bag and mask is contraindicated
(can cause aspiration).