219. Apparatus and Breathing Circuits Flashcards
What is the impact of breathing circuits on homeostasis in neonates?
Breathing circuits impact homeostasis in relation to thermal regulation, humidity, and ventilation via circuit dead space.
Infants are especially vulnerable to hypothermia due to their large ratio of body surface area to weight.
Why are heated, humidified breathing circuits preferred for infants?
They reduce heat loss and airway desiccation from evaporation.
Cold, dry air increases airway reactivity, creating obstructive ventilation patterns.
What is dead space in the context of breathing circuits?
Dead space is the volume of lung over which gas exchange (ventilation) does not occur.
Apparatus dead space may be significant for children aged 0-36 months.
What is the major determinant of airflow resistance in pediatric endotracheal tubes?
The radius of the tube is the major determinant of airflow resistance.
According to the Hagen-Poiseuille equation, a slight increase in radius can significantly reduce resistance.
What are the advantages of the circle system for pediatric patients?
The advantages include efficient gas exchange and reduced fresh gas flow requirements, but smaller diameter and more rigid circuits are used.
Accuracy of tidal volume monitoring is dependent on circuit compliance.
What is the safety rationale for using pressure control ventilation (PCV) in pediatrics?
PCV allows for safe initiation of mechanical ventilation without delivering tidal volumes from previous adult patients.
This prevents barotrauma or volutrauma in pediatric patients.
What is the efficiency of Mapleson D, E, and F circuits during spontaneous ventilation?
They require fresh gas flow of at least 1.5 to 2 times minute ventilation and do not conserve heat or humidity.
Jackson-Rees circuits are preferred due to lower resistances and better outcomes.
How does the Jackson-Rees circuit compare to the pediatric circle system?
Inspiratory and expiratory resistances, and arterial carbon dioxide tension in infants ventilated with the Jackson-Rees circuit are significantly lower.
This is why they are prevalent in pediatric anesthesia.
What is the function of an infant t-piece resuscitator (ITPR)?
ITPR provides tidal volume to the patient by building positive pressure in the circuit while allowing for exhalation when released.
It has limitations, including inadvertent positive end-expiratory pressure.
What are the components of a blender used for infant ventilation?
Oxygen and air e-cylinders, flowmeters, and a rotary knob to adjust FiO2.
Blenders help achieve low FiO2 while allowing for small amounts of supplemental oxygen.
What is a common anesthetic consideration for children requiring respiratory support during transport?
Using Jackson-Rees or ITPR with a blender to adjust FiO2.
This is crucial during the transfer from ICU to the operating room.
What influences the speed of inhalation induction in pediatric patients?
Inspired gas concentration (Fi), circuit volume, fresh gas flow (FGF), and circuit absorption.
Circle system circuit absorption can be reduced by leaving the circuit compressed.
What are the opposing priorities during the emergence of pediatric patients in the PACU?
Parental presence and safe transfer to PACU free of breathing complications.
Deep extubation is often used to mitigate risks such as laryngospasm.
