Determining the need for ventilatory support Flashcards
What kind of intervention is mechanical ventilation?
Supportive
When should ventilator support be initiated?
Before the patient’s condition becomes compromised by hemodynamic instability
When should a patient be placed on acute ventilatory failure?
PaCO2 greater than 50 mmHg, pH less than 7.30
What classifies a patient as acute oxygenation failure (hypoxemia)?
PaO2 less than 60mmHg
What must a patient be demonstrating in terms of respiratory rate in order to qualify for ventilator support?
greater than 35 breaths/min and increased work of breathing
What is the vital capacity for a patient that is being considered for ventilatory support?
less than 10-15 mL/kg (normal is 65-75)
What is normal vital capacity for a patient without respiratory distress?
65-70 mL/kg
What maximum inspiratory pressure for a patient being considered for ventilatory support?
less than -25cm to 0 cm H2O (normal: -100 to -50 cm H2O)
What is the normal maximum inspiratory pressure for a patient not experiencing respiratory distress?
-100 to -50 cm H2O
What are the 4 categories of pulmonary mechanics that are looked at when considering ventilatory support?
respiratory rate (f). vital capacity (VC), maximum inspiratory pressure, chest retractions Assymetrical chest motions
What can acute respiratory failure be indicative of?
failure of ventilation, failure of oxygenation, or a combination of both
What is the most common indicator for ventilator support?
acute ventilatory failure
What is acute ventilatory failure?
the inability of the lungs to maintain adequate alveolar ventilation
What would conditions such as asthma, pneumonia, COPD, and atelectasis cause?
a low V/Q ratio which may lead to hypoxemic respiratory failure
What is a low V/Q ratio associated with?
shunting
What is shunting?
the state in which pulmonary capillary perfusion is normal but alveolar ventilation is lacking
What does vital capacity refer to?
the maximum amount of air that is expired after a maximal inspiration, indicating a person’s greatest breathing capacity
What does negative inspiratory force reflect?
the strength of the respiratory muscles
What may cause a low NIF level?
A sustained respiratory rate above 35
What are changes in older adults that put them at risk for respiratory failure?
include decreased chest wall compliance, which increases the work of breathing; decreased oxygenation because of structural lung changes; and decreased lung volume and strength, which reduce cough effectiveness and increase the risk for infection
The term acute ventilatory failure refers to the inability of the lungs to do what?
Maintain adequate alveolar ventilation
Acute respiratory acidosis is defined clinically as:
PaCO2 greater than 50 mmHg and pH less than 7.30
A low V/Q exists when what occurs?
Perfusion is in excess of ventilation
