CPAP & PEEP

Question 1

indications for CPAP

Answer 1

Cardiogenic pulmonary oedema with moderate to severe respiratory distress, or

Asthma, COPD, or undifferentiated respiratory problem with severe respiratory distress that is not improving with treatment, or

An SpO2 of less than 92% due to a respiratory problem despite treatment (less than 88% if COPD or known chronic hypoxia).

Question 2

contraindications of CPAP

Answer 2

Active vomiting, or
Ineffective breathing.

Question 3

cautions of CPAP

Answer 3

An altered level of consciousness, or
Signs of shock, or
Clinical suspicion of pneumothorax.

Question 4

flow rates of CPAP

Answer 4

Commence at 5 cmH2O.

Increase to 10 cmH2O if it is being tolerated.

Consider increasing to 15 cmH2O if the patient is not improving.

Question 5

to ensure adequate seal of CPAP, before applying ensure….

Answer 5

The correct mask size is selected, and
Consideration of the contour of the face (especially the bridge of the nose and cheeks) and adjust the mask positioning as required, and
Dentures (if present) are kept in situ.

Question 6

The reduction in cardiac output may be significant in patients with…

Answer 6

A clinical condition reducing right ventricular filling, such as hypovolaemia.

A clinical condition increasing right ventricular afterload, such as pulmonary embolism.

these patients may benefit from fluids to expand IV volume

Question 7

in simple terms, outline the blood flow of the heart

Answer 7

1. blood returns to the heart on the R side
2. pushed through the lungs where gas exchange occurs
3. Oxygenated blood returns to the LS of the heart where it is then distributed to the body via the aorta

Question 8

outline the key pathologies that occur when CPAP is applied

Answer 8

• maintains positive end expiration pressure
• prevents collapse of the lung during expiration
• improve V/Q matching improving oxygenation

Question 9

explain the patho of how fluid gets into the lungs in a patient with cariogenic pulmonary oedema

Answer 9

• L side of heart not functional, fluid backs up into the lungs due to pulmonary HTN + L side ineffective pump
• results in fluid crossing into the lungs due to shift in concentration gradient between the capillaries and airspace in the lungs
• R side of the heart has significantly more pressure to overcome to pump blood due to backup of fluid

Question 10

how dose CPAP correct CPO

Answer 10

• reduces venous return on R side, less force to overcome to pump
• baroreceptors in heart detect increased intrathracic pressure -> further reduction in Q
• increased pressure in the airspace, evens out the concentration gradient between blood and air, this stops fluid leaking into lungs

Question 11

how CPAP helps in COPD/asthma

Answer 11

-splints open airway obstructed by mucus plug
- maintains postive pressure preventing collapse of alvioli
- bronchodilators able to get down into airway

Question 12

name some possible complications of CPAP

Answer 12

• not tolerated well
• air leaks

Question 13

when is peep contradicted

Answer 13

in cardiac arrest for adults and children

Question 14

why is peep not used in cardiac arrest for adults and children

Answer 14

PEEP is not applied to adults and children during CPR because an increase in intrathoracic pressure reduces the blood flow achieved during CPR. If ROSC is achieved it is appropriate to apply PEEP, but this is not an immediate priority.

Question 15

adults indication for PEEP

Answer 15

if manual ventilation is being provided:

Apply PEEP at 5 cmH2O if the patient has traumatic brain injury (TBI), COPD, asthma or signs of shock.

Apply PEEP at 10 cmH2O for all other conditions.

For an adult with cardiogenic pulmonary oedema if CPAP is indicated but unavailable

Question 16

children PEEP indcations

Answer 16

5cm for all conditions exept arrest if manual ventilation is being provided

Question 17

admin of PEEP for CPO when CPAP is n/a

Answer 17

Apply PEEP at 10 cmH2O. Focus on ensuring a tight seal with the mask and do not assist the patient’s breathing unless it is ineffective.

Consider increasing PEEP to 15cmH2O if the patient is not improving.

Use PEEP with caution if the patient has signs of shock.

Question 18

neonate PEEP indications

Answer 18

Apply PEEP to all pts requiring manual ventilation at 5 cmH2O, including during cardiac arrest

Question 19

why is PEEP applied to neonates in arrest

Answer 19

PEEP is applied to neonates during CPR because the cause of cardiac arrest is usually respiratory failure and the balance of risk is in favor of improving ventilation, even though this may reduce blood flow achieved during CPR.

Question 20

TBI and PEEP considerations

Answer 20

PEEP increases intracranial pressure in patients with TBI by reducing venous return from the brain. In this setting, there is a balance between the benefit of PEEP improving oxygenation and the risk of PEEP increasing intracranial pressure. This is why PEEP is set to 5 cmH2O for these patients.

Question 21

how dose peep reduce the workload of breathing

Answer 21

The expiratory pressure assists small and medium sized airways to remain open during expiration, reducing lung collapse. Once collapsed, significant additional pressures are required to re-expand them.

The positive pressure in the thoracic cavity reduces the preload (filling) of the right ventricle by reducing venous return to the heart.

The positive pressure in the thoracic cavity increases the afterload of the right ventricle. This reduces blood flow through lung vessels, reducing the amount of fluid entering the lungs.

The expiratory pressure increases the amount of air remaining in the lungs at the end of expiration, (the functional residual capacity) and this causes the lungs to be more expanded. From this more expanded resting position, less work is required for inspiration because of the non-linear compliance of the lungs, particularly when the lungs are wet

Question 22

what patients will be more susceptible to reduction in cardiac output from PEEP

Answer 22

A clinical condition reducing right ventricular filling, such as hypovolemia.

A clinical condition increasing right ventricular afterload, such as pulmonary embolism.

consider fluid to expand intravascular volume in theses patients.