Respiratory Support

Question 1

What is non-invasive ventilation?

Answer 1

using a full face mask, hood (covering the entire head) or a tight-fitting nasal mask to blow air forcefully into the lungs and ventilate them. An alternative to full intubation and ventilation to support the lungs in respiratory failure due to obstructive lung disease

Uses a full face mask or a tight fitting nasal mask to blow air forcefully into the lungs and ventilate them without having to intubate them.

BiPAP or CPAP

Question 2

What is intubation and ventilation?

Answer 2

nvolves giving the patient a general anaesthetic, putting a plastic tube into the trachea and ventilating the lungs artificially.

Question 3

What is BiPAP?

Answer 3

Bilevel positive airway pressure.

A a cycle of high and low pressure to correspond to the patients inspiration and expiration.

IPAP (inspiratory positive airway pressure) during inspirationion) - air is forced into the lungs
EPAP (expiratory positive airway pressure) during expiration- which stops the airways from collapsing.

Indications: type 2 respiratory failure, typically due to COPD.

Question 4

Criteria for initiating BiPAP

Answer 4

Respiratory acidosis (pH < 7.35, PaCO2 >6) despite adequate medical treatment.

Question 5

BiPAP contraindications

Answer 5

Untreated pneumothorax or any structural abnormality or pathology affecting the face, airway or GI tract.

*important to CXR to exclude pneumothorax before starting NIV

Question 6

BiPAP pressures explained

Answer 6

IPAP (inspiratory positive airway pressure) = the pressure during inspiration, air is forced into the lungs.

EPAP (expiratory positive airway pressure) = the pressure during expiration. This provides some pressure during expiration so that the airways don’t collapse and it helps air to escape the lungs in patients with obstructive lung disease.

The initial pressures are estimated based on the patients body mass and measured in cm of water. Potential starting points for an average male patient might be:

IPAP 16-20cm H2O
EPAP 4-6cm H2O

Question 7

Important monitoring during BiPAP

Answer 7

ABG: Repeat an ABG 1 hour after every change and 4 hours after that until stable.

The IPAP is increased by 2-5 cm increments until the acidosis resolves.

Question 8

What is CPAP?

Answer 8

CPAP stands for continuous positive airway pressure. It provides continuous air being blown into the lungs that keeps the airways expanded so that air can more easily travel in and out. It is used to maintain the patient’s airway in conditions where it is prone to collapse. the constant pressure to the lungs keeps the airways expanded (adds PEEP).

Question 9

Indications for CPAP

Answer 9

Obstructive sleep apnoea
Congestive cardiac failure
Acute pulmonary oedema

Question 10

respiratory complications on ICU

Answer 10

Ventilator-associated lung injury

Ventilator-associated pneumonia

Question 11

What is Ventilator-associated lung injury (and causes)

Answer 11

common complication of mechanical ventilation

Forcefully blowing air into the lungs can cause volutrauma (damage from over-inflating the alveoli), barotrauma (damage from pressure changes) and inflammation.

Question 12

Complications of Ventilator assisted lung injury

Answer 12

Short term: It can lead to pulmonary oedema and hypoxia.

Long-term: it can lead to fibrosis of lung tissue, reduced lung function, recurrent infections and cor-pulmonale.

Question 13

Prevention of Ventilator Assisted Lung Injury

Answer 13

Using optimal settings and pressures during mechanical ventilation helps reduce the risk of lung injury.

Question 14

Ventilator Associated Pneumonia

Answer 14

common and high risk (25%)

being ventilated increases the risk of bacteria being aspirated into the lungs.

prevention; Positioning the bed at a 30-degree angle with the patient’s head elevated reduces the risk of aspirating secretions from the stomach. Good oral care with regular mouth cleaning is also important to reduce the risk of ventilator-associated pneumonia.

Question 15

Respiratory support options

Answer 15

Oxygen therapy
High-flow nasal cannula
Non-invasive ventilation
Intubation and mechanical ventilation
Extracorporeal membrane oxygenation (ECMO)
Chest physiotherapy
Suction (help clear secretions and improve resp function)

Question 16

What is oxygen therapy?

Answer 16

Oxygen can be delivered by several methods:

nasal cannula
simple facemask
venturi mask
face mask with reservoir (non rebreather mask)

Question 17

FiO2 and oxygen flow rate

Answer 17

Oxygen can be delivered by several methods. The FiO2 (concentration of oxygen) will depend on the oxygen flow rate:

Nasal cannula: 24 – 44% oxygen
Simple face mask: 40 – 60% oxygen
Venturi masks: 24 – 60% oxygen
Face mask with reservoir (non-rebreather mask): 60 – 95% oxygen

Question 18

nasal cannula

Answer 18

oxygen flow rates and FiO2

oxygen flow rate of 1L/min gives approx 24% Fio2

oxygen flow rate of 2L/min gives approx 28% Fio2

oxygen flow rate of 4L/min gives approx 36% Fio2

Question 19

simple facemask

Answer 19

oxygen flow rate of 5L/min gives approx 40% Fio2

oxygen flow rate of 8L/min gives approx 60% Fio2

Question 20

face mask with reservoir (non rebreather mask)

Answer 20

oxygen flow rate of 8L/min gives approx 80% Fio2

oxygen flow rate of 10L/min gives approx 95% Fio2

Question 21

Venturi mask

Answer 21

this can be used to deliver exact concentratiosn of oxygen

indications- COPD where there is a risk of retaining CO2 if the FiO2 is too high

Question 22

Venturi mask colours

Answer 22

Blue
O2 flow rate: 2L/min
FiO2: 24%

White
O2 flow rate: 4L/min
Fio2: 28%

Orange
O2 flow rate: 6L/min
Fio2: 31%

Yellow
O2 flow rate: 8L/min
Fio2: 35%

Red
O2 flow rate: 10L/min
Fio2: 40%

Green
O2 flow rate: 15L/min
Fio2: 60%

BWOYRG

Question 23

PEEP- positive end expiratory pressure

Answer 23

Positive end-expiratory pressure (PEEP) is applied by the mechanical ventilator at the end of each breath (Can be applied to NIV)

End-expiratory pressure: refers to the pressure that remains in the airways at the end of exhalation.

Additional pressure in the airways at the end of exhalation stops the airways from collapsing. Forms of respiratory support that add positive end-expiratory pressure help keep the airways from collapsing and improve ventilation. It reduces atelectasis, improves ventilation of the alveoli, opens more areas for gas exchange and decreases the effort of breathing.

Positive end-expiratory pressure is added by:
High-flow nasal cannula
Non-invasive ventilation
Mechanical ventilation

Question 24

High flow nasal cannula

Answer 24

this allows for a carefully controlled flow rates (up to 60L/min of humidified and warmed oxygen)

Having a high flow rate reduces the amount of room air that the patient inhales alongside the supplementary oxygen, increasing the concentration of oxygen inhaled with each breath.

It also adds some PEEP to help prevent the airways from collapsing at the end of exhalation (although this effect is reduced if the patient opens their mouth).

Having a high flow of oxygen into the airways provides dead space washout. The physiological dead space is the air that does not contribute to gas exchange because it never reaches the alveoli. Dead space air remains in airways and oropharynx, not adding anything to respiration and collecting carbon dioxide. High-flow oxygen effectively clears this and replaces it with oxygen, improving patient oxygenation.

Question 25

non invasive ventilation (NIV)

Answer 25

BiPAP and CPAP

Question 26

mechanical ventilation

Answer 26

used where other forms of respiratory support (oxgen therapy or NIV) are inadequate or contraindicated.

ventilator machine is used to move air into and out of the lungs.

patients require a level of sedation whilst on a ventilator as it can be uncomfortable and distressing.

• ETT (endotracheal tube)
• tracheostomy

Question 27

examples of connections for mechanical ventilator

Answer 27

ETT or tracheostomy is required to connect the ventilator to the patients luncgs.

Question 28

basic settings for a mechanical ventilator.

Answer 28

FiO2 (concentration of oxygen)
Respiratory rate (breaths per minute)
Tidal volume (volume of air pushed in per breath)
Inspiratory:expiratory ratio (the ratio of time spent in inspiration and expiration)
Peak flow rate (the maximum rate of air flow during inspiration)
Peak inspiratory pressure (the maximum pressure during inspiration
Positive end-expiratory pressure (the positive pressure applied at the end of expiration to prevent airway collapse)

Question 29

modes of mechanical ventilation

Answer 29

Volume controlled ventilation (VC) – the machine is set to deliver a specific tidal volume per breath
Pressure controlled ventilation (PC) – the machine is set to deliver a specific pressure per breath
Assist control (AC) – breaths are triggered by the patient (or by the machine if there is no respiratory effort)
Continuous positive airway pressure (CPAP) – the patient breathes while the machine adds constant pressure

Question 30

extracorporeal membrane oxygenation

Answer 30

ECMO
most extreme form of resp support (rarely used) indicated in resp failure

blood is removed from the body, passed throguh the machine where o2 is addded and co2 is removed, then pumped back into the body (similar to haemodialysis)

only used short term if there is a reversible resp failure. can only be provided in ECMO centres