Week 3: Non Invasive Ventilation

Question 1

What are the types of ventilation failure?

Answer 1

Type 1 respiratory failure –oxygen failure

Type 2 hypercapnoeic respiratory failure -Effects on carbon dioxide

Question 2

What is ventilation?

Answer 2

The process of allowing fresh air into the lungs and exhaling carbon dioxide (byproduct of metabolism)

Question 3

How does inspiration occur?

Answer 3

Diaphragm flattens and ribs elevate → ↑ volume of the thoracic cavity
Increased intrathoracicvolume → ↓intrathoracic pressure
Intrathoracic volume falls below atmospheric pressure and because of this pressure difference, air flows into the lungs

Question 4

How does expiration work?

Answer 4

Inspiratory muscles relax
Natural elastic recoil of the lungs reduces the volume of the thoracic cavity
↓volume of the thoracic cavity → ↑intrapulmonary pressure.
Air moves out of lungs because the pressure in the alveolus is greater than atmospheric pressure.

Question 5

What is airway resistance?

Answer 5

Refers to the forces that oppose airflow within the respiratory passageways
Increased resistance increases work of breathing

Question 6

What are factors which increase work of breathing?

Answer 6

Bronchoconstriction/dilation
Patency of ETT
Size of ETT

Question 7

What is lung compliance?

Answer 7

Refers to the ease at which the lungs can be expanded e.g. a balloon that is easy to inflate is very compliant.

Question 8

What are conditions which affect lung compliance?

Answer 8

Pulmonary oedema
Adult Respiratory Distress Syndrome (ARDS)
Pulmonary fibrosis

Question 9

What is tidal volume?

Answer 9

Volume of one breath

Question 10

What is minute ventilation?

Answer 10

Total air inhaled and exhaled each minute

Question 11

How do you calculate minute ventilation?

Answer 11

MV = VT X RR

Question 12

What factors could change RR?

Answer 12

Increase: pain, exertion/exercise, stress/anxiety, medications (activation of SNS)
Decrease: medication (morphine), decrease LOC

Question 13

What factors could affect tidal volume?

Answer 13

Injury: fractured rib
Pneumothorax
LOC
Positioning: position of diaphragm (abdomen may impede), sit patient up
Lung disease

Question 14

What is functional residual capacity?

Answer 14

Amount of air in lungs at end of a normal expiration

Question 15

What is anatomical dead space?

Answer 15

Volume of air that takes no part in gas exchange nose, pharynx larynx, trachea, etc

Question 16

What is alveolar ventilation?

Answer 16

Volume of air that actually reaches alveoli

Question 17

How do you calculate alveolar ventilation?

Answer 17

Alveolar ventilation = TV - dead space ventilation

Question 18

How is gas exchange explained by Dalton’s law and Henry’s law?

Answer 18

Dalton’s law: pressure gradient. Higher O2 partial pressure in alveoli than capillaries –> O2 moves into blood. Opposite for CO2 partial pressure

Henry’s law: CO2 dissolves well in water (more soluble than O2)

Question 19

How is O2 transported in the blood?

Answer 19

97% carried on the Hb
3% dissolved in the plasma
Portion dissolved in plasma can be measured as partial pressure of arterial oxygen (PaO2) done by ABG analysis

Question 20

Include more on gas exchange

Answer 20

blank

Question 21

Include pulmonary oedema

Answer 21

blank

Question 22

Include V/Q relationship

Answer 22

blank

Question 23

What are first line pH buffers?

Answer 23

H+in the plasma is buffered by bicarbonate in the plasma
H+ + HCO3H2CO3CO2+ H2O
Some H+enters the cells and is buffered by intracellular bicarbonate
Haemoglobin
Albumen and globulin

Question 24

What are second line pH buffers?

Answer 24

If the amount acid exceeds the capability of the first line buffers the increased H+is detected by the chemoreceptorsin the medulla and the rate and depth of breathing is increased
Occurs when the ph <7.35
Increased rate and depth of breathing increases carbon dioxide removal reducing carbonic acid and H+load

Question 25

What are third line pH buffers?

Answer 25

Renal mechanisms is powerful but slower Peak in 72 hours Retain and excrete both H+and bicarbonate to bring pH back to normal

Question 26

What are the 5 steps of an ABG analysis?

Answer 26

``` Step one: Examine the pH Step two: Compare the CO2 and the pH Step 3: Consider the HCO3 and Base excess in conjunction with the pH Step 4: Assess the oxygen levels Step 5:Compare the PaO2 and SaO2 ```

Question 27

What are the causes of respiratory acidosis?

Answer 27

Respiratory disease (pneumonia, COPD), over-sedation

Question 28

What are the causes of respiratory alkalosis?

Answer 28

Overventilation due to pain or emotional distress

Question 29

What are the causes of metabolic acidosis?

Answer 29

DKA | Shock

Question 30

What are the causes of metabolic alkalosis?

Answer 30

Chronic vomiting | Sodium bicarb overdose

Question 31

What are the indications of Continuous Positive Airway Pressure?

Answer 31

``` Acute exacerbations of COPD Asthma Acute cardiogenic pulmonary oedema Hypoxemic respiratory failure Post-op respiratory failure - atelectasis Obstructive sleep apnoea ```

Question 32

How does Continuous Positive Airway Pressure work?

Answer 32

Gas delivered at constant preset pressure during both inspiration and expiration Ventilation (RR and TV) controlled by patient Supports ventilation, doesn't replace Decreases work of breathing to increase TV upon inspiration Inhibits paradoxical chest movements Increases functional residual capacity: Splints airway to keep open Forcing open collasped alveoli, preventing collaspe at end expiration Improved amount of O2 which crosses alveolar/capillary membrane

Question 33

What is FiO2?

Answer 33

blank

Question 34

Include PEEP

Answer 34

blank

Question 35

What is Bilevel Positive Airway Pressure?

Answer 35

Delivers positive pressure in two phases to a spontaneously breathing patient Includes: inspiration positive airway pressure (IPAP) during inhalation, and expiratory positive airway pressure (EPAP) during exhalation

Question 36

What are the indications for Bilevel Positive Airway Pressure?

Answer 36

``` Acute respiratory failure, type 2 Chronic airway limitation Pneumonia Congestive heart failure Acute pulmonary oedema Atelectasis Neuromuscular disease Sleep apnoea Poor candidates for mechanical ventilation ```

Question 37

How does Bilevel Positive Airway Pressure work?

Answer 37

As patient breathes, a positive pressure gradient is established until the preset inspiratory pressure support is reached. Enhances TV Detects reducing amount of airflow in, cuts out on expiration to allow natural elastic recoil to PEEP level Promotes CO2 removal

Question 38

What is IPAP and what does it do?

Answer 38

``` Inspiratory Positive Airway Pressure: Supports breath Improves TV Maximises removal of CO2 Reduces work of breathing Opens airways and alveoli ```

Question 39

What is EPAP and what does it do?

Answer 39

Expiratory Postiive Airway Pressure: Exerts positive intrapulmonary pressure on expiration Increases functional residual capacity Recruits underinflated lung tissue

Question 40

What are the physiological effects of Bilevel Positive Airway Pressure?

Answer 40

Increased functional residual capacity Reduced respiratory muscle work Atelectatic alveoli opened --> improved compliance Improved oxygenation Assistance inhaling --> increased transpulmonary pressure --> inflation of lungs and augmentation of alveolar ventilation --> augmentation of TV Improved cardiac performance: reduction in preload and afterload reducing myocardial oxygen consumption Upper airway able to warm and humidify gas

Question 41

What are the contraindications of Bilevel Positive Airway Pressure?

Answer 41

``` Respiratory arrest Facial trauma/surgery Excessive secretions/inability to clear Risk of aspiration Low GSC/agitation Severe hypoxia Haemodynamically unstable Upper GIT bleeding Upper airway obstruction ```

Question 42

How does Continuous Positive Airway Pressure improve oxygenation?

Answer 42

Splints open airways Forces alveoli open for gas exchange Pushes fluid back into capillaries

Question 43

What is the assessment and management of a patient receiving Continuous Positive Airway Pressure?

Answer 43

Assess: tolerance, mucous membranes, pressure areas, vitals, hourly ABGs for CO2, O2 and pH, mask fit and seal Management: reassure, educate, plan breaks, consider humidifier or dry mouth spray, dressings for pressure areas, positioning

Question 44

What is the usual range for Continuous Positive Airway Pressure?

Answer 44

5-15 cmH2O

Question 45

What variables need to be set on a Continuous Positive Airway Pressure device?

Answer 45

Oxygen % | PEEP level

Question 46

What paediatric medical conditions are treated with Continuous Positive Airway Pressure?

Answer 46

Altered control of breathing e.g. Congenital Central Hypoventilation Sydnrome Neuromuscular weakness e.g. Duchenne muscular dystrophy, spinal muscular dystrophy Upper spinal cord injury Upper airway obstruction (non-acute) e.g tracheobronchomalacia, some craniofacial abnormalities Chronic lung disease Obstructive sleep apnoea

Question 47

What are the four variable in Bilevel Positive Airway Pressure?

Answer 47

Expiratory positive airway pressure Inspiratory positive airway pressure Frequency of cycling or breath rate at 4-30 cycles per minute Proportion of each respiratory cycle spent in IPAP, 10-90%

Question 48

What are the four modes of Bilevel Positive Airway Pressure?

Answer 48

Spontaneous Spontaneous/timed Timed Continuous Positive Airway Pressure

Question 49

What are the complications of non-invasive positive pressure ventilation?

Answer 49

``` Decreased CO Ill fitting mask and leaks Decreased patient compliance Skin irritation Dry mucous membranes Gastric distension Aspiration Barotrauma and pneumothorax ```

Question 50

What primary assessment needs to be performed on a patient with non-invasive positive pressure ventilation?

Answer 50

``` A and B: RR, depth, work of breathing Patient-ventilator synchrony Chest wall movement Use of accessory muscles Continuous pulse oximetry ABG analysis ``` C: BP, HR, JVP, rhythm D: AVPU or GSC E

Question 51

What is the nursing management for a person with non-invasive positive pressure ventilation?

Answer 51

Oral care: Mouth washes Need to decide if it is appropriate to remove mask, ventilation takes priority Pressure relief from mask: Breaks Padding Nasal care: Humidification devices ``` Comfort: Positioning Promote secretion removal Analgesia Psychological support ``` Decrease O2 consumption: temperature control Nutritional support and adequate phosphate levels

Question 52

What are the indications that non-invasive positive pressure ventilation is not working?

Answer 52

Unstable cardiovascular system Deteriorating mental state Increasing RR Hypoxia and increased CO2