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Flashcards in Reduced Lung Volume Deck (40):
1

How is alveolar ventilation measured?

Respiratory rate x (tidal volume - deadspace)

2

What is regional ventilation?

Ventilation in specific regions of the lung

3

What is minute ventilation?

Respiratory rate x tidal volume

4

What is functional residual capacity?

Resting volume of the lung at the end of tidal breaths

5

What is the difference between atelectasis and lung collapse?

- Atelectasis is the collapse of alveoli
- Lung collapse is the collapse of whole regions of the lung

6

What is FRC a balance of?

- Inward elastic recoil of the lungs
- Springing out of the ribcage

7

What is closing capacity?

Volume of gas in the lungs at the time when small airways in the dependent portions (lower portions) of the lungs close during maximal exhalation

8

Why is pleural pressure less negative at the bottom of the lungs?

Because gravity pulls down the weight of the lung, making the space bigger (i.e. less pressure)

9

How is closing capacity measured?

Single breath nitrogen test

10

What factors does closing capacity increase with?

Age, COPD, smoking (loss of elastic recoil)

11

What is the relationship between closing capacity and body position?

- Higher when standing upright
- Lower when supine

12

What occurs when CC > FRC?

Dependent airway closure occurs during tidal breathing, i.e. much more likely to get lung collapse in those airways

13

What is the difference between CC and equal pressure point?

- CC is a volume
- EPP is where pleural pressure & pressure within alveoli are equal causing dynamic collapse (pressure-related, nothing to do with dependence/non-dependence)

14

What are the causes of reduced lung volume?

- External compression of lung tissue
- Reduced chest wall compliance
- Reduced central drive
- Decreased ability of respiratory muscles to generate force
- Loss of alveolar volume

15

What can cause external compression of lung tissue?

- Pleural space: Pleural effusion, empyema (pus), pneumothorax
- Abdomen: ascites (fluid), pregnancy, obesity
- Rib cage: Posture, flail segment, kyphoscoliosis

16

What causes reduced chest wall compliance?

- Kyphoscoliosis
- Obesity
- Pregnancy
- Age

17

What causes reduced central drive?

- Altered patterns of breathing
- Brainstem injury (medulla)
- Often causes reduction in tidal volume

18

What are some of the different patterns of reduced central drive?

- Cheyne-Stokes (just before death, breathing all over the place)
- Biot's breathing

19

What decreases the ability of respiratory muscles to generate force?

- Neuromuscular disease (MND, stroke, spinal injury, phrenic nerve palsy)
- Deconditioning or fatigue (mechanical ventilation, COPD, illness)

20

What is required in order for the lungs to remain compliant?

- Elasticity
- Surfactant

21

What causes loss of alveolar volume?

- Post-op atelectasis
- Mucus plugging
- Removal of lung tissue

22

How is laparoscopic abdominal surgery different to open laparotomy?

- Less pain
- Less analgesic requirements
- Improved mobility
- Reduced hospital length of stay
- Lower incidence of post-op pulmonary complication (PPC)

23

What type of pain is laparoscopic surgery associated with?

Shoulder tip pain
- cause uncertain
- may be related to CO2 insufflation, irritation of diaphragm or peritoneum
- often worse with deep breathing

24

Why do physios not routinely assess patients following laparoscopic procedures?

They are low risk, shoulder tip pain is non-mechanical (i.e. can't be fixed with physio)

25

What are examples of upper abdominal surgery?

- Splenectomy
- Liver resection
- Oesophagectomy (2 incisions, higher risk)
- Head of pancreas (2 incisions, higher risk)

26

What are examples of lower abdominal surgery?

- Colectomy
- Nephrectomy

27

What is an example of vascular abdominal surgery?

- Abdominal aortic aneurysm (AAA) repair & grafting
- High risk of PPC due to smoking history

28

What are some of the potential complications of surgery?

- Respiratory complications
- Wound infection
- Bleeding/haemorrhage
- Cardiovascular problems
- DVT
- Pulmonary embolus
- Renal failure
- Nausea/vomiting
- Psychosis
- Reduced gut mobility
- Musculoskeletal problems
- Exacerbation of pre-existing conditions

29

What surgeries are most commonly associated with PPCs?

Upper abdominal surgery & cardiothoracic surgery

30

What are the criteria for PPCs (requires 4 or more to be classified as PPC)?

1. CXR report of collapse/consolidation
2. Maximal oral temperature >38 deg for >1 consecutive days post op
3. SpO2 <90% on >1 consecutive day post op
4. Yellow/green sputum different to pre-op
5. Infection on sputum culture report
6. Unexplained high white cell count or prescription of antibiotic for respiratory infection
7. New abnormal breath sounds
8. Physician diagnosis of PPC

31

What are the 5 risk factors for PPC?

1. Duration of anaesthesia >180 mins
2. Surgery site (upper abdominal)
3. Current smoker
4. Respiratory co-morbidity
5. Low fitness

32

What are the effects of UAS on lung volume?

Causes a restrictive ventilatory pattern
Decreases
- FRC
- Tidal volume
- Inspiratory capacity
- Vital capacity

33

What causes reduced lung volume following UAS?

- Anaesthesia
- Analgesia
- Pain
- Diaphragm splinting
- Posture
- Mucus pooling
- Not being mobile

34

Why does anaesthesia cause reduced lung volume?

- Reduced phrenic nerve & diaphragm function
- Depressed hypercapnic drive & hypoxaemic response
- Supine posture

35

Why does analgesia cause reduced lung volume?

Decreases
- Respiratory drive
- Periodic sighs
- Cough reflex
- Breathing pattern
- Alveolar ventilation

36

Why does diaphragm splinting cause reduced lung volume?

- 60% reduction in diaphragm excursion
- Upper chest pattern of breathing

37

What are the consequences of reduced lung volume?

- Atelectasis
- Hypoxaemia (PaO2 < 80mmHg, SpO2 < 97%)

38

What auscultation findings can be expected in the presence of lung collapse?

- Reduced breath sounds
- Fine end inspiratory crackles
- Bronchial breath sounds

39

What are the signs of hypoxaemia?

- Restlessness
- Confusion
- Sweating
- Tachycardia
- Hypertension
- Cyanosis

40

What is compliance?

Volume change per unit pressure change