Acute respiratory failure Flashcards Preview

Internal Medicine > Acute respiratory failure > Flashcards

Flashcards in Acute respiratory failure Deck (19):
1

Definition of respiratory failure

Hypoxia, gas exchange inadequate. Subdivided into 2 categories
1. Type 1
2. Type 2

2

Type 1 respiratory failure: definition and causes

VQ mismatch
Hypoxia with normal or low CO2

Pneumonia
Pulmonary edema
Asthma
PE
Emphysema
Fibrosing alveolitis
ARDS

3

Type 2 respiratory failure: definition and causes

Alveolar hypoventilation
Hypoxic, hypercapnic

Pulmonary disease
Reduced respiratory drive
Neuromuscular disease
Thoracic wall

4

Pulmonary disease cause T2RF

Asthma
COPD
Pneumonia
Pulmonary fibrosis
OSA

5

Reduced respiratory drive causes of T2RF

Sedative drugs
Tumor
Trauma

6

NM causes of T2RF

Cervical cord
GBS
MG
Polymyositis
Diaphragmatic paralysis

7

Thoracic wall causes T2RF

Kyphoscoliosis
Flail chest

8

Clinical features

1. Underlying cause
2. Hypoxic->dyspnea, restless, agitation, confusion, central cyanosis. If long standing may have polycythemia, pulmonary hypertension, cor pulmonale
3. Hypercapnia->headache, peripheral vasodilation, tachy, asterixis, bounding pulse, tremor, confusion, drowsy, coma

9

Investigations

ABG->pH 50 mmHg on room air
ECG->evidence of PE, MI, heart disease
UEC
FBC->look for +WCC
CXR->diffuse or patchy infiltrates; pneumothorax; pulmonary effusion; hyper-inflation; asymmetrical opacification of lung fields; asymmetrical lucency of lung fields
Pulse oximetry-> Sp02% PEFR cultures

10

Management of Type 1

Depends on cause
ABC
Give oxygen by facemask, 35-60%
Assisted ventilation if required->NIPPV, ETT with mechanical

11

Management Type 2

Hypoxic drive
Treat underlying cause
Controlled 02 therapy 24%
Recheck ABG after 20 mins
If PCO2 is steady/lower, +02
If +PCO2 and still hypoxic, consider respiratory stimulant->doxapram, or NIPPV
If fails, intubate

12

Follow-up requirements

Close F/U for first week after recovery to evaluate development of complications after NIPPV: sinus infection, middle ear infection, skin necrosis or ETT use->tracheal inflammation, nosocomial infection, pneumonia, lung abscess.

Patients need education about underlying causes of respiratory failure.

13

Oxygen saturation aim for normal and those at risk of hypercapnia

Normal: 94-98
At risk of hypercapnia: 88-92

14

Nasal cannulae: typical flow rate and concentration

1-4 L
24-40% oxygen saturation

15

Simple face mask: risks, when not to use

Less precise than venturi
Do not use if hypercapnia or T2RF
Risk of CO2 accumulation if flow

16

Venturi mask

Provides precise O2% at high flow rates
24% Blue
28% White
35% Yellow
40% Red
60% Green

17

Non-rebreathing mask: oxygen concentration delivery, common use, when to avoid

Reservoir bag, deliver high oxygen 60-90% determined by inflow 10-15L/min
Commonly used in emergencies, imprecise, avoid in those requiring controlled 02 therapy.

18

Other ways to +oxygenation

Treat anemia->transfusion may be required
Improve CO->treat heart failure
Chest physio to +ventilation/perfusion mismatch

19

When to consider ABG

Unexpected deterioration in ill
Acute exacerbation of chronic chest condition
Impaired consciousness or impaired respiratory effort
Signs of CO2 retention
Drowsy, bounding pulse, asterixis, HA
Cyanosis, confusion, irritability, hallucinations
To validate measurements for transcutaneous oximetry