APO

Question 1

APO Definition

Answer 1

An accumulation of fluid within the lungs and alveoli, preventing adequate gas exchange.
interstitial space within the pulmonary vasculature as a result of increased hydrostatic pressure.

Question 2

Two main causes of APO

Answer 2

1. Haemodynamic disturbance
2. Increased capillary hydrostatic pressure and permeability

Question 3

Cardiac causes of APO

Answer 3

HF
AMI
Hypoxia
LVF
Chronic HTN
Tamponade

Question 4

Non-cardiac causes of APO

Answer 4

Liver disease
Renal disease
Pancreatitis
OD
CVA/ICH
PE Drowning
Rapid IV fluid administration
ARDS
Sepsis
Eclampsia

Question 5

Patient presentation of APO

Answer 5

• Acute dyspnoeic
  
  • Pale/cyanosis
  • Crackles on auscultation
  • Sympathetic response - tachycardia, HTN, diaphoretic
  • Decreased SpO2
  • Chest pain
  • Pink, frothy sputum
  • Orthopnoea
  • Wheezing/coughing
  • Decreased GCS
  • JVD
    Peripheral oedema

Question 6

APO Pathophysiology

Answer 6

• APO is a result of LV dysfunction, pulmonary HTN and alveoli flooding.
  ○ Decreased LVEF from cardiac or hypoxic causes results in decreased efficient cardiac out put.
  ○ Results in a build up of blood within the LV and pulmonary circulation, therefore, resulting in increased hydrostatic pressure as this exceeds oncotic pressure > causes a shift in fluid to pulmonary interstitial space and alveoli.
  In normal conditions, drainage of fluid within the lymphatic system occurs, however, in APO, becomes overwhelmed.
• A ventilation/perfusion (V/Q) mismatch occurs as there is less gas exchange.
  ○ Significant fluid overload can cause decreased alveoli surfactant, reducing surface tension, making alveoli difficult to reinflate = increased WOB. Hypoxia drives sympathetic NS response, causing an increase in RR, HR and BP.
  As pressure increases, RBC are forced out of the pulmonary capillaries, resulting in red, frothy sputum.

Question 7

Influences on SV

Answer 7

Preload
Afterload
Myocardial contractility

Question 8

Management of APO

Answer 8

1. Pulmonary oedema with SOB:
   
   • Basal/midzone crackles:
     ○ Posture sitting
     ○ GTN 400mcg every 5 mins until symptoms relieved
   • Full field crackles:
     ○ Treat as per basal/midzone
     ○ ICP back up: CPAP, furosemide
     GTN infusion

Question 9

LVF causes

Answer 9

AMI
Valvular dysfunction
HTN
infection
Hypoxia
Drugs