APO & PE

Question 1

APO: What is pulmonary oedema and how is it caused?

Answer 1

• accumulation of fluid within interstitial space and alveoli
• occurs when the amount of filtration from pulmonary capillaries is greater than what can be absorbed and managed by lymph

Question 2

APO: How does left ventricular failure cause pulmonary oedema?

Answer 2

-left ventricular and atrial end-diastolic pressure increases
=>increased pressure in pulm. caps. from venous side
=>increased hydrostatic pressure, decreased reabsorption and increased filtration on arterial side
=>oedema & decreased gas exchange = hypoxaemia

Question 3

APO: How does hypoxaemia cause a cycle of oedema through effects on the myocardium and sympathetic nervous system?

Answer 3

• reduced oxygen = reduced ATP levels so myocardium cant relax and stiffens, leading to increased end-diastolic pressure and less blood entering ventricles = backing up of pressure causing oedema
• hypoxaemia causes sympathetic response, leading to increasing force of contraction and HR, and higher oxygen demand of the myocardium & more hypoxia

Question 4

APO: Signs and symptoms of pulmonary oedema?

Answer 4

• shortness of breath: tachypnoeic, feeling of drowning, maintaining upright posture, pink/white sputum, crackles on lung auscultation
• hypoxia: reduced Sp02, cyanosis, irritability (cerebral hypoxia)
• sympathetic response: anxious, pale, sweating, tachy, hypertensive (can progress to hypotension as cardiogenic shock develops), chest pain, ECG signs

Question 5

APO: How would you treat a patient with suspected pulmonary oedema?

Answer 5

• oxygen: improves gas exchange and reduces hypoxia
• CPAP: decreases WOB, provides 100% O2, splints opem airways
• ECG: confirm cardiac ischaemia
• GTN: if indicated by BP, reduces cardiac workload
• Transport: potential to deteriorate quickly

Question 6

PE: What is a pulmonary embolism and what are the main factors contributing to it’s formation?

Answer 6

• occlusion of blood supply to part of the lungs, usually caused by a thromboembolism
• hypercoagulability (pregnancy, dehydration, cancer, SIRS), statis (stagnation of blood flow - bed bound, long haul flights), endothelial damage (vessel wall injury - trauma, atherosclerosis).

Question 7

PE: What are the respiratory and haemodynamic consequences of a PE?

Answer 7

Respiratory: -increased dead space (ventilated but not perfused), hypoxaemia (V/Q mismatch), hyperventilation, lung infarct
Haemodynamic: -decreased cross-sectional area of pulm. vascular bed => increased pulm. resistance => increased RV afterload => RV failure, obstructive shock and decreased cardiac output => worsed hypoxaemia

Question 8

What two factors will determine the effect the PE will have on the patient?

Answer 8

Size and location of the emobolis

A large embolus occludes a large portion of pulmonary circulation, and symptoms will have a sudden onset.

Question 9

PE: How would a patient with a PE appear?

Answer 9

• Resp: dyspnoea, tachypnoea, normal to lowering Sp02, normal breath sounds
• Cardiac: chest pain, tachy, hypotension, arrhythmias, RV dysfunction
• Concious levels consistent with levels of hypoxia
• Appearance: pale/cyanotic, coughing up blood (haemoptysis), evidence of DVT

Question 10

PE: How would you treat a patient with a suspected PE?

Answer 10

• Oxygen: helps with dyspnoea, offset any developing V/Q mismatch
• Posture: upright/sitting
• Pain relief
• GTN: not indicated if PE confirmed or cardiac caused excluded