Cyanosis: Definition and Causes

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Questions and Answers

What is the primary indication for performing an ECG in a patient with suspected cardiogenic pulmonary edema?

To assess the severity of pulmonary edema

To monitor the effects of oxygen therapy

To diagnose the underlying predisposing factor or cause (correct)

To evaluate the response to nitrate therapy

Which of the following chest X-ray findings is NOT typically seen in cardiogenic pulmonary edema?

Bilateral perihilar shadowing

Cardiomegaly

Unilateral perihilar shadowing (correct)

Kerley B lines

What is the primary goal of administering oxygen therapy in cardiogenic pulmonary edema?

To alleviate the symptoms of cardiac asthma

To reduce the workload on the heart

To improve oxygenation of the blood (correct)

To reduce the severity of pulmonary edema

What is the recommended dose of morphine for the treatment of cardiogenic pulmonary edema?

2.5-5 mg slowly I.V Signup and view all the answers

When is I.V infusion of nitrates initiated in the treatment of cardiogenic pulmonary edema?

When systolic pressure is above or equal to 100 mmHg Signup and view all the answers

What is the next step in the treatment of cardiogenic pulmonary edema if the patient is worsening?

Administer a further dose of furosemide and consider assisted ventilation Signup and view all the answers

What is the minimum concentration of deoxygenated hemoglobin required to produce cyanosis?

5 g/dl Signup and view all the answers

In which type of anemia is cyanosis more likely to appear?

Polycythemia Signup and view all the answers

What is the primary cause of central cyanosis in lung diseases?

Inadequate oxygen exchange Signup and view all the answers

Which of the following is a rare cause of central cyanosis?

Methemoglobinaemia Signup and view all the answers

What is the primary cause of peripheral cyanosis?

Changes in peripheral and cutaneous vascular systems Signup and view all the answers

Which of the following is a characteristic of cyanosis in polycythemia?

Occurs more readily Signup and view all the answers

Which of the following is a cause of central cyanosis that is not corrected by increasing the inspired oxygen?

Cyanotic congenital heart disease Signup and view all the answers

What is the term for the accumulation of fluid in the lungs?

Pulmonary edema Signup and view all the answers

What is the primary cause of fluid accumulation in the alveoli in pulmonary oedema due to acute left ventricular failure?

Increased hydrostatic pressure of pulmonary capillaries Signup and view all the answers

Which of the following is NOT a cause of pulmonary oedema?

Acute right ventricular failure Signup and view all the answers

What is the pathophysiological difference between pulmonary oedema due to acute left ventricular failure and acute respiratory distress syndrome?

Capillary permeability Signup and view all the answers

A patient with pulmonary oedema is likely to exhibit which of the following symptoms?

Sudden onset of dyspnea at rest Signup and view all the answers

Which of the following is an exacerbating factor of pulmonary oedema?

Infection Signup and view all the answers

What is the typical posture of a patient with pulmonary oedema?

Sitting up and leaning forward Signup and view all the answers

Which of the following vital signs is NOT typically seen in a patient with pulmonary oedema?

Hypotension Signup and view all the answers

What is the primary reason for asking about recent drug use in a patient with pulmonary oedema?

To identify potential precipitants of the condition Signup and view all the answers

Study Notes

Cyanosis

Dusky blue skin discoloration occurs when reduced form (deoxygenated) hemoglobin is ≥ 5 g/dl of Hb.
In anemia, cyanosis appears only in severe hypoxia, while in polycythemia, it occurs more readily.
There are two types of cyanosis: central (lips and tongue) and peripheral (fingers).

Causes of Central Cyanosis

Lung diseases: inadequate O2 exchange (e.g., luminal obstruction, pneumothorax, pneumonia, pulmonary edema) - corrected by increasing inspired O2.
Cyanotic congenital heart diseases: results in blood admixture, not corrected by increasing inspired O2.
Rare causes: methemoglobinaemia, congenital or acquired red cell disorders.

Causes of Peripheral Cyanosis

Peripheral cyanosis can occur in causes of central cyanosis, but also induced by peripheral and cutaneous vascular system changes in persons with normal O2 saturation (e.g., exposure to cold, hypovolemia, and arterial diseases).

Pulmonary Oedema

Definition: accumulation of fluid into the alveoli.
It's one of the medical emergencies that requires immediate and aggressive treatment.
Causes: acute left ventricular failure, acute respiratory distress syndrome, fluid overload, neurogenic, and others.

Pathophysiology (LV Failure)

Increase in left ventricular diastolic pressure.
Rising of left atrium, pulmonary veins, and capillaries pressures.
When hydrostatic pressure of pulmonary capillaries exceeds osmotic pressure of plasma, fluids move into the alveoli.

Pathophysiology (RDS)

Normal left ventricular diastolic pressure.
Normal left atrium, pulmonary veins, and capillaries pressures.
Fluids move into the alveoli due to increased capillary permeability (inflammation).

Exacerbating Factors of Pulmonary Oedema

Arrhythmias (e.g., atrial fibrillation).
Infection.
Pulmonary embolism.
Increase in blood pressure.
Anemia.
Inadequate therapy or poor drug compliance.
Thyroid disease.
Drug-induced (e.g., NSAIDS, corticosteroids, and verapamil).

Clinical Features

Symptoms: sudden onset of dyspnea at rest, orthopnoea, PND, prostration.
Signs: patient looks distressed, pale, and sweaty, with tachycardia, pulsus alternans, tachypnea, increased JVP, fine basal crackles, gallop/triple rhythm, and wheezing.

Investigations

Chest x-ray: important for diagnosis, shows cardiomegaly, sings of pulmonary edema.
ECG: shows signs of predisposing factor or cause.
Lab tests: electrolytes, cardiac enzymes, arterial blood gas analysis.
Echocardiography: can be considered.

Treatment

Begin treatment before investigations.
Sit the patient in an upright position.
Oxygen.
I.V access and monitor the ECG.
Morphine: 2.5-5 mg slowly I.V.
Furosemide: 40-80 mg slowly I.V.
Nitrates: GTN (systolic pressure > 90 mmHg) and I.V infusion of nitrates (systolic pressure > or = 100).
Consider assisted ventilation if the patient worsens.
Treat any arrhythmia, e.g., atrial fibrillation.
If the pressure is below 100 mmHg, treat as cardiogenic shock.

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Description

Learn about cyanosis, a condition characterized by dusky blue skin discoloration due to high levels of deoxygenated hemoglobin. Explore its types, causes, and relationship with anemia and polycythemia.