Pulmonary Embolism (PE) and Deep Vein Thrombosis (DVT)

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Questions and Answers

What percentage of acute pulmonary embolism originates from thrombi in the leg or pelvic veins?

75%

80%

95% (correct)

100%

What is the outcome of massive pulmonary emboli?

Sudden death due to right ventricular failure (correct)

Chronic pulmonary hypertension

Reversible lung damage

Mild symptoms and quick recovery

What happens to lung units in pulmonary embolism?

They remain unaffected

They increase carbon dioxide production

They become deadspace units, reducing oxygenation (correct)

They become more efficient at oxygen exchange

What is the effect of pulmonary embolism on right ventricular function?

Right ventricular dilation Signup and view all the answers

What is a common symptom of pulmonary embolism?

Abrupt onset of pleuritic chest pain Signup and view all the answers

What is the effect of hypoxia on the body in pulmonary embolism?

It stimulates the release of vasoconstrictors Signup and view all the answers

What is the primary characteristic of massive PE according to the American Heart Association?

Sustained hypotension with systolic BP < 90 mmHg for at least 15 min Signup and view all the answers

Which of the following is NOT a component of Virchow's triad?

Right ventricular dysfunction Signup and view all the answers

A patient presents with a systolic BP of 85 mmHg for 20 minutes and requires inotropic support. What category of PE would they most likely be classified as?

Massive PE Signup and view all the answers

What is the primary difference between sub-massive PE and low-risk PE?

Presence of right ventricular dysfunction Signup and view all the answers

A patient has a chest CTA that shows right ventricular dilatation. What category of PE would they most likely be classified as?

Sub-massive PE Signup and view all the answers

What is the primary mechanism by which leukocytic pyrogens reset the hypothalamic thermostat?

By responding to antigenic stimulation from invading pathogens Signup and view all the answers

What is the effect of fever on the body's metabolic rate?

It increases metabolic rate Signup and view all the answers

What is the primary symptom experienced by a patient before their core temperature reaches the new thermostat setting?

Chills and shivering Signup and view all the answers

What is the primary reason for the hypothalamic thermostat reset during fever?

To respond to antigenic stimulation from invading pathogens Signup and view all the answers

What is the effect of fever on the body's heat production and heat conservation mechanisms?

It increases both heat production and heat conservation mechanisms Signup and view all the answers

What occurs when the reason for the thermostat reset resolves?

The body's heat dissipation mechanisms come into play Signup and view all the answers

Which part of the brain contains neurons that respond to cold or warm stimuli?

Hypothalamus Signup and view all the answers

How does the body dissipate heat?

Through conduction, convection, and evaporation Signup and view all the answers

What is the normal variation in body temperature?

+/- 1°F (0.5°C) Signup and view all the answers

What is the effect of exercise on body temperature?

It raises body temperature by 2-3°C Signup and view all the answers

How long does it typically take for night shift workers to adjust to a day shift schedule?

Several days Signup and view all the answers

When do people who work during the day and sleep at night typically register their lowest body temperature?

Between 3:00 and 6:00 A.M. Signup and view all the answers

Study Notes

Classifications of Pulmonary Embolism (PE)

Massive PE: Characterized by sustained hypotension (systolic BP < 90 mmHg for at least 15 minutes) or inotropic support; may cause pulselessness or severe bradycardia (heart rate < 40 bpm) accompanied by shock symptoms.
Sub-massive PE: Shows signs of right ventricular (RV) dysfunction, including RV dilatation on chest CTA, echocardiographic indicators, and biomarkers like troponin or pro-BNP indicating myocardial stretching.
Low-risk PE: No evidence of RV dysfunction or laboratory indicators of strain.

Causes of Venous Thrombosis

Virchow's Triad: Three key abnormalities leading to venous thrombosis:
- Hypercoagulability
- Stasis of venous blood flow
- Endothelial injury

Fever: Definition and Mechanism

Definition: Body temperature maintained above normal, typically considered a fever if over 38.0°C (100.4°F) or 38.3°C (101°F).
Causes: Often a sign of infection, but can be triggered by various factors, including leukocytic pyrogens which elevate the hypothalamic thermostat.
Symptoms: Chills and shivering before reaching the new temperature set point; crisis occurs when the body temperature normalizes, leading to sweating.

Physiological Impact of Fever

Increased Metabolic Rate: Fever elevates both CO2 production and oxygen consumption, leading to rapid, deeper breathing.
Body Temperature Regulation: Hypothalamus monitors body temperature via core thermoreceptors and surface receptors. Heat loss or conservation regulated by blood flow changes and mechanisms like convection, conduction, and evaporation.

Natural Temperature Variations

Normal Body Temperature: Generally averages 98.6°F (37°C), fluctuating by ±1°F based on circadian rhythm and menstrual cycle.
Exercise Impact: Can raise body temperature by 2-3°C.
Diurnal Pattern: Lowest body temperature typically between 3:00-6:00 A.M. gradually rising to peak around 8:00-11:00 P.M.

Signs and Symptoms of Pulmonary Embolism

Deep Vein Thrombosis (DVT): Major source for venous thromboembolism (VTE) leading to PE, with 95% of acute cases originating from leg or pelvic vein thrombi.
Acute PE: Results in RV failure when a large embolus obstructs the pulmonary arterial circulation; small emboli are usually asymptomatic.
Symptoms of Massive PE: Can lead to sudden death; most diagnosed post-mortem.
Symptoms of Sub-massive PE: Includes acute pulmonary arterial hypertension, RV dilation, right ventricular infarction, pleuritic chest pain, shortness of breath, and hypoxia; may also present with low-grade fever and hemoptysis.

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Description

Learn about the causes and effects of pulmonary embolism, including how deep vein thrombosis leads to venous thromboembolism and acute pulmonary embolism. Understand how emboli pass through the right ventricle and reach the pulmonary arterial circulation.