Can pneumonia trigger thrombosis (blood clots)

From the Guidelines

Yes, pneumonia can trigger blood clots, particularly in severe cases, due to the activation of the body's coagulation system by the inflammatory response to the infection, as well as reduced mobility and potential development of sepsis. This is supported by a study published in 2022 1, which highlights the importance of thromboprophylaxis in patients with COVID-19 pneumonia. The study suggests that critically ill patients should receive standard thromboprophylaxis for venous thromboembolism (VTE), and moderately ill patients with a low bleeding risk may benefit from therapeutic heparin.

The connection between pneumonia and clotting is multifaceted:

• The inflammatory response to the infection can activate the body's coagulation system, making blood more likely to clot.
• Patients with pneumonia often become less mobile, which is a known risk factor for clot formation.
• Severe pneumonia can lead to a condition called sepsis, which further increases clotting risk.
• Bacterial pneumonia and COVID-19 pneumonia have been particularly associated with increased clotting risk, as shown in a study published in 2021 1, which reported a high incidence of VTE in ICU patients with COVID-19.

Patients hospitalized with pneumonia are often given preventive measures against clots, such as:

• Blood thinners, such as heparin or low-molecular-weight heparin (LMWH) 1.
• Compression stockings or intermittent pneumatic compression devices to improve blood flow and reduce the risk of clot formation.

It is essential for patients with pneumonia to stay as active as possible (within their doctor's recommendations) and to be aware of symptoms of blood clots, such as:

• Swelling or pain in the legs.
• Sudden shortness of breath.
• Chest pain or coughing up blood.

Overall, the risk of blood clots in patients with pneumonia is a significant concern, and preventive measures should be taken to minimize this risk, particularly in severe cases or in patients with underlying risk factors.

From the Research

Pneumonia and Thrombosis

• Pneumonia can trigger thrombosis (blood clots) due to the activation of the coagulation system and inflammation, as observed in studies 2, 3.
• The risk of thrombotic-related vascular disease, such as myocardial infarction, ischemic stroke, and venous thrombosis, is increased after pneumonia, with incidence rates ranging from 1% to 11% 3.
• Platelet aggregation and clotting system activation, as documented by up-regulation of tissue factor and down-regulation of activated protein C, contribute to the biological plausibility of this association 3.

Hypercoagulable State in Pneumonia

• Patients with pneumonia, including COVID-19 pneumonia, exhibit a hypercoagulable state, characterized by a shorter propagation phase of coagulation and increased maximum clot firmness 4, 5.
• COVID-19 pneumonia is associated with a more severe hypercoagulable state compared to other types of pneumonia, suggesting that COVID-19 itself may contribute to the prothrombotic state 4, 5.
• The hypercoagulable state in pneumonia is thought to be related to the inflammation and activation of the coagulation system, which can lead to the formation of blood clots 2, 3.

Clinical Implications

• The increased risk of thrombosis and hypercoagulable state in pneumonia highlights the importance of monitoring and managing coagulation profiles in patients with pneumonia 3, 4, 5.
• Antithrombotic drugs may be considered as a therapeutic strategy to prevent thrombotic-related complications in patients with pneumonia, although further research is needed to determine their effectiveness 2, 3.