What is a pulmonary embolism?
Pulmonary emboli are blood clots that travel to the lungs from larger thrombi, or clots, that form in the deep veins of the lower extremities. These larger thrombi occasionally develop in the pelvic veins, renal veins or the chambers of the right side of the heart. However, in the postoperative period, most pulmonary emboli result from thrombi in the veins of the legs. In the United States, the incidence of pulmonary embolism is estimated at one case per thousand people each year. In patients with lower extremity deep vein thrombosis (blood clot), the clot will break off or embolize and travel to the lungs in approximately 60% to 80% of this group.
Pulmonary embolism, also called “PE,” is the third most common cause of in-hospital mortality. Autopsy studies of patients who died in hospital have shown that 60% had pulmonary embolism, with missed diagnosis in almost 70% of cases
If you have reason to believe that a pulmonary embolism should have been diagnosed or treated and, as a result, a loved one has died, please contact the experienced medical malpractice lawyers of Passen & Powell today by calling 312-527-4500.
Why is it important to prevent pulmonary embolism?
To understand why a clot in the vascular system of the lungs can be a devastating condition, it helps to have some understanding of the circulatory system of blood. Basically, blood is the way oxygen from the environment is delivered to all of the body’s tissues, which require oxygen for cellular survival. Without oxygen, tissues of the body quickly die.
The arteries carry oxygen throughout the body and they perfuse the body’s tissues in capillary beds, nests of small and permeable blood vessels. This is where the hemoglobin molecule in red blood cells releases the oxygen molecule it acquired in the lung. The cells absorb the oxygen and simultaneously release carbon dioxide, a waste product of the metabolic processes that keep cells alive. Carbon dioxide diffuses into the venous system (veins) and is carried away from the tissue returning to the lungs once again, after traveling through the right side of the heart. When the deoxygenated blood with its burden of carbon dioxide waste reaches the lungs, the carbon dioxide diffuses out of the lungs during exhalation, and the hemoglobin molecule in the red blood cell once again attaches oxygen molecules and the process repeats itself.
The role of the heart:
If you wonder how often your blood circulates through your body, consider that each heart beat represents a contraction of the heart, and during the period of contraction, oxygenated blood that has traveled from the lungs to the left side of the heart is pumped out through the aorta, the largest artery in the body, to be distributed through the arterial system again. The normal heart rate varies among individuals, and well-conditioned athletes may have a more efficient cardiovascular system that pumps 50 beats per minute at rest, although most of us normally range around 72 beats per minute. When you exercise or when your body has a higher oxygen demand, you normally meet that demand by increasing your heart rate. So at rest, your blood travels the entire circuit, delivering oxygen and returning carbon dioxide waste 70 times a minute. On average, the heart pumps 5 liters or about 1.3 gallons of blood each minute, or about 1900 gallons each day.
A short explanation of the anatomy of the heart and lungs may help you understand the dangers caused by blockage of a pulmonary blood vessel with a blood clot.
The heart is built with four chambers, called atria and ventricles. The right side of the heart receives the venous, or deoxygenated blood from the rest of the body through the final common pathways of the superior and inferior vena cava. These vessels are labeled in the diagram below:
These two large veins empty into the first chamber of the right side of the heart, the right atrium. When the tricuspid valve opens during the cardiac cycle, the deoxygenated blood flows into the right ventricle and as the right ventricle contracts during the cardiac cycle, the pulmonary valve opens to allow the deoxygenated blood to flow into the lungs through the vessel called the pulmonary artery. (I want to clarify this briefly, because I said earlier that arteries carry oxygenated blood. The pulmonary artery is the only artery in the body that carries deoxygenated blood, and blood flows through this vessel into the lungs where it travels through the smaller arteries and arterioles to “vascular beds.”) In the lungs, the carbon dioxide is released and exhaled, while inhaled oxygen diffuses into the blood, which then flows into the pulmonary vein into the left side of the heart.
The left side of the heart is a workhorse, and it also has two chambers, the left atrium and left ventricle. The freshly oxygenated blood flows into the left atrium, and during the heart’s cycle of contraction, the atrium empties into the left ventricle. The left ventricle pumps the freshly oxygenated blood into the large aorta, under high pressure, and this blood then carries oxygen through the muscular vessels known as arteries throughout the circulation system to all of the cells in your body. A diagram of the circulatory system of the body is pictured below. By convention, the veins are always blue in these diagrams, and the arteries are red. When looking at the diagram, notice the large blue veins in the legs and thighs and trace their course back to the right side of the heart, where the deoxygenated blood returns to be pumped into the lungs to be refreshed.
What Happens When a Clot Travels from the Veins in the Legs to the Lungs?
This is what occurs in the condition known as pulmonary embolism. A piece of clotted blood travels back through the inferior vena cava into the right side of the heart and then into the lungs. If it is a large enough piece of clot, it will obstruct the blood vessel taking blood into the sections of the lung that depend upon that particular branch of the circulation to perfuse the lung tissue. This means that the portion of lung that is not receiving blood cannot oxygenate part of the blood flowing through the cardiopulmonary system. This results in lower levels of oxygen in the blood that returns to the body. The patient with this condition may become short of breath and experience chest pain. Supplemental oxygen is required. In addition to lower levels of oxygen in the blood, patients have death of lung tissue from failure to receive oxygen in the blocked region. Many patients hyperventilate in an effort to inspire more oxygen.
One important consequence of a pulmonary embolism is an increase in resistance to blood flow in the lungs from the right heart. This is because the area of the vascular bed is decreased due to the obstruction. When resistance to blood flow occurs in the lungs, it causes increased pressure on the right ventricle of the heart that is pumping blood into the lungs. Normally, the right ventricle does not have to push against high pressures, but in this case, if the pulmonary embolism is large enough, right-sided heart failure can occur. The consequences of this include hemodynamic collapse, or low blood pressures throughout the rest of the body since the left heart depends upon the action of the right heart to pump returning blood into the lungs so it can be oxygenated and pumped out through the left heart to the body. Death can rapidly ensue if this condition is not treated, and with a massive pulmonary embolism, treatment may be delayed due to misdiagnosis or delay of diagnosis, or the treatment may simply be too little, too late. Treatment may be invasive and not rapidly available.
Why Should You Worry About a Pulmonary Embolism After Surgery?
Under normal circumstances, small clots form and are lysed by the body’s natural enzymes throughout the day. However, some conditions are known to predispose patients to formation of large thrombi in the lower extremities. In medicine, the three types of risk factors that were first identified by Dr. Virchow are stasis of blood, coagulation abnormalities, and damage to the thin inner lining of the blood vessels.
These risk factors can occur under a variety of circumstances, including long plane trips, pregnancy, or cancer, but today we will focus on the formation of clots that cause pulmonary embolism in the postoperative patient.
When you have had surgery, you are immobilized. This causes your blood to pool in the venous system, which, unlike the arterial system, relies upon skeletal muscles to contract and compress the veins to return blood towards the heart. Valves within the veins also prevent backflow. Immobilization causes stasis, the first risk factor. Surgical procedures, particularly orthopedic procedures in the lower extremities, cause damage to the veins that have been transected in the course of the operation. This is one example of endothelial damage. These two factors are the primary reasons for formation of postoperative deep venous blood clots (DVT) in the postoperative patient.
All physicians should be aware of this and the standard of care after a surgery is for a patient to receive some sort of prophylactic, or preventative treatment. The majority of pulmonary embolisms in hospitalized patients can be prevented. Some measures commonly taken to prevent this dangerous complication include devices that sequentially compress the lower extremities, and medications that prevent coagulation (clotting). These medications include heparin or warfarin.
Medical Malpractice Issues Associated With Pulmonary Embolism
If you or a loved one has experienced a pulmonary embolism and your physician failed to anticipate and provide preventive treatments in high-risk situations, you may be a victim of medical malpractice.
This exact problem has resulted in multiple large clinical studies designed to reduce mortality and morbidity through development of clinical guidelines for management. Failure to adhere to the standards of care in this case may result in death. If an unexplained death occurs in your family member while hospitalized, contact us immediately and consider authorization of an autopsy, as many diagnoses of PE are made at autopsy and are a frequent cause of unexplained sudden death in hospitalized patients.
Other common bases for medical negligence cases arising out of pulmonary embolisms include the failure of the hospital staff or physician to adequately investigate the patient who is complaining of symptoms that could be consistent with a pulmonary embolism. These symptoms include hyperventilation, a feeling of impending doom or anxiety, and shortness of breath. Some doctors may diagnose unexplained postoperative chest pain as a musculoskeletal problem and they fail to begin the appropriate workup to determine whether or not the patient has a probable PE. If there is a high suspicion of a PE, anticoagulation therapy with heparin must be initiated, and if this is not done in a timely manner, the clot may increase in size with significant consequences for the patient.
Finally, the physician may fail to consider or to advise the patient of any other risk factors they have for development of PE, which include pregnancy, use of oral contraceptive pills, smoking, and other preexisting medical conditions.
If you or a family member has experienced severe injury or death as a result of inappropriate preoperative and postoperative care resulting in a pulmonary embolism, you should contact one of Passen & Powell’s Chicago trial attorneys with experience in medical malpractice cases. Call us at 312-527-4500.
