Carpal tunnel syndrome is one of the most common and familiar medical conditions seen in personal injury litigation. Almost everyone's heard of this condition and probably knows someone who has experienced it, but over the years I've realized how poorly it is actually understood. In this article I will provide a basic appreciation of the anatomy involved in this pervasive condition, as well as an overview of the surgical procedure that often prove necessary for treatment.
First, we must recognize that the carpal tunnel really is a tunnel. It is a passageway on the palmar side of the wrist, right beneath the wrist crease where the wrist bends on the end of the arm, where the tendons the bend the fingers pass from the arm down into the hand. This tunnel is bordered by the bones of the wrist (carpal bones) on the bottom and the flexor retinaculum (transverse carpal ligament) on the top and the tendons pass through this tunnel moving back and forth as they pull and release the fingers facilitating the normal actions of the hand. Of importance we note that, along with these tendons, the median nerve also passes through the carpal tunnel. The median nerve is a major nerve that branches off of the brachial plexus in the shoulder region and courses all the way down the arm, passing through the carpal tunnel into the hand. The median nerve is responsible for innervating much of the hand including the thumb, index finger, middle finger and the inner half of the ring finger. Under normal circumstances, the median nerve is unaffected by the frequent movement of the various flexor tendons around it within the carpal tunnel.
Carpal tunnel syndrome is an assortment of symptoms resulting from compression of the median nerve within the carpal tunnel. This can involve pain, numbness, tingling and weakness of the hand or extending up the arm toward the elbow. This compression of the median nerve occurs when other structures in the carpal tunnel region (tendons, bones, flexor retinaculum or synovial linings) become inflamed and swollen and push against the other structures overfilling the space within this tunnel. This inflammation can result after injury such as strain of the tendons or fracture of the bones, or as a result of the stress caused by repetitive motions such as typing, using hand tools, playing sports or playing a musical instrument, etc. There are also certain diseases such as arthritis, diabetes, acromegaly and hypothyroidism can contribute to carpal tunnel syndrome, but these factors are not as commonly seen in litigation. Carpal tunnel syndrome is often treated with immobilization for a few weeks with a splint or brace. Anti-inflammatory medications, such as ibuprofen, are also helpful and sometimes corticosteroid injections may be administered. But in some cases, these conservative treatments are not successful and surgery is necessary to decompress the median nerve. This surgery is called carpal tunnel release or median nerve decompression and it involves the complete transection (division) of the flexor retinaculum that forms the roof of the carpal tunnel. This surgery may be performed through an open incision or done arthroscopically with a scope and instruments inserted through much smaller incisions.
In personal injury litigation, orthopedics cases are generally the most straightforward. Unless there is a complex joint injury or a pre-existing condition, most laymen are going to be able to understand your average fracture case. Presentation of the injuries is usually quite straightforward as well, primarily because most orthopedics cases will have clear-cut radiological evidence: X-rays, CTs or MRIs. With such a straightforward topic and such abundant evidence and documentation, the demonstrative evidence solutions available are almost endless. The final option selected often depends on your personal preferences, presentation style, strategic priorities and budget. It comes down to, “How far do you want to take it?”
In this article I will discuss many of the various presentation options you have available to you in an orthopedics case ranging from the most simple to the most complex. I will provide the pro’s and con’s of each approach and try to provide some general ballpark figures for costs. I will also provide links to various examples so that you can better understand each option. Hopefully this will help you to decide which approach best meets your individual expectations when it is time for you to shop around for your demonstrative evidence solution.
If you’re in luck, you may have good film evidence that clearly shows the fractures in you case. X-rays can be printed and enlarged at a variety of facilities and can often prove to be adequate and inexpensive demonstrative evidence. This works best with long bone fractures in which the fracture is clear and unmistakable. It is not as effective if the fracture is small or in a complex region such as a joint or in the skull since those fractures are more difficult to identify on films. The upsides to simple enlargements include the price that will usually be around $200 and the ease of admissibility. The downsides include lack of drama with static black and white films and the intimidation factor that some laymen may feel when asked to review even the simplest radiological study.
A step above simple film prints is a radiological colorization. This is a process in which your illustrator will create a digital copy of your X-ray, CT or MRI and add simple flat color to the various structures and possibly more detail in the area of the actual injury. While this type of exhibit does not have the detail and clarity of a fully rendered medical illustration, it makes the film more accessible, understandable and dramatic while keeping costs down and retaining the authority of the actual film evidence. Simple colorizations can be acquired in the $300 to $600 range.
Next, in the level of complexity is what I refer to as a radiological film interpretation and is another product option based specifically on the film evidence. Unlike a colorization where simple flat color is added, interpretations provide a fully rendered illustration of the skeletal anatomy based on a precise tracing of the actual film evidence. This type of process gives the image more texture and three-dimensional appearance allowing even the smallest fragments and details to be shown. Since this type of image is more realistic in appearance, it will often be more dramatic as well. The costs for this type of presentation could range from $700 to $900.
Of course anatomical models continue to be a popular option for demonstrative evidence and there is a certain appeal to carrying a physical model into court that one can touch and pass around. The downside is that models most commonly are only available to demonstrate normal anatomy. While it is possible to acquire a custom model showing the actual injury, this custom process is often quite expensive. An alternative is to start with a normal anatomy model or skeleton and have your expert draw on the site or sites of fracture with a marker. While this would certainly help you to identify the sites of the injuries, it does not offer the drama that a depiction of the actual injury would provide. Anatomical models range widely in price, but even a full skeleton can be bought for as little as $300.
The most popular option for medical demonstrative evidence is still traditional medical illustrations. These are images created by a skilled illustrator based specifically on your case information. While these exhibits could certainly incorporate the film evidence, the illustrator is not tied to these films as the only source of information. Therefore, unique views are possible that may not be seen in any one film to best demonstrate the injuries in a clear and dramatic fashion. Surgeries may also be incorporated into medical illustrations. An experienced medical illustrator can interpret the narrative report from a written operative note and provide a step-by-step depiction of the key steps of this procedure. Another popular illustration format is to provide a “progression of condition” showing the same area of anatomy over time. This can allow you to compare normal anatomy, the post-accident injury, the post-operative condition and later complications. Flexibility is the primary attribute for this type of exhibits since almost any conceivable issue can be portrayed. Prices can range from $800 to over $2000 depending on your provider and the complexity of the information. The most dramatic type of presentation available is custom animation. Today’s technology allows for almost any structure to be modeled electronically in 3D so that your medical animator can show the anatomy, the injury or even the surgical procedure in a fully custom motion picture presentation. These animations present the information in an understandable and accessible way that appeals greatly to the younger generation that has come to expect such media. Animations are especially effective in cases that involve motion allowing you to show how injuries occur, how they affect bodily function or how they are repaired. The downsides are primarily the time and cost involved. Since the animation process is so much more involved, you should anticipate approximately 300 to 400% more time for production with a comparable increase in cost.
The final option we should cover is interactive electronic presentations. The may range from simple PowerPoint presentations combining a few pictures and text pages to fully custom professionally designed programs incorporating animations, video, photographs, illustrations and all kinds of supporting documentation. These types of presentations are growing in popularity as more and more in the legal market become comfortable with the technology required. The primary benefit of electronic presentation is the organizational advantages when all your demonstrative evidence is combined and accessible through your laptop. No longer do you have to carry multiple charts and graphs into the courtroom and constantly put up and take down items from the easel as you move from topic to topic. Disadvantages include the technology and equipment required for display and the possible limitations of your presentation environment. In other words, you will need to have a solution for projecting or displaying the presentation and you will need to become comfortable with the technology required, and you will need to give consideration as to the facility where you will be presenting and determine if any equipment will be available to you and if the light levels will allow for the proper viewing on your projection screen or monitor. Prices vary widely depending on the amount and complexity of your information.
So, as you have seen, even the most simplistic orthopedic case can leave you with a complex set of decisions to make when you begin to plan your presentation. You can stick with the basic traditional approaches or may decide to add dramatic impact by trying more modern technology solutions. Of course price is always and issue, so it is good to determine in advance what your budget will allow. At the end of the day, it all boils down to a question of “how far do you want to take it?”
The large majority of heart attack cases that we see litigated involve a failure to diagnose developing coronary artery disease and, to a lesser extent, the failure to treat it. To help provide a better understanding of these issues I’ll provide an overview of heart attacks and coronary artery disease, the reasons for and risks of misdiagnosis, and the most common types of treatment that are available when a timely diagnosis is made.
Even though blood is pumping constantly through the internal chambers of the heart, separate vessels called coronary arteries run along the surface of the heart and supply the blood to the actual muscles that make up this vital organ. A constant flow of oxygenated blood through these coronary arteries is essential if the heart is to continue working properly. If blood flow through one or more of these vessels is significantly slowed or blocked completely the heart muscle will struggle and eventually die, a condition called myocardial infarction (localized heart muscle death). This blockage of blood flow is most commonly caused by coronary artery disease, although other events such as emboli (blood clots) vegetative growths or even trauma can block these vessels. Coronary artery disease is a condition in which plaque (plak) builds up inside the coronary arteries. Plaque is made up of fat, cholesterol (ko-LES-ter-ol), calcium, and other substances found in the blood. When plaque builds up in the arteries, the condition is called atherosclerosis (ATH-er-o-skler-O-sis). This is generally a prolonged process that develops over time causing angina (an-JI-nuh) prior to a heart attack. Angina is chest pain or discomfort that occurs when not enough oxygen-rich blood is flowing to an area of heart muscle. Angina may feel like pressure or squeezing in the chest, or may occur in the shoulders, arms, neck, jaw, or back.
Because the formation of coronary artery disease is prolonged and is often heralded by angina pain, litigation often arises when a patient seeks treatment for typical pain complaints but is misdiagnosed when possible links to heart disease are overlooked. Pain is a common complaint and a treating physician may initially suspect that the symptoms are linked to muscle soreness or joint strain in the affected regions including the shoulder and spine. In such cases, specific tests for heart problems may not even be considered much less performed by the physician. This delay may prove disastrous if the blockages of the coronary arteries worsen and lead ultimately to a myocardial infarction.
If detected in time, there are several alternatives for the treatment of coronary artery disease. First, medication may be considered. These medications could include blood thinners to help the blood pass more freely through an area of partial blockage, or clot-buster medications to prevent or break up blood clots that may be contributing to the blockage of blood flow. Blood pressure and cholesterol control medications may also be given to provide more long-term treatment of coronary artery disease.
In addition to medications, there are a variety of surgical options that are also available for the treatment of coronary blockage. These consist mainly of angioplasty and surgical coronary artery bypass. Angioplasty is the treatment of an arterial blockage from the inside of the vessel. A catheter is inserted into an artery in the groin and advanced up through the aorta to gain access to the root of the coronary arteries. Through this catheter an inflatable balloon can be inserted into the area of blockage and expanded to push open a larger channel for the blood to flow. A stent (wire mesh tube) may also be placed into this site to hold the vessel open permanently. Coronary artery bypass involves the placement of a graft from above the site of blockage to below the site to allow blood flow to detour around the blockage. These grafts may be synthetic tubes or vessels harvested from the patients chest or leg. The mammary artery from the chest wall or the greater saphenous vein from the leg are both commonly used for this purpose.
There was a time when gallbladder and cholecystectomy issues were the most common medical malpractice cases that we saw. In recent years, complications of gastric bypass surgery may have become even more common in medical malpractice. The rise of the number of these cases being litigated is probably due to a number of factors and is open to debate, so I won't go into that nest of hornets. But I have seen a common need for a general orientation to the anatomy and surgical techniques involved, so that is the topic of this piece.
First, lets cover the purpose of gastric bypass. For those obese patients who find it impossible to lose weight through traditional diet and exercise programs, gastric bypass surgery can be effective. This surgery involves a dramatic reduction in the size of the stomach reducing the amount of food that can be consumed in any one meal and therefore imposing caloric intake restrictions on the patient after surgery.
To understand the surgery, you must first understand the basics of the anatomy involved. Food that is swallowed flows down through a muscular tube called the esophagus that extends from the throat down through the posterior chest, behind the heart, and into the upper abdomen where it empties into the stomach. After being substantially broken down by the gastric juices, the bolus of food then leaves the stomach and moves into the small intestine, another muscular tube that leads to the colon. It is also important to know that bile from the liver and pancreatic juices from the pancreas, which both affect digestion, also empty into the first segment of the small intestine just past the stomach.
In a gastric bypass the stomach is divided so that only a small portion of the upper part of the stomach is left attached to the esophagus. Although food can still get into this small pouch through the esophagus, it cannot get out, so a way must be devised to allow the food to exit. To accomplish this, the small intestine is divided a few feet below the stomach and the distal (furthest away) segment is pulled up and attached to the bottom of the stomach pouch. This connection of the small intestine to the newly created stomach pouch reestablishes the flow through the digestive system, but what of the gastric juices in the lower part of the stomach and the bile and pancreatic juices that enter into the proximal small intestine? They still need a route to escape and join with the digestive contents. Therefore the small segment of the small intestine above the loop that has been pulled up to the stomach is attached to the side of this loop so that the digestive juices in the proximal segment can join with the flow well below the stomach. When you look at this new architecture of the small bowel, it appears to form a Y, thus the name "Roux-en-Y".
Finally, let's look at the language a bit more closely. Most laymen are put off by the excessively medical sounding title "Roux-en-Y anastomosis". Don't let the name scare you. First, what is an anastomosis? It's simple. Just know that an anastomosis is a connection between two tubular structures. This could be a connection between two blood vessels, two bile ducts or in this case, two segments of bowel. So what about Roux-en-Y? Don't let the name of the famous Swiss surgeon throw you off. A Roux-en-Y anastomosis is any connection of any two segments of bowel in a Y-shaped pattern, so the "Y" part of the name is what is important for you to remember. So long as you understand that this procedure involves a transection of the bowel, connection of the distal segment to the stomach and connection of the proximal segment of the bowel lower down on the distal segment, it will be clear to you. See the animation at the top of the article and you will see that this is a rather straightforward concept.
Although previous articles have covered the basics of intervertebral disc injuries, as well as some other more unusual spinal injuries, I have been told that I have neglected to give a good overview of the more common spinal surgeries. Certainly it would be impossible to cover all the possible surgical procedures one might encounter in a case involving a spinal injury, but I can certainly provide a brief orientation to the surgeries most commonly seen in this type of litigation. These procedures include cervical, thoracic and lumbar surgeries, both anterior and posterior exposures, and everything from laminectomies and discectomies to foraminotomies and fusions.
Of course, as with any surgery, to fully understand what is being done you need a good fundamental grasp of the anatomy. But often I see that understanding each and every structure in the spine or struggling with the long words used in these surgeries is an impediment to a basic understanding of the procedures. I find that, rather than dwelling on the discs and various intricacies of the vertebrae, it is easier to first understand the simple basics of the spinal cord and nerve roots since the vast majority of these surgeries boils down to stabilizing or relieving pressure on these nerves. Think of the spinal cord as a major highway that runs its entire course within a tunnel. This tunnel is the spinal canal formed by the rings within the various vertebrae that are stacked one below the other from the skull all the way down to the pelvis. Think of the nerve roots as exits from the spinal cord highway that need to emerge from the tunnel of the spinal canal. These nerve roots exit through foramen, or channels, on either side both right and left where every two vertebrae come together. The surgeon’s primary concern is maintaining the flow of traffic through this highway and on these exits, making sure that the spinal cord and nerve roots are not compressed or pinched.
Let’s talk about the four most common types of spinal surgery first. These are laminectomy, discectomy, foraminotomy and fusion. We’ll deal with each separately although there is some crossover and any combination of these might be performed in the same surgery.
• Laminectomy – While the vertebral bodies and discs lie anterior to the spinal cord, the laminae are the flat shields of bone that form the posterior (back) border of the spinal canal. They normally protect the spinal cord from being damaged from direct impact from behind. If the disc protrudes beyond its normal location back into the spinal canal, the spinal cord can become compressed between the protruding disc material and the laminae. A laminectomy, or removal of the laminae, can be performed to decompress the spinal canal and give the spinal cord a bit more room to move around. This may be all that is required to relieve the problem. More often, the laminectomy is performed not so much for decompression, but rather to allow the surgeon to access the deeper structures within the spinal canal, to create a doorway. Variations of the laminectomy are the hemilaminectomy when only the right or left half of the laminae are removed, and the laminotomy in which only a window of bone is removed from the lamina.
• Discectomy – This procedure is simply the removal of all or part of the damaged intervertebral disc either because it is bulging or herniated back into the spinal canal. This can be done from the front (anteriorly) or from behind (posteriorly). The anterior approach is generally preferred in the cervical spine (neck) since it allows the surgeon to access the disc without having to manipulate or go around the spinal cord and therefore avoiding damage to the cord. On the other hand, even though the spinal cord has to be manipulated, a posterior approach is traditional in lumbar (lower back) cases since this approach avoids the issues of the abdominal structures and major vessels that lie anteriorly. But, over the years, anterior approaches in lumbar cases have become more and more common. Today you may be just as likely to encounter an anterior lumbar procedure.
• Foraminotomy – This procedure is simply an enlargement of the neural foramen, the channel through which the nerve roots exit the spinal canal. This passageway may be narrowed due to herniated disc material or by degenerative arthritis that manifests as an overgrowth of bone. Regardless, for one reason or another, if the foramen becomes narrowed it can put pressure on the exiting nerve root. This can lead to severe pain and neurological dysfunction. To relieve this condition the surgeon must access the foramen and scrape it out removing the offending disc or bone material.
• Fusion – Certainly there are more types of spinal fusion techniques than I can count on my fingers and toes combined. It seems that every year there are new hardware and materials being developed and new techniques associated with each. But let’s stick with the basics. If a disc is damaged and must be removed or if the interspace between two or more vertebrae is unstable, a fusion can be performed to make a permanent connection between two or more vertebrae. The eventual goal of any fusion procedure is to actually get the bone of the fused levels to grow together, using the power of the body’s own healing ability to create a strong connection. But this takes time, so a variety of hardware can be employed to temporarily stabilize the fusion site while the bone growth takes place. This hardware may consist of devices placed within the disc space, or plates, screws and rods placed either anteriorly or posteriorly. Due to the variety possible, I will publish future articles dealing with this topic in more detail.
Finally, I will mention a few additional procedures that, although not as common as those described above, may be encountered from time to time in your practice. A corpectomy is the complete or partial removal of a vertebral body. A kyphoplasty is the injection of cement or other synthetic material into a compressed or collapsed vertebral body to restore the proper height and alignment. Intradiscal electrothermal (IDET) therapy is the insertion of a wire or coil into a damaged disc that can be heated to cause the disc material to contract and relieve nerve compression. A disc replacement is the placement of a mechanical device into the disc space to restore stability without the loss of flexibility caused by traditional fusion. Click on any of the links above to see examples of the various procedures discussed in this article.
Most of you will have already read my January, 2009 article on the basics of shoulder dystocia and are familiar with the most common type of dystocia, or impediment to the delivery of a baby, where the anterior shoulder of the baby becomes lodged behind the pubic symphysis at the front of the mother’s pelvis. This is called anterior shoulder dystocia and accounts for the vast majority of dystocia cases I see litigated by my clients. If you are familiar with anterior shoulder dystocia, you have a great foundation, but there are other types of dystocia and other topics associated with this issue that I will cover in this article. This will provide you with a more advanced understanding of what you may encounter in future obstetrics malpractice cases.
Unlike anterior dystocia, where the anterior shoulder of the baby becomes lodged, in posterior shoulder dystocia the shoulder of the baby that is closest to the mother’s spine or sacrum is the one that becomes stuck. Generally, this posterior dystocia occurs when the posterior shoulder of the fetus becomes lodged on the protruding sacral promontory, which is the upper lip of the sacrum at the base of the lumbar spine. Also, I have seen one case that involved a mother with an unusually curved coccyx, tailbone, on which the posterior became stuck. Either way, the point is that posterior shoulder dystocia, while rare, is possible, so you should be sure of the facts before you assume your case involves the more common anterior type.
Another issue that arises in many of these shoulder dystocia cases is the actions taken by the healthcare provider that might exacerbate the situation. While attempting to dislodge an infant that is not progressing there are many things that should not be done, but in my experience there are two mistakes most commonly associated with brachial plexus nerve injuries. The first is excessive traction or pulling on the baby’s head, especially traction in which the head is pulled downward away from the lodged shoulder. This traction can be done with the hands, with a vacuum extractor or with forceps, and while some traction is necessary in many births, excessive traction in cases of shoulder dystocia can lead to devastating nerve injury. The second issue is fundal pressure. This is when a nurse or assistant pushes down on the upper part of the mother’s abdomen in an attempt to force the baby out. Once again, in cases where the shoulder is stuck, this force can lead to nerve injury. Force is the issue whether it is pulling force or pushing force. If the shoulder is stuck, it must first be dislodged before labor can progress.
Although downward traction and fundal pressure are maneuvers that should be avoided, there are several acceptable maneuvers that can often release the shoulder of the infant. Of all of these, some so desperate that they include fracturing the collar bone of the fetus, there are three that we so most frequently in these cases. The first is called the McRoberts maneuver. This is simply the elevation of the mother’s legs with the knees forced back toward the abdomen. This flexion of the hips causes a substantial change in the angle of the pelvic outlet that can often allow for more easy passage of the infant. Next, there is suprapubic pressure. In this maneuver, a nurse or assistant presses down on the lower abdomen directly above the mother’s pubic bone providing direct pressure on the baby’s shoulder and hopefully dislodging the dystocia. Finally, there is the Woods corkscrew maneuver. This maneuver involves the insertion of the doctor’s fingers into the vaginal canal just behind the baby’s posterior shoulder. Then, with gentle pressure, the shoulder can be rotated in a corkscrew fashion turning the baby into a more horizontal orientation and releasing the anterior shoulder from behind the pubic symphysis of the mother.
Looking back on 2009, our records show that, once again, pulmonary embolism ranked as the most common medical malpractice issue litigated by our clients. These cases involve blood clots formed in the veins that break off and travel to the chest, through the heart to become lodged in the lungs causing respiratory distress. The popularity of this topic encourages me to provide my readers with a bit of background information. Although the basic mechanism of a pulmonary embolism is straightforward, there are associated issues and terminology that you should be familiar with before you encounter one of these common cases in your future practice.
First of all, why are pulmonary embolism cases so common? Most likely this is because pulmonary emboli can be secondary conditions resulting from prolonged inactivity such as surgical procedures, bed rest or even lengthy airline travel. Therefore, there are a large number of situations that might put a person at risk for this dangerous complication. Generally litigation revolves around the failure to prevent, diagnose or properly treat these emboli.
To understand the mechanism of a pulmonary embolism, we must first understand the anatomy of the veins. The veins are the system of vessels throughout the body that return blood from the various body regions to the heart. Unlike arteries, the veins do not have high internal pressure to keep the blood moving along but actually require assistance from the muscle contractions involved in normal daily activity. This problem of moving the blood along is most pronounced the further the veins are from the heart, and since gravity also acts against venous flow the flow of blood is slowest in the lower extremities (legs and feet). This slowing of blood flow in the veins is a key component in the mechanism of pulmonary embolism. In situations when the body is immobilized due to surgery, convalescence or prolonged inactivity there are no muscle contractions to assist in speeding blood flow. In these cases, flow can slow to such an extent that the normal clotting factors within the blood begin to react and form blood clots. This is often seen at the site of a valve in the vein where blood can pool within the eddy behind the leaflet of the valve. This clot that remains at the site in which it originally formed is referred to as a thrombus. The formation of these clots is called deep vein thrombosis (DVT).
Once a thrombus is formed within a deep vein, it will continue to grow as additional clotting factors collect and adhere themselves to the original clot. But this thrombus is not completely stable. The real problem lies in the fact that pieces can break off from the thrombus and join in the blood stream to be carried upward toward the heart and lungs. Once a clot joins the blood stream and begins to move, we no longer call it a thrombus. It is now called an embolus. To reach the heart and lung from the legs, the embolus must travel up through the inferior vena cava, a large vein in the posterior abdomen. Eventually the embolus will reach the heart where it will travel through the left atrium and ventricle and be pumped out into the pulmonary arteries that lead to the lungs. This embolus will continue to travel within the pulmonary vasculature, which divides again and again into smaller and smaller arteries within this tree-like network, until the embolus reaches a vessel too small to pass through. At this point the embolus will become lodged forming a dam that will block further blood flow through this artery. This blockage of blood flow and the resulting reduction in lung function is called an embolism.
Generally, the smaller the embolus, the less severe the effects will be since a smaller percentage of lung volume will be affected by the blockage of a smaller pulmonary vessel. But often there are a number of emboli released at once or over time leading to a "shower" of emboli that can cause multiple blockages to one or both lungs. These multiple blockages can be as severe as one larger blockage resulting in a higher percentage of total lung function being lost. The most severe form of embolism is referred to as a saddle embolus. This type of embolus is so large that it cannot pass beyond the bifurcation (division) of the main pulmonary trunk into the left and right main pulmonary arteries and therefore causes a sudden blockage of blood flow into both lungs. This condition can often be almost instantly fatal.
The healthcare provider's first responsibility is prevention of deep vein thrombosis. During prolonged surgery, compression stockings and pneumatic compression devices can be used to increase circulation and prevent the pooling that leads to thrombosis. Medications can also be given to thin the blood and prevent clotting. If prevention of clotting in the legs is unsuccessful, medication or even surgery may be necessary to break up and remove the clots from the deep veins. Also, mechanical filters can be placed within the inferior vena cava beneath the heart to prevent emboli from reaching the lungs.
So, as you can see, these cases are generally rather straightforward. A thrombus forms in the deep veins due to inactivity. Pieces of the thrombus break of and join the bloodstream as emboli. These emboli travel through the inferior vena cava and heart to the lungs. These emboli block blood flow through pulmonary arteries creating an embolism that can lead to respiratory distress and possibly death. Those are the basics, and if you can appreciate the basic mechanism, it should be easy to understand any slight variations that may arise in any unique case.