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Cirrhosis and Its Complications Catch This Liver Scarring Problem Early, Because Its Effects Can Be Life-Threatening

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Cirrhosis and Its Complications Catch This Liver Scarring Problem Early, Because Its Effects Can Be Life-Threatening Cirrhosis and Its Complications Catch this liver scarring problem early, because its effects can be life-threatening By Scott R. Snyder, BS, NREMT-P, Sean M. Kivlehan, MD, MPH, NREMT-P, & Kevin T. Collopy, BA, FP-C, CCEMT-P, NREMT-P, WEMT This month’s CE article looks at cirrhosis and its complications. In an attempt to best understand the signs and symptoms and progression of this disease, we will review the anatomy, physiology and pathophysiology of the liver and cirrhosis and the clinical manifestations of the disease and its complications. ANATOMY OF THE LIVER The liver is the largest visceral organ in the body, and the majority of its mass is located in the upper right abdominal quadrant and extends into the upper left quadrant, lying directly below the diaphragm. It weighs about 3.3 lbs. (1.5 kg) in the average adult male. The liver is encased in a tough, fi brous capsule (Glisson’s capsule) and covered by a layer of visceral peritoneum. It is held in place in the abdomen by several ligaments, including the falciform, round and coronary ligaments. The gallbladder is a small, hollow, pear-shaped muscular sac that lies on the posterior surface of the liver. While not a true part of the liver, it works closely with the liver to store and secrete bile produced in the liver to aid digestion. Blood Supply The liver is the largest blood reservoir in the body, receiving about 25% of the cardiac output. It is unique in that it has a double blood supply, receiving blood from both the hepatic portal vein and hepatic arteries. The hepatic portal vein delivers approximately 66% of the liver’s blood supply and carries venous blood drained from the spleen, gastrointestinal tract and other organs.1 It supplies nutrients and other essential chemicals absorbed by the digestive tract. The hepatic arteries supply oxygenated arterial blood to the liver, accounting for the remaining 33% of its blood fl ow.1 Hepatic Portal Circulation The splenic vein, gastric vein, esophageal vein, and inferior and superior mesenteric veins all feed into the portal vein and together comprise the hepatic portal circulation. Some of these blood vessels surround the esophagus and stomach, and the mesenteric veins contain products absorbed from digestion in the GI tract. The liver then performs its functions on this venous blood, processing useful products of digestion and fi ltering out toxins. Liver Cells The liver is divided into approximately 100,000 individual lobules, the basic functional unit of the liver. Located in the lobules are the liver cells, or hepatocytes. Each hepatocyte is in contact with at least one of the sinusoid blood vessels that run between the portal and central veins. Another type of cells found in the liver are phagocytic macrophage cells called Kupffer cells. These are located in the sinusoids and engulf cell debris, pathogens and old or damaged red blood cells. Blood fl ows into the liver via the hepatic arteries and portal vein, then through the liver sinusoids and empties into the central vein of each lobule. The central veins coalesce into hepatic veins, which leave the liver and drain into systemic circulation via the inferior vena cava. As such, the blood supplied to the liver is brought into contact with hepatocytes, which perform the majority of functions performed by the liver (Table 1). Bile produced by the hepatocytes drains into bile canaliculi and then the hepatic ducts on its way to storage in the gallbladder. Simply put, the liver is like a large, blood-fi lled sponge that receives an ample supply of blood from both the hepatic arteries and the portal vein. For blood to move easily through this sponge and come into contact with hepatocytes and Kupffer cells, the functional units of the liver (the lobules) must be unobstructed and allow for proper fl ow. When this occurs, the liver can perform its required functions. Table 1: Major Functions of the Liver Digestive and metabolic functions Synthesis and secretion of bile; Storage and of glycogen and lipids; Regulation of blood glucose, fatty acids and amino acids; Storage of fat-soluble vitamins and minerals; Breakdown of hormones such as insulin and estrogen; Synthesis of angiotensinogen; Inactivation and absorption of toxins. Hematologic functions Synthesis of clotting factors; Removal of damaged and/or old RBCs and pathogens from circulation; Synthesis of plasma proteins. © 2015 EMSWorld.com 1 EMSWORLD.com PHYSIOLOGY OF THE LIVER The liver provides numerous essential functions in the body; some Esophageal vein Liver with sources claim more than 200. These many roles can be broken down cirrhosis Esophageal varices into three basic categories: metabolic regulation; hematologic regulation; and synthesis and secretion of bile.1 Gastric varices Metabolic Regulation The liver plays a major role in the metabolic regulation of many body functions. All the blood leaving the absorptive areas of Portal the digestive tract (stomach, small and large intestines) enters vein Spleen the hepatic portal system and flows into the liver. This gives the Gastric liver the opportunity to extract ingested and absorbed nutrients, vein Superior mesenteric metabolic waste products and toxins from the blood before it vein enters systemic circulation via the hepatic veins. Hepatocytes in the liver monitor the circulating levels of nutrients such as carbohydrates, amino acids and lipids (fats). Excess nutrients are removed from the blood and stored, and deficiencies can be Fran Milner, www.franimation.com corrected by tapping into stored reserves or synthesizing required nutrients. Excess glucose is stored in the liver as glycogen, and excess fatty acids as lipids, which can be utilized when deficiencies exist. In addition, fat-soluble vitamins such as A, D, K and E are absorbed by and stored in the liver, as are minerals such as iron and copper. Metabolic waste products and toxins are removed from circulation by the liver and deactivated, excreted and/or stored. The liver plays a major role in the breakdown of not only toxins from the environment (for example, some hydrocarbons or poison from an ingested mushroom) but also in the metabolism of alcohol, drugs and medications. It is also responsible for the breakdown of hormones such as estrogen, testosterone and even insulin. The liver plays an important role in blood pressure regulation via the synthesis of the inactive hormone angiotensinogen. When activated by renin (secreted by the kidney), angiotensinogen is converted to angiotensin, a hormone that will go on to increase blood pressure through a variety of functions. Hematologic Regulation As blood passes through the liver, many important processes take place. Phagocytic cells in the liver remove cellular debris, damaged and/or old RBCs, and pathogens from circulation. In addition, cells in the liver synthesize plasma proteins. The major plasma protein in the human body is albumin. Albumin is a relatively large molecule and helps create and maintain the colloidal osmotic pressure of the blood that keeps fluid (plasma) in the vasculature and out of the surrounding tissues. The liver plays an important role in the production of numerous clotting factors required for normal function of coagulation as well as the complement protein components of the immune system. SYNTHESIS AND SECRETION OF BILE Bile is synthesized by the liver, stored in the gallbladder and excreted into the proximal small intestine (duodenum). It is composed mostly of water (97%) and contains smaller amounts of bilirubin, ions and bile salts. Bile salts assist in the breakdown of lipids and absorption of fatty acids. The bile emulsifies fats entering the small intestine from the stomach, aiding in digestion. Key functions of the liver described here (Table 2) are but a small fraction of the total number it provides. As such, any condition that damages the liver and prevents it from performing its role in the body can result in a serious, life-threatening condition. Cirrhosis of the liver and chronic liver failure is one such condition. EPIDEMIOLOGY, ETIOLOGY AND PATHOPHYSIOLOGY The most recent data from the CDC reveals the overall mortality from chronic liver disease and cirrhosis in the United States in 2013 was 36,427 persons.2 The age groups with highest mortalities were 45–54 (8,785) and 55–64 (11,951); these accounted for more than half the deaths. Of persons who died of chronic liver disease and cirrhosis in 2013, 65% were male.2 Caucasians accounted for 87.4% of all deaths from chronic liver disease and cirrhosis.2 Caucasian males accounted for 57.2% of all deaths, while black males accounted for only 2.5%. Of the deaths in the U.S. in 2013 from liver disease and cirrhosis, alcoholic liver disease accounted for 49.8%, while other chronic liver disease and cirrhosis accounted for 50.2%.2 There are numerous etiologies of liver disease that can lead to cirrhosis, and the most common causes in the U.S. are hepatitis C, alcoholic liver disease and nonalcoholic liver disease. Together these three etiologies accounted for about 80% of patients on the liver transplant wait list between 2004–2013.3 While cirrhosis can be treated if identified in the early stages and its underlying cause corrected, late-stage cirrhosis is irreversible, and the only treatment option is a liver transplant. Patients with cirrhosis of the liver are thus subject to a wide range of complications and have decreased life expectancy. Cirrhosis is a slowly progressing, indolent disease in which healthy tissue in the liver is injured and replaced with scar tissue and ultimately progresses to hepatic fibrosis. This fibrosis interrupts the normal flow of blood through the liver, resulting in impaired function. As a result, vital functions such as the synthesizing and storage of nutrients, the secretion of clotting factors and plasma proteins, and the clearing of toxins in the blood cannot occur.
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