Medical devices occupy a prominent position in health care and among health-related products. According to reports from 2017 and 2018, more than 18,000 manufacturers produce an estimated 190,000 distinct medical devices that are regulated by the U.S. Food and Drug Administration (FDA). Spending on medical devices in the US was estimated at $173 billion in 2019, up from an estimated $36 billion (in 2019 dollars) in 1983. The medical device industry is regulated primarily under a framework established by the Medical Device Amendments of 1976 to the Food, Drug, and Cosmetics Act of 1938. Because of rapid technological advances since 1976, the U.S. Congress and the FDA modified regulatory standards to minimize unnecessary requirements, promote
Variants
Viruses are tiny, non-cellular infectious agents. They are approximately one one-hundredth the size of an average bacterium and cannot be seen with an optical microscope. They are often round and have projections on their outside coat, called spike proteins, and contain strands of RNA or DNA. The spike proteins act like an anchor, allowing the virus to attach itself to a cell. Once attached to a cell, the virus hijacks the cell, forcing it to make replications of the virus. Sometimes, during
Seizures
An epileptic seizure occurs when the brain sort of short circuits. The classic seizure is known as a grand mal seizure, or a tonic-clonic seizure. Tonic refers to the muscle stiffness that occurs first, followed by the clonic or convulsive phase. In a grand mal seizure, the patient suffers a sudden loss of consciousness, falls uncontrollably to the floor, and convulses. Breathing does not happen during a seizure, so the patient often turns blue. Tongue biting is common, as is incontinence. A
Hematuria
Hematuria is the presence of blood in a person’s urine. It can be visible, meaning the urine is red, called gross or macroscopic hematuria, or it can be nonvisible, or microscopic. Macroscopic hematuria can be striking and has been documented since ancient times, especially when it appears without a prior event such as trauma, painful urination (dysuria) due to a bladder infection, or flank pain from a kidney stone. Microscopic hematuria may go undetected for years and is only found when a
Pain in the Back
Low back pain is one of the most common reasons why people seek medical care. Most low back pain is caused by minor problems with muscles, joints, or ligaments in the back. In rare cases, less than 1%, low back pain is caused by a serious spinal problem. Low back pain is categorized by how long the pain lasts. Acute low back pain lasts less than four weeks, subacute four to 12 weeks, and chronic more than 12 weeks.
Evaluation of low back pain requires a detailed medical history and physical
Infertility
Infertility, defined as the failure to achieve pregnancy after 12 months of regular unprotected sexual intercourse, affects 8.8% of US women aged 15 to 49 years, and is often associated with significant physical and emotional stress. Heterosexual women desiring pregnancy who have not conceived after 12 months of unprotected intercourse or donor insemination should undergo an infertility evaluation. Earlier evaluation is recommended for women older than 35 who have not conceived after 6 months
Blood Flows and Heart Valves
Today I would like to tell you about advances in heart valve replacement techniques. But first, allow me to review how blood flows through the human heart. The main vein that returns unoxygenated blood to the heart is the vena cava. The superior vena cava drains the upper body, arms, and head while the inferior vena cava drains the lower body and legs. Blood flows from the vena cava into the right atrium, then through the tricuspid valve into the right ventricle. When the right ventricle
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