Blood pressure (BP) is the pressure of circulating blood on the walls of blood vessels. Most of this pressure is due to the work done by the heart in pumping blood round the circulation. Used without further specification, "blood pressure" usually refers to the pressure in large arteries of the systemic circulation. Blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure and is measured in millimeters of mercury (mmHg), above the surrounding atmospheric pressure.
Cardiac arrest is a sudden loss of blood flow resulting from the failure of the heart to effectively pump. Symptoms include loss of consciousness and abnormal or absent breathing. Some individuals may experience chest pain, shortness of breath, or nausea before cardiac arrest. If not treated within minutes, it typically leads to death.
Clinical death is the medical term for cessation of blood circulation and breathing, the two necessary criteria to sustain human and many other organisms' lives. It occurs when the heart stops beating, a condition called cardiac arrest. The term is also sometimes used in resuscitation research.
Shock is the state of not enough blood flow to the tissues of the body as a result of problems with the circulatory system. Initial symptoms may include weakness, fast heart rate, fast breathing, sweating, anxiety, and increased thirst. This may be followed by confusion, unconsciousness, or cardiac arrest as complications worsen.
Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There may also be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. In the very young, old, and people with a weakened immune system, there may be no symptoms of a specific infection and the body temperature may be low or normal, rather than high. Severe sepsis is sepsis causing poor organ function or insufficient blood flow. Insufficient blood flow may be evident by low blood pressure, high blood lactate, or low urine output. Septic shock is low blood pressure due to sepsis that does not improve after fluid replacement.
Cardiac output, is a term used in cardiac physiology that describes the volume of blood being pumped by the heart, in particular by the left or right ventricle, per unit time. Cardiac output is the product of the heart rate (HR), or the number of heart beats per minute (bpm), and the stroke volume (SV), which is the volume of blood pumped from the ventricle per beat; thus, CO = HR × SV. Values for cardiac output are usually denoted as L/min. For a healthy person weighing 70 kg, the cardiac output at rest averages about 5 L/min; assuming a heart rate of 70 beats/min, the stroke volume would be approximately 70 mL.
Diuresis is increased urination and the physiologic process that produces such an increase. It involves extra urine production in the kidneys as part of the body's homeostatic maintenance of fluid balance.
Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced with oral rehydration therapy (drinking), intravenous therapy, rectally such as with a Murphy drip, or by hypodermoclysis, the direct injection of fluid into the subcutaneous tissue. Fluids administered by the oral and hypodermic routes are absorbed more slowly than those given intravenously.
The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth, pinching one's nose shut while pressing out as if blowing up a balloon. Variations of the maneuver can be used either in medical examination as a test of cardiac function and autonomic nervous control of the heart, or to clear the ears and sinuses when ambient pressure changes, as in diving, hyperbaric oxygen therapy, or air travel.
The diving reflex, also known as the diving response and mammalian diving reflex, is a set of physiological responses to immersion that overrides the basic homeostatic reflexes, and is found in all air-breathing vertebrates studied to date. It optimizes respiration by preferentially distributing oxygen stores to the heart and brain, enabling submersion for an extended time.
Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath, rapid breathing, and bluish skin coloration. Among those who survive, a decreased quality of life is relatively common.
Hypotension is low blood pressure, especially in the arteries of the left sided systemic circulation. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. A systolic blood pressure of less than 90 millimeters of mercury or diastolic of less than 60 mm Hg is generally considered to be hypotension. However, in practice, blood pressure is considered too low only if noticeable symptoms are present.
Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a consequence, the cardiac muscle is forced to work harder than normal.
Major trauma is any injury that has the potential to cause prolonged disability or death. There are many causes of major trauma, blunt and penetrating, including falls, motor vehicle collisions, stabbing wounds, and gunshot wounds. Depending on the severity of injury, quickness of management and transportation to an appropriate medical facility may be necessary to prevent loss of life or limb. The initial assessment is critical, and involves a physical evaluation and also may include the use of imaging tools to determine the types of injuries accurately and to formulate a course of treatment.
Hypovolemic shock is a medical emergency and an advanced form of hypovolemia due to insufficient amounts of blood and/or fluid inside human body to let heart pump enough blood to the body. More specifically, hypovolemic shock occurs when there is decreased intravascular volume to the point of cardiovascular compromise. The hypovolemic shock could be due to severe dehydration through a variety of mechanisms or from blood loss.
A fat embolism is a type of embolism in which the embolus consists of fatty material. They are often caused by physical trauma such as fracture, soft tissue trauma, or burns. Fat embolism syndrome is distinct from the presence of fat emboli, symptoms usually occur 1–3 days after a traumatic injury and are predominantly pulmonary, neurological, dermatological, and haematological. The syndrome manifests more frequently in closed fractures of the pelvis or long bones.
Permissive hypotension or hypotensive resuscitation is the use of restrictive fluid therapy, specifically in the trauma patient, that increases systemic blood pressure without reaching normotension. The goal blood pressure for these patients is a mean arterial pressure of 40-50mmHg or a systolic blood pressure less than or equal to 80. This goes along with certain clinical criteria. Following traumatic injury some patients experience hypotension that is usually due to blood loss (hemorrhage) but can be due to other causes as well. In the past, physicians were very aggressive with fluid resuscitation to try to bring the blood pressure to normal values. Recent studies have found that there is some benefit to allowing specific patients to experience some degree of hypotension in certain settings. This concept does not exclude therapy by means of i.v. fluid, inotropes or vasopressors, the only restriction is to avoid completely normalizing blood pressure in a context where blood loss may be enhanced. When a person starts to bleed the body starts a natural coagulation process that eventually stops the bleed. Issues with fluid resuscitation without control of bleeding is thought to be secondary to dislodgement of the thrombus that is helping to control further bleeding. Thrombus dislodgement was found to occur at a systolic pressure greater than 80mm Hg. In addition, fluid resuscitation will dilute coagulation factors that help form and stabilize a clot, hence making it harder for the body to use its natural mechanisms to stop the bleeding. These factors are aggravated by hypothermia.
Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a procedure that involves placement of an endovascular balloon in the aorta to control bleeding, augment afterload and maintain blood pressure temporarily in traumatic hemorrhagic shock. REBOA is considered a minimally-invasive alternative to thoracotomy with aortic cross-clamping (ACC).
Vasodilatory shock, vasogenic shock, or vasoplegic shock is a medical emergency belonging to shock along with cardiogenic shock, septic shock, allergen-induced shock and hypovolemic shock. When the blood vessels suddenly relax, it results in vasodilation. In vasodilatory shock, the blood vessels are too relaxed leading to extreme vasodilation and blood pressure drops and blood flow becomes very low. Without enough blood pressure, blood and oxygen don’t be pushed to reach the body’s organs. If vasodilatory shock lasts more than a few minutes, the lack of oxygen starts to damage the body’s organs. Vasodilatory shock like other types of shock should be treated quickly, otherwise it can cause permanent organ damage or death as a result of multiple organ dysfunction.
