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Dead Space (physiology)
Dead space is the volume of air that is inhaled that does not take part in the gas exchange, because it either remains in the conducting airways or reaches alveoli that are not perfused or poorly perfused. It means that not all the air in each breath is available for the exchange of oxygen and carbon dioxide. Mammals breathe in and out of their lungs, wasting that part of the inhalation which remains in the conducting airways where no gas exchange can occur. Components ''Total dead space'' (also known as physiological dead space) is the sum of the anatomical dead space and the alveolar dead space. Benefits do accrue to a seemingly wasteful design for ventilation that includes dead space. #Carbon dioxide is retained, making a bicarbonate-buffered blood and interstitium possible. #Inspired air is brought to body temperature, increasing the affinity of hemoglobin for oxygen, improving O2 uptake. #Particulate matter is trapped on the mucus that lines the conducting airways, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventilation/perfusion Ratio
In respiratory physiology, the ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching of two variables: * V – ventilation – the air that reaches the alveoli * Q – perfusion – the blood that reaches the alveoli via the capillaries The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute—a ratio of volumetric flow rates. These two variables, V and Q, constitute the main determinants of the blood oxygen (O2) and carbon dioxide (CO2) concentration. The V/Q ratio can be measured with a ventilation/perfusion scan. A V/Q mismatch can cause Type 1 respiratory failure. Physiology Ideally, the oxygen provided via ventilation would be just enough to saturate the blood fully. In the typical adult, 1 litre of blood can hold about 200 mL of oxygen; 1 litre of dry air has about 210 mL of oxygen. Therefore, under these cond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Volume
Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per inspiration or 7 ml/kg of body mass. Mechanical ventilation Tidal volume plays a significant role during mechanical ventilation to ensure adequate ventilation without causing trauma to the lungs. Tidal volume is measured in milliliters and ventilation volumes are estimated based on a patient's ideal body mass. Measurement of tidal volume can be affected (usually overestimated) by leaks in the breathing circuit or the introduction of additional gas, for example during the introduction of nebulized drugs. Ventilator-induced lung injury such as Acute lung injury (ALI) /Acute Respiratory Distress Syndrome 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 (dy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulmonary Function Testing
Pulmonary function testing (PFT) is a complete evaluation of the respiratory system including patient history, physical examinations, and tests of pulmonary function. The primary purpose of pulmonary function testing is to identify the severity of pulmonary impairment. Pulmonary function testing has diagnostic and therapeutic roles and helps clinicians answer some general questions about patients with lung disease. PFTs are normally performed by a pulmonary function technician, respiratory therapist, respiratory physiologist, physiotherapist, pulmonologist, or general practitioner. Indications Pulmonary function testing is a diagnostic and management tool used for a variety of reasons, such as: * Diagnose lung disease. * Monitor the effect of chronic diseases like asthma, chronic obstructive lung disease, or cystic fibrosis. * Detect early changes in lung function. * Identify narrowing in the airways. * Evaluate airway bronchodilator reactivity. * Show if environmental fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Respiratory Therapy
A respiratory therapist is a specialized healthcare practitioner trained in critical care and cardio-pulmonary medicine in order to work therapeutically with people who have acute critical conditions, cardiac and pulmonary disease. Respiratory therapists graduate from a college or university with a degree in respiratory therapy and have passed a national board certifying examination. The NBRC (National Board for Respiratory Care) is responsible for credentialing as a CRT ( certified respiratory therapist), or RRT ( registered respiratory therapist), The specialty certifications of respiratory therapy include: CPFT and RPFT (Certified or Registered Pulmonary Function Technologist), ACCS (Adult Critical Care Specialist), NPS (Neonatal/Pediatric Specialist), and SDS (Sleep Disorder Specialist). Respiratory therapists work in hospitals in the intensive care units (Adult, Pediatric, and Neonatal), on hospital floors, in emergency departments, in pulmonary functioning laboratories ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Respiratory Physiology
In physiology, respiration is the movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide in the opposite direction that's to the environment. The physiological definition of respiration differs from the biochemical definition, which refers to a metabolic process by which an organism obtains energy (in the form of ATP and NADPH) by oxidizing nutrients and releasing waste products. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the diffusion and transport of metabolites between the organism and the external environment. Gas exchanges in the lung occurs by ventilation and perfusion. Ventilation refers to the in and out movement of air of the lungs and perfusion is the circulation of blood in the pulmonary capillaries. In mammals, physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orinasal Mask
An orinasal mask, oro-nasal mask or oral-nasal mask is a breathing mask that covers the mouth and the nose only. It may be a complete independent item, as an oxygen mask, or on some anaesthetic apparatuses, or it may be fitted as a component inside a fullface mask on underwater breathing apparatus, a gas mask or an industrial respirator to reduce the amount of dead space. It may be designed for its lower edge to seal on the front of the lower jaw or to go under the chin. An orinasal mask may carry a filter for ambient air, or be supplied from a user-carried breathing gas supply or a remote gas supply using a supply hose. Another application is the resuscitation pocket mask, which is used as an infection barrier between the rescuer and a non-breathing casualty for expired air resuscitation. Applications Stand-alone orinasal units *Hyperbaric oxygen provision: The built-in breathing systems (BIBS) used for providing oxygen for treatment and accelerated decompression in hyp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Helmet
A diving helmet is a rigid head enclosure with a breathing gas supply used in underwater diving. They are worn mainly by professional divers engaged in surface-supplied diving, though some models can be used with scuba equipment. The upper part of the helmet, known colloquially as the ''hat'' or ''bonnet'', may be sealed directly to the diver using a ''neck dam'', connected to a diving suit by a lower part, known as a ''breastplate'', or ''corselet'', depending on regional language preferences. or simply rest on the diver's shoulders, with an open bottom, for shallow water use. The helmet isolates the diver's head from the water, allows the diver to see clearly underwater, provides the diver with breathing gas, protects the diver's head when doing heavy or dangerous work, and usually provides voice communications with the surface (and possibly other divers). If a helmeted diver becomes unconscious but is still breathing, most helmets will remain in place and continue to deliver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Full Face Mask
A full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece, demand valve or constant flow gas supply that provides the diver with breathing gas. The full face mask has several functions: it lets the diver see clearly underwater, it provides the diver's face with some protection from cold and polluted water and from stings, such as from jellyfish or coral. It increases breathing security and provides a space for equipment that lets the diver communicate with the surface support team. Full-face masks can be more secure than breathing from an independent mouthpiece; if the diver becomes unconscious or suffers an oxygen toxicity convulsion, the diver can continue to breathe from the mask, unlike a scuba mouthpiece which is normally gripped between the teeth. Full-face diving masks are often used in professional diving. They are relatively rarely used in recreational diving. Function The full-face mask ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breathing Gas
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraft, submarines, space suits, spacecraft, medical life support and first aid equipment, and anaesthetic machines. Oxygen is the essential component for any breathing gas, at a partial pressure of between roughly 0.16 and 1.60 bar at the ambient pressure. The oxygen is usually the only metabolically active component unless the gas is an anaesthetic mixture. Some of the oxygen in the breathing gas is consumed by the metabolic processes, and the inert components are unchanged, and serve mainly to dilute the oxygen to an appropriate concentration, and are therefore also known as diluent gases. Most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Ventilator
A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators are computerized microprocessor-controlled machines, but patients can also be ventilated with a simple, hand-operated bag valve mask. Ventilators are chiefly used in intensive-care medicine, home care, and emergency medicine (as standalone units) and in anesthesiology (as a component of an anesthesia machine). Ventilators are sometimes called "respirators", a term commonly used for them in the 1950s (particularly the "Bird respirator"). However, contemporary medical terminology uses the word " respirator" to refer instead to a face-mask that protects wearers against hazardous airborne substances. Function In its simplest form, a modern positive pressure ventilator, consists of a compressible air reservoir or turbine, air and oxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bohr Equation
The Bohr equation, named after Danish physician Christian Bohr (1855–1911), describes the amount of physiological dead space in a person's lungs. This is given as a ratio of dead space to tidal volume Tidal volume (symbol VT or TV) is the volume of air moved into or out of the lungs during a normal breath. In a healthy, young human adult, tidal volume is approximately 500 ml per inspiration or 7 ml/kg of body mass. Mechanical vent .... It differs from anatomical dead space as measured by Fowler's method as it includes alveolar dead space. Description The Bohr equation is used to quantify the ratio of physiological dead space to the total tidal volume, and gives an indication of the extent of wasted ventilation. The original formulation by Bohr, required measurement of the alveolar partial pressure PA. :\frac = \frac The modification by Enghoff replaced the mixed alveolar partial pressure of CO2 with the arterial partial pressure of that gas. The Boh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Balance
In physics, a mass balance, also called a material balance, is an application of conservation of mass to the analysis of physical systems. By accounting for material entering and leaving a system, mass flows can be identified which might have been unknown, or difficult to measure without this technique. The exact conservation law used in the analysis of the system depends on the context of the problem, but all revolve around mass conservation, i.e., that matter cannot disappear or be created spontaneously. Therefore, mass balances are used widely in engineering and environmental analyses. For example, mass balance theory is used to design chemical reactors, to analyse alternative processes to produce chemicals, as well as to model pollution dispersion and other processes of physical systems. Closely related and complementary analysis techniques include the population balance, energy balance and the somewhat more complex entropy balance. These techniques are required for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
