In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols , , or , is the volumetric flow rate of the heart's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time. Cardiac output (CO) is the product of the heart rate (HR), i.e. the number of heartbeats per minute (bpm), and the stroke volume (SV), which is the volume of blood pumped from the left ventricle per beat; thus giving the formula:
Mechanical ventilation or assisted ventilation is the medical term for using a ventilator machine to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs. Various healthcare providers are involved with the use of mechanical ventilation and people who require ventilators are typically monitored in an intensive care unit.
Oxygen therapy, also referred to as supplemental oxygen, is the use of oxygen as medical treatment. Supplemental oxygen can also refer to the use of oxygen enriched air at altitude. Acute indications for therapy include hypoxemia, carbon monoxide toxicity and cluster headache. It may also be prophylactically given to maintain blood oxygen levels during the induction of anesthesia. Oxygen therapy is often useful in chronic hypoxemia caused by conditions such as severe COPD or cystic fibrosis. Oxygen can be delivered via nasal cannula, face mask, or endotracheal intubation at normal atmospheric pressure, or in a hyperbaric chamber. It can also be given through bypassing the airway, such as in ECMO therapy.
Spirometry is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is helpful in assessing breathing patterns that identify conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD. It is also helpful as part of a system of health surveillance, in which breathing patterns are measured over time.
A plethysmograph is an instrument for measuring changes in volume within an organ or whole body. The word is derived from the Greek "plethysmos", and "graphein".
A photoplethysmogram (PPG) is an optically obtained plethysmogram that can be used to detect blood volume changes in the microvascular bed of tissue. A PPG is often obtained by using a pulse oximeter which illuminates the skin and measures changes in light absorption. A conventional pulse oximeter monitors the perfusion of blood to the dermis and subcutaneous tissue of the skin.
Electrical impedance tomography (EIT) is a noninvasive type of medical imaging in which the electrical conductivity, permittivity, and impedance of a part of the body is inferred from surface electrode measurements and used to form a tomographic image of that part. Electrical conductivity varies considerably among various types of biological tissues or due to the movement of fluids and gases within tissues. The majority of EIT systems apply small alternating currents at a single frequency, however, some EIT systems use multiple frequencies to better differentiate between normal and suspected abnormal tissue within the same organ.
A heart rate monitor (HRM) is a personal monitoring device that allows one to measure/display heart rate in real time or record the heart rate for later study. It is largely used to gather heart rate data while performing various types of physical exercise. Measuring electrical heart information is referred to as electrocardiography.
Capnography is the monitoring of the concentration or partial pressure of carbon dioxide (CO
2) in the respiratory gases. Its main development has been as a monitoring tool for use during anesthesia and intensive care. It is usually presented as a graph of CO
2 (measured in kilopascals, "kPa" or millimeters of mercury, "mmHg") plotted against time, or, less commonly, but more usefully, expired volume (known as volumetric capnography). The plot may also show the inspired CO
2, which is of interest when rebreathing systems are being used. When the measurement is taken at the end of a breath (exhaling), it is called "end tidal" CO
2 (PETCO2).
The peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR) and peak flow measurement, is a person's maximum speed of expiration, as measured with a peak flow meter, a small, hand-held device used to monitor a person's ability to breathe out air. It measures the airflow through the bronchi and thus the degree of obstruction in the airways. Peak expiratory flow is typically measured in units of liters per minute (L/min).
The respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute.
Impedance cardiography (ICG) is a non-invasive technology measuring total electrical conductivity of the thorax and its changes in time to process continuously a number of cardiodynamic parameters, such as stroke volume (SV), heart rate (HR), cardiac output (CO), ventricular ejection time (VET), pre-ejection period and used to detect the impedance changes caused by a high-frequency, low magnitude current flowing through the thorax between additional two pairs of electrodes located outside of the measured segment. The sensing electrodes also detect the ECG signal, which is used as a timing clock of the system.
High-frequency ventilation (HFV) is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury (VALI), especially in the context of Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.
A pulmonary contusion, also known as lung contusion, is a bruise of the lung, caused by chest trauma. As a result of damage to capillaries, blood and other fluids accumulate in the lung tissue. The excess fluid interferes with gas exchange, potentially leading to inadequate oxygen levels (hypoxia). Unlike pulmonary laceration, another type of lung injury, pulmonary contusion does not involve a cut or tear of the lung tissue.
Respiratory inductance plethysmography (RIP) is a method of evaluating pulmonary ventilation by measuring the movement of the chest and abdominal wall.
Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional preferences, since there is a paucity of evidence indicating that the mode affects clinical outcome. The most frequently used forms of volume-limited mechanical ventilation are intermittent mandatory ventilation (IMV) and continuous mandatory ventilation (CMV). There have been substantial changes in the nomenclature of mechanical ventilation over the years, but more recently it has become standardized by many respirology and pulmonology groups. Writing a mode is most proper in all capital letters with a dash between the control variable and the strategy.
Sniffing is a perceptually-relevant behavior, defined as the active sampling of odors through the nasal cavity for the purpose of information acquisition. This behavior, displayed by all terrestrial vertebrates, is typically identified based upon changes in respiratory frequency and/or amplitude, and is often studied in the context of odor guided behaviors and olfactory perceptual tasks. Sniffing is quantified by measuring intra-nasal pressure or flow or air or, while less accurate, through a strain gauge on the chest to measure total respiratory volume. Strategies for sniffing behavior vary depending upon the animal, with small animals displaying sniffing frequencies ranging from 4 to 12 Hz but larger animals (humans) sniffing at much lower frequencies, usually less than 2 Hz. Subserving sniffing behaviors, evidence for an "olfactomotor" circuit in the brain exists, wherein perception or expectation of an odor can trigger brain respiratory center to allow for the modulation of sniffing frequency and amplitude and thus acquisition of odor information. Sniffing is analogous to other stimulus sampling behaviors, including visual saccades, active touch, and whisker movements in small animals. Atypical sniffing has been reported in cases of neurological disorders, especially those disorders characterized by impaired motor function and olfactory perception.
quantium Medical Cardiac Output (qCO) uses impedance cardiography in a simple, continuous, and non-invasive way to estimate the cardiac output (CO) and other hemodynamic parameters such as the stroke volume (SV) and cardiac index (CI). The CO estimated by the qCO monitor is referred to as the "qCO". The impedance plethysmography allows determining changes in volume of the body tissues based on the measurement of the electric impedance at the body surface.
Pendelluft refers to the movement of gas between two regions of the lung, usually between regions of differing compliance or airway resistance. Pendelluft is an important physiological concept to take into account during mechanical ventilation, particularly in patients with an open thorax, severe bronchospasm, or with heterogeneous lung compliance. It was first published as a physiological concept in 1956.
Impulse oscillometry (IOS), also known as respiratory oscillometry, forced oscillatory technique (FOT), or just oscillometry, is a non-invasive lung function test that measures the mechanical properties of the respiratory system, particularly the upper and intrathoracic airways, lung tissue and chest wall, usually during the patient's tidal breathing.
