Page 744 - Clinical Application of Mechanical Ventilation

710 Glossary

compression factor: The amount of expansion of the ventilator circuit or humidifier during the inspiratory phase
measured in mL/cm H O. This volume is considered “lost” and unavailable to the patient.
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compressor: A device capable of building up pressure by compressing the volume of air.
constant flow waveform (CFW): Flow-time waveform where the peak flow occurs at or near beginning inspiration and
remains constant until end-inspiration.
continuous positive airway pressure (CPAP): CPAP is PEEP applied to the airway of a patient who is breathing
spontaneously. It is used to treat refractory hypoxemia in patients who are able to maintain adequate spontaneous
ventilation.
contractility: Pumping strength of the heart. Contractility may be increased by improving the blood volume or by
positive inotropic medications.
control mode: In control mode, the ventilator delivers the preset tidal volume at a set time interval (time-triggered
frequency).
controlled mandatory ventilation (CMV): Time-triggered mandatory breaths provided by the ventilator. Also called
controlled mechanical ventilation or continuous mandatory ventilation.
controller: The mechanism that provides a mode of ventilation within a specific parameter (pressure, time, volume, or flow).
corticosteroids: Hormones that are released from the cortex of the adrenal gland. Their potent anti-inflammatory
effects make corticosteroids useful in the treatment of asthma and chronic bronchitis. Corticosteroids are available
for intravenous administration as well as inhalation. Examples of inhaled steroids are dexamethasone (Decadron,
Respihaler), beclomethasone (Beclovent, Vanceril), flunisolide (AeroBid), and triamcinolone (Azmacort).
culture and sensitivity: A laboratory procedure that grows the microbes in a medium and tests their sensitivity or
resistance to different antimicrobial drugs.
cycle variable: A measurement that causes the breath to end.
deadspace ventilation: Ventilation in excess of perfusion; wasted ventilation.
decremental recruitment maneuver: A method of titration for optimal PEEP by setting a high CPAP (and PEEP) and
gradually decreasing the pressure and F O .
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depolarizing agents: Drugs that prolong the depolarization phase of muscle contraction, thus rendering the
repolarization/depolarization sequence (normal mechanism for muscle movement) impossible and causing muscle
blockade. An example is succinylcholine (Anectine, Quelicin).
desaturation index: Average number of oxygen desaturations of 4% or more from baseline in each hour of sleep during
a test.
descending ramp flow waveform (DRFW): Flow-time waveform where the peak flow occurs at or near beginning
inspiration and decreases to baseline at end-inspiration.
dexmedetomidine (Precedex): An intravenous drug that offers anxiolysis and analgesia but no respiratory depression.
diffusion defect: Pathologic condition leading to impaired gas exchange through the alveolar-capillary membrane (e.g.,
interstitial or pulmonary edema).
double-lumen endobronchial tube: A special airway for independent lung ventilation. It has two separate lumens, two
cuffs, and two pilot balloons.
dual control mode: A combined mode between two control variables (e.g., pressure and volume) that are regulated
by independent feedback loops so that the delivered breath switches between pressure-controlled and volume-
controlled.
dyshemoglobins: Hemoglobins that do not carry oxygen (e.g., carboxyhemoglobin, methemoglobin). In the presence
of dyshemoglobins, the pulse oximeter reads higher than actual SaO .
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endotracheal tubes: An artificial airway inside the trachea that is inserted through the mouth or nostril.
end-tidal carbon dioxide monitoring: The CO level measured at the end of exhalation; measured in mm Hg.
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