Page 749 - Clinical Application of Mechanical Ventilation

Glossary 715

pressure-regulated volume control (PRVC): A mode of ventilation that provides volume-controlled breaths with the
lowest pressure possible by altering the flow and inspiratory time.
pressure-triggered: Initiation of a mechanical breath based on the drop in airway pressure that occurs at the beginning
of a spontaneous inspiratory effort.
pressure-volume loop (PVL): Graphic display of changes in pressure and volume during a complete respiratory cycle.
prone positioning (PP): A procedure to temporarily improve a patient’s oxygenation by placing the bed and patient in a
Trendelenberg position at 15 to 30 degrees.
prophylactic ventilatory support: Early intervention of potential ventilatory failure by means of mechanical ventilation.
propofol (Diprivan): An intravenous drug that provides a spectrum of CNS effects ranging from light sedation to deep
general anesthesia.
proportional assist ventilation (PAV): A mode that uses variable pressure to provide pressure support. The variable
pressure is in proportion to the patient’s pulmonary characteristics (elastance and airflow resistance) and demand
(volume or flow).
pulmonary artery pressure (PAP): Pressure measured in the pulmonary artery. It reflects the volume status of the
pulmonary artery and the functions of the ventricles. Right ventricular afterload.
pulmonary capillary wedge pressure (PCWP): Pressure measured in the pulmonary artery with a balloon inflated to
stop pulmonary blood flow. It reflects the volume status and functions of the left heart. Left ventricular preload.
pulmonary vascular resistance: Resistance of the arterial system into which the right heart is pumping. Normal range
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is 50–150 dynes.sec/cm .
pulse contour analysis: A less invasive method to calculate the stroke volume and stroke volume index by using the
area under the arterial pressure waveform and specific patient data.
pulse oximeter: A device that estimates arterial oxygen saturation (SpO ) by emitting dual wavelengths of light
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through a pulsating vascular bed.
radiopaque: Impenetrable to X-rays. It appears as a light area on the radiograph.
Ramsay Scale: The scoring system with a scale ranging from level I to level VI; used to assess the degree of sedation.
rapid sequence intubation (RSI): Intubation with an endotracheal tube under controlled conditions.
rapid shallow breathing index (RSBI): The RSBI (f/V ratio) is calculated by dividing the spontaneous breathing
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frequency (breaths/min) by the average spontaneous V (L). Absence of rapid shallow breathing, as defined by an
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f/V ratio of less than 100* breaths/min/L, is an accurate predictor of weaning success. (*rounded from 105
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breaths/min/L.)
refractory hypoxemia: A persistent low level of oxygen in blood that is not responsive to medium to high
concentration of inspired oxygen. It is usually caused by intrapulmonary shunting.
renal perfusion: Blood flow to the kidneys. It is decreased when blood volume or cardiac output is low.
SALT: A mass casualty triage algorithm consists of Sort, Assess, Life-saving interventions, and Treatment/Transport.
servo: A feedback system that typically consists of a sensing element, an amplifier, and a servomotor, used in the
automatic control of the mechanical device of a ventilator.
sine wave: A graphic presentation of flow and time that has a horizontal “S” appearance.
sniffing position: An ideal head position for endotracheal intubation. It is done by tilting the forehead back slightly and
moving the mandible anteriorly to the patient.
SOFA: The Sequential Organ Failure Assessment (SOFA) score is a triage system that uses six criteria to predict the
outcomes of critically ill patients in the hospital.
solenoid valves: A valve controlled by an electronic switching device that is used to regulate the specific functions of a
ventilator.

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