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| Pa |
Pascals - Unit of pressure;
1 cm H2O = 98.06 Pa. |
| Palv |
Alveolar Pressure - Representative
pressure in the alveoli of the lungs. |
| Panting |
Spontaneous, high frequency
(in the range of 3 breaths/second) low tidal volume breathing. |
| Pao |
Pressure at the airway opening,
e.g., at the interface between the patient's airways and
the end of the patient circuit, or the atmosphere. |
| Partial Pressure |
In a gas mixture: the pressure
that a component, X, of a gas mixture would exhibit if
X alone occupied the volume that is occupied by the entire
mixture at the temperature of the mixture. Symbol: PX.
For example: the partial pressure of oxygen is PO2, and
the partial pressure of carbon dioxide is PCO2. |
| Partial Volume |
The volume that the amount
of a component gas in a gas mixture would occupy if that
amount of the component gas existed at the pressure of
the total mixture. |
| Patient
Circuit (also Breathing Circuit) |
The tubing that carries
the gas between the ventilator and the patient. It can
include a humidifier, water traps, nebulizer, sensors,
and various connectors and valves. |
| Patient System |
Those parts of the ventilator
and patient circuit (including attachments) through which
gas moves at physiologic pressures during ventilation
of the patient. |
| Patient System Compliance |
The effective compliance
of the patient system; reflects the distensibility of
the patient circuit and the other structures comprising
the system as well as the compressibility of the gas within
all of these structures. |
| Patient
Wye |
The connector that joins
the inspiratory and expiratory limbs of a two-limb patient
circuit to the patient airway. |
| Patm |
Atmospheric Pressure - Usually
the same as ambient, or local, pressure in the vicinity
of the patient. |
| PCV |
Pressure-Controlled Ventilation (See
Pressure Control Mode.)
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| PEEP |
Positive End-Expiratory
Pressure - Airway pressure is maintained above ambient
during a machine-generated breath. |
| PF |
Peak Flow, Peak Inspiratory
Flow |
| pH Electrode |
Electrochemical device sensitive
to the concentration of H+ ions in solution. |
| Phase (of a breath) |
Various portions of the
breathing cycle defined by the direction and sequence
of flow; e.g., in the inspiratory phase, flow is either
into the lungs or has stopped after the lungs have expanded;
during the expiratory phase, flow is either out of the
lungs or has stopped after the lungs have deflated. |
| PIP |
Peak Inspiratory Pressure
- The maximum value achieved by the pressure in the patient
circuit during a machine inspiration. |
| Plateau Pressure |
A pressure value that is
maintained constant during a portion of the inspiratory
phase of the breath. |
| Pneumatic System |
A system in which gas pressure
differences and their rates of change are related to gas
flows, their integrals and their rates of change. |
| Pneumotachometer |
A device that measures the
flow of gas through it under local conditions of temperature
and pressure. |
| Poisseuille's Law |
An expression of the linear
relationship between the pressure gradient (difference)
along a straight tube and the velocity of a viscous gas
undergoing laminar flow through the tube. |
| Power |
The rate of change of energy
or, equivalently, the rate of change of work; expressed
in units of watts, BTU's or joules. |
| PPS |
(See Proportional
Pressure Support). |
| PPV |
Positive Pressure Ventilation
- Mechanical ventilation that applies a pressure above
ambient to the airways to produce or assist inspiration. |
| Pressure |
Force per unit area; expressed
in units such as cm H2O, pascals, kilopascals, or pounds
per square inch (psi). |
| Pressure
Augmentation |
A combination of pressure
control and volume control to provide the fast flow response
to patient demand of pressure control. along with the
assured volume delivery of volume control. Also called
VAPS (Volume-Assured Pressure Support). |
| Pressure Limited Ventilation |
A preset peak pressure is
reached and maintained before the end of inspiration.
When used in the volume control mode, the delivered volume
is limited also since excess flow is vented to the atmosphere. |
| Pressure-Control
Mode |
A mode of ventilator operation
in which the ventilator attempts to deliver a preset pressure
waveform during inspiration. Typically, sufficient flow
is provided to achieve and maintain a set pressure in
the patient circuit during the inspiratory phase of the
breath. |
| Prioritized Alarms |
Alarms that have audible
and visible signals that differ according to the severity
of the conditions causing the alarm. |
| Proportional
Pressure Support PPS™ |
Proportional Pressure Support
PPS™ compensates for the additional workload due to pathological
increased resistance and decreased compliance of the patient.
Proportional Pressure Support PPS™ has its origins in
Proportional Assist Ventilation PAV which was introduced
by Prof. Magdy Younes in the early 90s. The principle
is now used under license by Dräger (Source: Dräger
Medizintechnik GmbH). The distinctive feature of this
mode in comparison to other support modes is that positive
pressure delivered at the airway is directly proportional
to patient effort. |
| PSV |
Pressure Support Ventilation
- A mode supplement that augments the patient's spontaneous
inspiratory effort by providing flow sufficient to establish
and maintain a preset pressure in the patient circuit
throughout inspiration. Expiration begins when the required
flow drops below a preset level. PSV may be applied to
spontaneous breaths during ventilatory modes such SIMV. |
| Pulmonary |
Pertaining to the lungs. |
| Pulse Oximeter |
A device that measured the
pulse rate of the heart and the oxygen saturation of the
blood using differential reflectance colorimeter technology. |
