P high, is high airway pressure.
P low, means low airway pressure.
T high, is the duration of high airway pressure.
T low, is the duration of airway bottom pressure.
I. Classification according to the type of use or application
(I) Controlled mechanical ventilation (CMV)
1. Definition: the patient's breathing is generated, controlled, and regulated exclusively by a mechanical ventilator in the presence of weakened or absent spontaneous breathing.?2. It is applied to: the disappearance or weakening of voluntary respiration caused by disease; the irregularity or excessive frequency of voluntary respiration, when mechanical ventilation can not be coordinated with the patient, the voluntary respiration will be suppressed or weakened by artificial methods.
(ii). Assisted mechanical ventilation (AMV)
1. Definition: The patient's breathing is assisted or augmented by the ventilator in the presence of breathing. The various kinds of mechanical ventilation are triggered primarily by the patient's inspiratory negative pressure or inspiratory airflow.?
2. It is applied to patients whose voluntary respiration is weakened and ventilation is insufficient although voluntary respiration exists and is more regular.
Extended information:
I. Major modes of mechanical ventilation
(i) Interstitial positive pressure ventilation (IPPV): positive pressure in the inspiratory phase and zero pressure in the expiratory phase.
1. Working principle: the ventilator generates positive pressure in the inspiratory phase and presses the gas into the lungs. After the pressure rises to a certain level or the volume of inhalation reaches a certain level, the ventilator stops supplying air, the expiratory valve opens, and the patient's thorax and lungs passively atrophy, generating expiration.?
2. Clinical application: all kinds of patients with respiratory failure mainly in ventilation function, such as COPD.
(2) Interstitial positive and negative pressure ventilation (IPNPV): positive pressure in the inspiratory phase and negative pressure in the expiratory phase.?
1. Principle of operation: the ventilator can work in both the inspiratory and expiratory phases.
2. Clinical application: negative pressure in the expiratory phase can cause alveolar atrophy, resulting in medically induced atelectasis.
Baidu Encyclopedia - Ventilator