Mechanical ventilation: educational concepts

Educational work by a pre-medical student — not medical advice. Not a clinical protocol, prescription, or patient handout, and not for patient care. See DISCLAIMER.

Measurement and scope

Lower tidal-volume strategies in ARDS are expressed per predicted body weight, a height-based estimate, not actual body weight. Plateau pressure is interpreted during appropriate no-flow measurement conditions, and patient effort and chest-wall mechanics can affect its meaning. Static compliance is tidal volume divided by plateau pressure minus total PEEP under suitable passive conditions. Auto-PEEP matters.

Driving pressure is associated with outcome in ARDS. In the Amato et al. secondary analysis (N Engl J Med 2015;372:747-755; DOI), risk rose with higher driving pressure, and roughly 15 cm H2O is the value commonly cited from that and later observational work. That association is not a validated treatment target for every patient. Oxygen and carbon dioxide goals are likewise context-dependent; values from an ARDS trial are not general targets for all ICU disease states.

Modes and interaction

Volume control and adaptive pressure modes such as PRVC are distinct. A set or targeted volume does not guarantee delivery under leaks, pressure limits, or changing effort. Pressure control limits the set inspiratory pressure but does not guarantee lung protection or a fixed tidal volume. Mode names alone do not establish safety.

PEEP can recruit lung or overdistend it, with different effects on gas exchange and RV loading. Avoid blanket “low PEEP” rules in RV dysfunction; both derecruitment and overdistension can increase RV stress. See physiology notes.

Evidence interpretation

ARDS definitions: the 2012 Berlin definition grades severity by PaO2/FiO2 with at least 5 cm H2O PEEP (severe at or below 100 mmHg). The 2024 Global Definition (Matthay et al., Am J Respir Crit Care Med 2024;209:37-47; DOI) keeps that framework and adds SpO2/FiO2, non-intubated patients on high-flow oxygen, and ultrasound imaging, especially for resource-limited settings.

ATS 2024 conditionally supports higher PEEP without recruitment maneuvers for moderate-to-severe ARDS and recommends against prolonged recruitment maneuvers. Neuromuscular blockade and ECMO recommendations concern selected populations and are conditional; neither is an automatic first-line treatment for every low oxygenation ratio.

Liberation from ventilation involves assessment of the underlying illness, respiratory reserve, airway protection, secretions, and the planned post-extubation support. A fixed PEEP, oxygen fraction, respiratory rate, or recovery score does not independently determine readiness. This note provides no ventilator settings, intubation protocol, or rescue algorithm.

Sources and applicability

SCCM/ESICM 2026 adult sepsis guideline (Prescott et al.; co-published in Intensive Care Med, DOI, and Crit Care Med, DOI): the current guideline supersedes the 2021 edition. For ongoing fluid decisions, dynamic responsiveness assessment is preferable to isolated filling pressures.
ATS 2024 ARDS guideline: conditionally favors higher PEEP without recruitment maneuvers in moderate-to-severe ARDS and recommends against prolonged recruitment maneuvers.
ATS/ESICM/SCCM 2017 ventilation guideline: lower tidal volumes use predicted body weight, not actual body weight. Its PEEP, recruitment-maneuver and ECMO questions were re-addressed and are superseded by the ATS 2024 update; the low-tidal-volume/predicted-body-weight and prone-positioning recommendations remain in use.
ESICM 2023 ARDS guideline (Grasselli et al., Intensive Care Med 2023;49:727-759): a European comparator whose recommendations on PEEP and other adjuncts differ in places from ATS 2024.
ESICM 2025 circulatory shock and hemodynamic monitoring guideline (Monnet et al., Intensive Care Med 2025;51:1971-2012): current society guidance on shock assessment, including dynamic over static preload markers, echocardiography as first-line imaging for shock type, and cardiac-output monitoring in patients not responding to initial therapy. It updates the 2014 ESICM consensus.

These summaries are educational and do not reproduce the full guideline, its exceptions, or its implementation requirements.