Ventilator Management Basics: Modes, Settings, and Airway Pressures
CA-1 · intraoperative teaching CA-1 Bootcamp day 7. Authored from cited abstracts; every claim carries a PMID.
THE QUESTIONWhere the evidence disagrees
This topic was selected because an evidence synthesis beats a textbook on it: the trials disagree, or the guidance has moved recently.
THE EVIDENCE
What each source contributes, and how strong it is
Study design first — a cohort and a randomised trial do not carry the same weight.
Design
Year
Journal
What it found
Other
2019
Br J Anaesth
An international expert consensus recommends starting intraoperative ventilati
Other
2025
Br J Anaesth
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep
Other
2020
JAMA
Low tidal volume is not a charm you cast on its own — a randomised trial of 6
Other
2016
Lancet Respir Med
Plateau pressure minus PEEP is the driving pressure
Other
2008
Anesth Analg
Volume control promises a tidal volume, pressure control promises a pressure a
Other
2025
Anesth Analg
In a meta-analysis of 51 randomised trials in adults having abdominopelvic sur
10 resolved citations behind this deck; every point above traces to one of them.
IN PRACTICE
What the cohorts and reviews add
6 findings, each on the slide that follows.
Br J Anaesth 2019
An international expert consensus recommends starting intraoperative ventilati
An international expert consensus recommends starting intraoperative ventilation at a tidal volume of 6 to 8 mL per kilogram of predicted body weight…
Br J Anaesth 2025
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep dialling it up, because in a pooled analysis of two large…
JAMA 2020
Low tidal volume is not a charm you cast on its own — a randomised trial of 6
Low tidal volume is not a charm you cast on its own — a randomised trial of 6 versus 10 mL/kg predicted body weight with PEEP of 5 in both arms found…
Lancet Respir Med 2016
Plateau pressure minus PEEP is the driving pressure
Plateau pressure minus PEEP is the driving pressure
IN PRACTICE
An international expert consensus recommends starting intraoperative ventilati
Other · Br J Anaesth
An international expert consensus recommends starting intraoperative ventilation at a tidal volume of 6 to 8 mL per kilogram of predicted body weight with PEEP of 5 cm H2O, individualising PEEP thereafter and using the lowest effective pressure and fewest breaths when recruiting — which means the tidal volume is calculated from the patient's height, not from what the scale said.
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep
Other · Br J Anaesth
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep dialling it up, because in a pooled analysis of two large intraoperative ventilation trials the patients whose end-tidal CO2 ran below 4.7 kPa received higher weight-adjusted minute ventilation and developed more postoperative pulmonary complications (34% versus 23%), with an inverse linear relationship between mean end-tidal CO2 and complications.
Low tidal volume is not a charm you cast on its own — a randomised trial of 6
Other · JAMA
Low tidal volume is not a charm you cast on its own — a randomised trial of 6 versus 10 mL/kg predicted body weight with PEEP of 5 in both arms found no difference in postoperative pulmonary complications (38% versus 39%), while a Bayesian network meta-analysis found the benefit came from low tidal volume combined with moderate PEEP of 5 to 8 cm H2O rather than from the small tidal volume alone.
Plateau pressure minus PEEP is the driving pressure
Other · Lancet Respir Med
Plateau pressure minus PEEP is the driving pressure, and in an individual-patient meta-analysis of 17 randomised trials driving pressure was associated with postoperative pulmonary complications (odds ratio 1.16 per 1 cm H2O) while tidal volume on its own was not; the gap between peak and plateau is a different quantity altogether — it is resistive, and it grows with airway resistance, smaller endotracheal tubes and shorter inspiratory times.
Volume control promises a tidal volume, pressure control promises a pressure a
Other · Anesth Analg
Volume control promises a tidal volume, pressure control promises a pressure and assures neither the other, and pressure support only assists breaths the patient starts — and each has a catch worth knowing: the volume a traditional anaesthesia ventilator actually delivers in volume control is degraded by breathing-circuit compliance and fresh gas flow until the machine compensates for both, while adding pressure support to a spontaneously breathing patient with a laryngeal mask cut the postoperative fall in end-expiratory lung volume from about 17% to about 8%.
In a meta-analysis of 51 randomised trials in adults having abdominopelvic sur
Other · Anesth Analg
In a meta-analysis of 51 randomised trials in adults having abdominopelvic surgery, second-generation supraglottic airways reduced major perioperative airway complications compared with tracheal tubes (risk ratio 0.41) with no clear difference in regurgitation or aspiration and much less sore throat, hoarseness and coughing, but they more than tripled the risk of inadequate ventilation (risk ratio 3.36) — so the supraglottic airway buys a quieter throat and the tube buys a ventilation you can count on.
de Carvalho et al., Anesth Analg 2025 · PMID 39466638
IN THE ROOM
What this changes about the next case
Colour is the strength of the evidence behind each step, not the urgency.
1
1
An international expert consensus recommends starting intraoperative ventilation at a tidal volume of 6 to 8 mL per kilogram of predicted body weight with PEEP of 5 cm H2O, individualising PEEP thereafter and using the lowest effective pressure and fewest breaths when recruiting — which means the tidal volume is calculated from the patient's height, not from what the scale said.
2
2
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep dialling it up, because in a pooled analysis of two large intraoperative ventilation trials the patients whose end-tidal CO2 ran below 4.7 kPa received higher weight-adjusted minute ventilation and developed more postoperative pulmonary complications (34% versus 23%), with an inverse linear relationship between mean end-tidal CO2 and complications.
3
3
Low tidal volume is not a charm you cast on its own — a randomised trial of 6 versus 10 mL/kg predicted body weight with PEEP of 5 in both arms found no difference in postoperative pulmonary complications (38% versus 39%), while a Bayesian network meta-analysis found the benefit came from low tidal volume combined with moderate PEEP of 5 to 8 cm H2O rather than from the small tidal volume alone.
4
4
Plateau pressure minus PEEP is the driving pressure, and in an individual-patient meta-analysis of 17 randomised trials driving pressure was associated with postoperative pulmonary complications (odds ratio 1.16 per 1 cm H2O) while tidal volume on its own was not; the gap between peak and plateau is a different quantity altogether — it is resistive, and it grows with airway resistance, smaller endotracheal tubes and shorter inspiratory times.
5
5
Volume control promises a tidal volume, pressure control promises a pressure and assures neither the other, and pressure support only assists breaths the patient starts — and each has a catch worth knowing: the volume a traditional anaesthesia ventilator actually delivers in volume control is degraded by breathing-circuit compliance and fresh gas flow until the machine compensates for both, while adding pressure support to a spontaneously breathing patient with a laryngeal mask cut the postoperative fall in end-expiratory lung volume from about 17% to about 8%.
The oral-boards stem on the next slide puts these into one scenario.
KEY TAKEAWAYS
What to carry into the next case
An international expert consensus recommends starting intraoperative ventilati
Br J Anaesth 2019
Set the respiratory rate to the end-tidal CO2 and then resist the urge to keep
Br J Anaesth 2025
Low tidal volume is not a charm you cast on its own — a randomised trial of 6
JAMA 2020
Plateau pressure minus PEEP is the driving pressure
Lancet Respir Med 2016
Set tidal volume off the patient's height rather than his weight, put PEEP on from the start, and read peak and plateau as two separate measurements — the gap between them belongs to the airway, the plateau belongs to the lung.
Questions I'll ask you in the room
What is this patient's predicted body weight, and how far is it from what the scale said?
Peak went up and plateau barely moved — is that a lung problem or a tube problem, and how would you tell?
You are hyperventilating him to an end-tidal CO2 of 28. What is that buying you, and what is it costing?
If this were a 40-minute knee arthroscopy instead, would you still put a tube in — and what would you give up if you did not?
Oral boards stem
A 58-year-old man, 170 cm and 92 kg, is having a laparoscopic sigmoid colectomy. You have induced, given rocuronium, intubated with an 8.0 tube and confirmed the position. The examiner points at a blank ventilator screen and asks you to set it — mode, rate, tidal volume, PEEP — and to say where on that screen you would look to know whether your settings are being delivered. Then the surgeon insufflates, the peak pressure rises from 19 to 32, and the plateau moves from 15 to 19; the examiner asks what has just happened and what you would change.
The bottom lineSet tidal volume off the patient's height rather than his weight, put PEEP on from the start, and read peak and plateau as two separate measurements — the gap between them belongs to the airway, the plateau belongs to the lung.
Sources
[1] Young et al., Br J Anaesth 2019 · PMID 31587835 open
[2] Nasa et al., Br J Anaesth 2025 · PMID 40930872 open
[3] Karalapillai et al., JAMA 2020 · PMID 32870298 open
[4] Deng et al., Br J Anaesth 2020 · PMID 32007240 open
[5] Neto et al., Lancet Respir Med 2016 · PMID 26947624 open
[6] Ilia et al., Pediatr Crit Care Med 2020 · PMID 31688716 open
[7] Bachiller et al., Anesth Analg 2008 · PMID 18420850 open
[8] Sudy et al., Acta Anaesthesiol Scand 2024 · PMID 37923301 open
[9] de Carvalho et al., Anesth Analg 2025 · PMID 39466638 open
[10] Bernardini et al., Anaesthesia 2009 · PMID 19860753 open