Anaes · Anaesthetic ventilators
Anaesthetic ventilators
Also known as Anaesthesia ventilator · Bag-in-bottle ventilator · Bellows ventilator · Piston ventilator · Turbine ventilator · Volume-controlled ventilation · Pressure-controlled ventilation
The anaesthetic ventilator provides the controlled ventilation during the general anaesthesia, integrated into the anaesthetic machine and the circle system. The framework rests on five exam-critical ideas: the drive mechanism (the bellows, the piston, the turbine); the hanging versus the standing bellows; the volume-controlled versus the pressure-controlled ventilation; the dual and the adaptive modes (the PCV-VG, the pressure support, the spontaneous modes); and the anaesthesia versus the ICU ventilator differences. The clinical application is the lung-protective ventilation in the operating theatre (the low tidal volume, the PEEP, the low driving pressure) which reduces the postoperative pulmonary complications.
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Red flags
- A rising peak airway pressure in volume control signals a falling compliance (the circuit kink, the bronchospasm, the endobronchial intubation, the abdominal distension). Do not simply silence the alarm — find the cause, because the same set tidal volume into a stiff lung raises the driving pressure and the risk of the lung injury.
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A morbidly obese patient is ventilated in volume control at 500 mL using actual body weight. Peak pressure 45 cmH2O, driving pressure 22 cmH2O. Why is this dangerous, and what do you change?[5]
The tidal volume was set on actual weight, not predicted body weight — the lungs are being overdistended. A driving pressure of 22 cmH2O is high, and the driving pressure is the key intraoperative mediator of postoperative pulmonary complications (odds ratio 1.16 per 1 cmH2O increase). Reduce the tidal volume to 6 to 8 mL per kg of predicted body weight, apply PEEP, and consider a pressure-controlled or adaptive mode to keep the driving pressure as low as possible.[5][7]
References7ShowHide
- [1]Jackson K, Wands B Review of Anesthesia Versus Intensive Care Unit Ventilators and Ventilatory Strategies: COVID-19 Patient Management Implications AANA J, 2021.PMID 33501910
- [2]Coisel Y, Millot A, Carr J, et al. How to choose an anesthesia ventilator? Ann Fr Anesth Reanim, 2014.PMID 25138358
- [3]Feldman JM. Optimal ventilation of the anesthetized pediatric patient Anesth Analg, 2015.PMID 25625261
- [4]Liu Z, Liu W, Zhao P, et al. Effect of pressure-controlled ventilation-volume guaranteed mode on intraoperative respiratory mechanics, oxygenation and postoperative pulmonary complications: a systematic review and network meta-analysis Ann Med, 2025.PMID 41157953
- [5]Neto AS, Hemmes SNT, Barbas CSV, et al. Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data Lancet Respir Med, 2016.PMID 26947624
- [6]Severgnini P, Selmo G, Lanza C, et al. Protective mechanical ventilation during general anesthesia for open abdominal surgery improves postoperative pulmonary function Anesthesiology, 2013.PMID 23542800
- [7]Futier E, Pereira B, Jaber S, et al. Personalized driving pressure-guided positive end-expiratory pressure in patients at risk of postoperative respiratory failure (IMPROVE-2): a multicenter, pragmatic, randomized clinical trial Intensive Care Med, 2025.PMID 40839096