ICU · Respiratory
Mechanical ventilation: modes, settings, troubleshooting, and weaning
Also known as Mechanical ventilation · Ventilator modes · Ventilator settings · Ventilator weaning · Lung-protective ventilation · SBT
Mechanical ventilation provides respiratory support for patients with respiratory failure (hypoxaemic, hypercapnic, or both). MODES: (1) VOLUME-CONTROLLED (VC — set Vt + RR — guaranteed volume — pressure varies). (2) PRESSURE-CONTROLLED (PC — set pressure + RR — guaranteed pressure — volume varies). (3) PRESSURE-REGULATED VOLUME CONTROL (PRVC — volume-targeted + pressure-limited — best of both). (4) PRESSURE SUPPORT (PS — patient triggers — ventilator assists — for spontaneous breathing/weaning). (5) CPAP — continuous positive pressure — for spontaneous breathing. SETTINGS: Vt 6 mL/kg IBW (lung-protective — ARDSNet), RR 10-20 (adjust to PaCO2/pH), PEEP 5-10 cmH2O (standard; higher for ARDS), FiO2 (minimal to maintain SpO2 92-96%), I:E ratio (1:2 standard; 1:3-4 for obstructive). LUNG-PROTECTIVE: Vt 6 mL/kg IBW + plateau ≤30 cmH2O + permissive hypercapnia. WEANING: SAT (spontaneous awakening trial) + SBT (spontaneous breathing trial) DAILY — if passes → extubate. ABCDEF bundle. COMPLICATIONS: VAP (head up 30°, oral chlorhexidine), volutrauma/barotrauma, auto-PEEP (COPD/asthma), patient-ventilator asynchrony, ICU-acquired weakness.
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Red flags
- Vt 6 mL/kg PREDICTED body weight (not actual) — ARDSNet — 22 per cent relative mortality reduction (31.0% vs 39.8%)
- Plateau pressure ≤30 cmH2O — if above, reduce the tidal volume further
- PEEP titrated to oxygenation — aggressive recruitment with high PEEP is harmful (ART)
- SAT + SBT DAILY — more unassisted breathing days and better 1-year survival (ABC trial)
- VAP prevention bundle — head of bed elevated, oral care, subglottic suction, minimise ventilator days
- Auto-PEEP in COPD/asthma — check + manage (longer expiration)
Meet the patient
A 62-year-old with severe community-acquired pneumonia has just been intubated. The junior has set the ventilator: Vt 500 mL on a 95-kg patient, PEEP 5, FiO2 0.9. Plateau is 32 cmH2O, driving pressure 20, SpO2 90 per cent. You ask for the height (175 cm) before doing anything else — because the ventilator is set on actual body weight, and the lung is not. Five minutes of arithmetic buys the ARDSNet mortality difference — 31.0 vs 39.8 per cent.[1]
The mantra: Vt 6 mL/kg PREDICTED body weight, not actual. Plateau ≤30. Driving pressure — keep it low. SAT + SBT daily. These four rules and one bundle are the bedside creed.[1][6][2]
[1] [6] [2] [7]References21ShowHide
- [1]Brower RG, Matthay MA, Morris A, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med, 2000.PMID 10793162
- [2]Girard TD, Kress JP, Fuchs BD, et al. Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial. Lancet, 2008.PMID 18191684
- [3]Esteban A, Frutos F, Tobin MJ, et al. A comparison of four methods of weaning patients from mechanical ventilation. Spanish Lung Failure Collaborative Group. N Engl J Med, 1995.PMID 7823995
- [4]Girard TD, Alhazzani W, Kress JP, et al. An Official American Thoracic Society/American College of Chest Physicians Clinical Practice Guideline: Liberation from Mechanical Ventilation in Critically Ill Adults. Rehabilitation Protocols, Ventilator Liberation Protocols, and Cuff Leak Tests. Am J Respir Crit Care Med, 2017.PMID 27762595
- [5]Lee CH, Peng MJ, Wu CL Dexamethasone to prevent postextubation airway obstruction in adults: a prospective, randomized, double-blind, placebo-controlled study. Crit Care, 2007.PMID 17605780
- [6]Amato MB, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med, 2015.PMID 25693014
- [7]Guérin C, Reignier J, Richard JC, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med, 2013.PMID 23688302
- [8]Cavalcanti AB, Suzumura ÉA, Laranjeira LN, et al. Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial. JAMA, 2017.PMID 28973363
- [9]Young D, Harrison DA, Cuthbertson BH, Rowan K; TracMan Collaborators Effect of early vs late tracheostomy placement on survival in patients receiving mechanical ventilation: the TracMan randomized trial. JAMA, 2013.PMID 23695482
- [10]Beitler JR Bedside respiratory physiology to detect risk of lung injury in acute respiratory distress syndrome. Curr Opin Crit Care, 2019.PMID 30531534
- [11]Chu DK, Kim LH, Young PJ, et al. Mortality and morbidity in acutely ill adults treated with liberal versus conservative oxygen therapy (IOTA): a systematic review and meta-analysis. Lancet, 2018.PMID 29726345
- [12]Gray A, Goodacre S, Newby DE, et al. Noninvasive ventilation in acute cardiogenic pulmonary edema. N Engl J Med, 2008.PMID 18614781
- [13]Jurecki MC, Chatburn RL, Sasidhar M Accuracy of the Electronic Health Record: Patient Height. Respir Care, 2015.PMID 26286734
- [14]Laher AE Mechanically Ventilating the Severe Asthmatic. J Intensive Care Med, 2018.PMID 29105540
- [15]Mosier JM Mechanical Ventilation Strategies for the Patient with Severe Obstructive Lung Disease. Emerg Med Clin North Am, 2019.PMID 31262414
- [16]Darioli R, Perret C Mechanical controlled hypoventilation in status asthmaticus. Am Rev Respir Dis, 1984.PMID 6703497
- [17]Holanda MA, Vasconcelos RDS, Ferreira JC, et al. Patient-ventilator asynchrony. J Bras Pneumol, 2018.PMID 30020347
- [18]Thille AW, Rodriguez P, Cabello B, et al. Patient-ventilator asynchrony during assisted mechanical ventilation. Intensive Care Med, 2006.PMID 16896854
- [19]Klompas M, et al. Strategies to prevent ventilator-associated pneumonia in acute care hospitals: 2014 update. Infect Control Hosp Epidemiol, 2014.PMID 25376073
- [20]Ranieri VM, Rubenfeld GD, Thompson BT, et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA, 2012.PMID 22797452
- [21]Yang KL, Tobin MJ A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med, 1991.PMID 2023603