Book contents
- Frontmatter
- Contents
- List of contributors
- Foreword
- Section I Basic sciences
- Section II Anaesthesia and peri-operative care for surgical specialties
- Section III At a glance
- Chapter 22 Scoring systems
- Chapter 23 Modes of mechanical ventilation
- Chapter 24 Fluids
- Chapter 25 Coagulation
- Chapter 26 Pre-operative echocardiography
- Chapter 27 Common drugs and doses
- Chapter 28 Physiology and risk in special circumstances
- Chapter 29 Medicolegal aspects of consent
- Chapter 30 Nerve injury
- Chapter 31 Pre-operative investigations
- Chapter 32 Enhanced recovery
- Chapter 33 Post-operative cognitive dysfunction
- List of abbreviations
- Index
- References
Chapter 23 - Modes of mechanical ventilation
Published online by Cambridge University Press: 05 July 2014
- Frontmatter
- Contents
- List of contributors
- Foreword
- Section I Basic sciences
- Section II Anaesthesia and peri-operative care for surgical specialties
- Section III At a glance
- Chapter 22 Scoring systems
- Chapter 23 Modes of mechanical ventilation
- Chapter 24 Fluids
- Chapter 25 Coagulation
- Chapter 26 Pre-operative echocardiography
- Chapter 27 Common drugs and doses
- Chapter 28 Physiology and risk in special circumstances
- Chapter 29 Medicolegal aspects of consent
- Chapter 30 Nerve injury
- Chapter 31 Pre-operative investigations
- Chapter 32 Enhanced recovery
- Chapter 33 Post-operative cognitive dysfunction
- List of abbreviations
- Index
- References
Summary
Mechanical ventilation is used during surgery or respiratory failure to optimise gas exchange until the end of surgery or while waiting for the improvement of the underlying respiratory disease.
Modern mechanical ventilation involves positive pressure insufflation of gas into the lungs rather than negative pressure generated by the respiratory muscles, and is therefore harmful by default. However, short spells of mechanical ventilation during anaesthesia and surgery seem to be well tolerated by the majority of patients without major side effects.
Positive pressure ventilation of the lungs causes a number of undesirable side effects which can lead to lung injury, even in healthy lungs. These can sometimes lead to multiorgan dysfunction or failure (Figure 23.1).
For this reason the least harmful mode of mechanical ventilation until the end of surgery or respiratory failure recovery is likely to yield most patient benefit.
Mechanical ventilation can be non-invasive (through face masks or hoods), or invasive (through tracheal or bronchial tubes, or tracheostomy).
Both modes of mechanical ventilation employ the same principles, but non-invasive ventilation:
Does not require sedation
Can be done at home
Does not impair the mucociliary apparatus
Continuous positive airways pressure (CPAP) is not per se a mode of mechanical ventilation, but often used as such. It involves administration of positive pressure throughout the respiratory cycle (inspirium and expirium) but the patient has to generate negative pressure to inflate the lungs. This mode is least invasive, and efficient for:
Improving pulmonary oedema (by increasing the intra-alveolar pressure during expirium and reducing the work of breathing)
Improving oxygenation
Improving lung collapse and atelectasis
- Type
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- A Surgeon's Guide to Anaesthesia and Peri-operative Care , pp. 269 - 272Publisher: Cambridge University PressPrint publication year: 2014