Capnography in Anesthesia and Sedation Monitoring
Capnography monitoring is essential at all times in patients with tracheal tubes, supraglottic airway devices, and those who are sedated and do not respond verbally, serving as a vital monitor of airway patency and alveolar ventilation. 1
Critical Role in Airway Management
Confirming Tracheal Intubation
- Waveform capnography is the gold standard for detecting correct tracheal intubation with both high sensitivity and specificity. 1
- Alternative methods such as palpation and auscultation lack adequate sensitivity and specificity for this critical safety check. 1
- A flat capnogram after attempted tracheal intubation should be considered to indicate oesophageal intubation until this has been excluded. 1
- Even during cardiac arrest, if the trachea is correctly intubated, an attenuated capnogram trace will be present. 1
Detecting Oesophageal Intubation
- Capnography is the gold standard for correctly detecting accidental oesophageal intubation with both high sensitivity and specificity. 1
- Failure to detect oesophageal intubation due to failure to use or correctly interpret capnography has been classified as a Never Event in the UK. 1
Continuous Monitoring Requirements During Anesthesia
Uninterrupted capnography monitoring should occur during induction of anaesthesia, airway insertion, maintenance of anaesthesia, during any transfers, and during emergence from anaesthesia. 1
- Monitoring must continue until a tracheal tube or supraglottic airway is removed. 1
- This applies to monitoring the airway during anaesthesia, wherever that takes place. 1
Monitoring During Procedural Sedation
When Capnography is Mandatory
- Capnography should be used whenever verbal contact with the patient is lost during sedation. 1
- Continually monitor ventilatory function with capnography unless precluded or invalidated by the nature of the patient, procedure, or equipment. 1
- For uncooperative patients, institute capnography after moderate sedation has been achieved. 1
Lighter Sedation Levels
- Capnography is also advised for lighter levels of sedation to aid monitoring of airway patency, respiratory rate, and pattern. 1
- During procedures where verbal response is not possible (e.g., oral surgery, upper endoscopy), check the patient's ability to respond to verbal or tactile stimulation. 1
Additional Monitoring Roles
Capnography has numerous other monitoring roles beyond airway confirmation: 1
- Detecting bronchospasm or other lung pathology 1, 2
- Identifying rebreathing of carbon dioxide 1
- Signaling alterations in metabolic status such as malignant hyperthermia 1
- Providing information on ventilation, perfusion, and metabolism in both intubated and spontaneously breathing patients 3
Universal Application
- These recommendations apply to all patients, of all ages, and in all locations. 1
- The safe use and interpretation of waveform capnography in very small babies (e.g., <1 kg) requires specialist expertise. 1
Training Requirements
Essential Competencies
- Clinicians who manage the airway independently should be skilled at recognition and interpretation of normal and abnormal capnogram patterns. 1
- Those monitoring patients with capnography during emergence from anaesthesia or sedation should be trained in the recognition of safe and unsafe capnography patterns. 1
- Basic understanding of capnography interpretation is poor among nursing staff and allied health professionals but improves with simple training. 2
Common Pitfalls to Avoid
- Never rely solely on clinical signs (palpation, auscultation) to confirm tube placement, as these methods lack adequate sensitivity and specificity. 1
- Do not discontinue capnography monitoring prematurely—continue until the airway device is removed. 1
- Ensure proper interpretation: a flat capnogram indicates oesophageal intubation even in cardiac arrest scenarios. 1
- Capnography should be used in conjunction with clinical assessment and other monitoring modalities, not in isolation. 3