Table 4.
Potential causes of failure to detect sustained exhaled carbon dioxide (CO2) despite tracheal placement of tube [96, 97, 106, 107]. Many of these will often be associated with additional clinical cues.
| Sampling error |
| Mainstream (In‐line) sensor: not in circuit; inappropriately placed |
| Side‐stream sampling: low flow rate; loose, disconnected, leaking; not in circuit; inappropriately placed; obstructed |
| Excessive equipment dead space (esp. in association with significant positive end expiratory pressure) |
| Excessive fresh gas flow rate in some circuits |
| Leak around tube |
| Massive tracheo‐oesophageal fistula or traumatic tracheal disruption with tube proximal to tracheal defect |
| Massive broncho‐pleural fistula |
| Monitoring failure |
| Faulty monitor |
| CO2 detection module/cable disconnected from monitor |
| CO2 detection device warming up/calibrating |
| Equipment problem proximal to tracheal tube |
| Absence of driving pressure for positive pressure ventilation: circuit leak or disconnection; error in ventilation device function, assembly or settings; inadequate fresh gas flow |
| Obstructed circuit: stuck valve, incorrect circuit assembly, obstructed filter/heat and moisture exchanger or other circuit components |
| Airway obstruction |
| Tracheal tube obstruction: foreign body; secretions; blood; vomitus; pus; severe pulmonary oedema; kinking |
| Obstruction distal to tip of tracheal tube: foreign body; secretions; blood; vomitus; pus; severe pulmonary oedema; intraluminal tracheal mass; anterior mediastinal mass causing tracheal compression |
| Severely reduced pulmonary compliance with insufficient inspiratory pressures |
|
Severe bronchospasm (incl. anaphylaxis) Tension pneumothorax |
| Inadequate pulmonary blood flow |
|
Unrecognised cardiac arrest Pulmonary embolus Cardiopulmonary bypass |