The simultaneous use of a heat and moisture exchanger and a heated humidifier causes critical airway occlusion in less than 24 hours.
OBJECTIVE
Heat and moisture exchangers (HMEs) and heated humidifiers (HHs) may be used together inadvertently. Such an incident occurred at our institution resulting in airway occlusion.


METHODS
A bench-top study was conducted to compare the incidence of airway occlusion when using (1) no airway humidification, (2) HME alone, (3) HH alone, and (4) both HME and HH in combination as part of a standard breathing circuit.


RESULTS
The simultaneous use of a HME and a HH was associated with a reduction in tidal volume (no airway humidification, P ≤ .05; HME alone, P ≤ .01; and HH alone, P ≤ .01) and an increased incidence of airway occlusion (no airway humidification, 0/7; HME alone, 0/7; HH alone, 0/7; and HME and HH in combination, 7/7; P < .0001).


CONCLUSIONS
The use of a HME and a HH in combination is likely to result in airway occlusion. Precautions should be taken to ensure that both systems are not used together in clinical practice.
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET; Specialty trainee, Barts and the London School of Anaesthesia, The Royal London Hospital, Whitechapel, London, UK, E1 1BB.
Alexander
A
Doyle
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET.
Maryanne
M
Mariyaselvam
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET.
Gayathri
G
Wijewardena
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET.
Natalie
N
English
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET.
Emma
E
Gent
Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital, Gayton Road, Kings Lynn, Norfolk, UK, PE30 4ET. Electronic address: peteryoung101@gmail.com.
Peter
P
Young
D000402:Airway Obstruction / Q000209:etiology*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D000068998:Humidifiers; D006813:Humidity / Q000009:adverse effects*; D015994:Incidence; D019300:Medical Errors / Q000009:adverse effects*; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000295:instrumentation; D013990:Tidal Volume; D013997:Time Factors
complications; intubation; mechanical ventilation; occlusion; patient safety