Journal of Anaesthesiology Clinical Pharmacology

LETTER TO EDITOR
Year
: 2012  |  Volume : 28  |  Issue : 2  |  Page : 269--270

Failed ventilation due to heat and moisture exchanger filters malfunction


Sukhminder Jit Singh Bajwa, Amarjit Singh 
 Department of Anaesthesiology and Intensive Care, Gian Sagar Medical College and Hospital, Ram Nagar, Banur, Punjab, India

Correspondence Address:
Sukhminder Jit Singh Bajwa
Associate Professor, House No-27-A, Ratan Nagar, Tripuri, Patiala, Punjab - 147 001
India




How to cite this article:
Bajwa SJ, Singh A. Failed ventilation due to heat and moisture exchanger filters malfunction.J Anaesthesiol Clin Pharmacol 2012;28:269-270


How to cite this URL:
Bajwa SJ, Singh A. Failed ventilation due to heat and moisture exchanger filters malfunction. J Anaesthesiol Clin Pharmacol [serial online] 2012 [cited 2020 Aug 8 ];28:269-270
Available from: http://www.joacp.org/text.asp?2012/28/2/269/94923


Full Text

Sir,

The consequences and catastrophes due to manufacturing defects in the medical equipment can increase mortality and morbidity especially if such malfunctioning goes undetected for a fairly long duration. Heat and moisture exchanger filters (HMEF) are commonly used during surgeries of moderate to long duration for preserving pulmonary hydration and temperature as they are economical and easy to use. [1] There have been concerns regarding the malfunctioning of HMEF when the patient stays on mechanical ventilation for a long duration. [2] We report the case of complete respiratory obstruction due to a manufacturing defect in the HMEF in a 38-year-old woman, scheduled for laparoscopic cholecystectomy.

After induction of anesthesia and tracheal intubation with cuffed 7.5-mm ID endotracheal tube (ETT) ventilator settings were adjusted to 500 ml tidal volume, respiratory rate of 12/min, and oxygen:nitrous ratio of 40: 60. The HMEF was attached beyond the Y-connector of the breathing circuit. After 3-4 min of mechanical ventilation, it was observed that patient's chest did not show any breathing movements, which was confirmed by absence of air entry on auscultation but there were no changes in ventilator parameters and spirometry. The capnograph did not show a trace. The closed breathing circuit was disconnected immediately. Ventilation was difficult even with a Bains circuit attached thereafter. The HMEF was detached and we were able to ventilate the patient with ease. The procedure was uneventful thereafter. A detailed inspection of the HMEF later revealed that one its component had dislodged which possibly caused the obstruction [Figure 1] and [Figure 2].{Figure 1}{Figure 2}

The routine use of HMEF has been strongly recommended to avoid the obstruction during use of mass spectrometer in patients undergoing general anesthesia. [3] HMEF obstruction by contaminants, condensed water, hemoptysis, and proteinaceous material have been reported. However, a complete breathing obstruction of HMEF due to manufacturing defect, such as one-way valve causing air trapping, is rare. [4],[5] Tension pneumothorax after the soiling of the HMEF (in the expiratory limb) with sputum, inflammatory cells, and ciliary epithelium has been described. [6] The obstruction can mimic airway obstruction, silent chest due to severe bronchospasm, pneumothorax, ventilator malfunction, unseen leakage, and breathing circuit obstruction. [2],[4],[5],[6] In the present case, inspiratory obstruction occurred and the airway monitors failed to detect it as the gases passed out through the sensor in the expiratory limb.

The inner component of the filter may have been loose and may have been dislodged by the positive pressure ventilation. Although monitoring on modern machines is reliable, this case shows that such accidents may still occur.

References

1Rathgeber J. Devices used to humidify respired gases. Respir Care Clin N Am 2006;12:165-82.
2Wilkes AR. Heat and moisture exchangers and breathing system filters: Their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients. Anaesthesia 2011;66:40-51.
3Srinivasan NM. Use of heat and moisture exchanger in intubated patients reduces the blockage in gas sampling tube of the mass spectrometer. Saudi J Anaesth 2011;5:112-3.
4Casta A, Houck C. Acute intraoperative endotracheal tube obstruction associated with a heat and moisture exchange in an infant. Anesth Analg 1997;84:938-9.
5Prados W. A dangerous defect in a heat and moisture exchanger. Anesthesiology 1989;71:804.
6McEwan AI, Dowell L, Karis JH. Bilateral tension pneumothorax caused by a blocked bacterial filter in an anesthesia breathing circuit. Anesth Analg 1993;76:440-2.