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In Response:

Foulis, Mike

Section Editor(s): Saidman, Lawrence

doi: 10.1213/ane.0b013e3181b2abcd
Letters to the Editor: Letters & Announcements

Life Support Solutions; Datex-Ohmeda, Inc.; Wisconsin;

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In Response:

The experience related by Dr. Kummar1 has not been described to us before. However, we reviewed the case as presented and tested two scenarios. First, how well is absorbent material held captive in the canister? Second, can loose absorbent material travel from the absorber through the breathing circuit to the condenser water trap?

  1. Absorbent material in the reusable canister is mechanically held captive by two elements.
    1. The cover assembly (Fig. 1, canister item 2) has a metal grate designed to contain all of the absorbent material. Particles larger than 1 mm are held captive by this plate.
    2. Figure 1.

      Figure 1.

    3. Foam filters (Fig. 1, canister item 3) are designed to trap dust particles in the absorbent material and additionally hold the absorbent material captive.
    4. Our review of the current design shows that the absorbent material is held captive and will not pass either barrier into the breathing circuit.
  2. A number of tests were conducted to understand whether any absorbent material unintentionally left on the outside of the canister after filling could migrate to the condenser.

In conclusion, we cannot explain the presence of the absorbent material in the condenser, which caused the circuit leak in this case. The reusable canister design incorporates two separate mechanisms to prevent the migration of absorber material into the circuit, and as such it is highly unlikely the particle came from here. The more likely explanation in the absence of further evidence is that loose material left from the filling process has at some time entered the breathing circuit and finally found a path to the low point of the condenser. We agree with Dr. Kummar’s comment regarding the importance of in-service training when using a new anesthesia workstation.

Mike Foulis

Life Support Solutions

Datex-Ohmeda, Inc.


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1.Kummar P, Korula G, Kumar S, Sarawaman PA. Unusual cause of leak in Datyx Aisys. Anesth Analg 2009; 109:1350–1
© 2009 International Anesthesia Research Society