Surprising Results: Sodasorb™ performs better than LithoLyme™ in a standard clinical setting

Introduction:Litholyme™ (Allied Healthcare Products Inc., St. Louis, MO, USA) utilize Ca(OH)2 as the primary absorbent of CO2 in their granules, while Sodasorb™ (W.R. Grace, Lexington, MA, USA) utilizes a proprietary... [ view full abstract ]

Introduction:

Litholyme™ (Allied Healthcare Products Inc., St. Louis, MO, USA) utilize Ca(OH)₂ as the primary absorbent of CO₂ in their granules, while Sodasorb™ (W.R. Grace, Lexington, MA, USA) utilizes a proprietary mixture of CA(OH)₂, NaOH, and KOH (1,2). The NaOH levels of Sodasorb™ require the wasted granules to be disposed of in medical waste. An obvious advantage with Litholyme™ granules is that it can be disposed of with normal waste.

Litholyme™ has been reported to have particularly favorable data in respect to CO₂ absorbent capabilities (3). In in vitro experiments utilizing a model anesthetic setup, Litholyme™ had an absorptive capacity 1.5x that of its nearest competitor (4).

This study is a direct comparison between Litholyme™ and Sodasorb™ in a clinical setting by measuring CO₂ absorbent depletion times.

Methods:

The study was conducted, over a 12 week period in 2016-17, at the Stanford University Hospital and approved by the University of Stanford Institutional Review Board.

20 CO₂ canisters were filled with Sodasorb™ (n=10) or Litholyme™ (n=10) per standard operating theatre policies regarding the refilling of the reusable canisters, and were placed in Drager Apollo® anesthetic machines. A resident (C.F.) or an attending (M.B.) were present for all the anesthetic cases studied. The CO₂ absorbent was randomly assigned throughout the study period. General endotracheal anesthesia was administered and the fresh gas flow (FGF) recorded. During the induction and emergence phases of the case, FGFs were approximately 10 L/min. FGFs of less than 2 L/min were used during the maintenance phase of the case. The CO₂ absorber was counted as expired when there was evidence of exhaustion as determined by inspired CO₂ fraction (FiCO₂) at 1.0 %. There was no restriction to the type of the surgery case. Liters of FGF processed by the same volume of absorbent in each canister were the primary endpoint and extracted from the automated anesthetic record.

Results:

There was no difference in surgical case type or patient characteristics between the cases done by the attending (M.B) or resident (C.F). The CO₂ absorbents had similar characteristics when handled by the resident or attending, with no statistical difference seen between the Litholyme or Sodasorb canisters when controlling for investigator (Figure 1a).

Significant difference was noted between the Litholyme™ and Sodasorb™ CO₂ absorbents with respect to total liters of gas absorbed by each absorbent (p<0.005, two-tailed t test, Figure 1b).

Conclusion:

Despite previously reported favorable data for Litholyme™, in this clinical study, Sodasorb™ was able to absorb 1.4x as much CO₂ as Litholyme™.