Insensible Water Loss During Extracorporeal Membrane Oxygenation: An In Vitro Study

Abstract

To measure insensible fluid loss from silicone membrane oxygenators during extracorporeal membrane oxygenation (ECMO), an in vitro system was used. A standard neonatal ECMO circuit (Avecor) was connected to a noncompliant reservoir, which was then primed with normal saline. The experiment was conducted by using two silicone oxygenators (Avecor 0.4 and 0.8 m2), three gas flow rates (0.5, 1.0, and 2.0 L/min) (sweep), and two fluid flow rates (200 and 400 ml/min). Two methods were used to measure the water loss. One method was to replace the water to the noncompliant circuit by using a calibrated burette, and the other method was to collect condensed water after cooling the postmembrane sweep gas to 0 degrees C. The influence of the amount of sweep, fluid flow rate, size of membrane, and inlet and outlet sweep gas temperatures on measured water loss was statistically determined. The amount of water loss correlated with sweep (r2 = 0.81; p<0.00001) but was not related to the fluid flow rate, membrane size, or inlet and outlet sweep gas temperature. The average daily fluid loss measured with replacement and collection methods for each liter of sweep per minute were 72.0+/-12.6 and 62.3+/-10.0 ml, respectively. This information may be applied to clinical practice to accurately manage fluid balance in the sick neonate on ECMO.

Insensible water loss from the Jostra Quadrox D oxygenator: an in vitro study

“…Camacho, et al showed that silicone membranes, historically used for ECMO, had evaporative water loss that correlated with gas flow rate across the membrane surface. 12 Membrane size, transmembrane pressure gradient, and pump flow rate were shown not to be factors of water loss in this study. The silicone membrane is the only oxygenation device currently approved by the FDA for long-term use.…”

“…Our data are similar to data from the Camacho, et al study, suggesting that membrane types without micro-porous surfaces yield a somewhat lower insensible water loss value than that of micro-porous membrane oxygenators ( Figure 3). 6,12,13 In conclusion, the Jostra Quadrox D oxygenator has lower insensible water loss per liter of sweep gas than other types of oxygenators described in the recent literature. This study provides useful data for management of fluid balance in patients of all sizes who need ECMO support in the critical care setting.…”

Insensible water loss from the Hilite 2400LT oxygenator: an in vitro study

“…4 We were unable to explain why such a difference between the two PMP membrane devices existed. Eventually, we ran a pilot study, comparing the Quadrox D and the Hilite ® 2400LT.…”

“…The volume of actual water loss has been shown to vary between individual devices and the particular membranes used within the device. Camacho et al, 4 using a silicone membrane oxygenator, reported a 72-ml water loss over a 24-hour period, per litre/minute (L/min) of gas flow. Alexander et al 5 studied a microporous, hollow-fibre, membrane oxygenator and reported an 83-ml water loss over a 24 hour period, per L/min gas flow.…”

Insensible Water Loss From the Medtronic Minimax Oxygenator: An In Vitro Study

“…We also chose our methods on the basis of the previous reports of crystalloid to assess in vitro membrane performance. 9,10 It should be noted that the fluid loss across a membrane may vary over time. The initial 72-hour run suggests that the evaporative fluid loss remains constant over an extended period.…”