Sir,
Given the ill-effects of hypothermia, preservation of intraoperative normothermia is of utmost importance.[1] To this end, fluid warmers are used to warm intravenous fluids and blood products prior to administration to patients and hence prevent hypothermia. We intend to report a complication associated with the use of a fluid warmer (Astotherm plus™), which can affect the patients' health very adversely.
Astotherm plus™ is a fluid/blood infusion warmer [Figure 1], which consists of a heat exchange cylinder having slots on which an infusion line (Astotube) is coiled. As fluid/blood passes through the Astotube, it gets warmed due to coming in contact with the heat cylinder. The warm fluid/blood is then infused to the patient. This assembly is covered by a “heat protection sleeve” to minimize heat loss to environment.
Figure 1.
Components of Astotherm plus. Black arrow - heat protection sleeve. Blue arrow - the Astotube. Orange arrow - a heat exchange cylinder
A 32-year-old male patient being operated for a supratentorial meningioma was being administered packed red blood cells (PRBC) in view of ongoing blood loss during the surgery. The anesthesia team was using Astotherm plus™ blood and infusion warmer to warm the PRBCs before administration. During the course of PRBC administration, presence of air bubbles was detected in the blood infusion line distally to exit from the blood warmer. We ruled out any loose connections or any leak in PRBC bag or infusion set. However, upon opening the “heat protection sleeve” of the fluid warmer, we detected presence of many small air bubbles in the “Astotube™” as it coiled around the heat exchange cylinder of the infusion device [Figure 1]. We observed that with flow of blood, many of these small air bubbles were coalescing leading to air bubbles as long as 2 cm in the Astotube™. These air bubbles if administered intravenously can manifest as air embolism leading to disastrous complications. Occurrence of air bubbles continued even after administration of iv fluid post blood administration [Figure 2].
Figure 2.
Air bubbles inside the Astotube
Packed RBCs are stored at 4 degree Celsius and rapid warming causes decreased solubility of gases because the Bunsen solubility coefficients of gases existing in stored blood changes when blood is rapidly warmed toward 37 degree Celsius. We report this to caution fellow anesthesiologists to this possible complication while managing long duration surgeries.
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Conflicts of interest
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Reference
- 1.Owens CD, Stoessel K. Surgical site infections: Epidemiology, microbiology and prevention. J Hosp Infect. 2008;70(Suppl 2):3–10. doi: 10.1016/S0195-6701(08)60017-1. [DOI] [PubMed] [Google Scholar]