An inherently dangerous fluid warmer design.

A Hotline® fluid warmer is a device commonly used by anesthesia providers in the operating room to warm and infuse blood products and large fluid volumes. The purpose of the fluid warmer is to counter heat loss, which occurs under anesthesia. Despite normal checks performed prior to its use, we discovered a breach in the fluid warming set attached to the Hotline® fluid warmer during blood administration. The breach contaminated the patient's sterile intravenous line. We describe the quality and safety processes we undertook in detail. We discuss the notion that monitoring alarms are an important safety feature of most modern devices utilized by anesthesia providers. We believe the Hotline® fluid warmer lacks a crucial monitor for detecting a breach within the fluid warming set, and therefore recommend the addition of an alarm to improve this device's safety.

Aluminium release and fluid warming: provocational setting and devices at risk.

BACKGROUND: Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution. RESULTS: Saline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device. CONCLUSION: Uncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Fluid warming with parylene-coated enFlow cartridge: Bench and pilot animal study of aluminum extraction due to prolonged use.

OBJECTIVES: Intravenous fluid warming devices with surface heating systems transfer heat using aluminum blocks, which if uncoated elute toxic levels of aluminum into the infusate. This study examined extractable aluminum detected from prolonged use of the updated version of the enFlow® cartridge, which uses a parylene-coated aluminum heating block. METHODS: In dynamic bench tests, we measured the concentration of aluminum that leached into three solutions (Sterofundin ISO, Plasma-Lyte 148, and whole blood) that were continuously pumped (0.2 and 5.5 mL min-1) and warmed to 40°C by the enFlow cartridge (parylene-coated) for 5 h. Prolonged quasi-static bench tests measured aluminum concentration in 16 solutions which were gently rocked within the enFlow cartridge (parylene-coated) for 72 h at 40°C. Aluminum concentrations were measured using inductively coupled mass spectroscopy and matrix blank corrected. Measured aluminum concentrations were compared to a Tolerable Exposure limit to calculate Margins of Safety based on the US Food and Drug Administration maximum recommended concentration in parenteral fluids (25 µg L-1). A parallel pilot in vivo animal study was performed using mice injected with fluids warmed for 72 h by the enFlow cartridge (parylene-coated). RESULTS: The enFlow cartridge (parylene-coated) demonstrated low toxicological risks in all tests. Sterofundin ISO resulted in the highest aluminum concentration after simulated prolonged use of the enFlow cartridge (parylene-coated) (3.11 µg device-1), which represents a 99.2% decrease from the enFlow cartridge (uncoated) and Margin of Safety of 1.7. Dynamic tests at two different flow rates with three challenge solutions resulted in concentrations less than the method detection limits (20.6 or 41.2 µg L-1) of the analysis method. The animals in the in vivo study showed no evidence of toxicity. CONCLUSION: Observed toxicological risk levels associated with the enFlow cartridge (parylene-coated) intravenous fluid warmer were below those set by the Food and Drug Administration and suggest that the use of enFlow cartridge (parylene-coated) is safe with a variety of intravenous solution types and in different therapeutic scenarios.

Intraoperative Irrigation: Fluid Administration and Management Amidst Conflicting Evidence.

Surgeons use irrigation during open cavity procedures to improve their view of the patient's anatomy and to reduce the patient's risk of infection. However, there are no standard guidelines that recommend a specific type of fluid, additive, or volume of irrigation to use during open procedures. Intraoperative hypothermia can occur if irrigation fluids have not been warmed or have cooled before use, causing adverse patient outcomes. In addition, failing to manage (eg, measure and document) fluid volume accurately may affect clinical decision making and cause other complications. Perioperative personnel should evaluate new technologies that may improve the efficiency and accuracy of irrigation temperature and volume measurements. More research is needed to develop standardized practice guidelines for intraoperative irrigation and fluid management.

Warming blood prior to transfusion using latent heat.

OBJECTIVE: Major trauma is associated with blood loss and hypothermia. It is common to replace lost fluid with red cells stored at 2-6°C, and/or colloid/crystalloid fluid stored at ambient temperature, thus increasing hypothermia risk. At trauma and medical retrieval sites, mains electricity powered fluid warmers cannot be generally used. Latent heat provides an alternate practical method of portable temperature-controlled intravenous fluid warming. This work investigates the safety and efficacy of a fluid warmer powered by latent heat. METHODS: Twenty-five haematology patients received red cell transfusions, one through a fluid warmer, using latent heat from a super-cooled liquid and one without warming. Temperature of donor red cell units was measured after passing through fluid warmers. Blood samples were collected from red cell units and patients, prior and after each transfusion. These were tested for haemolysis markers (plasma haemoglobin, potassium, lactate dehydrogenase, bilirubin) and for traces of super-cooled liquid. Patient physiological parameters (oxygen saturation, pulse, temperature, blood pressure, respiration) were monitored during each transfusion. RESULTS: Patient's physiological signs remained stable and no transfusion reactions were observed during warm transfusions. Latent heat fluid warmers increased the temperature of red cell units to approximately 35°C. There were no significant differences in haemolysis markers following warmed and unwarmed transfusions, and no contamination of red cell units by super-cooled liquid was detected. CONCLUSION: The latent heat fluid warmer was shown to safely warm transfused blood in a controlled clinical setting.

Warming efficacy of Ranger™ and FT2800 fluid warmer under different room temperatures and flow rates.

The comparison of the heating capabilities with different warming system between 3M™ Ranger™ warmer (3M) and FT2800 fluid warmer (FT) under different room temperatures and infusion rates, has been rarely reported previously. The study was then aimed to compare the warming efficacies of dry heat technology (3M) and coaxial warming system (FT) under different room temperatures and infusion rates, the advantages and disadvantages of both infusion systems would be compared to provide reference for clinical infusion practice. In the study, both target warming temperatures of 3M and FT warmer were set at 41 °C, fluid was administrated under 20, 22 and 24 °C room temperatures and drip rates of 60, 80, 100, 120, 140, 160, 200, 350 drops min-1. The fluid temperature at the outlet of the infusion tube (Toutlet) was measured and compared. The Toutlet of FT was higher than that of 3 M (P < 0.001) under different room temperatures. The Toutlet of FT increased with the room temperature raised (P < 0.05). As for 3M, Toutlet was lowest at 20 °C (P < 0.001) and no statistical difference of Toutlet was found between 22 and 24 °C (P = 0.667). Linear regression showed that the Toutlet of 3M increased with the speed up of drip rate, while the Toutlet of FT was decreased. The relationship between Toutlet & room temperature & drip rate for both 3M and FT warmers was calculated by a formula. 3M Ranger™ and FT2800 show different heating capabilities under different room temperatures and drip rates. 3M is more efficient at high flow rate while FT is more efficient at low flow rate. There is a formula relationship between Toutlet & room temperature & drip rate for both 3M and FT warmers.

Beneficial effect of fluid warming in elderly patients with bladder cancer undergoing Da Vinci robotic-assisted laparoscopic radical cystectomy

OBJECTIVES: The enhanced recovery after surgery (ERAS) protocol recommends prevention of intraoperative hypothermia. However, the beneficial effect of maintaining normothermia after radical cystectomy has not been evaluated. This study aimed to investigate the efficacy of fluid warming nursing in elderly patients undergoing Da Vinci robotic-assisted laparoscopic radical cystectomy. METHODS: A total of 108 patients with bladder cancer scheduled to undergo DaVinci robotic-assisted laparoscopic radical cystectomy were recruited and randomly divided into the control group (n=55), which received a warming blanket (43°C) during the intraoperative period and the warming group (n=53), in which all intraoperative fluids were administered via a fluid warmer (41°C). The surgical data, body temperature, coagulation function indexes, and postoperative complications were compared between the two groups. RESULTS: Compared to the control group, the warming group had significantly less intraoperative transfusion (p=0.028) and shorter hospitalization days (p<0.05). During the entire intraoperative period (from 1 to 6h), body temperature was significantly higher in the warming group than in the control group. There were significant differences in preoperative fibrinogen level, white blood cell count, total bilirubin level, intraoperative lactose level, postoperative thrombin time (TT), and platelet count between the control and warming groups. Multivariate linear regression analysis demonstrated that TT was the only significant factor, suggesting that the warming group had a lower TT than the control group. CONCLUSION: Fluid warming nursing can effectively reduce transfusion requirement and hospitalization days, maintain intraoperative normothermia, and promote postoperative coagulation function in elderly patients undergoing Da Vinci robotic-assisted laparoscopic radical cystectomy.

Characterisation of aluminium release by the enFlow® fluid-warming system in crystalloids and blood products.

The use of uncoated aluminium-heated plates in an intravenous fluid-warming system has been shown to produce high levels of aluminium in Sterofundin 1/1E, a balanced crystalloid solution. However, the effect of this fluid-warming device on other balanced crystalloid solutions and blood products has not been studied. Using mass spectrometry we measured aluminium levels in Plasma-Lyte 148, compound sodium lactate solution, 4% human albumin solution, expired resuspended packed red cells and fresh frozen plasma that were pumped through an enFlow® fluid-warming system at 2 ml.min-1 . Samples were taken at baseline before heating and then at 10-min intervals up to 60 min with the system set to warm the fluids to 40 °C. High concentrations of aluminium were found for Plasma-Lyte 148 and compound sodium lactate solutions (mean (SD) 223 (0.6) µmol.l-1 and 163 (0.2) µmol.l-1 at 60 min, respectively); both concentrations were significantly greater than the United States Food and Drug Administration recommended maximum limit for aluminium in intravenous nutrition of 25 µg.l-1 (0.9 µmol.l-1 ). Lower aluminium levels were found in 4% human albumin solutions, expired resuspended red cells and fresh frozen plasma at 60 min (mean (SD) 5.7 (0.1) µmol.l-1 , 2.7 (0.0) µmol.l-1 and 2.3 (0.4) µmol.l-1 , respectively). The process allowing addition of aluminium to be added to Sterofundin 1/1E by the enFlow fluid warmer also occurs in Plasma-Lyte 148 and compound sodium lactate solutions and to a lesser degree in blood products. The exact mechanism facilitating this process and its clinical significance remain unclear.

Aluminium release by coated and uncoated fluid-warming devices.

The use of fluid-warming systems is recommended for infusion rates > 500 ml.h-1 to avoid peri-operative hypothermia. Some fluid-warming devices use disposable aluminium-heated plates for heat transfer, but there is no protective coating to separate the fluid from the heated aluminium surface. It is unknown if this could promote release of aluminium into infusion fluids. We investigated a coated (Fluido compact) and an uncoated (enFlow) fluid-warming device using normal saline or balanced electrolyte solution as infusion fluids, pumped through the heated disposables at flow rates of 2, 4 and 8 ml.min-1 for 60 min each. Aluminium concentrations in the fluid samples were analysed using graphite furnace atomic absorption spectrometry. With saline the coated and uncoated devices yielded aluminium concentrations below the level of quantification (< 128 µg.l-1 ). Similarly, balanced electrolyte solution in the coated device yielded aluminium concentrations < 128 µg.l-1 . However, balanced electrolyte solution in the uncoated device yielded aluminium concentrations of up to 6794 (3465-8002 [1868-7421]) µg.l-1 . Repeating this last study at a flow rate of 2 ml.min-1 resulted in quite high aluminium concentrations when the uncoated device was not heated (~1000 µg.l-1 ) and higher concentrations after the device was heated. We conclude that using uncoated aluminium plates in fluid-warming systems can lead to a risk of administering potentially harmful concentrations of aluminium when balanced crystalloid solutions are used. The mechanism is unclear, but heat is in part involved. Coating for aluminium within medical devices in direct contact with infusion fluids should be recommended.

Synergistic experimental and numerical characterization of a dry-heat, fluid-warming device.

Fluids that are infused into the human body must be at a temperature that is compatible with the internal thermal state of the body. Since infusants are typically stored at temperatures that are too low for compatibility, a heating means is required to achieve the appropriate infusion temperature. This paper sets forth a synergistic investigation involving coupled experimentation and numerical simulation of the characteristics of one of the main categories of body-fluid heating means. The methodology developed here serves equally well as a design optimization tool. The paper encompasses two stages: (a) an experimental and numerical evaluation of a generic warming device in common use and (b) a redesign utilizing the same tools to elevate the performance of devices of this category. The numerical simulation dealt with steady and unsteady three-dimensional fluid flow and heat transfer which are endemic to devices of this kind. The two-pronged approach developed here was shown to be capable of coping with an operating feature called stopflow wherein an officiating physician orders an immediate cessation of fluid flow. The thermal events following stopflow are well described by the numerical simulations.

Does the addition of active body warming to in-line intravenous fluid warming prevent maternal hypothermia during elective caesarean section? A randomised controlled trial.

INTRODUCTION: Inadvertent perioperative hypothermia occurs frequently during elective caesarean section but perioperative active body warming is not widely used. There is a paucity of evidence of its use in the obstetric population, and no applicable guidelines. We set out to identify a superior active warming method for preventing inadvertent perioperative hypothermia. METHODS: Following ethical approval, 132 women presenting for uncomplicated elective caesarean section under spinal anaesthesia were recruited. All participants received in-line intravenous fluid warming and were randomised to one of three parallel groups: no active body warming; forced air warming; and conduction mattress warming. The primary outcome was the difference in mean core temperature, measured on admission to the recovery room, between study groups. Core temperature and thermal comfort were measured perioperatively at 15-min intervals. Estimated blood loss, haemoglobin change, length of hospital stay and neonatal core temperature were also recorded. RESULTS: One-hundred-and-thirty-one women completed the study. There was no significant difference in mean core temperature on admission to the recovery room (36.6°C vs. 36.6°C vs. 36.6°C, η2=0.005, P=0.74). Maternal hypothermia was prevented in all groups with only 0.3% hypothermic at any of the temperature measurements (3/1016). There was no difference in mean neonatal core temperature (36.3°C vs. 36.3°C vs. 36.3°C, η2=0.003, P=0.82); however, 59.4% (76/128) of all neonates were hypothermic. CONCLUSION: In-line intravenous fluid warming is sufficient to prevent maternal hypothermia and maintain core temperature. The addition of active body warming conferred no added benefit.

Effects of forced-air prewarming combined with fluid warmingon body temperature and thermal comfort in patients undergoing lobectomy / 基础医学与临床

Objective To investigate the effects of forced-air prewarming combined with fluid warming on body temperature and thermal comfort in patients undergoing lobectomy.Methods Forty six patients scheduled for video-assisted thoracoscopic surgery (VATS) of lobectomy were randomized into two groups (n=23 each):warming group (group T) and the control group (group C).Forced-air prewarming combined with infusion heating was applied in the warming group,while only conventional passive warming was used in control group.The tympanic membrane temperatures were recorded before prewarming,after prewarming, during the anesthesia, the end of operation, the moment in and out of the postanesthesia care unit (PACU).Incidence of postoperative shivering, thermal comfort and the time in the PACU were recorded.Results The warming group had a slower temperature decrease at 1,2, 3 hours after operation and end of operation(P< 0.01), warming group had significantly lower incidence of hypothermia and shivering than control group(8.7% vs 56.5%, 4.3% vs 34.8%,P<0.05),and the thermalcomfort score was higher in warming group than in control group(8.52±0.94 vs 7.65±0.83,P<0.05).Conclusions Forced-air prewarming combined with fluid warming has significant clinical effects to stabilize patients` body temperature during operations,to reduce the incidence of hypothermia and shivering and to improve the thermal comfort, which provides a simple and effective temperature protection strategy for patients undergoing lobectomy.

Comparative analysis of techniques to prevent laparoscopic fogging.

PURPOSE: To evaluate the efficiency and efficacy of two common and commercially available methods to resolve lens fogging: a Fluid Warming System (O.R. Solutions, Chantilly, VA) and the Clearify Visualization System (Covidien, Mansfield, MA). MATERIAL AND METHODS: We prospectively evaluated 40 patients undergoing laparoscopic renal procedures with the Fluid Warming System (first 20 cases) and then the Clearify Visualization System (second 20 cases). We utilized the standard Fluid Warming System per a 30-second modified protocol established in our laboratory. We used the Clearify according to manufacturer instructions. For each procedure we documented the etiology of each episode of visual obstruction, procedure type and surgery duration. We performed a cost analysis. For all cases we used the same insufflator, insufflation trocar location and trocar configuration. RESULTS: All 40 patients completed the study protocol without incident. The mean fogging events per hour for the Fluid Warming System and Clearify Visualization System were 0.7 (0-2.52) and 1.4 (0-5.02), respectively (P = 0.045). Surgery duration and cost per procedure were similar for both systems. CONCLUSION: The Fluid Warming System with modified technique was found to have less fogging events than the Clearify Visualization System, with no difference in operative time or cost.

Clinical evaluation of a newly designed fluid warming kit on fluid warming and hypothermia during spinal surgery.

BACKGROUND: The Mega Acer Kit® (MAK) is a newly designed heated and humidified breathing circuit that warms fluid passing through the circuit lumen. In this study, we investigated the system's efficacy for the perioperative prevention of hypothermia and fluid warming. METHODS: Ninety patients undergoing spinal surgery were enrolled in this study and randomly assigned to 3 groups based on the fluid warming device used: no fluid warming system (Group C, n = 30), via a Standard Ranger (Group R, n = 30), or via the MAK (Group M, n = 30). Distal esophageal temperatures (Teso) and infusion fluid temperature (TF) were recorded at 15 min intervals for duration of 180 min during surgery. If Teso was < 35.0℃, a forced-air convective warming device was used. RESULTS: Final Teso values were 34.8 ± 0.3℃, 35.1 ± 0.1℃, and 35.8 ± 0.3℃ in groups C, R, and M, respectively (P < 0.01). Teso was significantly higher in group M when compared with that in groups C and R throughout the study period (P < 0.05). The number of patients requiring a forced-air convective warming device was significantly lower in group M (n = 0) when compared with that in groups R (n = 17) and C (n = 30) (P < 0.05). The final infusion fluid temperature was higher in group M when compared with that in groups C and R throughout the study period (35.4 ± 1.0 vs. 23.0 ± 0.3 and 32.8 ± 0.6℃; P < 0.01). CONCLUSIONS: The MAK is more effective for preventing hypothermia and for warming fluid than the Standard Ranger.

Clinical evaluation of a newly designed fluid warming kit on fluid warming and hypothermia during spinal surgery / 대한마취과학회지

BACKGROUND: The Mega Acer Kit(R) (MAK) is a newly designed heated and humidified breathing circuit that warms fluid passing through the circuit lumen. In this study, we investigated the system's efficacy for the perioperative prevention of hypothermia and fluid warming. METHODS: Ninety patients undergoing spinal surgery were enrolled in this study and randomly assigned to 3 groups based on the fluid warming device used: no fluid warming system (Group C, n = 30), via a Standard Ranger (Group R, n = 30), or via the MAK (Group M, n = 30). Distal esophageal temperatures (Teso) and infusion fluid temperature (TF) were recorded at 15 min intervals for duration of 180 min during surgery. If Teso was < 35.0degrees C, a forced-air convective warming device was used. RESULTS: Final Teso values were 34.8 +/- 0.3degrees C, 35.1 +/- 0.1degrees C, and 35.8 +/- 0.3degrees C in groups C, R, and M, respectively (P < 0.01). Teso was significantly higher in group M when compared with that in groups C and R throughout the study period (P < 0.05). The number of patients requiring a forced-air convective warming device was significantly lower in group M (n = 0) when compared with that in groups R (n = 17) and C (n = 30) (P < 0.05). The final infusion fluid temperature was higher in group M when compared with that in groups C and R throughout the study period (35.4 +/- 1.0 vs. 23.0 +/- 0.3 and 32.8 +/- 0.6degrees C; P < 0.01). CONCLUSIONS: The MAK is more effective for preventing hypothermia and for warming fluid than the Standard Ranger.

The Effects of Temperature Monitoring Methods and Thermal Management Methods during Spinal Surgery / 대한마취과학회지

BACKGROUND: The precise measurement of body temperature during anesthesia is important to prevent hypothermia.The aim of this study was to compare the urinary bladder temperature to the esophageal, nasopharyngeal, rectal and skin temperatures, and to compare three heating methods during spine surgery. METHODS: Forty-two patients with ASA physical status I-II, who were scheduled to undergo spine surgery in the prone position, were included in this study.The patients were randomly divided into 4 groups:Group I was treated without any heating methods; group 2, with fluid-warmers; group 3, with forced air-warmers; and group 4, with a combination of both heating methods.After the induction of anesthesia, the esophageal, nasopharyngeal, rectal, urinary bladder and skin temperature was monitored every 15 minute for 3 hours.The urinary bladder temperature was compared to the esophageal, nasopharyngeal, rectal and skin temperatures. RESULTS: The urinary bladder temperature was found to be higher than the esophageal and the nasopharyngeal temperatures (P < 0.01).The urinary bladder temperature of group 3 was higher than that of group 1 at 180 minutes after induction of anesthesia (P < 0.05).The urinary bladder temperature of group 4 was higher than that of group 1 at 150 minutes (P < 0.05), as well as at 165 and 180 minutes (P < 0.05).The skin temperatures of groups 3 and 4 were higher than group 1 (P < 0.001). CONCLUSIONS: The urinary bladder temperature was higher than the esophageal temperature and correlated with the esophageal, nasopharyngeal and rectal temperatures.During spine surgery in the prone position, a forced air-warmer was found to be the most effective but a combination of all the methods tested was found to be even more effective.