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

Effect of active airway warming with a heated-humidified breathing circuit on core body temperature in patients under general anesthesia: a systematic review and meta-analysis with trial sequential analysis

BACKGROUND

The application of a heated-humidified breathing circuit (HHBC) may reduce respiratory heat loss during mechanical ventilation, but its effect in preventing intraoperative hypothermia is controversial. This study aimed to investigate the effectiveness of HHBC in maintaining the core temperature of patients receiving mechanical ventilation under general anesthesia.

METHODS

We searched MEDLINE, Embase, Cochrane library (CENTRAL), and Google Scholar to identify all randomized controlled trials (RCTs) up to February 2022 that compared the intraoperative core temperature in patients with heated humidifier (HH) and other circuit devices. The primary outcome was the intraoperative core temperature at the end of surgery. The weighted mean differences (WMDs) between the groups and their 95% CIs were calculated for each outcome. We performed a trial sequential analysis of the primary outcomes to assess whether our results were conclusive.

RESULTS

Eighteen RCTs with 993 patients were included in the analysis. A significantly higher core temperature was observed at the end of surgery in patients with HH than those with no device (WMD = 0.734, 95% CI [0.443, 1.025]) or heat and moisture exchanger (WMD = 0.368, 95% CI [0.118, 0.618]), but with substantial heterogeneity.

CONCLUSIONS

Although HHBC did not absolutely prevent hypothermia, this meta-analysis suggests that it can be used as an effective supplemental device to maintain the intraoperative core temperature under general anesthesia. However, considering the substantial heterogeneity and limitations of this study, further well-designed studies are needed to clarify the effectiveness of HHBC.

Hypothermia as a potential remedy for canine and feline acute spinal cord injury: a review

Severe spinal cord injury (SCI) resulting in permanent sensory-motor and autonomic dysfunction caudal to a damaged spinal cord (SC) segment is a catastrophic event in human as well as in veterinary medicine. The situation of paraplegic/tetraplegic people or animals is further impaired by serious complications and often displays an image of permanent suffering. Therapeutic hypothermia (TH) has shown neuroprotective capacity in numerous experimental and several clinical studies or case reports. Hence, the method draws increasing attention of neuroscientists as well as health care workers. While systemic TH is a too complex procedure for veterinary practice, local application of TH with a reduced risk of the whole body temperature fluctuations and minimal side effects can become one of the therapeutic tools considered in the treatment of acute traumatic SCIs in bigger animals, especially when surgical decompression of spinal medulla and vertebral column reconstruction is indicated. Still, additional large prospective randomized studies are essential for the standardization of therapeutic protocols and the introduction of the method into therapeutic armamentarium in canine and feline spinal traumatology. The research strategy involved a PubMed, MEDLINE (Ovid), EMBASE (Ovid), and ISI Web of Science search from January 2000 to July 2021 using the terms “canine and feline spinal cord injuryˮ, “hypothermiaˮ, and “targeted temperature managementˮ in the English language literature; also references from selected studies were scanned and relevant articles included.

Clinical practice guideline. Unintentional perioperative hypothermia

The importance of the safety of our patients in the surgical theatre, has driven many projects. The majority of them aimed at better control and clinical performance; mainly of the variables that intervene or modulate the results of surgical procedures, and have a direct relationship with them. The Spanish Society of Anesthesiology, Critical Care and Therapeutic Pain (SEDAR), maintains a constant concern for a variable that clearly determines the outcomes of our clinical processes, "unintentional hypothermia" that develops in all patients undergoing an anesthetic or surgical procedure. SEDAR has promoted, in collaboration with other scientific Societies and patient Associations, the elaboration of this clinical practice guideline, which aims to answer clinical questions not yet resolved and for which, up to now, there are no documents based in the best scientific evidence available. With GRADE methodology and technical assistance from the Ibero-American Cochrane Collaboration office, this clinical practice guideline presents three recommendations (weak in favor) for active heating methods for the prevention of hypothermia (skin, fluid or gas); three for the prioritization of strategies for the prevention of hypothermia (too weak in favor and one strongly in favor); two of preheating strategies prior to anesthetic induction (both weak in favor); and two for research.

Comparative Study of the Effect of Warming at Various Temperatures on Biochemical, Hematologic, and Hemodynamic Parameters During Spinal Fusion Surgery Under Intravenous Anesthesia

BACKGROUND

Perioperative inadvertent hypothermia (PIH) commonly occurs after major surgical procedures under local or general anesthesia and increases the risk of complications such as organ failure, hypoperfusion, and peripheral vasoconstriction, as well as adverse postoperative outcomes, such as wound infection and increased surgical bleeding.

OBJECTIVES

We hypothesized that the intra-operative warming may affect these complications and thus, we aimed to compare the most appropriate temperature of the warmer to decrease patients' complications.

METHODS

The present randomized clinical trial investigated 90 patients undergoing total intravenous anesthesia in posterior spinal fusion surgery, randomly divided into two groups of 45. The warmer was set at 38°C for group "A" during surgery and at 40°C for group "B." Patient's demographic characteristics, the serum level of hemoglobin, hematocrit, and platelet counts, mean core temperature, systolic blood pressure (BP), heart rate, and respiratory rate were recorded before and after the surgery. Variables were compared between the two groups at three time intervals (during induction, during operation, and during recovery).

RESULTS

The mean temperature was not different between the two groups at the three time intervals. Other laboratory serum tests, vital signs, and oxygen consumption were maintained within the normal range although they did not improve significantly in two groups at the three time intervals.

CONCLUSIONS

There was no significant difference in warming of the patients during operation at 38 or 40°C to prevent hypothermia-induced complications during induction, operation, and recovery.

Mega Acer Kit® is more effective for warming the intravenous fluid than Ranger™ and ThermoSens® at 440 ml/h of infusion rate: an experimental performance study

BACKGROUND

Few studies have investigated the effectiveness of intravenous fluid warmers at low and moderate flow rates below 1,000 ml/h. In this study, we compared the effectiveness of three different fluid warmers at a low flow rate (440 ml/h).

METHODS

We experimentally investigated the fluid warming performances of Mega Acer Kit® (Group M, n = 10), Ranger™ (Group R, n = 10), and ThermoSens® (Group T, n = 10) at 440 ml/h for 60 min. All devices were set at a warming temperature of 41℃ with preheating for 10 min. Intravenous fluids were then delivered through them. The fluid temperature (primary endpoint) was measured at 76 cm from the device after infusion for 60 min. The expected decrease in mean body temperature (secondary endpoint) after 5 h infusion for a 70 kg patient (ΔMBT5) was also calculated.

RESULTS

The fluid temperature (mean [95% CI]) at 76 cm from the device, 60 minutes after the infusion was higher in group M (36.01 [35.73-36.29]℃), compared to groups T (29.81 [29.38-30.24]℃) and R (29.12 [28.52-29.72]℃) (P < 0.001). The ΔMBT5 (mean [95% CI]) was significantly smaller in group M (-0.04 [-0.04 to -0.03]℃) than that in groups T (-0.27 [-0.28 to -0.29]℃; P < 0.001) and R (-0.30 [-0.32 to -0.27]℃; P < 0.001). However, none of the fluid warmers provided a constant normothermic temperature above 36.5℃.

CONCLUSIONS

Mega Acer Kit® was more effective in warming the intravenous fluid with the smallest expected change in the mean body temperature, compared to Ranger™ and ThermoSens®, at a flow rate of 440 ml/h.

Experimental comparison of performances of Mega Acer Kit, Ranger and ThermoSens according to flow rates and distances

We experimentally investigated the fluid warming performances of three warmers with different technology, according to flow rates and distances. We used the following intravenous fluid warmers: Mega Acer Kit (Group M, n = 8), Ranger (group R, n = 8), and ThermoSens (group T, n = 8). Fluids that had been stored in the operating room over the previous 24 h were delivered at sequent flow rates of from 440 mL/h up to 2500 mL/h through preheated warming devices. The fluid temperatures were recorded at the inlet point, 76-cm proximal (P_out1) and 166-cm distal outlet points (P_out2) every 1 min for 10 min. We repeated each test eight times. The delivered fluid temperature [mean (95% confidence interval)] was significantly higher in group M than group R and T at flow rates up to 650 mL/h with the highest value at 440 mL/h [34.30 (33.35-35.24)°C] (P < 0.001), and was higher in group T and R at flow rates over 1140 mL/h at P_out1 [36.67 (36.62-36.73)°C and 37.85 (37.52-38.17)°C at 2500 mL/h, respectively] (P < 0.001). It was significantly higher at the P_out1 than the P_out2 at all flow rates for each device (P < 0.001). Mega Acer Kit can warm fluid more effectively compared with ThermoSens and Ranger at the low flow rate whereas the ThermoSens and the Ranger are suitable at higher flow rates. Furthermore, the device performance is more effective with shorter extension lines.