Hypothermia in Adult ICUs: Changing Incidence But Persistent Risk Factor for Mortality

Associations Between Core Temperature Disorders and Outcomes of Pediatric Intensive Care Unit Patients

BACKGROUND

The few studies of associations between fever and outcomes in pediatric intensive care unit (PICU) patients have conflicting findings. Associations between hypothermia and patient outcomes have not been studied.

OBJECTIVE

To investigate the incidence and characteristics of fever and hypothermia and their associations with adverse outcomes among PICU patients.

METHODS

Patients consecutively admitted to 2 PICUs in a 2-year period were prospectively studied. Core temperature was mainly measured by rectal or axillary thermometry. Fever and hypothermia were defined as core temperatures of greater than 38.0 °C and less than 36.0 °C, respectively. Prolonged mechanical ventilation, prolonged PICU stay, and PICU mortality were the adverse patient outcomes studied. Associations between patient outcomes and core temperature disorders were evaluated with univariate comparisons and multivariate analyses.

RESULTS

Of 545 patients enrolled, fever occurred in 299 (54.9%) and hypothermia occurred in 161 (29.5%). Both temperature disorders were independently associated with prolonged mechanical ventilation and prolonged PICU stay (P < .001) but not with PICU mortality. Late onset of fever (P < .001) and hypothermia (P = .009) were independently associated with prolonged mechanical ventilation, fever magnitude and duration (both P < .001) were independently associated with prolonged PICU stay, and fever magnitude (P < .001) and infectious cause of hypothermia (P= .01) were independently associated with higher PICU mortality.

CONCLUSIONS

These findings provide evidence that the manifestation and characteristics of fever and hypothermia are independent predictors of adverse outcomes in PICU patients.

Accuracy of zero-heat-flux thermometry and bladder temperature measurement in critically ill patients

Core temperature (T_Core) monitoring is essential in intensive care medicine. Bladder temperature is the standard of care in many institutions, but not possible in all patients. We therefore compared core temperature measured with a zero-heat flux thermometer (T_ZHF) and with a bladder catheter (T_Bladder) against blood temperature (T_Blood) as a gold standard in 50 critically ill patients in a prospective, observational study. Every 30 min T_Blood, T_Bladder and T_ZHF were documented simultaneously. Bland–Altman statistics were used for interpretation. 7018 pairs of measurements for the comparison of T_Blood with T_ZHF and 7265 pairs of measurements for the comparison of T_Blood with T_Bladder could be used. T_Bladder represented T_Blood more accurate than T_ZHF. In the Bland Altman analyses the bias was smaller (0.05 °C vs. − 0.12 °C) and limits of agreement were narrower (0.64 °C to − 0.54 °C vs. 0.51 °C to – 0.76 °C), but not in clinically meaningful amounts. In conclusion the results for zero-heat-flux and bladder temperatures were virtually identical within about a tenth of a degree, although T_ZHF tended to underestimate T_Blood. Therefore, either is suitable for clinical use.

German Clinical Trials Register, DRKS00015482, Registered on 20th September 2018, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00015482.

Hypothermia during CRRT, a comparative analysis

BACKGROUND

One of the most common adverse events during continuous renal replacement therapy (CRRT) is hypothermia, reported to occur in over 4/10 cases. In turn, hypothermia is known to be associated with higher mortality rates among patients treated in intensive care units (ICU). The present study examined if a novel warming device in the current generation of CRRT systems could lower incidence of hypothermia compared to previous generation technology.

METHODS

We included ICU patients >18 years, at Skåne University Hospital, Lund from November 2006 to August 2019 and treated with CRRT. Temperature measurements were recorded from the CRRT systems and from the patients hourly.

RESULTS

In total, 310 patients treated with the older system vs 32 patients treated using the newer CRRT system were included. We found that historic Prismaflex patients spent 11.43% of their time in hypothermia, as compared to the novel Prismax CRRT system, where 10.06% of patient hours were below 36.0°C (Chi-Square P = .0063). The novel blood warmer is associated with less heat loss compared to the older warmer: mean patient temperature was 37°C vs 36.5°C for these two groups and mean set return temperature was 37.9°C vs 40.9°C (both P < .001).

CONCLUSIONS

The current generation CRRT system and blood warmer significantly decreases the risk of hypothermia among critically ill patients treated with continuous renal replacement therapy as compared to historic controls. Achieving target temperature is easier with the new system.

Secondary hypothermia in patients with super-refractory status epilepticus managed with propofol and ketamine

BACKGROUND

Therapeutic hypothermia as a potent nonpharmacologic antiseizure therapy has been investigated experimentally in animal models and humans. Although induced hypothermia has been shown to be neuroprotective in acute convulsive status epilepticus, whether its use will translate into improved outcomes for patients with super-refractory nonconvulsive status epilepticus (SRNCSE) has been debated. No clinical data are available on the occurrence and prognostic impact of secondary hypothermia (s-HT) in patients with SRNCSE. With the possibility of core to periphery redistribution of heat with propofol and a centrally mediated dose-dependent fall in body temperature with ketamine, we aimed to investigate the incidence of s-HT events in patients with SRNCSE managed with propofol and ketamine and their impact on clinical outcomes.

METHODS

We performed a retrospective observational analysis of consecutive patients with SRNCSE managed with propofol and/or ketamine in a single-center neurological intensive care unit between December 1, 2012 and December 31, 2015. Patients were divided according to the occurrence of hypothermia (temperature < 35.0 °C) into an s-HT group and a nonhypothermia (n-HT) group. Patients who received targeted temperature management therapy were excluded. We compared the demographics, comorbidities, treatment characteristics, and outcomes between groups.

RESULTS

Ninety-nine consecutive patients with SRNCSE managed with propofol and/or ketamine were identified during the study period. Twenty patients who received targeted temperature management were excluded, leaving a total of 79 patients for analysis. Hypothermia was observed in 52% (41/79) of the study population. Ketamine was used in 63/79 patients (80%). Ketamine infusion rates were higher and of longer duration among patients who developed s-HT compared with those who did not (mean dosage: 57.35 ± 26.6 mcg/kg/min vs 37.17 ± 15 mcg/kg/min, P = 0.001; duration: 116.36 ± 81.9 h vs 88 ± 89.7 h, P = 0.048). Propofol was used in 78/79 patients (99%), with no significant differences in characteristics between groups (mean dosage: 46.44 ± 20.2 mcg/kg/min vs 36.9 ± 12.9 mcg/kg/min, P = 0.058; duration: 125.43 ± 96.4 h vs 102.3 ± 87.1 h, P = 0.215). No significant differences in demographics, comorbidities, status epilepticus duration and resolution rates, and outcomes were observed between groups.

CONCLUSION

In this single-center retrospective analysis of patients whose SRNCSE is being treated, higher doses and longer durations of ketamine were associated with the occurrence of s-HT. Further investigation is warranted to clarify the thermogenic effects of ketamine and its effect on status epilepticus outcomes.

A Feasibility Study of Intermittent Electrical Stimulation to Prevent Deep Tissue Injury in the Intensive Care Unit

Objective: The primary goal of this study was to investigate the feasibility of utilizing intermittent electrical stimulation (IES) in an intensive care environment as a potential method for preventing pressure ulcers. Furthermore, we wished to evaluate the practicality of the innovation and end-user acceptability. Approach: Twenty immobile subjects, age ranging from 19 to 86 years old with a Braden Scale score ranging from 9 to 16 (very high to moderate risk of developing pressure ulcers), were enrolled. Intermittent 35 Hz electrical stimulation was administered through surface electrodes to the gluteal muscles causing them to contract for 10 s every 10 min. Subjects utilized IES on a program that increased from 4 to 24 h per day over 8 days and lasted up to a maximum of 4 weeks. Results: Bedside nurses reported that IES was simple to use, took an average of 6 min to apply, and 2 min to remove. Furthermore, IES could be easily incorporated into routine patient care. No pressure ulcers occurred in any subject during the study. No untoward reactions or adverse events had occurred directly as a result of IES. Innovation: IES represents a potential method of preventing bedsores. This study represents a necessary pilot study, investigating safety and feasibility before proceeding with a larger randomized controlled trial to determine efficacy. Conclusion: Our results suggest that IES is both safe and feasible to implement in intensive care units.

Acute circulatory failure-chronic liver failure-sequential organ failure assessment score: a novel scoring model for mortality risk prediction in critically ill cirrhotic patients with acute circulatory failure

BACKGROUND AND AIM

Acute circulatory failure (ACF) is associated with high mortality rates in critically ill cirrhotic patients. Only a few accurate scoring models exist specific to critically ill cirrhotic patients with acute circulatory failure (CICCF) for mortality risk assessment. The aim was to develop and evaluate a novel model specific to CICCF.

PATIENTS AND METHODS

This study collected and analyzed the data on CICCF from the Multiparameter Intelligent Monitoring in Intensive Care-III database. The acute circulatory failure-chronic liver failure-sequential organ failure assessment (ACF-CLIF-SOFA) score was derived by Cox's proportional hazards regression. Performance analysis of ACF-CLIF-SOFA against CLIF-SOFA and model for end-stage liver disease systems was completed using area under the receiver operating characteristic curve.

RESULTS

ACF-CLIF-SOFA identified six independent factors: mean arterial pressure [hazard ratio (HR)=0.984, 95% confidence interval (CI): 0.978-0.990, P<0.001], vasopressin (HR=1.548, 95% CI: 1.273-1.883, P<0.001), temperature (HR=0.764, 95% CI: 0.694-0.840, P<0.001), bilirubin (HR=1.031, 95% CI: 1.022-1.041, P<0.001), lactate (HR=1.113, 95% CI: 1.084-1.142, P<0.001), and urine output (HR=0.854, 95% CI: 0.767-0.951, P=0.004). ACF-CLIF-SOFA showed a better predictive performance than CLIF-SOFA and model for end-stage liver disease in terms of predicting mortality (0.769 vs. 0.729 vs. 0.713 at 30 days, 0.757 vs. 0.707 vs. 0.698 at 90 days, 0.733 vs. 0.685 vs. 0.691 at 1 year, respectively, all P<0.05).

CONCLUSION

ACF-CLIF-SOFA, as the first model specific to CICCF, enables a more accurate prediction at 30-day, 90-day, and 1-year follow-up periods than other existing scoring systems.

Inadvertent hypothermia and mortality in critically ill adults: Systematic review and meta-analysis

OBJECTIVE

Considering that inadvertent hypothermia (IH) is common in Intensive Care Unit (ICU) patients and can be followed by severe complications, this systematic review identified, appraised and synthesised the published literature about the association between IH and mortality in adults admitted to the ICU.

DATA SOURCES

By using key terms, literature searches were conducted in Pubmed, CINAHL, Cochrane Library, Web of Science and EMBASE.

REVIEW METHODS

According to PRISMA guidelines, articles published between 1980-2016 in English-language, peer-reviewed journals were considered. IH was defined as core temperature of <36.5°C or lower, present on ICU admission or manifested during ICU stay. Outcome measure included ICU, hospital or 28-day mortality. Selected cohort studies were evaluated with the Newcastle-Ottawa Scale. Extracted data were summarised in tables and synthesised qualitatively and quantitatively, with adjusted odds ratios (ORs) for mortality being combined in meta-analyses.

RESULTS

Eighteen observational studies met inclusion criteria. All of them had high methodological quality. In twelve out of fifteen studies, unadjusted mortality was significantly higher in hypothermic patients compared to non-hypothermic ones. Likewise, in thirteen out of sixteen studies, IH or lowest core temperature was independently associated with significantly higher mortality. High severity and long duration of IH were also associated with higher mortality. Mortality was significantly higher in patients with core temperature <36.0°C (pooled OR 2.093, 95% CI 1.704-2.570), and in those with core temperature <35.0°C (pooled OR 2.945, 95% CI 2.166-4.004).

CONCLUSIONS

These findings indicate that IH predicts mortality in critically ill adults and pose suspicion that this may contribute to adverse patient outcome.