Hypothermia in a surgical intensive care unit

BACKGROUND: Inadvertent hypothermia is not uncommon in the immediate postoperative period and it is associated with impairment and abnormalities in various organs and systems that can lead to adverse outcomes. The aim of this study was to estimate the prevalence, the predictive factors and outcome of core hypothermia on admission to a surgical ICU. METHODS: All consecutive 185 adult patients who underwent scheduled or emergency noncardiac surgery admitted to a surgical ICU between April and July 2004 were admitted to the study. Tympanic membrane core temperature (Tc) was measured before surgery, on arrival at ICU and every two hours until 6 hours after admission. The following variables were also recorded: age, sex, body weight and height, ASA physical status, type of surgery, magnitude of surgical procedure, anesthesia technique, amount of intravenous fluids administered during anesthesia, use of temperature monitoring and warming techniques, duration of the anesthesia, ICU length of stay, hospital length of stay and SAPS II score. Patients were classified as either hypothermic (Tc ≤ 35°C) or normothermic (Tc> 35°C). Univariate analysis and multiple regression binary logistic with an odds ratio (OR) and its 95% Confidence Interval (95%CI) were used to compare the two groups of patients and assess the relationship between each clinical predictor and hypothermia. Outcome measured as ICU length of stay and mortality was also assessed. RESULTS: Prevalence of hypothermia on ICU admission was 57.8%. In univariate analysis temperature monitoring, use of warming techniques and higher previous body temperature were significant protective factors against core hypothermia. In this analysis independent predictors of hypothermia on admission to ICU were: magnitude of surgery, use of general anesthesia or combined epidural and general anesthesia, total intravenous crystalloids administrated and total packed erythrocytes administrated, anesthesia longer than 3 hours and SAPS II scores. In multiple logistic regression analysis significant predictors of hypothermia on admission to the ICU were magnitude of surgery (OR 3.9, 95% CI, 1.4–10.6, p = 0.008 for major surgery; OR 3.6, 95% CI, 1.5–9.0, p = 0.005 for medium surgery), intravenous administration of crystalloids (in litres) (OR 1.4, 95% CI, 1.1–1.7, p = 0.012) and SAPS score (OR 1.0, 95% CI 1.0–1.7, p = 0.014); higher previous temperature in ward was a significant protective factor (OR 0.3, 95% CI 0.1–0.7, p = 0.003). Hypothermia was neither a risk factor for hospital mortality nor a predictive factor for staying longer in ICU. CONCLUSION: The prevalence of patient hypothermia on ICU arrival was high. Hypothermia at time of admission to the ICU was not an independent factor for mortality or for staying longer in ICU

MRI protocol for critically ill patients

BACKGROUND Ventilators compatible with magnetic resonance imaging machines are not universally available. However, the lack of such equipment should not preclude magnetic resonance imaging. We have developed a method by which a critically ill patient requiring mechanical ventilation can safely undergo such imaging without compatible equipment. METHOD By using extended ventilator tubing and calculating volume lost due to tubing compliance, safe and reliable mechanical ventilation can be achieved from a distance without impairing scan quality. RESULTS We devised a method to calculate volume lost due to mechanical compliance of the tubing with ventilator circuits employing 20, 30, and 50 feet of tubing. We added the estimated loss of volume to the set tidal volume of 700 mL to give a delivered volume of 700 mL. Twenty breaths were evaluated for each length of tubing. The evaluation of the 20- and 30-foot lengths of tubing demonstrated 10- and 52-mL discrepancies, respectively, between predicted and measured volumes. The 50-foot length showed a 121-mL discrepancy between predicted and measured volumes. CONCLUSIONS Our method appears to be clinically accurate for predicting volume lost due to tubing compliance for lengths of ventilator tubing less than or equal to 30 feet. We have found this technique to be a safe and effective way to ensure patient safety and scan quality in patients requiring mechanical ventilation during magnetic resonance imaging.</jats:p