Cardiac magnetic resonance, transthoracic and transoesophageal echocardiography: a comparison of in vivo assessment of ventricular function in rats.

In vivo assessment of ventricular function in rodents has largely been restricted to transthoracic echocardiography (TTE). However 1.5 T cardiac magnetic resonance (CMR) and transoesophageal echocardiography (TOE) have emerged as possible alternatives. Yet, to date, no study has systematically assessed these three imaging modalities in determining ejection fraction (EF) in rats. Twenty rats underwent imaging four weeks after surgically-induced myocardial infarction. CMR was performed on a 1.5 T scanner, TTE was conducted using a 9.2 MHz transducer and TOE was performed with a 10 MHz intracardiac echo catheter. Correlation between the three techniques for EF determination and analysis reproducibility was assessed. Moderate-strong correlation was observed between the three modalities; the greatest between CMR and TOE (intraclass correlation coefficient (ICC) = 0.89), followed by TOE and TTE (ICC = 0.70) and CMR and TTE (ICC = 0.63). Intra- and inter-observer variations were excellent with CMR (ICC = 0.99 and 0.98 respectively), very good with TTE (0.90 and 0.89) and TOE (0.87 and 0.84). Each modality is a viable option for evaluating ventricular function in rats, however the high image quality and excellent reproducibility of CMR offers distinct advantages even at 1.5 T with conventional coils and software.

Utilization of intensive care unit days in a Canadian medical-surgical intensive care unit.

OBJECTIVES: To analyze the utilization of intensive care unit (ICU) days in a Canadian medical-surgical ICU and to identify ICU patients with prolonged ICU length of stay (LOS). DESIGN: Prospective descriptive study. SETTING: A Canadian tertiary care medical-surgical ICU. PATIENTS: Consecutive patients admitted to an adult medical-surgical ICU. Neurosurgical, cardiac surgical, and coronary care unit patients were excluded. MEASUREMENTS: For each ICU admission, patient demographics, diagnosis, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, ICU LOS, and hospital mortality were collected. The patients' risk of death was calculated using the APACHE II equation. Admissions were stratified by ICU LOS into four groups: 1 to 2, 3 to 6, 7 to 13, and > or = 14 days. Among the four LOS groups, the number of ICU days and observed and predicted death rates were compared. Admissions were also stratified by risk of death into five probability range quintiles. Among the five risk groups, ICU LOS was compared between survivors and nonsurvivors. RESULTS: A total of 1,960 admissions utilized 9,298 ICU days. ICU LOS (mean +/- SEM) was 4.74 +/- 0.2 (median, 2; range, 1 to 178) days. Short-stay patients (ICU LOS < or = 2 days) accounted for 60.3% of total admissions but consumed only 16.4% of total ICU days. Long-stay patients (ICU LOS > or = 14 days) accounted for 7.3% of total admissions but consumed 43.5% of total ICU days. Among the long-stay patients, the most common reasons for admission were pneumonia, multiple trauma, neuromuscular weakness, and septic shock. The mortality for long-stay patients approached 50%. When analyzed by patients' mortality risks, those with a risk of death >0.8 (predicted to die) or <0.2 (predicted to live) whose outcomes were opposite to that predicted had twice the ICU LOS compared with patients whose outcomes were consistent with prediction. CONCLUSION: In a Canadian medical-surgical ICU, patients with ICU LOS > or = 14 days accounted for 7.3% of total admissions but consumed 43.5% of total ICU days. Identification of patients with prolonged ICU LOS who would ultimately die in the ICU may lead to earlier withdrawal of therapy in these patients, resulting in a substantial reduction in suffering and cost savings. In our study population, outcome prediction using the APACHE II equation did not provide sufficient power to accurately discriminate between nonsurvivors and survivors.

A quantitative assessment of how Canadian intensivists believe they utilize oxygen in the intensive care unit.

OBJECTIVES: To investigate attitudes and practices regarding oxygen therapy in intensive care units (ICUs) and to devise quantitative descriptive indices. SETTING: Canadian university-affiliated adult ICUs. PARTICIPANTS: Fifty-two medical directors of ICUs in 48 institutions. INTERVENTION: Structured postal questionnaire returned by 48 participants. MEASUREMENTS AND MAIN RESULTS: Attitudes, beliefs, and stated practices relating to oxygen use in ICUs were determined. Novel descriptors S-50min (minutes of oxygen saturation [Sao2] acceptable to >50% of respondents), F-50max (maximum F(IO)2 above which <50% of respondents would increase F(IO)2), and F-50min (minimum F(IO)2 below which <50% of respondents would decrease F(IO)2) were determined. All respondents believed that oxygen toxicity was a concern. Twenty-nine percent of respondents indicated that they did not always assess tissue oxygenation in critical cases. A stepwise reduction in acceptance of progressive desaturation and increasing duration of hypoxemia was found. Presented with a stable patient with Sao2 of 98%, the maximum level of F(IO)2 above which respondents stated that they would not increase the F(IO)2 was 0.41+/-0.17 (mean +/- SD). For stable patients with Sao2 of 85%, the minimum F(IO)2 below which respondents would not reduce F(IO)2 was 0.59+/-0.23 (mean +/- SD). F-50max was 0.8 vs. 0.5 for Sao2 of 80%-85% vs. 85%-90%, respectively; F-50min was 0.6 vs. 0.21 for Sao2 of 90%-95% vs. 95%-100%, respectively. CONCLUSIONS: Considerable variation exists in the attitudes, beliefs, and stated practices relating to the management of oxygen therapy in the ICU. These data are amenable to quantitative description and illustrate the necessity for documentation of actual practice and development of support systems for decision-making in this and similar areas.

A comparison of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and the Trauma-Injury Severity Score (TRISS) for outcome assessment in intensive care unit trauma patients.

OBJECTIVE: To assess the ability of the Acute Physiology and Chronic Health Evaluation (APACHE II) system and Trauma-Injury Severity Scoring (TRISS) system in predicting group mortality in intensive care unit (ICU) trauma patients. DESIGN: Prospective study. SETTING: A Canadian adult trauma tertiary referral hospital. PATIENTS: Consecutive trauma patients admitted to the medical-surgical ICU or the neurosurgical ICU. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: For each patient, demographic data, mechanism of injury, and surgical status were collected. Revised Trauma Scores and Injury Severity Scores were calculated from emergency room and operative data. The APACHE II score was calculated based on the data from the first 24 hrs of ICU admission. The probability of death was calculated for each patient based on the APACHE II and TRISS equations. The ability to predict group mortality for APACHE II and TRISS was assessed by receiver operating characteristic curve analysis, two by two decision matrices, and calibration curve analysis. Four hundred seventy trauma patients were admitted to the ICU. Sixty-three (13%) patients died and 407 (87%) survived. There were significant differences between survivors and nonsurvivors in age, Glasgow Coma Scale, Revised Trauma Score, Injury Severity Score, and APACHE II score. By receiver operating characteristic curve analysis, the areas under the curves (+/- SEM) of APACHE II and TRISS were 0.92 +/- 0.02 and 0.89 +/- 0.02, respectively. Using two by two decision matrices with a decision criterion of 0.5, the sensitivities, specificities, and percentages correctly classified were 50.8%, 97.3%, and 91.1%, respectively, for APACHE II, and 50.8%, 97.1%, and 90.9%, respectively, for TRISS. From the calibration curves, the r2 value was .93 (p = .0001) for APACHE II and .67 (p = .004) for TRISS. CONCLUSIONS: Both APACHE II and TRISS scores were shown to accurately predict group mortality in ICU trauma patients. APACHE II and TRISS may be utilized for quality assurance in ICU trauma patients. However, neither APACHE II nor TRISS provides sufficient confidence for prediction of outcome of individual patients.