Background:
Intermittent measurement of cardiac output may be performed using a lithium dilution technique (LiDCO). This can then be used to calibrate a pulse power algorithm of the arterial waveform which provides a continuous estimate of this variable. The purpose of this study was to examine the duration of accuracy of the pulse power algorithm in critically ill patients with respect to time when compared to measurements of cardiac output by an independent technique.
Methods:
Pulse power analysis was performed on critically ill patients using a proprietary commercial monitor (PulseCO). All measurements were made using an in-dwelling radial artery line and according to manufacturers instructions. Intermittent measurements of cardiac output were made with LiDCO in order to validate the pulse power measurements. These were made at baseline and then following 1, 2, 4 and 8 hours. The LiDCO measurement was considered the reference for comparison in this study. The two methods of measuring cardiac output were then compared by linear regression and a Bland Altman analysis. An error rate for the limits of agreement (LOA) between the two techniques of less than 30% was defined as being acceptable for this study.
Results:
14 critically ill medical and surgical patients were enrolled over a three month period. At baseline patients showed a wide range of cardiac output (median 7.5 L/min, IQR 5.1 -9.0 L/min). The bias and limits of agreement between the two techniques was deemed acceptable for the first four hours of the study with percentage errors being 29%, 22%, and 285 respectively. The percentage error at eight hours following calibration increased to 36%. The ability of the PulseCo to detect changes in cardiac output was assessed with a similar analysis. The PulseCO tracked the changes in cardiac output with adequate accuracy for the first four hours with percentage errors being 20%, 24% and 25%. However at eight hours the error had increased to 43%.
Conclusion:
The agreement between lithium dilution cardiac output and the pulse power algorithm in the PulseCO monitor remains acceptable for up to four hours in critically ill patients.

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Background:
Trauma and surgery may be complicated by pulmonary dysfunction, acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), but the mechanisms are incompletely understood.
Methods:
We evaluated lung capillary protein permeability non-invasively with help of the 67Ga-transferrin pulmonary leak index (PLI) technique and extravascular lung water (EVLW) by the transpulmonary thermal-dye dilution technique in consecutive, mechanically ventilated patients in the intensive care unit within 24 h of direct, blunt thoracic trauma (n = 5, 2 with ARDS), and within 12 h of indirect trauma by transhiatal oesophagectomy (n = 8), abdominal surgery for cancer (n = 6) and bone surgery (n = 4). We studied transfusion history, haemodynamics, oxygenation and mechanics of the lungs. The lung injury score (LIS, 0–4) was calculated. Plain radiography was also done to judge densities and atelectasis.
Results:
The PLI and EVLW were elevated above normal in 61 and 30% of patients, respectively, and the PLI directly related to the number of red cell concentrates given (rs = 0.69, P < 0.001), without group differences. Oxygenation, lung mechanics, radiographic densities and thus the LIS (1.0 [0.25–3.5]) did not relate to PLI and EVLW. However, groups differed in oxygenation and airway pressures and impaired oxygenation related to the number of radiographic quadrants with densities (rs = 0.55, P = 0.007). Thoracic trauma patients had a worse oxygenation requiring higher airway pressures and thus higher LIS than the other patient groups, unrelated to PLI and EVLW but attributable to a higher cardiac output and thereby venous admixture. Finally, patients with radiographic signs of atelectasis had more impaired oxygenation and more densities than those without.
Conclusion:
The oxygenation defect and radiographic densities in mechanically ventilated patients with pulmonary dysfunction and ALI/ARDS after trauma and surgery are likely caused by atelectasis rather than by increased permeability-oedema related to red cell transfusion.

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Background:
In addition to mortality, Health Related Quality of Life (HRQOL) has increasingly been claimed as an important outcome variable. The aim of this study was to assess HRQOL and independence in activities of daily living (ADL) six months after discharge from an Intensive Care Unit (ICU), and to study its determinants.
Methods:
All post-operative adult patients admitted to a surgical ICU between October 2004 and July 2005, were eligible for the study. The following variables were recorded on admission: age, gender, American Society of Anesthesiologists physical status (ASA-PS), type and magnitude of surgical procedure, ICU and hospital length of stay (LOS), mortality and Simplified Acute Physiology Score II (SAPS II). Six months after discharge, a Short Form-36 questionnaire (SF-36) and a questionnaire to assess dependency in ADL were sent to all survivors. Descriptive statistics was used to summarize data. Patient groups were compared using non-parametric tests. A logistic regression analysis was performed to identify covariate effects of each variable on dependency in personal and instrumental ADL, and for the change-in-health question of SF-36.
Results:
Out of 333 hospital survivors, 226 completed the questionnaires. Fifty-nine percent reported that their general level of health was better on the day they answered the questionnaire than 12 months earlier. Patients with greater co-morbidities (ASA-PS III/IV), had lower SF-36 scores in all domains and were more frequently dependent in instrumental and personal ADL. Logistic regression showed that SAPS II was associated with changes in general level of health (OR 1.06, 95%CI, 1.01 – 1.11, p = 0,016). Six months after ICU discharge, 60% and 34% of patients, respectively, were dependent in at least one activity in instrumental ADL (ADLI) and personal ADL (ADLP). ASA-PS (OR 3.00, 95%CI 1.31 – 6.87, p = 0.009) and age (OR 2.36, 95%CI, 1.04 – 5.34, p = 0.04) were associated with dependency in ADLI. For ADLP, only ASA-PS (OR 4.58, 95%CI, 1.68–12.46, p = 0.003) was associated with higher dependency.
Conclusion:
ASA-PS, age, type of surgery, ICU LOS and SAPS II could be seen as determinants of HRQOL.

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Background:
Several techniques have been discussed as alternatives to the intermittent bolus thermodilution cardiac output (COPAC) measurement by the pulmonary artery catheter (PAC). However, these techniques usually require a central venous line, an additional catheter, or a special calibration procedure. A new arterial pressure-based cardiac output (COAP) device (FloTrac™, Vigileo™; Edwards Lifesciences, Irvine, CA, USA) only requires access to the radial or femoral artery using a standard arterial catheter and does not need an external calibration. We validated this technique in critically ill patients in the intensive care unit (ICU) using COPAC as the method of reference.
Methods:
We studied 20 critically ill patients, aged 16 to 74 years (mean, 55.5 ± 18.8 years), who required both arterial and pulmonary artery pressure monitoring. COPAC measurements were performed at least every 4 hours and calculated as the average of 3 measurements, while COAP values were taken immediately at the end of bolus determinations. Accuracy of measurements was assessed by calculating the bias and limits of agreement using the method described by Bland and Altman.
Results:
A total of 164 coupled measurements were obtained. Absolute values of COPAC ranged from 2.80 to 10.80 l/min (mean 5.93 ± 1.55 l/min). The bias and limits of agreement between COPAC and COAP for unequal numbers of replicates was 0.02 ± 2.92 l/min. The percentage error between COPAC and COAP was 49.3%. The bias between percentage changes in COPAC (?COPAC) and percentage changes in COAP (?COAP) for consecutive measurements was -0.70% ± 32.28%. COPAC and COAP showed a Pearson correlation coefficient of 0.58 (p < 0.01), while the correlation coefficient between ?COPAC and ?COAP was 0.46 (p < 0.01).
Conclusion:
Although the COAP algorithm shows a minimal bias with COPAC over a wide range of values in an inhomogeneous group of critically ill patients, the scattering of the data remains relative wide. Therefore, the used algorithm (V 1.03) failed to demonstrate an acceptable accuracy in comparison to the clinical standard of cardiac output determination.

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