29 Apr 06
Posted in Critical Care, General at 16:39 by Laci
By A Araghi, JJ Bander and JA Guzman
Critical Care 2006;10:R64 http://ccforum.com/content/10/2/R64
Blood pressure measurements frequently guide management in critical care. Direct readings, commonly from a major artery, are considered to be the gold standard. Because arterial cannulation is associated with risks, alternative noninvasive blood pressure (NIBP) measurements are routinely used. However, the accuracy of NIBP determinations in overweight patients in the outpatient setting is variable, and little is known about critically ill patients. This prospective, observational study was performed to compare direct intra-arterial blood pressure (IABP) with NIBP measurements obtained using auscultatory and oscillometric methods in overweight patients admitted to our medical intensive care unit.
Method
Adult critically ill patients with a body mass index (BMI) of 25 kg/m2 or greater and a functional arterial line (assessed using the rapid flush test) were enrolled in the study. IABP measurements were compared with those obtained noninvasively. A calibrated aneroid manometer (auscultatory technique) with arm cuffs compatible with arm sizes and a NIBP monitor (oscillometric technique) were used for NIBP measurements. Agreement between methods was assessed using Bland-Altman analysis.
Results
Fifty-four patients (23 males) with a mean (± standard error) age of 57 ± 3 years were studied. The mean BMI was 34.0 ± 1.4 kg/m2. Mean arm circumference was 32 ± 0.6 cm. IABP readings were obtained from the radial artery in all patients. Only eight patients were receiving vasoactive medications. Mean overall biases for the auscultatory and oscillometric techniques were 4.1 ± 1.9 and -8.0 ± 1.7 mmHg, respectively (P < 0.0001), with wide limits of agreement. The overestimation of blood pressure using the auscultatory technique was more important in patients with a BMI of 30 kg/m2 or greater. In hypertensive patients both NIBP methods underestimated blood pressure as determined using direct IABP measurement.
Conclusion
Oscillometric blood pressure measurements underestimated IABP readings regardless of patient BMI. Auscultatory measurements were also inaccurate, tending to underestimate systolic blood pressure and overestimate mean arterial and diastolic blood pressure. NIBP can be inaccurate among overweight critically ill patients and lead to erroneous interpretations of blood pressure.
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Posted in Critical Care at 16:38 by Laci
By U Hoffmann, M Borggrefe and M Brueckmann
Critical Care 2006;10:134 http://ccforum.com/content/10/2/134
B-type natriuretic peptide (BNP) and amino-terminal pro-BNP (NT-proBNP) are promising cardiac biomarkers that have recently been shown to be of diagnostic value in decompensated heart failure, acute coronary syndromes and other conditions resulting in myocardial stretch and volume overload. In view of the high prevalence of cardiac disorders in the intensive care unit, the experience of elevated natriuretic peptide levels in the critically ill might be of enormous diagnostic and therapeutic value. BNP and NT-proBNP levels rise to different degrees in critical illness and may also serve as markers of severity and prognosis in diseases beyond acute or chronic heart failure. The diagnostic and prognostic use of natriuretic peptides in the intensive care setting for patients with various forms of shock could be an attractive alternative as noninvasive markers of cardiac dysfunction that could obviate the need for pulmonary artery catheterization in some patients.
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27 Apr 06
Posted in Critical Care, Mechanical ventilation at 16:35 by Laci
By PM Suter
Critical Care 2006;10:139 http://ccforum.com/content/10/2/139
Mechanical ventilation can cause structural and functional disturbances in the lung, as well as other vital organ dysfunctions. Apoptosis is thought to be a histological sign of distant organ damage in ventilator-induced lung injury (VILI). Nakos and colleagues observed a protective effect of prone positioning against VILI in normal sheep. Less alteration in the lung architecture and function and in liver transaminases, and lower indices for apoptosis in the liver, the diaphragm and the lung were noted in the prone position compared with the supine position. If confirmed, these data open a new hypothesis for pathogenesis and prevention of VILI and its extrapulmonary complications.
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25 Apr 06
Posted in Critical Care, Infection at 12:37 by Laci
By BA Cunha
Critical Care 2006;10:141
Traditionally, ventilator-associated pneumonia (VAP) has been treated either with double drug therapy or with monotherapy. Double drug therapy has been used to increase spectrum, for possible synergy, and to decrease the emergence of resistance. VAP therapy should be directed primarily against Pseudomonas aeruginosa, which also provides aerobic gram-negative coverage, the usual pathogens in VAP. The potent anti-P. aeruginosa antibiotics available today have sufficient activity that double drug coverage is unnecessary. Double drug therapy does not decrease resistance if a “high resistance potential” antibiotic is used in the combination. The study by Damas in this issue supports monotherapy for VAP. Optimal therapy for VAP selecting a potent anti-P. aeruginosa antibiotic with a “low resistance potential”, minimizes drug/drug interactions, minimizes resistance potential, and is cost effective. Monotherapy of VAP should be the standard of care.
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