Use of N-terminal pro-brain natriuretic peptide to detect acute cardiac dysfunction during weaning failure in difficult-to-wean patients with chronic obstructive pulmonary disease.

OBJECTIVE: To evaluate the utility of serial measurements of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) to detect acute cardiac dysfunction during weaning failure in difficult to wean patients with chronic obstructive pulmonary disease. DESIGN: Prospective observational cohort study. SETTING: A 14-bed general intensive care unit in a university hospital. PATIENTS: Nineteen patients mechanically ventilated for chronic obstructive pulmonary disease exacerbation who were difficult to wean. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Cardiac and hemodynamic variables, arterial and central venous blood gas, breathing pattern, respiratory mechanics, indexes of oxygen cost of breathing, and plasma levels of NT-proBNP were measured and analyzed immediately before (baseline) and at the end of a spontaneous breathing trial. Eight of 19 patients (42%) were identified with acute cardiac dysfunction at the end of the weaning trial. Baseline NT-proBNP levels were significantly higher (median 5000, interquartile range 4218 pg/mL) in these patients than in patients without evidence of acute cardiac dysfunction (median 1705, interquartile range 3491 pg/mL). Plasma levels of NT-proBNP increased significantly at the end of the spontaneous breathing trial only in patients with acute cardiac dysfunction (median 12,733, interquartile range 16,456 pg/mL, p < .05). The elevation in NT-proBNP at the end of the weaning trial had a good diagnostic performance in detecting acute cardiac dysfunction, as estimated by area under the receiver operating characteristic curve analysis (area under the curve 0.909, se 0.077, 95% confidence interval 0.69-0.98; p < .0001, cutoff = 184.7 pg/mL). CONCLUSIONS: Serial measurements of NT-proBNP plasma levels provided a noninvasive manner to detect acute cardiac dysfunction during an unsuccessful weaning trial in difficult to wean patients with chronic obstructive pulmonary disease. The utility of this test as a complement of the standard clinical monitoring of the weaning trial deserves further investigation.

A comparison between fenoldopam and low-dose dopamine in early renal dysfunction of critically ill patients.

OBJECTIVE: Fenoldopam mesylate is a selective dopamine-1 agonist, with no effect on dopamine-2 and alpha1 receptors, producing a selective renal vasodilation. This may favor the kidney oxygen supply/demand ratio and prevent acute renal failure. The aim of the study was to investigate if fenoldopam can provide greater benefit than low-dose dopamine in early renal dysfunction of critically ill patients. DESIGN: Prospective, multiple-center, randomized, controlled trial. SETTING: University and city hospital intensive care units. PATIENTS: One hundred adult critically ill patients with early renal dysfunction (intensive care unit stay<1 wk, hemodynamic stability, and urine outputor=1.5 mg/dL and10% of the baseline value at the end of infusion, compared with only 46% in dopamine group (chi-square=4.06, p=.04). Total urinary output during drug infusion was not significantly different between groups. After 1 day, urinary output was lower in group F compared with group D (p<.05). CONCLUSIONS: In critically ill patients, a continuous infusion of fenoldopam at 0.1 microg/kg/min does not cause any clinically significant hemodynamic impairment and improves renal function compared with renal dose dopamine. In the setting of acute early renal dysfunction, before severe renal failure has occurred, the attempt to reverse renal hypoperfusion with fenoldopam is more effective than with low-dose dopamine.

Effects of high versus low positive end-expiratory pressures in acute respiratory distress syndrome.

A recent study by the Acute Respiratory Distress Syndrome Network compared the traditional lower end-expiratory pressure strategy with a higher end-expiratory pressure strategy in patients with the acute respiratory distress syndrome ventilated with low tidal volumes. Clinical outcomes were similar whether lower or higher positive end-expiratory pressure (PEEP) levels were used. We applied both the lower (9 +/- 2 cm H2O) and higher (16 +/- 1 cm H2O) PEEP strategy in 19 patients. In nine recruiters, the higher end-expiratory pressure strategy resulted in significant alveolar recruitment (587 +/- 158 ml), improvement in arterial oxygen partial pressure/inspired oxygen fraction ratio (from 150 +/- 36 to 396 +/- 138), and reduction in static lung elastance (from 23 +/- 3 to 20 +/- 2 cm H2O/L). In 10 nonrecruiters, alveolar recruitment was minimal, oxygenation did not improve, and static lung elastance significantly increased (from 26 +/- 5 to 28 +/- 6 cm H2O/L). The increase in oxygenation, the reduction in static lung elastance, and the shape of the volume-pressure curve during the lower PEEP strategy were independently associated with alveolar recruitment. In conclusion, the protocol proposed by the Acute Respiratory Distress Syndrome Network, lacking solid physiologic basis, frequently fails to induce alveolar recruitment and may increase the risk of alveolar overinflation.