Ultrasound estimation of volume of pleural fluid in mechanically ventilated patients.

OBJECTIVE: The aim was to develop a practical method for estimation of the volume of pleural effusion using ultrasonography in mechanically ventilated patients. DESIGN: Prospective observational study. SETTING: 20-bed general intensive care unit in the university hospital. PATIENTS AND PARTICIPANTS: 81 patients were included after initial suspicion of pleural fluid on chest supine X-ray and pre-puncture ultrasound confirming effusion. Patients with thoracic deformities, post-lung surgery, with diaphragm pathology, haemothorax, empyema and with incomplete aspiration of pleural fluid on post-puncture ultrasound were excluded. INTERVENTIONS: Patients were supine with mild trunk elevation at 15 degrees . Probe was moved upwards in posterior axillary line, and transverse section perpendicular to the body axis was obtained with pleural separation visible at lung base. The maximal distance between parietal and visceral pleura (Sep) in end-expiration was recorded. Thoracentesis was performed at previous probe position and volume of pleural fluid (V) recorded. MEASUREMENTS AND RESULTS: 92 effusions were evaluated and drained; 11 (12%) were excluded for incomplete aspiration. Success rate of obtaining fluid under ultrasound guidance was 100%; the incidence of pneumothorax or bleeding was zero. Mean Sep was 35+/-13 mm. Mean V was 658+/-320 ml. Significant positive correlation between both Sep and V was found: r=0.72; r(2)=0.52; p<0.001. The amount of pleural fluid volume can be estimated with the simplified formula: V (ml)=20 x Sep (mm). Mean prediction error of V using Sep was 158.4+/-160.6 ml. CONCLUSIONS: Easy quantification of pleural fluid may help to decide about performing thoracentesis in high-risk patients, although thoracentesis under ultrasound guidance appears to be a safe procedure.

Prostacyclin versus citrate in continuous haemodiafiltration: an observational study in patients with high risk of bleeding.

BACKGROUND: The efficacy and safety of prostacyclin (PGI2) and citrate (ACD) anticoagulation were observed and compared during continuous haemodiafiltration. METHODS: Mechanically ventilated patients received either the PGI2 analogue epoprostenol (group A, n = 17) in escalating doses of 4.5-10.0 ng.kg(-1).min(-1) in combination with heparin (6 IU.kg(-1).h(-1)) or 2.2% ACD (group B, n = 15). Blood flow was set to match the circuit-filling volume per unit time equal to the intravascular half-life of PGI2. RESULTS: Median filter lifetimes were 26 h (interquartile range 16-37) in group A (39 filters) and 36.5 h (interquartile range 23-50) in group B (56 filters; p < 0.01). In group A, 4 patients (23.5%, p < 0.05) had the dose reduced due to hypotension. The final mean dose of PGI2 was 8.7 +/- 2.4 ng.kg(-1).min(-1). Four patients in group A (23.5%, p < 0.05) were switched to ACD due to a decrease in platelet count. No bleeding episodes, decrease in platelet count or adverse haemodynamic effects were encountered in group B. The cost of epoprostenol plus low dose heparin (EUR 204.73 +/- 53.04) was significantly higher than the cost of ACD-based anticoagulation (EUR 93.92 +/- 45.2, p < 0.05). CONCLUSION: ACD offers longer filter survival, has no impact on platelet count and is less expensive. Increasing the dose of PGI2 up to the average of 8.7 ng.kg(-1).min(-1) did not increase the haemodynamic side effects.