Ajuste a la ventilación mecánica guiado por curvas presión-volumen de flujo lento en pacientes con síndrome de distress respiratorio agudo e injuria pulmonar aguda / Mechanical ventilatory parameters guided by the low flow pressure-volume curve in patients with acute lung injury/acute respiratory distress syndrome

Background: Mechanical ventilation may contribute to lung injury and then enhance systemic inflammation. Optimal ventilatory parameters such as tidal volume (V T) and positive end expiratory pressure (PEEP) can be determined using different methods. Low flow pressure volume (P/V-LF) curve is a useful tool to assess the respiratory system mechanics and set ventilatory parameters. Aim: To set V T and PEEP according P/V-LF curve analysis and evaluate its effects on gas exchange and hemodynamic parameters. Materials and methods: Twenty seven patients underwent P/V-LF within the first 72 hours of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). P/V-LF curves were obtained from the ventilator and both lower and upper inflexion points determined. Gas exchange and hemodynamic parameters were measured before and after modifying ventilator settings guided by P/V-LF curves. Results: Ventilatory parameters set according P/V-LF curve, led to a rise of PEEP and reduction of V T: 11.6±2.8 to 14.1±2.1 cm H2O, and 9.7±2.4 to 8.8±2.2 mL/kg (p <0.01). Arterial to inspired oxygen fraction ratio increased from 158.0±66 to 188.5±68.5 (p <0.01), and oxygenation index was reduced, 13.7±8.2 to 12.3±7.2 (p <0.05). Cardiac output and oxygen delivery index (IDO2) were not modified. Demographic data, gas exchange improvement and respiratory system mechanics showed no significant difference between patients with extra-pulmonary and pulmonary ALI/ARDS. There was no evidence of significant adverse events related with this technique. Conclusion: P/V-LF curves information allowed us to adjust ventilatory parameters and optimize gas exchange without detrimental effects on oxygen delivery in mechanically ventilated ALI/ARDS patients.

Volumen sanguíneo intratorácico versus presión arterial de oclusión pulmonar como estimadores de precarga cardíaca en pacientes críticos / Intrathoracic blood volume versus pulmonary artery occlusion pressure as estimators of cardiac preload in critically ill patients

Background:Monitoring of cardiac preload by determination of pulmonary artery occlusion pressure (PAOP) has been traditionally used to guide fluid therapy to optimize cardiac output (CO). Since factors such as intrathoracic pressure and ventricular compliance may modify PAOP, volumetric estimators of preload have been developed. The PiCCO system is able to measure CO and intrathoracic blood volume (ITBV) by transpulmonary thermodilution. Aim: To compare a volumetric (ITBV) versus a pressure (PAOP) determination to accurately estimate cardiac preload in severely ill patients. Patients and Methods: From June 2001 to October 2003, 22 mechanically ventilated patients with hemodynamic instability underwent hemodynamic monitoring with pulmonary artery catheter (PAC) and PiCCO system. ITBV index (ITBVI), PAOP and CI were measured simultaneously by both methods. One hundred thirty eight deltas (D) were obtained from the difference of ITBVI, PAOP, CI-PAC and CI-PiCCO between 6-12 am and 6-12 pm. Linear regression analysis of DITBVI versus Ð CI-PiCCO and Ð PAOP versus DCI-PAC were made. Results: Mean age of patients was 60.8 ± 19.4 years. APACHE II was 23.9 ± 7. Fifteen patients met criteria for acute respiratory distress syndrome (ARDS). Delta ITBVI significantly correlated with DCI-PiCCO (r=0.54; 95% confidence interval = 0.41-0.65; p <0.01). There was no correlation between DPAOP and Ð CI-PAC. Conclusion: ITBVI correlated better with CI than PAOP, and therefore it seems to be a more accurate estimator of preload in unstable, mechanically ventilated patients.

Síndrome hemolítico urémico y streptococcus pneumoniae / Hemolytic uremic syndrome after an infection caused by streptococcus pneumoniae

Hemolytic-uremic syndrome (HUS) is an uncommon complication of pneumococcal infection. Highly suggesting findings in a patient with Streptococcus pneumoniae infection are: microangyopatic hemolytic anemia, thrombocytopenia and acute renal failure. We report a 41 years old woman, admitted to the hospital due to a severe pneumonia, that required the surgical drainage of an empyema. On admission, a drop in packed red cell volume from 41 to 25 percent, the presence of schistocytes in the blood smear, an elevation of LDH to 1,700 IU/L, a fall in haptoglobin to 5.8 mg/dL and a thrombocytopenia of 72,000 per mm3 were detected. These alterations coincided with an oliguric acute renal failure. She was treated with hemodialysis and the hemolytic syndrome was managed with plasmapheresis. She was discharged 35 days after admission and in the follow up, after 2.5 months, her serum creatinine is 1.2 mg/dL and her packed red cell volume is 41 percent