Evaluation of the left ventricular performance through equilibrium radionuclide angiocardiography.

In patients with severe heart failure due to acute myocardial infarction (AMI) breathing with PEEP can be of additional therapeutic value. This study was designed to assess the effects of CPAP through face mask with 15 cm H2O on left ventricular performance in AMI patients, using equilibrium radionuclide angiocardiography (ERA). In response to lung inflation, high levels of PEEP have been shown to decrease heart rate and stroke volume. The sum of the TPF pathological prolongation and the Mean-FR reduction suggests a decrease in the left ventricular compliance determined by the restriction imposed by the positive pressure. The global systolic performance is preserved.

[Airway continuous positive pressure in acute respiratory failure caused by Pneumocystis carinii pneumonia]. / Presión positiva continua de la vía aérea en la insuficiencia respiratoria aguda debida a neumonía por Pneumocystis carinii.

OBJECTIVE: To evaluate the efficiency of continuous positive airway pressure through a face mask in acute respiratory insufficiency (ARI) secondary to Pneumocystis carinii pneumonia. DESIGN: Prospective study. SETTING: Multidisciplinary ICU. PATIENTS: Fifteen patients with ARI secondary to Pneumocystis carinii pneumonia were studied. INTERVENTIONS: Initially al patients received high flow oxygen therapy through a face mask for 60 minutes (Pre-CPAP phase); then CPAP through a face mask, with identical FiO2 and for a similar period of time (Pst-CPAP phase). At the end of each phase the following parameters were evaluated: respiratory rate, heart rate, arterial gases, acid-base balance, and respiratory muscle motility. MEASUREMENTS: After oxygen therapy all fifteen patients had similar variables. After 60 minutes with CPAP through a face mask, significant improvements were noted for respiratory rate, heart rate, muscular effort, PaO2, SaO2, and PaO2/FiO2 (p < 0.001) in eleven patients, who survived after a mean stay of 8.5 days in the ICU with no evidence of major complications. In contrast, CPAP failed in four patients as respiratory rate, heart rate and vigorous muscle effort remained unchanged and, although PaO2 and SaO2 increased, the obtained values were significantly lower than in the remaining patients. Consequently, they underwent intubation and mechanical ventilation and after a mean stay of fourteen days with this ventilatory option died. CONCLUSIONS: These results confirm that CPAP through a face mask is an effective means to improve oxygenation in patients with Pneumocystis carinii pneumonia who develop hypoxemic respiratory insufficiency. Its early introduction in hospital protocols can help improving the prognosis in certain patients with severe PCP and avoid their admission to ICU, which would be thus preserved for those patients requiring mechanical ventilation.

[Acute respiratory failure in chronic obstructive lung disease. Effective weaning and excess base]. / Fallo respiratorio agudo en la enfermedad pulmonar obstructiva crónica. Desconexión eficaz y exceso de base.

To establish whether the weaning from assisted mechanical ventilation (AMV) should be accompanied by continuous respiratory support (synchronized intermittent mandatory ventilation [SIMV]) or discontinuous support (O2 in T) in patients affected by chronic obstructive lung disease (COLD) who are recovering from acute respiratory failure (ARF), and also to identify any possible predictive value of gasometric measurements. Sixteen patients with COLD and ARF were studied prospectively during their stay in the intensive care unit. Ten had acute bronchitis, 3 had left ventricular failure and 2 had pneumonia. In 1 case the etiology was unknown. The following protocol was used for the first attempt at weaning: 1) SIMV for 30 min, 2) return to rest period with AMV for 2 hours, 3) O2 in T-tube for 30 min. After 30 min both SIMV and O2 in T had produced a rise in PaCO2 to 55.1 and 54.6 mmHg, respectively (p < 0.001), with a subsequent lowering of pH to 7.32 and 7.36 (p < 0.001). When weaning was well tolerated, pH decreased significantly due to an increase in PaCO2 with both techniques, while base excess (BE) remained stable. Values of pH also decreased significantly when weaning was poorly tolerated, and the fall was greater with SIMV; increases in PaCO2 were similar, but decreases in BE were significant. When pH is kept within normal range by a high BE, the withdrawal of AMV, accompanied by either support system, is usually well-tolerated.

Modifications of tissular oxygenation and systemic hemodynamics after the correction of hypocapnia induced by mechanical ventilation.

The modifications of systemic hemodynamics, oxygen transport and tissular oxygenation in mechanically-ventilated critical ARF (acute respiratory failure) patients, after the correction of its hypocapnia by addition of dead space (VD) are determined. The prospective and randomized study was carried out in a multidisciplinary ICU. Fifteen ARF patients were studied within the first 48 hours of evolution. All the patients were intubated and mechanically ventilated. Three stages were delimited: I) 30 min after the beginning of anesthesia; II) 30 min after adding 30 cm of VD; III) 30 min after replacing the previous VD with a VD of 60 cm. Similar steady states had been reached when the measurements were taken. Ventilation parameters and FiO2 were kept stable. In stage I the patients presented a pure respiratory alkalosis and, with respect to hemodynamics, a hyperdynamic situation. In stage II the acid-base balance was normalized with a continuation of the hyperdynamic situation and an increase in mixed venous oxygen tension and saturation (PvO2 and SvO2) (p < 0.001). Stage III was characterized by a pure hypercapnic acidosis and an increase in capillary wedge pressure (CWP) (p < 0.05), right atrial pressure (RAP) (p < 0.001) and cardiac output (Qt) (p < 0.001); simultaneously, the systemic vascular resistances (SVR) decreased (p < 0.01), the PvO2, SvO2 and oxygen delivery (DO2) increased (p < 0.001); oxygen utilization coefficient (OUC) decreased (p < 0.01). The results suggest that the variations in PvO2 and SvO2 are a direct consequence of the modifications in blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)