Non-invasive assessment of respiratory muscle activity during pressure support ventilation: accuracy of end-inspiration occlusion and least square fitting methods.

Pressure support ventilation (PSV) should be titrated considering the pressure developed by the respiratory muscles (P) to prevent under- and over-assistance. The esophageal pressure (P) is the clinical gold standard for P assessment, but its use is limited by alleged invasiveness and complexity. The least square fitting method and the end-inspiratory occlusion method have been proposed as non-invasive alternatives for P assessment.

Effect of external PEEP in patients under controlled mechanical ventilation with an auto-PEEP of 5 cmH2O or higher.

Background: In some patients with auto-positive end-expiratory pressure (auto-PEEP), application of PEEP lower than auto-PEEP maintains a constant total PEEP, therefore reducing the inspiratory threshold load without detrimental cardiovascular or respiratory effects. We refer to these patients as "complete PEEP-absorbers." Conversely, adverse effects of PEEP application could occur in patients with auto-PEEP when the total PEEP rises as a consequence.

Assessment of Factors Related to Auto-PEEP.

Background: Previous physiological studies have identified factors that are involved in auto-PEEP generation. In our study, we examined how much auto-PEEP is generated from factors that are involved in its development.

Methods: One hundred eighty-six subjects undergoing controlled mechanical ventilation with persistent expiratory flow at the beginning of each inspiration were enrolled in the study.

Cardiac index and oxygen delivery during low and high tidal volume ventilation strategies in patients with acute respiratory distress syndrome: a crossover randomized clinical trial.

Introduction: The beneficial effect of low tidal volume (TV) ventilation strategy on mortality in patients with acute respiratory distress syndrome (ARDS) has been attributed to the protective effect on ventilator-induced lung injury, and yet its effect on cardiovascular function might also play an important role. The aim of this study was to assess whether low TV ventilation improves cardiac output and oxygen delivery compared with high TV ventilation strategy in patients with ARDS.

Methods: In this crossover randomized clinical trial 16 ARDS patients were recruited in an intensive care unit at a university-affiliated hospital.

Prediction of arterial pressure increase after fluid challenge.

Background: Mean arterial pressure above 65 mmHg is recommended for critically ill hypotensive patients whereas they do not benefit from supranormal cardiac output values. In this study we investigated if the increase of mean arterial pressure after volume expansion could be predicted by cardiovascular and renal variables. This is a relevant topic because unnecessary positive fluid balance increases mortality, organ dysfunction and Intensive Care Unit length of stay.

Remifentanil improves breathing pattern and reduces inspiratory workload in tachypneic patients.

Background: Properly titrated opiates decrease respiratory rate but do not affect tidal volume or induce respiratory acidosis.

Objective: To determine whether remifentanil improves breathing pattern or reduces inspiratory effort in patients with acute respiratory failure and tachypnea or rapid shallow breathing.

Methods: We studied 14 patients who developed tachypnea and/or rapid shallow breathing if the pressure support level was reduced.

Arterial versus plethysmographic dynamic indices to test responsiveness for testing fluid administration in hypotensive patients: a clinical trial.

In the present study, we compared indices of respiratory-induced variation obtained from direct arterial blood pressure measurement with analogous indices obtained from the plethysmogram measured by the pulse oximeter to assess the value of these indices for predicting the cardiac output increase in response to a fluid challenge. Thirty-two fluid challenges were performed in 22 hypotensive patients who were also monitored with a pulmonary artery catheter. Hemodynamic and plethysmographic data were collected before and after intravascular volume expansion.

Variations in arterial blood pressure and photoplethysmography during mechanical ventilation.

We analyzed ventilation-induced changes in arterial blood pressure and photoplethysmography from waveforms obtained by monitoring 57 patients in the operating room and intensive care unit. Analysis of systolic and pulse pressure variations during positive pressure ventilation, DeltaUp, DeltaDown, and changes in the preejection period on both arterial and photoplethysmographic waveforms were possible in 49 (86%) patients. The pulse pressure variation and preejection period were similar when calculated using both arterial blood pressure and photoplethysmography, whereas the other variables were different.

Norepinephrine and metaraminol in septic shock: a comparison of the hemodynamic effects.

Objective: To compare the effects of norepinephrine and metaraminol on hemodynamics in septic shock patients.

Design And Setting: Open-label, controlled clinical trial in the general intensive care unit of a university-affiliated hospital.

Patients And Participants: Ten consecutive septic shock patients receiving norepinephrine to maintain the mean arterial pressure higher than 65 mmHg.

Standard Laryngeal Mask Airway and LMA-ProSeal during laparoscopic surgery.

Study Objective: To compare the frequency of airway seal and sore throat with the LMA-ProSeal (PLMA) and the standard Laryngeal Mask Airway (LMA) during laparoscopic surgery.

Design: Prospective, controlled, randomized, nonblinded clinical study.

Setting: University-affiliated hospital.