Antonio Corrado Pneumologic Centre “Misericordia”, Sesto Fiorentino, Florence, Italy
Teresa Renda Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Marco Chiostri Division of General Cardiology, Careggi University Hospital, Florence, Italy; Department of Experimental and Clinical Medicine, University of Florence, Italy
Giuseppe Villella Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Annika Augustynen Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Gianni Misuri Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Stefania Bertini Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy;
Donatella Tozzi Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Roberta Ginanni Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Nazzarena Maluccio Pneumology Unit, Section of Respiratory Critical Care, Cardio-thoracic and Vascular Department, Careggi University Hospital, Florence, Italy
Salvatore Mario Romano Division of General Cardiology, Careggi University Hospital, Florence, Italy; Department of Experimental and Clinical Medicine, University of Florence, Italy
DOI: 10.36166/2531-4920-2017-32-37
Spontaneous inspiration and Negative Pressure Ventilation (NPV) produce a negative pleural pressure, and this reduction in intrathoracic pressure is transmitted to the right atrium. In contrast, intermittent Positive Pressure Ventilation (PPV) produces inspiratory increases in intrathoracic pressure and therefore right atrial pressure. The comparison of the cardiopulmonary effects between NPV and PPV has been previously reported in physiologic researches carried out both in animal model and in paediatric patients. Our hypothesis was that in healthy adults the application of NPV by iron lung might result in hemodynamic advantages in comparison with PPV. The hemodynamic effects of NPV and PPV, administered through iron lung and mask-ventilation respectively, were studied in 10 normal subjects. Continuous and non-invasive blood pressure and heart rate measurements were recorded by digital oscillometric photoplethysmography both at baseline and during mechanical ventilation. Iron Lung Ventilation (ILV), using intermittent NPV/CNEEP (Continuous Negative Extrathoracic End-expiratory Pressure) in assist control mode, and mask-ventilation by Bi-Level in ST mode were administered at two different settings (NPV: -15/- 4 and -20/-4 cmH2O), (PPV: +15/+4 and +20/+4 cmH2O) respectively. The measurements lasted three minutes per setting without interruption. The mean values of all hemodynamic variables at baseline, during each step of ventilatory treatment and during the recovery phase, showed no statistically significant difference with ILV, on the contrary, during the application of mask-ventilation there was a significant decrease of diastolic, systolic, dicrotic and mean arterial pressure (p = 0.010, 0.002, 0.027, and 0.002 respectively), of cardiac output (p = 0.002), and dP/dtmax (p = 0.037), whereas stroke volume, pulse rate and systemic vascular resistance did not change. Our data show that both spontaneous breathing and mechanical breathing, during ILV, have the same effect on venous return in healthy subjects. In contrast, mask-ventilation produces transient hemodynamic effects due to a reduction in venous return. These results may represent the starting point for further investigation in patients with critical patients undergoing mechanical ventilation.