Traditionally, adequate tidal volume is considered to be a necessary condition to support respiratory patient breathing. But the high frequency ventilation (HFV) with a small tidal volume can still support the respiratory patient breathing well. In order to further explore the mechanisms of HFV, the pendelluft ventilation between left and right lungs was proposed in this paper. And a test platform by using two fresh sheep lungs was developed for investigating the pendelluft ventilation between the left and right lungs. Furthermore, considering the viscous resistance ( ), inertance ( ) and lung compliance ( ) in the lung, a second-order lung ventilation model was designed to inspect and evaluate the pendelluft ventilation between left lung and right lungs. On referring to both results of experiments in practice and simulation in MATLAB Simulink, between the left and right lungs, the phase difference in their airflow happens during HFV at some frequencies. And the pendelluft ventilation between the left and right lungs is resulted by the phase difference, even if the total airflow entering a whole lung is 0. Under HFV, the pendelluft ventilation between left and right lungs will benefit the lungs being more adequately ventilated, and will be improve the utilization rate of oxygen in the lungs.
Animals ; High-Frequency Ventilation ; Humans ; Lung ; physiology ; Pulmonary Gas Exchange ; Respiration, Artificial ; Sheep ; Tidal Volume

Acclimatization ; physiology ; Adolescent ; Altitude ; Humans ; Male ; Nitric Oxide ; blood ; Nitric Oxide Synthase ; blood ; Oxygen ; physiology ; Pulmonary Gas Exchange ; Young Adult

Based on the principles of the sheet-flow model, oxygen transport in pulmonary capillaries was considered as a process in which oxygen first enters plasma through the respiratory membranes, and then combines with the Hbc. A novel mathematical model about oxygen transport in pulmonary capillaries was established according to the relationship of the oxygen concentration inside the red blood cells with the concentration of haemoglobin and the blood saturation, and according to the basic formula for the correlation between blood saturation and oxygen partial pressure. Furthermore, we adopted the Lax-Wendroff Finite Difference Method and obtained certain valuable results under different physiological states. It was well concluded that the established model could be used to provide useful data for medical researchers as well as doctors.
Biological Transport ; physiology ; Capillaries ; physiology ; Humans ; Models, Biological ; Oxygen ; blood ; Partial Pressure ; Pulmonary Alveoli ; blood supply ; Pulmonary Circulation ; physiology ; Pulmonary Gas Exchange

OBJECTIVETo evaluate the effects of continuous blood purification on the hemodynamics and oxygenation in patients with acute respiratory distress syndrome (ARDS).

METHODSTwenty-one patients with ARDS were treated with continuous veno-venous hemofiltration (CVVH) combined with plasma exchange. Hemodynamics and oxygenation were measured or calculated at scheduled intervals using Swan-Ganz catheters.

RESULTSThe mean arterial pressure, partial pressure of arterial oxygen, oxygen delivery, oxygen consumption increased, heart rate, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, blood lactate concentration all decreased significantly after the treatment, and the oxygen extraction ratio underwent no obvious changes.

CONCLUSIONSContinuous blood purification can increase blood and oxygen supply but has no significant effects on oxygen extraction ratio in ARDS patients.

Adult ; Female ; Hemodynamics ; Hemofiltration ; methods ; Humans ; Male ; Middle Aged ; Oxygen ; blood ; Oxygen Consumption ; physiology ; Partial Pressure ; Plasma Exchange ; methods ; Pulmonary Gas Exchange ; Respiratory Distress Syndrome, Adult ; therapy

BACKGROUND: Partial liquid ventilation (PLV) and prone positioning can improve the arterial oxygenation (PaO2) in acute lung injury (ALI). We evaluated the effect of prolonged prone positioning during partial liquid ventilation (PLV) in a canine model of acute lung injury. METHODS: Six mongrel dogs (weighing 17.4 +/- 0.7 kg each) were anesthetized, intubated and mechanically ventilated. After 1 hour of baseline stabilization, the dogs' lungs were instilled with 40 mL/kg perfluorocarbon (PFC). PLV was first performed in the supine position for 1 hour (S1), then in the prone position for 3 hours with hourly measurements (P1, P2, P3), and finally, PLV was performed with the animal turned back to the supine position for 1 hour (S2). RESULTS: After instillation of the PFC, the PaO2 significantly increased from 99.2 +/- 32.6 mmHg at baseline to 198.1 +/- 59.2 mmHg at S1 (p=0.001). When the dogs were turned to the prone position, the PaO2 further increased to 288.3 +/- 80.9 mmHg at P1 (p=0.008 vs. S1) : this increase was maintained for 3 hours, but the PaO2 decreased to 129.4 +/- 62.5 mmHg at S2 (p< 0.001 vs. P3). Similar changes were seen in the shunt fraction. There were no significant differences for the systemic hemodynamic parameters between the prone and supine positions. CONCLUSION: Prolonged prone positioning during PLV in an animal model of ALI appears to improve oxygenation without any hemodynamic compromise.
Animals ; Dogs ; Liquid Ventilation/*methods ; Models, Animal ; Prone Position/*physiology ; Pulmonary Gas Exchange/*physiology ; Research Support, Non-U.S. Gov't ; Respiratory Distress Syndrome, Adult/physiopathology/*therapy

PURPOSE: Hypoxemia during one-lung ventilation (OLV) remains a serious problem, particularly in the supine position. We investigated the effects of alveolar recruitment (AR) and positive end-expiratory pressure (PEEP) on oxygenation during OLV in the supine position. MATERIALS AND METHODS: Ninety-nine patients were randomly allocated to one of the following three groups: a control group (ventilation with a tidal volume of 8 mL/kg), a PEEP group (the same ventilatory pattern with a PEEP of 8 cm H2O), or an AR group (an AR maneuver immediately before OLV followed by a PEEP of 8 cm H2O). The tidal volume was reduced to 6 mL/kg during OLV in all groups. Blood gas analyses, respiratory variables, and hemodynamic variables were recorded 15 min into TLV (TLVbaseline), 15 and 30 min after OLV (OLV15 and OLV30), and 10 min after re-establishing TLV (TLVend). RESULTS: Ultimately, 92 patients were analyzed. In the AR group, the arterial oxygen tension was higher at TLVend, and the physiologic dead space was lower at OLV15 and TLVend than in the control group. The mean airway pressure and dynamic lung compliance were higher in the PEEP and AR groups than in the control group at OLV15, OLV30, and TLVend. No significant differences in hemodynamic variables were found among the three groups throughout the study period. CONCLUSION: Recruitment of both lungs with subsequent PEEP before OLV improved arterial oxygenation and ventilatory efficiency during video-assisted thoracic surgery requiring OLV in the supine position.
Adult ; Aged ; Anoxia ; Female ; Humans ; Lung/physiopathology ; Lung Compliance/physiology ; Male ; Middle Aged ; One-Lung Ventilation/*methods ; Oxygen/*blood ; Positive-Pressure Respiration/*methods ; Pulmonary Alveoli/*physiology ; Pulmonary Gas Exchange ; Respiratory Mechanics/*physiology ; *Supine Position ; Thoracic Surgery, Video-Assisted ; Tidal Volume

A reduction in diaphragm mobility has been identified in patients with chronic obstructive pulmonary disease (COPD) and has been associated with a decline in pulmonary function parameters. However, little information exists regarding the potential role of diaphragm mobility on hypercapnia in COPD. A new method of assessing the mobility of the diaphragm, using ultrasound, has recently been validated. The purpose of the present study was to investigate the relationship between diaphragm mobility and pulmonary function parameters, as well as that between arterial blood gas values and diaphragm mobility, in COPD patients. Thirty seven COPD patients were recruited for pulmonary function test, arterial blood gas analysis and diaphragm mobility using ultrasound to measure the craniocaudal displacement of the left branch of the portal vein. There were significant negative correlations between diaphragmatic mobility and PaCO2 (r = -0.373, P = 0.030). Diaphragmatic mobility correlated with airway obstruction (FEV1, r = 0.415, P = 0.011) and with ventilatory capacity (FVC, r = 0.302, P = 0.029; MVV, r = 0.481, P = 0.003). Diaphragmatic mobility also correlated significantly with pulmonary hyperinflation. No relationship was observed between diaphragm mobility and PaO2 (r = -0.028, P = 0.873). These findings support a possibility that the reduction in diaphragm mobility relates to hypercapnia in COPD patients.
Aged ; Airway Resistance/physiology ; Carbon Dioxide/blood/physiology ; Diaphragm/physiopathology/*ultrasonography ; Female ; Humans ; Hypercapnia/complications/*physiopathology ; Male ; Middle Aged ; Portal Vein ; Pulmonary Disease, Chronic Obstructive/complications/*physiopathology/ultrasonography ; Pulmonary Gas Exchange ; Respiratory Muscles/physiopathology

We conducted a randomized animal study to determine whether there is a cumulative effect on hemodynamics, pulmonary function, and gas exchange when low dose nitric oxide (NO) is added to partial liquid ventilation (PLV) in acute lung injury. ighteen newborn piglets were saline-lavaged repeatedly, and randomly divided into two groups: PLV with perfluorocarbon group (n=8) and lavage only (control) group (n=10). Perfluorodecalin (30 mL/kg) was instilled into the endotracheal tube for 30 min, followed by 5-10 mL/kg/hr. Fifteen minutes after the completion of perfluorodecalin dosing, NO (10 ppm) was added to the inspiratory gas in an "on/off" manner. Perfluorodecalin instillation produced a significant improvement in gas exchange, pulmonary mechanics, shunt, and pulmonary arterial pressure (PAP). The addition of NO produced a further significant improvement in PaO2 and PAP. The "on/off" response to NO was seen apparently in PAP, PaO2, dynamic compliance, and shunt. All the variables in control group were remained at near the after-lavage levels without significant improvements until the end of the experiment. We concluded that NO might have a cumulative effect on gas exchange when combined with PLV, and this might be attributable to deceased PAP and V/Q mismatching.
Administration, Inhalation ; Animals ; Animals, Newborn ; Fluorocarbons/metabolism ; Hemodynamic Processes ; *Liquid Ventilation ; Nitric Oxide/administration & dosage/*metabolism ; Plasma Substitutes/metabolism ; Pulmonary Gas Exchange/*physiology ; Random Allocation ; *Respiratory Distress Syndrome, Adult ; Respiratory Mechanics ; *Respiratory Physiology ; Support, Non-U.S. Gov't ; Swine

The aim of this study was to determine the effect of partial liquid ventilation (PLV) using a perfluorocarbon (PFC) on gas exchange and lung inflammatory response in a canine acute lung injury model. After inducing severe lung injury by oleic acid infusion, beagle dogs were randomized to receive either gas ventilation only (control group, n = 6) or PLV (PLV group, n = 7) by sequential instillation of 10 mL/kg of perfluorodecalin (PFC) at 30 min intervals till functional residual capacity was attained. Measurements were made every 30 min till 210 min. Then the lungs were removed and bronchoalveolar lavage (BAL) (35 mL/kg) was performed on the right lung and the left lung was submitted for histologic analysis. There was significant improvement in PaO2 and PaCO2 in the PLV group compared to the control group (p < 0.05) which was associated with a significant decrease in shunt (p < 0.05). There was no significant difference in parameters of lung mechanics and hemodynamics. There was a significant decrease in cell count and neutrophil percentage in BAL fluid and significantly less inflammation and exudate scores in histology in the PLV group (p < 0.05). We conclude that PLV with perfluorodecalin improves gas exchange and decreases inflammatory response in the acutely-injured lung.
Animal ; Blood Cell Count ; Bronchoalveolar Lavage Fluid ; Carbon Dioxide/analysis ; Disease Models, Animal ; Dogs ; Female ; Fluorocarbons/pharmacology* ; Hemodynamics ; Histocytochemistry ; Inflammation/prevention & control ; Lung Diseases/physiopathology* ; Lung Diseases/chemically induced ; Male ; Oleic Acid ; Oxygen/analysis ; Pulmonary Gas Exchange/drug effects* ; Pulmonary Ventilation/physiology* ; Respiratory Function Tests ; Ventilators, Mechanical