A. S. Tütüncü

Intratracheal perfluorocarbon administration combined with mechanical ventilation in experimental respiratory distress syndrome: dose-dependent improvement of gas exchange.

ObjectivesTo test the efficacy of intratracheal instillation of a perfluorocarbon, combined with conventional mechanical ventilation, as well as to establish the dose response of this application on pulmonary parameters in adult animals with acute respiratory failure. DesignProspective, randomized, placebo-controlled study. SettingAnesthesiology laboratory of a university. SubjectsTwelve, adult male New Zealand rabbits. InterventionsAfter inducing respiratory failure by repeated lung lavage with saline, one group of animals was treated with perfluorocarbon, while another group was treated with saline to serve as controls (n = 6 per group). Treatment consisted of intratracheal instillation of incremental doses of 3 mL/kg of each liquid up to a total volume of 15 mL/kg. Animals were mechanically ventilated for 15 mins after each treatment dose with volume-controlled ventilation, a tidal volume of 12 mL/kg, frequency of 30 breaths/min, Fio2 of 1.0, and a positive end-expiratory pressure of 6 cm H2O. Measurements and Main ResultsArterial blood gases and lung mechanics were determined. In the perfluorocarbon group, Pao2 increased with increases in dosage from 75 ± 15 to 420 ± 27 torr (10.0 ± 2.0 to 55.9 ± 3.6 kPa) Paco2 decreased from 49 ± 6 to 43 ± 5 torr (6.5 ± 0.8 to 5.7 ± 0.6 kPa) after the first dose, and remained stable thereafter. Airway pressures were significantly lower after treatment compared with pre-treatment values. ConclusionThe remarkable improvements in pulmonary parameters suggest that this type of ventilatory support offers an effective and simple method of perfluorocarbon application in acute respiratory failure.

Intratracheal Perfluorocarbon Administration as an Aid in the Ventilatory Management of Respiratory Distress Syndrome

BackgroundRespiratory distress syndrome carries a high morbidity and mortality when treated with mechanical ventilation with positive end-expiratory pressure. Perfluorocarbon liquieds are employed in liquied ventilation due to low surface tension and high gas solubility. To assess whether intratracheal administration of the perfluorocarbon, perflubron, in combination with conventional mechanical ventilation could be of therapeutic benefit in respiratory distress syndrome, the authors tested the effects of different doses of intratracheal perflubron administration on gas exchange and lung mechanics in adult animals with respiratory failure during a 6-h observation period. MethodsRespiratory failure was induced in 30 rabbits by saline lung lavage (arterial oxygen tension < 100 mmHg at 100% oxygen with the following ventilator settings: tidal volume, 12 ml·kg-1; respiratory frequency, 30 per min; inspiratory/expiratory ratio, 1:2; and positive en-expiratory pressure of 6 cm H2O). Twenty-four rabbits were treated with different perfluorocarbon doses (3, 6, 9, and 12 ml ± kg-1), and the remaining six served as controls while mechanical ventilation was continued with the aforementioned settings. Additionally, in ten healthy rabbits who were used as healthy controls, the lungs were mechanically ventilated either alone or in combination with intratracheal perfluorocarbon administration (3 ml·kg-1) for 6 h. ResultsIn all treatment groups, arterial oxygen pressure increased significantly (P < 0.0001) in a dose-related fashion (193 ± 40, 320 ± 70, 353 ± 125, and 410 ± 45 mmHg at 15 min), and peak airway pressures decreased significantly (range, 18–23%; P < 0.0001) from pretreatment values. These findings were in contrast to those for the controll group. The improvements were time-dependent in all four tested perfluorocarbon doses. However, the improvements in pulmonary parameters could be extended to 6 h only in groups treated with 9 ml.kg-1 and 12 ml.kg-1 perflubron. At the end of the 6-h period, the data for these groups and the data for the control group at 6 h. There were no clinically significant changes in pulmonory parameters in healthy animals due either to mechanical ventialtion alone or mechanical ventilation in combination with intratracheal perfluorocarbon administration for 6 h. ConclusionsThe results of this study imply that there is no association between the lung mechanics and gas exchange parameters for mechanical ventilation in combination with intratracheal perfluorocarbon administration. The data suggest that this type of perfluorocarbon administration with conventinal mechanical ventilation offers a simple, alternative treatment of respiratory distress syndrome. With this technique, adequate pulmonary gas exchange can be maintained at relatively low airway pressures with high perfluorocarbon doses for several hours.

Evaluation of lung function after intratracheal perfluorocarbon administration in healthy animals

OBJECTIVES To investigate the effects of partial liquid ventilation (i.e., mechanical ventilation in combination with intratracheal administration of perfluorocarbon) on lung function, with particular attention to the integrity of the alveolocapillary membrane in healthy adult animals. DESIGN Prospective, randomized, controlled study. SETTING Laboratory at the Department of Experimental Anesthesiology, Erasmus University Rotterdam. SUBJECTS Ten adult male New Zealand rabbits. INTERVENTIONS Five rabbits were intratracheally treated with 12 mL/kg of perfluorocarbon while conventional mechanical ventilation (volume-controlled, tidal volume of 12 mL/kg, respiratory rate of 30 breaths/min, inspiration/expiration ratio of 1:2, positive end-expiratory pressure of 2 cm H2O, and an FIO2 of 1.0) was applied for 3 hrs. To assess the permeability of the alveolocapillary membrane, pulmonary clearance of inhaled technetium-99m-labeled diethylenetriamine pentaacetic acid (99mTc-DTPA) measurements were performed at 3 hrs and compared with data from the control group (n = 5) treated with mechanical ventilation only, using the same ventilatory parameters. MEASUREMENTS AND MAIN RESULTS Pulmonary gas exchange and lung mechanical parameters were measured in both groups at 30-min intervals. Mean values for PaO2 in the perfluorocarbon group, although at adequate levels, were less than those values of the control group during the 3-hr study period (370 +/- 44 vs. 503 +/- 44 torr at 3 hrs [49.3 +/- 5.9 vs. 67.1 +/- 5.9 kPa]). Peak and mean airway pressures were higher in the perfluorocarbon group (ranging from 1.9 to 3.4 cm H2O and 0.7 to 1.3 cm H2O, respectively) compared with the control group, while end-inspiratory airway pressure was similar in both groups. The half-life of 99mTc-DTPA was 83.7 +/- 24.5 mins in the control group, which was significantly longer (p < .01) than in the perfluorocarbon group (49.8 +/- 6.1 mins). CONCLUSIONS These findings suggest that partial liquid ventilation with perfluorocarbons lowers pulmonary gas exchange in healthy animals, and the increased pulmonary clearance of 99mTc-DTPA after 3 hrs of this type of ventilatory support may reflect minimal reversible changes in the lung surfactant system.

Comparison of pressure- and flow-triggered pressure-support ventilation on weaning parameters in patients recovering from acute respiratory failure.

ConclusionThe application of pressure- or flow-triggered PSV with Servo 300 ventilator does not make significant changes, in the short-term, on gas exchange, respiratory mechanics and inspiratory work-load in non-COPD patients recovering from acute respiratory failure.

Dose Dependent Improvement of Gas Exchange by Intratracheal Perflubron (Perfluorooctylbromide) Instillation in Adult Animals with Acute Respiratory Failure

Liquid ventilation with oxygenated perfluorocarbons (PFC) has been shown to improve pulmonary gas exchange and lung mechanics in preterm animals with respiratory failure [1–4]. Histological studies also reveal that liquid ventilation is less harmful to the lung structures than conventional gas ventilation [3,5]. Moreover, the first human application of liquid ventilation has been reported with promising success in premature infants with severe respiratory distress in whom conventional therapies had failed [6].

Respiratory and haemodynamic effects of conventional volume controlled PEEP ventilation, pressure regulated volume controlled ventilation and low frequency positive pressure ventilation with extracorporeal carbon dioxide removal in pigs with acute ARDS

The purpose of this study was to evaluate whether any benefit of low frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV–ECCO2R) existed over either volume controlled ventilation (VCV) with measured best–PEEP or pressure regulated volume controlled ventilation (PRVCV) with an inspiration/expiration (I/E) ratio of 4:1, with respect to arterial oxygenation, lung mechanics and haemodynamics, in acute respiratory failure.

Effects of Volume Controlled Ventilation with Peep, Pressure Regulated Volume Controlled Ventilation and Low Frequency Positive Pressure Ventilation with Extracorporeal Carbon Dioxide Removal on Total Static Lung Compliance and Oxygenation in Pigs with ARDS

Adult respiratory distress syndrome (ARDS) is characterised by decreased lung compliance and functional residual capacity (FRC) and increased intrapulmonary shunting resulting in hypoxemia. The immediate treatment of this critical situation is respiratory therapy of one form or the other and various modes have been recommended since the description of the disease. Positive end expiratory pressure (PEEP) with large tidal volume (VT), which recruits atelectatic areas and increases FRC, was once suggested as the treatment of ARDS.1-6 However, this mode of ventilation may cause barotrauma and/or morphological changes due to high peak inspiratory pressures (PIP).

Perflubron (Perfluorooctylbromide) Instillation Combined with Mechanical Ventilation: An Alternative Treatment of Acute Respiratory Failure in Adult Animals

Experimental studies have shown that adequate gas exchange can be accomplished during liquid ventilation with oxygenated perfluorocarbons (PFC) in animals with respiratory failure in which conventional mechanical ventilation could be insufficient to support life [1,2]. Moreover, a number of studies have reported improvements in lung functions after liquid ventilation which has been attributed to the residual PFC in the lungs [3,4].

Gas Exchange and Lung Mechanics during Long-Term Mechanical Ventilation with Intratracheal Perfluorocarbon Administration in Respiratory Distress Syndrome

Respiratory distress syndrome (RDS) is mainly characterized by hypoxemia and pronounced alveolar collapse, associated with high surface forces in the alveoli. Several methods of artificial ventilation have been introduced to support such lungs and maintain adequate oxygenation until recovery of lung function occurs [1–5]. Since perfluorocarbon (PFC) liquids were recognized as a useful media for pulmonary gas exchange, animal studies with PFC liquid ventilation have demonstrated that elimination of high surface forces in the PFC-filled lung can offer an alternative respiratory medium to improve gas exchange and lung expansion [6–8].

Comparison of Gastric Intramucosal pH Measurements with Oxygen Supply, Oxygen Consumption and Arterial Lactate in Patients with Severe Sepsis

Tissue hypoxia caused by the imbalance between the oxygen demand and the oxygen uptake, is considered to be the most important factor to the mortality and morbidity in patients with severe sepsis. However, the assessment of tissue oxygenation is still contraversial, since direct measurement of the adequacy of tissue oxygenation has not yet been available in the clinical setting.