K. Akpir

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.

Effects of sustained inflation and postinflation positive end- expiratory pressure in acute respiratory distress syndrome: Focusing on pulmonary and extrapulmonary forms*

ObjectiveTo investigate whether the response to sustained inflation and postinflation positive end-expiratory pressure varies between acute respiratory distress syndrome with pulmonary (ARDSp) and extrapulmonary origin (ARDSexp). DesignProspective clinical study. SettingMultidisciplinary intensive care unit in a university hospital. PatientsA total of 11 patients with ARDSp and 13 patients with ARDSexp. InterventionsA 7 ml/kg tidal volume, 12–15 breaths/min respiratory rate, and an inspiratory/expiratory ratio of 1:2 was used during baseline ventilation. Positive end-expiratory pressure levels were set according to the decision of the primary physician. Sustained inflation was performed by 45 cm H2O continuous positive airway pressure for 30 secs. Postinflation positive end-expiratory pressure was titrated decrementally, starting from a level of 20 cm H2O to keep the peripheral oxygen saturation between 92% and 95%. Fio2 was decreased, and baseline tidal volume, respiratory rate, inspiratory/expiratory ratio were maintained unchanged throughout the study period. Measurements and Main ResultsBlood gas, airway pressure, and hemodynamic measurements were performed at the following time points: at baseline and at 15 mins, 1 hr, 4 hrs, and 6 hrs after sustained inflation. After sustained inflation, the Pao2/Fio2 ratio improved in all of the patients both in ARDSp and ARDSexp. However, the Pao2/Fio2 ratio increased to >200 in four ARDSp patients (36%) and in seven ARDSexp patients (54%). In two of those ARDSp patients, the Pao2/Fio2 ratio was found to be <200, whereas none of the ARDSexp patients revealed Pao2/Fio2 ratios of <200 at the 6-hr measurement. Postinflation positive end-expiratory pressure levels were set at 16.7 ± 2.3 cm H2O in ARDSexp and 15.6 ± 2.5 cm H2O in ARDSp. The change in Pao2/Fio2 ratios was found statistically significant in patients with ARDSexp (p = .0001) and with ARDSp (p = .008). Respiratory system compliance increased in ARDSexp patients (p = .02), whereas the change in ARDSp was not statistically significant. ConclusionsSustained inflation followed by high levels of postinflation positive end-expiratory pressure provided an increase in respiratory system compliance in ARDSexp; however, arterial oxygenation improved in both ARDS forms.

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.

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).

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.

The effects of airway pressure and inspiratory time on bacterial translocation.

BACKGROUND: Mechanical ventilation with high peak inspiratory pressure (PIP) induces lung injury and bacterial translocation from the lung into the systemic circulation. We investigated the effects of increased inspiratory time on translocation of intratracheally inoculated bacteria during mechanical ventilation with and without extrinsic positive end-expiratory pressure (PEEP). METHODS: Rats were ventilated in pressure-controlled mode with 14 cm H2O PIP, 0 cm H2O PEEP, I:E ratio 1/2, and Fio2 1.0. Subsequently, 0.5 mL of 105 cfu/mL Pseudomonas aeruginosa was inoculated through tracheostomy and rats were randomly assigned to six groups; two low-pressure groups (LP)1/2, 14 cm H2O PIP, 0 cm H2O PEEP, I:E = 1/2, and LP2/1 14 cm H2O PIP, 0 cm H2O PEEP, I:E = 2/1; two high-pressure groups (HP)1/2, 30 cm H2O PIP, 0 cm H2O PEEP, I:E = 1/2, and HP2/1, 30 cm H2O PIP, 0 cm H2O PEEP, I:E = 2/1; two HP PEEP groups (HPP)1/2, 30 cm H2O PIP, 10 cm H2O PEEP, I:E = 1/2, and HPP2/1, 30 cm H2O PIP, 10 cm H2O PEEP, I:E = 2/1. Blood cultures were obtained every 30 min. The rats were killed and their lungs were processed. RESULTS: When compared with baseline values, Pao2 decreased in the LP1/2, LP2/1, HP1/2, and HP2/1 groups at the last time point, but the decline in Pao2 reached statistical significance in only the HP1/2 group. The bacterial translocation rate was greater in group HPP2/1 than group HPP1/2 (P = 0.01). CONCLUSIONS: We found that high PIP, with or without prolonged inspiratory time, increased the rate of bacterial dissemination. PEEP prevented bacterial translocation in the high PIP group. However, the protective effect of PEEP was lost when inspiratory time was prolonged.

Evaluation of Oxygenation with Different Modes of Ventilation in Patients with Adult Respiratory Distress Syndrome

Positive end-expiratory pressure (PEEP) was suggested to be the therapy of the adult respiratory distress syndrome (ARDS) by Asbaugh and colleagues1. However recent articles clearly indicate that any type of ventilatory management is merely a supportive measure to provide adequate gas exchange and has little effect in treatment of the underlying pathology2–4. In spite of this knowledge, new mechanical ventilatory approaches have been continuously introduced in the last two decades, aiming to provide adequate oxygenation and to avoid damage to the lungs which could be caused by the ventilation mode itself (for review see B. Lachmann et al.5).

Comparison of different modes of artificial ventilation with extracorporeal CO2 elimination on gas exchange in an animal model of acute respiratory failure.

Positive end-expiratory pressure (PEEP) was suggested to be the therapy of the adult respiratory distress syndrome (ARDS) by Asbaugh and colleagues1. However recent articles clearly indicate that any type of ventilatory management is merely a supportive measure to provide adequate gas exchange and has little effect in treatment of the underlying pathology2–4. In spite of this knowledge, new mechanical ventilatory approaches have been continuously introduced in the last two decades, aiming to provide adequate oxygenation and to avoid damage to the lungs which could be caused by the ventilation mode itself (for review see B. Lachmann et al.5).