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Research paper thumbnail of Reducing inadvertent peep by controlling end-tidal pressures in the trachea

Pediatric Pulmonology, 1989

Mechanical ventilation using exhalation times too brief for completion of exhalation results in i... more Mechanical ventilation using exhalation times too brief for completion of exhalation results in inadvertent positive end-expiratory pressure (IPEEP) and increased functional residual capacity (FRC). The endotracheal (ET) tube with side lumen allows us to monitor tracheal airway pressures and to determine the contributions of the ET tube to IPEEP. We hypothesized that, during rapid rate ventilation, controlling the positive end-expiratory pressure (PEEP) level in the trachea rather than at the ET tube adaptor will counter effects of the ET tube on IPEEP and result in less increase of FRC.

Research paper thumbnail of Exhalation time effects on arterial and venous blood oxygen content and arterial PCO2 during high frequency jet ventilation of surfactant-depleted cats

Pediatric Pulmonology, 1987

Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of e... more Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of expiratory gas, one would predict that the time allowed for exhalation would have serious effects on cardiopulmonary function. To document these effects we lavaged the lungs of ten cats with 30 mllkg of saline six times, then sampled arterial and venous blood while the animals were ventilated conventionally at 30 BPM and then with HFJV at 600 BPM, varying inspiratorylexpiratory ratios (IIE) from 1:l to 1.5. The animals breathed 1000/0 O2 throughout the study, and the mean airway pressure was held constant for each animal when the IIE was varied during HFJV. Decreasing the IIE from 1:1 to 1.5 during HFJV resulted in an increase of arterial oxygen content (C~Q) from 11.3 f 1.2s E to 13.6 f 1.2 ml 02/100 ml blood (P < 0.01), a decrease of PWO, from 43 f 6 to 27 f 4 mm Hg, and an increase of alveolar to arterial oxygen gradient from 351 f 49 to 377 f 49 mm Hg. The ratio of systemic blood flow to oxygen consumption (anlo,) was similar during conventional ventilation and with HFJV at IIE of 1:l (18.9 f 3.7 vs 18.0 f 2.9) but decreased when IIE was reduced to 1.5 during HFJV (13.9 2.1). The ratio of the product of C k , and Q (systemic oxygen availability) to VO, (SO,T~O,) remained unchanged during all modes of ventilation (1.75 f 0.15). The increase in Cao, observed when IIE was reduced from 1:l to 1.5 during HFJV was counterbalanced by a decrease in WO, such that So,TNo, remained relatively constant. Pediatr Pulmonol 1987;3:19-23.

Research paper thumbnail of Comparative Efficacy of Oral Ibuprofen Arginine and Intramuscular Ketorolac in Patients with Postoperative Pain

Clinical Drug Investigation, 1996

t As representatives of the investigator group of the Spanish multicentre study on the analgesic ... more t As representatives of the investigator group of the Spanish multicentre study on the analgesic treatment of postoperative pain following total hip replacement. For a list of investigators see page 285.

Research paper thumbnail of Phospholipids in Tracheal Effluent from Infants with Severe Respiratory Distress Syndrome

American Journal of Perinatology, 1984

The physiologic aberration that causes abnormal alveolar surface tension in the lungs of infants ... more The physiologic aberration that causes abnormal alveolar surface tension in the lungs of infants with RDS was investigated by measuring relative quantities of surfactant-related phospholipids in tracheal effluent from infants with RDS. A preliminary study in premature lambs demonstrated that the percent DSPC (molar ratio of DSPC to total phospholipid) is similar in tracheal effluent and lung lavagate. The percent DSPC in tracheal effluent from human infants with RDS was similar to the percent DSPC in effluent from non-RDS infants on the first day of life (47.4% +/- 2.9 vs 46.7% +/- 1.2), and remained constant during the first 8 days of life. Phosphatidylglycerol (PG) was universally absent in effluent from RDS infants on the first and second day of life but appeared by the eighth day of life in all infants who remained intubated. PG was present in tracheal effluent from only 10 of 16 non-RDS infants on the first day of life. These findings suggest that, in regard to the surface-active lecithin content, surfactant from RDS infants is qualitatively normal and that the absence of RDS is not dependent on the presence of PG.

Research paper thumbnail of Rapid Mechanical Ventilation Effects on Tracheal Airway Pressure, Lung Volume, and Blood Gases of Rabbits

American Journal of Perinatology, 1986

The purpose of this study was to demonstrate that ventilation of rabbit lungs (whose mechanics ar... more The purpose of this study was to demonstrate that ventilation of rabbit lungs (whose mechanics are similar to those of human infants) at rapid rates will lead to large alterations in tracheal airway pressures, tidal volume, and functional residual capacity (FRC) with only minor changes in arterial blood gases. Thirteen rabbits were ventilated at rates of 30, 60, 90, and 120 breaths per minutes (BPM) with pressures of 17/2 cm H2O. Tracheal peak inspiratory pressure (PIP) was always lower than ventilator PIP and decreased to 11 +/- 1 cm H2O at 120 BPM. Positive end-expiratory pressure (PEEP) in the trachea was always greater than 2 cm H2O and increased with rate (3.5 cm H2O at 120 BPM). Tidal volume decreased as rates were increased such that rates above 60 BPM resulted in insignificant changes in minute ventilation and arterial blood gases. However, the FRC increased from 16 (30 BPM) to 25 ml/kg (120 BPM), a 56% increase, suggesting large increases in end-expiratory alveolar pressure. We conclude that rapid-rate ventilation (greater than 60 BPM) of healthy rabbits results in significant increases in both tracheal PEEP and FRC without significantly affecting arterial blood gases. The increased tracheal PEEP and FRC are manifestations of inadvertent PEEP. The increased FRC without concomitant increase in PaO2 implicates alveolar overdistention. We speculate that rapid-rate ventilation of human infants having lung mechanics similar to rabbits, will also result in inadvertent PEEP and alveolar overdistention.

Research paper thumbnail of Reducing inadvertent peep by controlling end-tidal pressures in the trachea

Pediatric Pulmonology, 1989

Mechanical ventilation using exhalation times too brief for completion of exhalation results in i... more Mechanical ventilation using exhalation times too brief for completion of exhalation results in inadvertent positive end-expiratory pressure (IPEEP) and increased functional residual capacity (FRC). The endotracheal (ET) tube with side lumen allows us to monitor tracheal airway pressures and to determine the contributions of the ET tube to IPEEP. We hypothesized that, during rapid rate ventilation, controlling the positive end-expiratory pressure (PEEP) level in the trachea rather than at the ET tube adaptor will counter effects of the ET tube on IPEEP and result in less increase of FRC.

Research paper thumbnail of Exhalation time effects on arterial and venous blood oxygen content and arterial PCO2 during high frequency jet ventilation of surfactant-depleted cats

Pediatric Pulmonology, 1987

Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of e... more Since high frequency jet ventilation (HFJV) relies on lung mechanics for the passive removal of expiratory gas, one would predict that the time allowed for exhalation would have serious effects on cardiopulmonary function. To document these effects we lavaged the lungs of ten cats with 30 mllkg of saline six times, then sampled arterial and venous blood while the animals were ventilated conventionally at 30 BPM and then with HFJV at 600 BPM, varying inspiratorylexpiratory ratios (IIE) from 1:l to 1.5. The animals breathed 1000/0 O2 throughout the study, and the mean airway pressure was held constant for each animal when the IIE was varied during HFJV. Decreasing the IIE from 1:1 to 1.5 during HFJV resulted in an increase of arterial oxygen content (C~Q) from 11.3 f 1.2s E to 13.6 f 1.2 ml 02/100 ml blood (P < 0.01), a decrease of PWO, from 43 f 6 to 27 f 4 mm Hg, and an increase of alveolar to arterial oxygen gradient from 351 f 49 to 377 f 49 mm Hg. The ratio of systemic blood flow to oxygen consumption (anlo,) was similar during conventional ventilation and with HFJV at IIE of 1:l (18.9 f 3.7 vs 18.0 f 2.9) but decreased when IIE was reduced to 1.5 during HFJV (13.9 2.1). The ratio of the product of C k , and Q (systemic oxygen availability) to VO, (SO,T~O,) remained unchanged during all modes of ventilation (1.75 f 0.15). The increase in Cao, observed when IIE was reduced from 1:l to 1.5 during HFJV was counterbalanced by a decrease in WO, such that So,TNo, remained relatively constant. Pediatr Pulmonol 1987;3:19-23.

Research paper thumbnail of Comparative Efficacy of Oral Ibuprofen Arginine and Intramuscular Ketorolac in Patients with Postoperative Pain

Clinical Drug Investigation, 1996

t As representatives of the investigator group of the Spanish multicentre study on the analgesic ... more t As representatives of the investigator group of the Spanish multicentre study on the analgesic treatment of postoperative pain following total hip replacement. For a list of investigators see page 285.

Research paper thumbnail of Phospholipids in Tracheal Effluent from Infants with Severe Respiratory Distress Syndrome

American Journal of Perinatology, 1984

The physiologic aberration that causes abnormal alveolar surface tension in the lungs of infants ... more The physiologic aberration that causes abnormal alveolar surface tension in the lungs of infants with RDS was investigated by measuring relative quantities of surfactant-related phospholipids in tracheal effluent from infants with RDS. A preliminary study in premature lambs demonstrated that the percent DSPC (molar ratio of DSPC to total phospholipid) is similar in tracheal effluent and lung lavagate. The percent DSPC in tracheal effluent from human infants with RDS was similar to the percent DSPC in effluent from non-RDS infants on the first day of life (47.4% +/- 2.9 vs 46.7% +/- 1.2), and remained constant during the first 8 days of life. Phosphatidylglycerol (PG) was universally absent in effluent from RDS infants on the first and second day of life but appeared by the eighth day of life in all infants who remained intubated. PG was present in tracheal effluent from only 10 of 16 non-RDS infants on the first day of life. These findings suggest that, in regard to the surface-active lecithin content, surfactant from RDS infants is qualitatively normal and that the absence of RDS is not dependent on the presence of PG.

Research paper thumbnail of Rapid Mechanical Ventilation Effects on Tracheal Airway Pressure, Lung Volume, and Blood Gases of Rabbits

American Journal of Perinatology, 1986

The purpose of this study was to demonstrate that ventilation of rabbit lungs (whose mechanics ar... more The purpose of this study was to demonstrate that ventilation of rabbit lungs (whose mechanics are similar to those of human infants) at rapid rates will lead to large alterations in tracheal airway pressures, tidal volume, and functional residual capacity (FRC) with only minor changes in arterial blood gases. Thirteen rabbits were ventilated at rates of 30, 60, 90, and 120 breaths per minutes (BPM) with pressures of 17/2 cm H2O. Tracheal peak inspiratory pressure (PIP) was always lower than ventilator PIP and decreased to 11 +/- 1 cm H2O at 120 BPM. Positive end-expiratory pressure (PEEP) in the trachea was always greater than 2 cm H2O and increased with rate (3.5 cm H2O at 120 BPM). Tidal volume decreased as rates were increased such that rates above 60 BPM resulted in insignificant changes in minute ventilation and arterial blood gases. However, the FRC increased from 16 (30 BPM) to 25 ml/kg (120 BPM), a 56% increase, suggesting large increases in end-expiratory alveolar pressure. We conclude that rapid-rate ventilation (greater than 60 BPM) of healthy rabbits results in significant increases in both tracheal PEEP and FRC without significantly affecting arterial blood gases. The increased tracheal PEEP and FRC are manifestations of inadvertent PEEP. The increased FRC without concomitant increase in PaO2 implicates alveolar overdistention. We speculate that rapid-rate ventilation of human infants having lung mechanics similar to rabbits, will also result in inadvertent PEEP and alveolar overdistention.