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Arterial to end-tidal CO2 gradients during spontaneous breathing, intermittent positive-pressure ventilation and jet ventilation

Capan LM; Ramanathan S; Sinha K; Turndorf H
Arterial to end-tidal CO2 tension gradients were measured in 18 dogs during spontaneous breathing (SB), intermittent positive-pressure ventilation (IPPV), and both low-frequency and high-frequency jet ventilation (LFJV and HFJV). The dogs were anesthetized with nembutal and permitted to breathe spontaneously through an 8-mm internal diameter endotracheal tube; blood gas tensions, cardiac output, and end-tidal CO2 partial pressure (PetCO2) were measured. IPPV, LFJV, and HFJV were then instituted in a random sequence and measurements repeated. PaO2, PaCO2 and cardiac output were similar during all four ventilatory modes. The mean PaCO2 differed significantly (p less than .001) from PetCO2 during IPPV, LFJV, and HFJV but not during SB. The mean PaCO2-PetCO2 gradient was 3.7 +/- 1 (SD), 12.6 +/- 5.0, and 24.3 +/- 8 torr during IPPV, LFJV and HFJV, respectively. The large gradients during LFJV and HFJV were not produced by dilution of tracheal CO2 by entrained air or by oxygen delivered by the jet. These results suggest that both LFJV and HFJV may be associated with a large PaCO2-PetCO2 gradient
PMID: 3928248
ISSN: 0090-3493
CID: 23472

Humidification and airway pressures during high-frequency jet ventilation delivered through the suction-biopsy channel of a flexible bronchofiberscope

Ramanathan S; Sinha K; Arismendy J; Chalon J; Turndorf H
The suction-biopsy channel (SBC) of a flexible bronchofiberscope was used to deliver gas into the trachea during high-frequency jet ventilation (HFJV) at a rate of 95 cycle/min and a tidal volume (VT) of 95 ml. A Portex epidural catheter inserted into the SBC was used to entrain water for humidification by the injector principle. Inspired humidity (IH) was regulated by adjusting the distance (D) between the injector and jet portals. Airway pressures, pulmonary gas exchange and IH levels were measured in 11 dogs. In addition, tracheal cytology scores (TCS, a sensitive index of tracheal epithelial damage caused by breathing dry gases) were assessed in 12 patients. The system maintained adequate pulmonary gas exchange in both dogs and humans. In dogs the mean tracheal pressure was 2.8 +/- 0.5 (SD) torr with a peak pressure of 3.8 +/- 0.5 torr. The upper-airway pressure was subatmospheric (-2 +/- 0.2 torr) during the first half of jet inspiration, but peaked synchronously with tracheal pressures during the second half. Both the upper airway and the trachea had a positive end-expiratory pressure (PEEP) of 1.8 +/- 0.2 torr. When D was 0.3 cm, the system delivered gas with an IH of 44 mg H2O/L (almost saturated at 37 degrees C). Human TCS did not change significantly after 2 h of humidified HFJV, suggesting efficient humidification
PMID: 6432444
ISSN: 0090-3493
CID: 45801

Arterial-end-tidal CO2 gradients with different ventilatory modes [Meeting Abstract]

Capan L; Ramanathan S; Sinha K; Poscablo T; Chalon J; Turndorf H
ORIGINAL:0005069
ISSN: 0003-3022
CID: 47429

Bronchofiberscopic high frequency ventilation [Meeting Abstract]

Ramanathan S; Sinha K; Arismendy J; Chalon J; Turndorf H
ORIGINAL:0005073
ISSN: 0003-3022
CID: 47433