The Science Journal of the American Association for Respiratory Care

1995 OPEN FORUM Abstracts

OPEN DISCONNECT VERSUS CLOSED IN-LINE SUCTIONING DURING HFOV.

Dale Gerstmann MD, Larry Cooper RRT, Ron Haskill RRT, Gordon Lassen RRT. Neonatology and Respiratory Therapy, Utah Valley Reg Med Cen, Provo, UT.

Introduction: This study compared the effects on mean tracheal airway pressure (PTr) and real-time oxygenation (P_aO_2) of open circuit suctioning (OCS) versus closed circuit in-line suctioning (CCS) during HFOV. Method: Ten white rabbits (2.2-2.8 kg) underwent sedation, analgesia, tracheostomy, intubation, paralysis and 21 suctioning episodes prior to and after saline lavage (Total episodes = 420). ABGs were normalized by adjusting mean PAW, F_iO_2, and pressure amplitude (PAmp) at a frequency (Freq) of 10Hz. Various ETT (2.0, 2.5, 3.0mm) and catheter sizes (5.0, 6.0, 8.0F) were used. Suction pressure was -90 mmHg. Suctioning episodes were done with random adjustments of Freq (6, 10, 15 Hz) and PAmp (PAmp=0, PAmp+0, PAmp+10 cmH_2O) along with disconnect suctioning every 7th episode. PTr was measured with a small monitoring tube 2cm below the tip of the ETT. Real-time P_aO_2 was measured with an electrode catheter in the right carotid artery at the level of the aortic arch. Each suction episode was divided into 5 segments based on PTr: pre-baseline, ready, suction, recovery, and post-baseline. Segment interval time, PTr, and P_aO_2 were measured and recorded.

Results: The OCS ready interval was 39% longer than for CCS (8.0±0.4 vs 5.8±0.1sec, p < 0.001). PTr recovery time after suctioning was more with OCS (4.2±0.3 vs 2.7±0.1sec, p < 0.001). The change in PTr during the ready interval was greater with OCS compared to CCS (-75.1±5.4% vs -4.4±1.1%, p < 0.001). PTr was = <ambient during suctioning except for CCS CATH=5.0 + ETT=3.0 where the change was -57±2%. There was no difference in the change in post-baseline PTr between OCS and CCS (4.2±0.6% vs. 0.0±0.3%). P_aO_2 decreased more during suctioning with OCS than with CCS (-18±2 vs. -10±1 torr, p < 0.001) and the change in post-baseline P_aO_2 was also greater (-6±2 vs 0±1 torr, p < 0.001).

Conclusions: Catheter introduction was faster with CCS than with OCS. CCS promoted PTr maintenance during the ready interval, and allowed faster PTr recovery after suctioning. CCS lessened the drop in real-time P_aO_2 during and after suctioning. Gas trapping or inadvertent increases in PTr were not seen with OCS or CCS during any episode segment. (Funded by a grant from Ballard Medical Products, Draper, UT.)

OF-95-229

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