The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

VOLUME LOSS THROUGH SWIVEL ADAPTERS

Jenni L. Raake, RRT. AAS. Children's Hospital Medical Center Cincinnati, Ohio

Background: Many clinicians use swivel adapters to connect ventilator circuits to endotracheal tubes. The adapters, usually elbow shaped, allow for flexibility in maintaining patient airways. These adapters, however, can be sources of volume loss.

Method: Eight adapters were evaluated using three different tests: #1) a "tightness" test, #2) a water-leak test, and #3) mechanical ventilation tests. The tightness test, a standard test performed on the Hamilton Veolar ventilator, allowed the clinician to check the circuit for leaks by maintaining a set pressure. The water-leak test was performed with the adapter inverted into a basin of water while connected to a test lung. As volume was passed through the ventilator circuit, air bubbles coming from the adapter indicated a loss of volume. The mechanical ventilation test was performed with the Hamilton Veolar connected to the Biotek VT-1 ventilator tester. The ventilator was set at a rate of 20, PEEP of 5 cm H_{2}O, and V_{t} of 100cc, 200cc, 300cc, 400cc, and 500cc. The set volume minus the compressible volume loss (0.76cc/foot on an 8 foot long Baxter circuit #1019-703), was considered to be the optimal volume. The test focused on which adapter(s) had the greatest optimal volumes. Results: Four of the adapters passed the tightness test. Two of these adapters also passed the water-leak test. These same two adapters consistently delivered volumes closest to those that were optimal. The chart below demonstrates the results of the adapters tested. Experience: Some volume loss during mechanical ventilation is expected due to compression of gases within the circuit. This testing examined volume lost within the swivel adapters. One manufacturer reported acceptable volume loss through their adapter as 0.5cc at 120cm H_{2}O. However, the loss through this adapter was greater at lower pressures. Conclusion: Based on the above tests, the Diemolding Healthcare Division's (DHD) Swivel Elbo (66-1995) without Suction Port, and the Concord/Portex Swivel Adapter (525350) with PEEP Keep was able to pass all three tests without overt volume loss.

Manufacturer/Part# Test 1 Test 2 Test 3 percent of optimal volumes:

100cc 200cc 300cc 400cc 500cc Cost

Carden 545700 pass fail 87% 89% 93% 92% 91% $18.00

DHD w/port 66-1991 pass fail 94% 91% 93% 94% 94% $1.94

DHD w/o port 66-1995 pass pass 100% 96% 97% 98% 96% $1.59

Portex 525350 pass pass 97% 96% 98% 98% 96% $3.68

Seven Harvest 746 fail fail 94% 95% 94% 94% 94% $0.82

Gibeck 23312 fail fail 90% 93% 93% 94% 92% $2.64

Medicomp MC-4450 fail fail 95% 94% 93% 94% 94% $1.25

Medicomp MC-4475 fail fail 92% 94% 94% 94% 94% $1.50

w/port

Reference: OF-96-123

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