The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

BENCH STUDY EXAMINING TWO METHODS OF CUFF LEAK DURING ADULT HFOV

J. S. Emberger1, J. Brown1


Background: Our facility recently acquired the capability to perform adult HFOV. Evidence has shown that creating a cuff leak can facilitate increased carbon dioxide removal. There are currently two methods described for creating the cuff leak on HFOV. Both methods initially deflate the cuff for a 5 cmH2O reduction in measured mean airway pressure (MAP). One method uses MAP Adjust to return measured MAP back to the initial value with the cuff leak (MAP-ADJ Method). The other method uses Bias Flow adjustment to return the measured MAP back to the initial value with the cuff leak (FLOW-ADJ Method). There is concern that the MAP will increase if the cuff leak is inadvertently sealed. We wanted to determine the difference between these two methods of creating a cuff leak, if the cuff leak becomes sealed.

Method: We setup the 3100B Adult Oscillator on a standard Michigan Training Test Lung with a lung compliance of 20 mL/cmH2O. We tested both of the described cuff leak methods on a range of settings: 60 to 90 cmH2O amplitude and 20 to 35 cmH2O MAP. Hertz was 5.0 and I-time was 33%. With each setting, we created a cuff leak by the described method, and then re-sealed the cuff to determine how much the MAP would increase if the cuff became sealed.

Results: The increase in MAP after sealing the cuff was not significantly different between the two methods, but the FLOW-ADJ Method consistently had a smaller increase than the MAP-ADJ Method. The average MAP increase for the FLOW-ADJ Method after sealing the cuff = 5.0 ± 0.5 cmH2O. The average MAP increase for the MAP-ADJ Method after sealing the cuff = 8.4 ± 2.1 cmH2O. See Table 1 for data on each setting.

Conclusions: When comparing the two cuff leak methods after an inadvertent re-sealing of the patient’s cuff, our study shows the following:
1) FLOW-ADJ Method causes a smaller increase in MAP, typically about 5 cmH2O.
2) MAP-ADJ Method causes a larger increase in MAP and will more likely activate the high MAP alarm.
3) While both methods can cause an increase in MAP if the cuff becomes sealed, neither method exhibited a significant safety concern.

Amount of MAP Increase When Cuff Leak is Sealed
MAP AmplitudeMAP Increase When Cuff Leak Is Sealed: FLOW-ADJ MethodMAP Increase When Cuff Leak Is Sealed: MAP-ADJ Method
20 60 4.6 10.8
20 90 5.5 12.0
25 60 4.4 5.9
25 90 5.3 6.5
30 60 5.1 6.9
30 90 5.7 9.0
35 60 5.1 7.8
35 90 4.5 8.5



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