1. Charité-Universitätsmedizin Berlin
Monitoring of Ventilation and Air Leakage during CPAP
Gerd Schmalisch
Clinic of Neonatology
Charité-Universitätsmedizin Berlin

2. Outline Ventilation and air leakage measurements during MV
Peculiarities of ventilation monitoring during CPAP
Theoretical background
Air leakages and volume correction
Clinical studies
Conclusions and outlook

3. Volume monitoring during MV
Displayed volume:
Vexp
Displayed air leakage:

4. Relationship between volume error and displayed leak during MV
Mahmoud R, et al. Acta Paediatr. 98 (2009)

5. Endotracheal tube leakage in newborns
Frequency distribution of ET leakage of 163 ventilated (>5h) newborns
No ET leakage:
79/163 (48%)
ET leakage < 20%:
125/163 (77%)
ET leakage >40%:
12/163 (7.4%)
Temporarily ET leakage >40% during MV
59/163 (36%)

6. Peculiarities of ventilation monitoring during CPAP
Different aims of monitoring
Different patient interfaces
Much higher air leakages
Spontaneous breathing (breath detection)
Worse signal-to-noise ratio
No suitable equipment !

7. Current ventilation monitoring during CPAP
Indirect methods
Breathing belts (inductive (RIP), capacitive)
Transthoracic impedance
Pressure capsules
Advantages:
No influence on breathing (resistance, dead space)
Measurement of thoraco-abdominal synchrony
Disadvantage:
No reliable measurement of VT, V’E,…
No information about air leakages

8. Direct ventilatory measurements during CPAP
Interface
Oro- /nasopharyngeal tube
Endotracheal tube
Face mask
Binasal prongs
Head box
Benveniste valve
Infant Flow™ nCPAP System
Schmalisch G. Yearbook equipments and technology in NIPPV

9. Ventilation and leak flow
How we can separate breathing flow and leakage flow?
(Prerequisite for breath detection and ventilation measurements)

10. Bubble CPAP and variable leak flow
Under this conditions is the separation of breathing flow and leakage flow is a big challenge!

11. Quantification of the air leakage - 1
Schmalisch G. Year book of NIPPV 2009

12. Quantification of the air leakage - 2
The quantification of air leakages by the leak flow is more informative than by the currently use of percentages.

13. - modeling and in-vitro measurements -
Relationship between air leakage and volume error
- modeling and in-vitro measurements -
Volume error
V`E - measured minute ventilation
maxV‘CPAP - maximal CPAP flow
Tin/Tex - inspiratory/expiratory time
Schmalisch G, et al. Med. Eng Phys. 31 (2009)
Fischer HS,, et al. Physiol. Meas. 29 (2008)

14. Volume correction during CPAP
- in vitro study -

15. Clinical applications – 1
Hückstädt T et al. Intens. Care Med. 29 (2003)
Clinical cross-over study N=69
Comparison of Infant Flow system vs. Babylog 8000 by TB parameters
Custom-made equipment (Flow-Through Technique)
49/69 (72%) infants excluded due to incompensable air leaks

16. Clinical applications – 2
Fischer HS, et al. Intens. Care Med. (2009) (in press)
Clinical cross-over study N=32
Air leaks during mononasal CPAP with and without nostril occlusion
Commercial Ventilator (Leoni M, Heinen&Löwenstein)
11/32 (34.4%) infants excluded due to air leaks >90%
* After BTPS Correction
1) Schmalisch G, et al. BMC Pediatrics 2009

17. Fischer HS, et al. ERS Vienna 2009

18. Effect of mouth opening on measured leak
Nasopharyngeal CPAP with occluded contralateral nostril
Fischer HS, et al. Intens. Care Med (in press)

19. What is relevant for the CPAP treatment in newborns?
Clinical impact of air leakages during CPAP
Consequences of air leakages during nasal mask ventilation in adults
Rabec CA et al. Leak Monitoring in Noninvasive Ventilation. Arch Bronconeumol 2004;40(11):508-17
What is relevant for the CPAP treatment in newborns?

20. Conclusion
Monitoring of ventilation and air leakages during CPAP is much more difficult compared to mechanical ventilation
For most CPAP interfaces used in neonates no suitable measuring technique is available
Air leakages during CPAP (e.g. mouth leaks) are very common and should be quantified by the leak flow.
To which extent a breath detection (e.g. for CPAP triggering) and volume monitoring is possible in the presence of large air leakages is still unknown.
New clinical studies are necessary to investigate the effect of air leakages on the efficiency of the CPAP treatment.