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Monitoring of Ventilation and Air Leakage during CPAP. Gerd Schmalisch. Clinic of Neonatology Charité-Universitätsmedizin Berlin. Outline. Ventilation and air leakage measurements during MV Peculiarities of ventilation monitoring during CPAP Theoretical background
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Monitoring of Ventilation and Air Leakage during CPAP Gerd Schmalisch Clinic of Neonatology Charité-Universitätsmedizin Berlin
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
Volume monitoring during MV Displayed volume: Vexp Displayed air leakage:
Relationship between volume error and displayed leak during MV Mahmoud R, et al. Acta Paediatr. 98 (2009) 1116-1122
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%)
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 !
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
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 - 2009
Ventilation and leak flow How we can separate breathing flow and leakage flow? (Prerequisite for breath detection and ventilation measurements)
Bubble CPAP and variable leak flow Under this conditions is the separation of breathing flow and leakage flow is a big challenge!
Quantification of the air leakage - 1 Schmalisch G. Year book of NIPPV 2009
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.
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) 124-130 Fischer HS,, et al. Physiol. Meas. 29 (2008) 95-107
Volume correction during CPAP - in vitro study -
Clinical applications – 1 Hückstädt T et al. Intens. Care Med. 29 (2003) 1134-1140 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
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
Effect of mouth opening on measured leak Nasopharyngeal CPAP with occluded contralateral nostril Fischer HS, et al. Intens. Care Med. 2009 (in press)
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?
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.