Correlations between capnographic waveforms and peak flow meter measurement in emergency department management of asthma

Hisamuddin, N A R Nik; Rashidi, A.; Chew, Keng Sheng; Kamaruddin, J; Idzwan, Z Mohd; Howe, Teo Aik

doi:10.1007/s12245-009-0088-9

Cited by 46 publications

(36 citation statements)

References 16 publications

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“…This finding is in accord with the postulate of the close link between the airway cross-sectional area and SIII, based on spirometric data obtained previously in spontaneously breathing patients (1,3,28). Representing (G) or incorporating lung parenchymal resistive component (RL and Rvent) weakened the correlation substantially (p<0.0001; Fig.…”

Section: Phase-iii Slopesupporting

confidence: 92%

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

Csorba

Peták

Nevery

et al. 2016

Anesthesia &Amp; Analgesia

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Section: Phase-iii Slopesupporting

confidence: 92%

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

Csorba

Peták

Nevery

et al. 2016

Anesthesia &Amp; Analgesia

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“…6A). This finding is in accord with the postulate of the close link between the airway cross-sectional area and SIII, based on spirometric data obtained previously in spontaneously breathing patients (50,53,57). Representing (G) or incorporating lung parenchymal resistive component (RL and Rvent) weakened the correlation substantially (p<0.0001; Fig.…”

Section: Phase III Slopesupporting

confidence: 92%

“…Therefore this technique can be used for a lot more than to verify the technical correctness of the airway management and respiratory therapy as a polar question. Capnography also provides important bedside pathophysiological information about the uniformity of lung emptying and adverse changes in the overall airway geometry (19,21,33,50,52,53), and it can serve as a valuable tool for the recognition of pulmonary microcirculatory abnormalities (27,45,46 (52) merely a modest association (43,53) or even a lack of correspondence (57). Furthermore, significant correlations were observed between the total respiratory resistance (Rrs) and SIII in mechanically ventilated patients, however SIII had limited clinical applicability to predict Rrs (59).…”

Section: Clinical Aspectsmentioning

confidence: 99%

Relationships between capnogram parameters and respiratory mechanics in ventilated patients

Csorba

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Capnography is one of the most frequently used monitoring methods in anaesthesia and intensive therapy. However, details as to how the resistive and/or elastic properties of the respiratory system affect the various indices derived from the capnogram curve are lacking from the literature. The aims of the present thesis were therefore to establish the connections between the various phase, shape, dead space or pulmonary shunt circulation parameters of the time or volumetric capnogram and those reflecting the airway and respiratory tissue mechanics, expiratory flow and gas exchange.A large cohort of patients scheduled for elective cardiac surgery was enrolled in this thesis. After induction of total intravenous anaesthesia, the patients were intubated and ventilated. Forced oscillation technique was applied to measure airway resistance (Raw), tissue damping (G) and elastance (H). Time and volumetric capnography were performed to assess parameters reflecting the phase II (SII) and III slopes (SIII), their transition (D2min), and the deadspace indices according to Fowler, Bohr and Enghoff approach. The respiratory resistance (Rrs) and the dynamic compliance (Crs) displayed by the ventilator were registered, and arterial and central venous blood gas analysis were performed. In the first study (Study 1) the measurement was performed in open-chest condition before and 5 min after cardiopulmonary bypass (CPB), whereas in the second study (Study 2) of this thesis, the measurements were accomplished at positive end-expiratory pressure (PEEP) levels of 3, 6 and 9 cm H2O in patients with healthy lungs, and in patients with respiratory symptoms involving low (Group LC), medium (Group MC) or high Crs (Group HC).In Study 1, SII and D2min exhibited the closest associations with H (0.65 and 0.57; p<0.0001, respectively), whereas SIII correlated most strongly with Raw (r=0.63; p<0.0001) before CPB, whereas significant elevations in Raw and G, with smaller but still significant increases in H were induced by CPB. These adverse mechanical changes were reflected consistently in SII, SIII and D2min, with weaker correlations with the dead-space indices. The intrapulmonary shunt expressed as the difference between the Enghoff and Bohr dead-space parameters was increased after CPB (95±5% vs. 143±6%; p<0.001). The results confirm that the capnographic parameters from the early phase of expiration (SII and D2min) are linked to the pulmonary elastic recoil, while the effect of airway patency on SIII dominates over the lung tissue stiffness in mechanically ventilated patients. However, severe deteriorations in lung resistance or elastance affect both capnogram slopes.In Study 2, SIII,T and SIII,V exhibited similar PEEP dependencies and distribution between the protocol groups formed on the bases of Crs. A wide inter-individual scatter was observed in the overall RawSIII,V relationship, which was primarily affected by Crs. Decreases in Raw with increasing PEEP were reflected in sharp falls in SIII in Group HC, whereas SIII,T was ins...

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“…The extension of this technique to intubated infants has been limited by technical problems associated with the capnographic indices [5], [12].…”

Section: Discussionmentioning

confidence: 99%

Association between Capnogram and Respiratory Flow Rate Waveforms during Invasive Mechanical Ventilation

Rasera¹,

Gewehr²

2013

IJBBB

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Abstract-Capnography refers to the continuous and noninvasive measurement of carbon dioxide (CO 2 ) concentration in respiratory gases and it provides a real-time assessment of ventilatory status. The aim of this paper is to demarcate the inspiratory and expiratory segments of a time capnogram using data from respiratory flow rate waveforms. The measurements were obtained from 38 infants under mechanical ventilation in intensive care unit. A comparison was made between CO 2 and respiratory flow waveforms to determine the inspiratory segment (phase 0) and the expiratory segment and its subdivisions (phases I, II, and III). The coefficients of determination were 0.83 (p < 0.001) for end-tidal CO 2 pressure and inspiratory flow during rebreathing; and 0.97 (p < 0.001) during the weaning process. The end of expiration almost coincides with the downslope of the CO 2 waveform in the capnograms when there is no rebreathing, during the weaning process. However, in the presence of rebreathing, the alveolar plateau is prolonged and includes a part of inspiration, in addition to the expiratory alveolar plateau.Index Terms-Capnogram, invasive mechanical ventilation, monitoring device, respiratory flow rate.

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Correlations between capnographic waveforms and peak flow meter measurement in emergency department management of asthma

Cited by 46 publications

References 16 publications

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics

Relationships between capnogram parameters and respiratory mechanics in ventilated patients

Association between Capnogram and Respiratory Flow Rate Waveforms during Invasive Mechanical Ventilation

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