Single-breath analysis of carbon dioxide concentration records

Berengo, A; Cutillo, A

doi:10.1152/jappl.1961.16.3.522

Cited by 24 publications

(5 citation statements)

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“…Early studies, in the 1960s, focused on characterizing the shape of the capnogram in normal subjects (3), on demonstrating differences between their capnograms and capnograms from OD subjects (4,8,9), and on determining the physiological mechanisms underlying the capnogram changes in OD (3,(5)(6)(7). More recent studies, in the mid-1990s, demonstrated a correlation between FEV 1 and the shape of the capnogram in adult asthma subjects (10,11).…”

Section: Discussionmentioning

confidence: 99%

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Capnogram Shape in Obstructive Lung Disease

Krauss¹,

Deykin²,

Lam³

et al. 2005

Anesthesia &Amp; Analgesia

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Small, preliminary studies have suggested that capnograms of obstructive lung disease (OD) exhibit a characteristic shape and that this shape may be correlated to changes in forced expiratory volume in 1 s (FEV(1)). We evaluated the association between capnograms and spirometry from subjects with OD with normal and restrictive lung disease (RD) subjects. The study was conducted in a prospective, nonrandomized manner using a convenience sample of 262 subjects presenting to a pulmonary function laboratory. Capnograms were recorded before pulmonary function testing. Subjects with OD had capnograms that were significantly different from normal and RD subjects. These differences were progressive, increasing with disease severity. The average take-off angle of the ascending phase for severe OD was 7.2 degrees less (95% confidence interval [CI]: 4.0, 10.4) than for normals. The average alveolar plateau elevation angle was 0.8 degrees more (95% CI: 0.14, 1.4) for moderate OD than for normals, whereas the average elevation angle was 3.6 degrees more (95% CI: 2.9, 4.3) for severe OD than for normals. Differences between OD capnograms and normal and RD capnograms, correlating to changes in FEV(1), were sufficiently large enough to suggest that the capnogram could be used to discriminate between OD and normal.

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Section: Discussionmentioning

confidence: 99%

“…The capnogram achieves a maximal value at the end of exhalation (the end-tidal CO 2 [ETco 2 ] concentration) then decreases rapidly to zero as inhalation begins ( Fig. 1) (1)(2)(3)(4).…”

mentioning

confidence: 99%

Capnogram Shape in Obstructive Lung Disease

Krauss¹,

Deykin²,

Lam³

et al. 2005

Anesthesia &Amp; Analgesia

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“…The normal capnogram has an almost square wave pattern (Fig. 1 ), marked by alternating inspiratory (P insp CO 2 equals zero) and expiratory phases [ 3 , 4 ]. Expiration itself consists of three successive phases: (1) a latency phase (phase 1), corresponding to the expiration of the anatomical dead space (P exp CO 2 equals zero), which is indistinguishable from the preceding inspiration; (2) slope phase (phase 2) marked by a very rapid rise in P exp CO 2 , corresponding to expiration of mixed air; and (3) plateau phase (phase 3), reflecting the elimination of alveolar air (slightly increasing P exp CO 2 ) resulting in a peak at the end of tidal expiration (P et CO 2 close to alveolar carbon dioxide tensions P A CO 2 ) [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2009

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BackgroundThe usual method for initial assessment of an acute asthma attack in the emergency room includes the use of peak flow measurement and clinical parameters. Both methods have their own disadvantages such as poor cooperation/effort from patients (peak flow meter) and lack of objective assessment (clinical parameters). We were looking into other methods for the initial asthma assessment, namely the use of capnography. The normal capnogram has an almost square wave pattern comprising phase 1, slope phase 2, plateau phase 3, phase 4 and angle α (between slopes 2 and 3). The changes in asthma include decrease in slope of phase 2, increase in slope 3 and opening of angle α.AimsOur objective was to compare and assess the correlation between the changes in capnographic indices and peak flow measurement in non-intubated acute asthmatic patients attending the emergency room.MethodsWe carried out a prospective study in a university hospital emergency department (ED). One hundred and twenty eight patients with acute asthma were monitored with peak flow measurements and then had a nasal cannula attached for microstream sampling of expired carbon dioxide. The capnographic waveform was recorded onto a PC card for indices analysis. The patients were treated according to departmental protocols. After treatment, when they were adjudged well for discharge, a second set of results was obtained for peak flow measurements and capnographic waveform recording. The pre-treatment and post-treatment results were then compared with paired samples t-test analysis. Simple and canonical correlations were performed to determine correlations between the assessment methods. A p value of below 0.05 was taken to be significant.ResultsPeak flow measurements showed significant improvements post-treatment (p < 0.001). On the capnographic waveform, there was a significant difference in the slope of phase 3 (p < 0.001) and alpha angle (p < 0.001), but not in phase 2 slope (p = 0.35). Correlation studies done between the assessment methods and indices readings did not show strong correlations either between the measurements or the magnitude of change pre-treatment and post-treatment.ConclusionPeak flow measurements and capnographic waveform indices can indicate improvements in airway diameter in acute asthmatics in the ED. Even though the two assessment methods did not correlate statistically, capnographic waveform analysis presents several advantages in that it is effort independent and provides continuous monitoring of normal tidal respiration. They can be proposed for the monitoring of asthmatics in the ED.

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“…The normal capnogram ( fig. 1a) has a square wave pattern, marked by alternating inspiratory (PICO 2 equals zero) and expiratory phases [1][2][3]. Expiration itself consists of three successive phases: 1) a latency phase, "E1", corresponding to expiration of the anatomical dead space (PECO 2 =0), indistinguishable from the preceding inspiration; 2) phase "E2", marked by a very rapid rise in PECO 2 , corresponding to expiration of mixed air; and 3) plateau phase, "E3", reflecting the elimination of alveolar air (slightly increasing PECO 2 ) resulting in a peak at the end of tidal expiration (PETCO 2 , close to alveolar carbon dioxide tension (PAco 2 )), which immediately precedes the start of the following inspiration.…”

mentioning

confidence: 99%

Expiratory capnography in asthma: evaluation of various shape indices

You¹,

Peslin²,

Duvivier³

et al. 1994

Eur Respir J

132

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The shape of the capnogram is modified by airway obstruction, and the evaluation of this deformation, using measurable indices, could allow an indirect measurement of bronchial patency. A previous study undertaken in asthmatic subjects showed a good correlation between a capnographic index (end-tidal slope) and a spirometric parameter (forced expiratory volume in one second as a percentage of predicted (FEV1 %pred)) and suggested the study of other indices. The correlations between capnographic and spirometric indices were measured in 10 healthy subjects and 30 asthmatic patients. The usefulness of eight descriptive indices, analysing the successive phases of the capnogram, was assessed by measuring their reproducibility and their sensitivity to airway obstruction. The intraindividual and interindividual variabilities (Vi and VI) and the noise/signal ratio (Vi/VI) were measured by comparing the results of two successive capnographic measurements in 14 asthmatic subjects. The results show an increasing noise/signal ratio along the expiration (between 23 and 62%). Significant correlations between spirometry and capnography were found with all indices, but the strongest were observed with indices analysing the intermediate phase of the capnogram, that is the angle between the ascending phase (E2) and the alveolar plateau (E3). The correlations show that the analysis of the capnogram's shape is a quantitative method for evaluating the severity of bronchospasm. This ability, added to specific advantages (noninvasiveness, effort-independency, measurements during tidal breathing) opens new fields of application to capnography, such as measurement of bronchospasm in children and computerized monitoring of asthma.

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Single-breath analysis of carbon dioxide concentration records

Cited by 24 publications

References 0 publications

Capnogram Shape in Obstructive Lung Disease

Capnogram Shape in Obstructive Lung Disease

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

Expiratory capnography in asthma: evaluation of various shape indices

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