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Forced oscillations and respiratory system modeling in adults with cystic fibrosis.

Lima AN, Faria AC, Lopes AJ, Jansen JM, Melo PL - Biomed Eng Online (2015)

Bottom Line: The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p<0.0006) and reduced dynamic compliance (p<0.0001).In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p<0.0005) and reduced compliance (p < 0.0004) and inertance (p<0.005).The FOT adequately assessed the biomechanical changes associated with CF.

View Article: PubMed Central - PubMed

Affiliation: Pulmonary Function Laboratory - Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil. adna.lima@yahoo.com.br.

ABSTRACT

Background: The Forced Oscillation Technique (FOT) has the potential to increase our knowledge about the biomechanical changes that occur in Cystic Fibrosis (CF). Thus, the aims of this study were to investigate changes in the resistive and reactive properties of the respiratory systems of adults with CF.

Methods: The study was conducted in a group of 27 adults with CF over 18 years old and a control group of 23 healthy individuals, both of which were assessed by the FOT, plethysmography and spirometry. An equivalent electrical circuit model was also used to quantify biomechanical changes and to gain physiological insight.

Results and discussion: The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p<0.0006) and reduced dynamic compliance (p<0.0001). In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p<0.0005) and reduced compliance (p < 0.0004) and inertance (p<0.005). Significant reasonable to good correlations were observed between the resistive parameters and spirometric and plethysmographic indexes. Similar associations were observed for the reactive parameters. Peripheral resistance, obtained by the model analysis, presented reasonable (R=0.35) to good (R=0.64) relationships with plethysmographic parameters.

Conclusions: The FOT adequately assessed the biomechanical changes associated with CF. The model used provides sensitive indicators of lung function and has the capacity to differentiate between obstructed and non-obstructed airway conditions. The FOT shows great potential for the clinical assessment of respiratory mechanics in adults with CF.

No MeSH data available.


Related in: MedlinePlus

Electrical representation of a two-compartment model used to analyze respiratory impedance. Resistance, inductance and capacitance are the analogs of mechanical resistance, inertance and compliance, respectively. R is analogous to central airway resistance and Rp describes peripheral resistance, I is associated with airway, gas and tissue inertance, while C is related with alveolar compliance. This analysis also evaluated the total resistance (Rt = R + Rp), which included the effects of central and peripheral airways.
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Fig1: Electrical representation of a two-compartment model used to analyze respiratory impedance. Resistance, inductance and capacitance are the analogs of mechanical resistance, inertance and compliance, respectively. R is analogous to central airway resistance and Rp describes peripheral resistance, I is associated with airway, gas and tissue inertance, while C is related with alveolar compliance. This analysis also evaluated the total resistance (Rt = R + Rp), which included the effects of central and peripheral airways.

Mentions: Compartmental model analysis was performed using the extended RIC (eRIC) model (Figure 1), in which R is analogous to central airway resistance, Rp describes peripheral resistance, I is associated with lung inertance and C is associated with alveolar compliance [16]. This model is proposed as an improvement to the basic RIC model [4,15]. Specifically, the added peripheral resistance Rp allows for observation of the frequency dependence of typical real impedance data, which is beyond the capability of the RIC model. This additional component describes the resistance presented by the small airways of the respiratory system. We also evaluated the total resistance (Rt = R + Rp), which includes the effects of the central and peripheral airways. Model parameters were estimated using the Levenberg-Marquardt algorithm to determine the set of coefficients of the nonlinear model that best represents the input data set in the least squares sense. Along with the corresponding model estimates, this analysis also provided the evaluation of the total error value, which is an overall measure of “goodness of fit” for the model. Herein, this parameter is defined as the square root of the sum of the real and imaginary squared impedance estimation errors. The mean relative distance from the model and measured resistance and reactance values was also measured [34,35].Figure 1


Forced oscillations and respiratory system modeling in adults with cystic fibrosis.

Lima AN, Faria AC, Lopes AJ, Jansen JM, Melo PL - Biomed Eng Online (2015)

Electrical representation of a two-compartment model used to analyze respiratory impedance. Resistance, inductance and capacitance are the analogs of mechanical resistance, inertance and compliance, respectively. R is analogous to central airway resistance and Rp describes peripheral resistance, I is associated with airway, gas and tissue inertance, while C is related with alveolar compliance. This analysis also evaluated the total resistance (Rt = R + Rp), which included the effects of central and peripheral airways.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4334397&req=5

Fig1: Electrical representation of a two-compartment model used to analyze respiratory impedance. Resistance, inductance and capacitance are the analogs of mechanical resistance, inertance and compliance, respectively. R is analogous to central airway resistance and Rp describes peripheral resistance, I is associated with airway, gas and tissue inertance, while C is related with alveolar compliance. This analysis also evaluated the total resistance (Rt = R + Rp), which included the effects of central and peripheral airways.
Mentions: Compartmental model analysis was performed using the extended RIC (eRIC) model (Figure 1), in which R is analogous to central airway resistance, Rp describes peripheral resistance, I is associated with lung inertance and C is associated with alveolar compliance [16]. This model is proposed as an improvement to the basic RIC model [4,15]. Specifically, the added peripheral resistance Rp allows for observation of the frequency dependence of typical real impedance data, which is beyond the capability of the RIC model. This additional component describes the resistance presented by the small airways of the respiratory system. We also evaluated the total resistance (Rt = R + Rp), which includes the effects of the central and peripheral airways. Model parameters were estimated using the Levenberg-Marquardt algorithm to determine the set of coefficients of the nonlinear model that best represents the input data set in the least squares sense. Along with the corresponding model estimates, this analysis also provided the evaluation of the total error value, which is an overall measure of “goodness of fit” for the model. Herein, this parameter is defined as the square root of the sum of the real and imaginary squared impedance estimation errors. The mean relative distance from the model and measured resistance and reactance values was also measured [34,35].Figure 1

Bottom Line: The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p<0.0006) and reduced dynamic compliance (p<0.0001).In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p<0.0005) and reduced compliance (p < 0.0004) and inertance (p<0.005).The FOT adequately assessed the biomechanical changes associated with CF.

View Article: PubMed Central - PubMed

Affiliation: Pulmonary Function Laboratory - Faculty of Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil. adna.lima@yahoo.com.br.

ABSTRACT

Background: The Forced Oscillation Technique (FOT) has the potential to increase our knowledge about the biomechanical changes that occur in Cystic Fibrosis (CF). Thus, the aims of this study were to investigate changes in the resistive and reactive properties of the respiratory systems of adults with CF.

Methods: The study was conducted in a group of 27 adults with CF over 18 years old and a control group of 23 healthy individuals, both of which were assessed by the FOT, plethysmography and spirometry. An equivalent electrical circuit model was also used to quantify biomechanical changes and to gain physiological insight.

Results and discussion: The CF adults presented an increased total respiratory resistance (p < 0.0001), increased resistance curve slope (p<0.0006) and reduced dynamic compliance (p<0.0001). In close agreement with the physiology of CF, the model analysis showed increased peripheral resistance (p<0.0005) and reduced compliance (p < 0.0004) and inertance (p<0.005). Significant reasonable to good correlations were observed between the resistive parameters and spirometric and plethysmographic indexes. Similar associations were observed for the reactive parameters. Peripheral resistance, obtained by the model analysis, presented reasonable (R=0.35) to good (R=0.64) relationships with plethysmographic parameters.

Conclusions: The FOT adequately assessed the biomechanical changes associated with CF. The model used provides sensitive indicators of lung function and has the capacity to differentiate between obstructed and non-obstructed airway conditions. The FOT shows great potential for the clinical assessment of respiratory mechanics in adults with CF.

No MeSH data available.


Related in: MedlinePlus