Digital computer calculation of human pulmonary mechanics using a least squares fit technique

Uhl, Richard R.; Fj, Lewis

doi:10.1016/0010-4809(74)90027-5

Cited by 110 publications

(54 citation statements)

References 4 publications

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“…Thus, it is possible to estimate the static P/V data from zero endexpiratory pressure by extrapolating the MLRelastance line to 0 cmH 2 O level in the P/V diagram. The MLR technique as originally described [12], used the entire respiratory cycle to calculate the mechanics. However, the respiratory system mechanics can be calculated for any portion of the respiratory cycle, by appropriate definitions of the data to be analysed.…”

Section: Resultsmentioning

confidence: 99%

“…These techniques are sometimes not practical to perform or require the presence of a trained investigator and the respirator settings may need to be changed. With the increasing availability of computer-based data acquisition systems, high speed data collection and analyses are now possible using the computerized least-squares multiple regression analysis technique [12]. Using a multiple linear regression (MLR) analysis to analyse the flow and pressure changes at the airway opening during mechanical ventilation, permits dynamic mechanics to be measured noninvasively without interfering with the ventilation pattern being employed.…”

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confidence: 99%

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Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis

et al. 2001

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The elastic pressure/volume (P/V) curve obtained by the multiple linear regression (MLR) technique using a new model, was compared with the quasi-static P/V points obtained by the rapid airway occlusion technique.Seven infants were studied during mechanical ventilation using a pressure controlled mode. The resistive pressure was subtracted from airway opening pressure, thus determining the elastance related pressure, which was then plotted against the volume to make an MLR-elastance curve. Quasi-static P/V curves of the rapid occlusion technique were constructed by plotting the different inspiratory and expiratory volumes against the corresponding values of the quasi-static airway pressure.The calculated MLR-elastance curves closely fit the experimental quasi-static P/V points obtained by the occlusion technique. There were, however, some discrepancies due to the viscoelastic behaviour of the respiratory system.Although slightly altered by these discrepancies, the multiple linear regressionelastance curves did fit the observed quasi-static pressure/volume characteristics for use in clinical practice. Respiratory system elastance has been shown to exhibit a negative lung volume dependence due to the curvilinear character of static pressure/volume [1 -3] (P/V) curves. During mechanical ventilation, the lungs are frequently inflated to the nonlinear level on the P/V curve. It is generally accepted that a graphic presentation of the P/V relationship at a given respirator setting can provide great insight regarding whether or not lung overdistension occurs.The static P/V relationship, as a parameter for the elasticity of the respiratory system, can be determined by various methods. The super syringe technique is a continuous procedure of step-by-step inflation and deflation using a large syringe while the patient is disconnected from the ventilator [4]. The interrupter technique consists of rapid occlusions within a single breath cycle [5,6] or of interrupting airways at different inflation and deflation volumes [7 -9]. All occlusion data can then be plotted on a P/V diagram. The constant flow technique is performed during volume controlled mechanical ventilation using a very slow constant inflation flow of 3 L?min -1 or 9 L?min -1 , and thus pressure consumed by the flow resistance in the airway is not considered to be of any clinical relevance [10,11]. These techniques are sometimes not practical to perform or require the presence of a trained investigator and the respirator settings may need to be changed. With the increasing availability of computer-based data acquisition systems, high speed data collection and analyses are now possible using the computerized least-squares multiple regression analysis technique [12]. Using a multiple linear regression (MLR) analysis to analyse the flow and pressure changes at the airway opening during mechanical ventilation, permits dynamic mechanics to be measured noninvasively without interfering with the ventilation pattern being employed. An MLR analysis also allows...

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis

et al. 2001

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“…The module measures dynamic compliance, which is the ratio of change in volume to the change in pressure during inspiration. Dynamic compliance is calculated using the least squares fitting method of the flow, volume, and raw pressure waveform [16][17][18]. Blood pressure was measured with an automated NIBP device (Philips Intellivue MP70).…”

Section: Methodsmentioning

confidence: 99%

Cardiorespiratory Effects of Derotational Casting during Anesthesia for Children with Early Onset Scoliosis

Jensen¹,

Stasic²,

Kishan³

et al. 2014

OJAnes

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Study Design: A prospective, observational case series of eighteen children with early onset scoliosis undergo spine manipulation and casting. Objective: Determine if respiratory system compliance decreases during casting warrants tracheal intubation in all Derotational casting procedures. Background: Children with early onset scoliosis with a Cobb angle greater than 25 degrees will have significant progression of their scoliosis. Surgical techniques cannot result in spine fusion as growth retardation will ensue. Serial thoracolumbar casting may correct the scoliosis or delay the need for surgery. The cast, however, is highly restrictive until the cast is appropriately cut. Does respiratory system compliance decrease a significant degree to require tracheal intubation in all Derotational casting procedures? Methods: Eighteen children (mean age: 4.5 years, mean weight: 16.9 kg) undergoing initial scoliosis casting were enrolled. Anesthesia was induced with sevoflurane in oxygen, an intravenous catheter was inserted, intravenous propofol administered and tracheal intubation performed. Baseline measurements of heart rate, blood pressure, SpO 2 , peak inspiratory pressure (PIP), and pulmonary compliance were made before casting, immediately after casting, and after cast cut-out. Results: PIP increased from 15.8 cm H 2 O to 42.6 after cast application and decreased to 20.2 after cast cut-out. Compliance decreased from 1.08 ml/cm H 2 O/kg to 0.21 after cast application and increased to 0.61 after cast cut-out. There were no clinically significant changes in heart rate, blood pressure, or SpO 2 . Conclusion: The thoracolumbar cast applied for scoliosis treatment causes severe restriction of chest wall movement and subsequent deterioration of pulmonary function. The time of severe restriction of chest wall motion is short and is relieved once cast cut-outs are performed. The marked increase in PIP and decrease in compliance that occurs during the casting process necessitates tracheal intubation.

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“…Using this mathematical determination of Ptrach the inertance of the ETT has been considered. Dynamic respiratory system mechanics were determined by MLR based on the equation of motion of the passive respiratory system [9,10]:…”

Section: Methodsmentioning

confidence: 99%

Dynamic respiratory system mechanics in infants during pressure and volume controlled ventilation

Kessler¹,

Guttmann²,

Newth³

2001

Eur Respir J

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Dynamic respiratory system mechanics can be determined using multiple linear regression (MLR) analysis. There is no need for a particular ventilator setting or for a special ventilatory manoeuvre. The purpose of this study was to investigate whether or not different ventilator modes and the¯ow-dependent resistance of the endotracheal tube (ETT) in¯uence the determination of resistance and compliance by MLR.Ten paediatric patients who were on controlled mechanical ventilation for various disorders were investigated. The ventilator modes were changed between pressure control (PC) and volume control (VC). Flow and airway pressure were measured and tracheal pressure was continuously calculated. Each mode was applied for 3 min, and 10 consecutive breaths at the end of each period were analysed. Respiratory mechanics were determined by MLR based on either airway pressure, thus including the resistance of the ETT, or tracheal pressure.Resistance was found to be slightly higher in PC than in VC. There was no effect on determination of compliance between the different modes. Elimination of the¯ow-dependent resistance of the ETT preserved the differences between the modes.The authors conclude that using multiple linear regression compliance is not affected by the actual ventilator mode, whereas resistance is. Eur Respir J 2001; 17: 115±121. Sophisticated analysis of respiratory mechanics has been proposed for mechanically ventilated infants and children in the intensive care unit [1]. During each analysis, the physician at the bedside can assess pulmonary state and course, by evaluating respiratory system resistance (Rrs) and/or compliance (Crs) [2]. The effects of bronchodilators and other treatments can also be assessed [3], and the ventilator settings can be adjusted with respect to the actual mechanical state of the patient's lung [4,5] in order to minimize the mechanical stress for the patient's lung, and to prevent ventilator associated lung injury [6±8]. Thus, for respiratory monitoring, the physician at the bedside has to obtain Rrs and Crs easily and quickly, preferably on-line. Multiple linear regression (MLR) analysis is a method for analysis of pulmonary mechanics, that does not require any special ventilator setting or manoeuvre. However, the respiratory system must be passive, since the pressure generated by respiratory muscle activity cannot be predicted. The parameters Rrs and Crs are determined by solving the equation of motion of the passive respiratory system by least square ®tting, using the continuously measured samples of pressure,¯ow, and volume [9±12]. The advantages of MLR are obvious: 1) there are no cumbersome or time-consuming manoeuvres to perform; 2) MLR permits simultaneous determination of both Crs and Rrs; 3) parameters can be determined on-line, on a breath-by-breath basis, without changing the actual ventilator setting during ongoing mechanical ventilation.However, as the method uses all data points sampled during one breath and as different ventilator modes produce different¯o...

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Digital computer calculation of human pulmonary mechanics using a least squares fit technique

Cited by 110 publications

References 4 publications

Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis

Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis

Cardiorespiratory Effects of Derotational Casting during Anesthesia for Children with Early Onset Scoliosis

Dynamic respiratory system mechanics in infants during pressure and volume controlled ventilation

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