Archive for the ‘Pulmonary Function’ Category


dynamic pulmonary volumeTable 1 summarizes the anthropometric characteristics of the patients and three normal subjects.

Table 2 shows the results of Pimax and PEmax. The reference value of the maximum static pressure for patients 2 and 3 is obtained from the equations of Gaultier and Zinman. For patient 1, the reference value of Leech and her associates is used. The measured results are expressed as a percentage of the reference value based on age, sex, and size of the individuals tested, as well as a percentage of the reference value based on vital capacity (VC) according to Gaultier and Zinman (Pim>vc and PEm,vc). Our results show that PEmax is slightly better preserved than Pimax, but this relation reversed for patients 1 and 3 when they are expressed as a percentage of predicted values based on VC.

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  • Comments Off on Canadian Health&Care Mall: Results of Pulmonary Function and Ventilatory Response
  • We routinely use 5 cm H20 of PEEP during the weaning process until liberation is achieved from the mechanical ventilation. There are several benefits of PEEP on inspiratory muscle load: (a) improving pulmonary mechanic function that is attenuated by the loss of glottic function, which is caused by the presence of the tracheal tube; (b) overcoming the loss of end-expiratory lung volume that occurs when patients are supine or semiupright; and (c) preventing dynamic airway collapse or overcoming dynamic hyperinflation in patients with dynamic hyperinflation, such as those with airway disease.
    We attribute the findings of prolonged duty cycle, presence of auto-PEEP, and higher expiratory airway resistance in our study to the use of the Whisper Swivel valve in the circuit. This was not detrimental in our group of patients, as there was no difference in respiratory muscle performance between the BiPAP S/T-D and the Servo Ventilator 900C. (more…)

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  • Respiratory Muscle Performance, Pulmonary Mechanics, and Gas Exchange: OutcomeIn our group of patients, the mean values of PTP using the BiPAP S/T-D and the Servo Ventilator 900C were similar, despite different triggering mechanisms. This suggests that, with adequate ventilatory reserves following gradual unloading of the respiratory muscles, the impact of the triggering system (ie, triggering by flow or pressure) may not affect the overall respiratory muscle performance. We routinely use a trigger sensitivity of —2 cm of H20 with the Servo Ventilator 900C during the weaning process. The mean absolute value of PTP in both ventilators was within the normal range (200 to 300 cm H20/s/min). Thus, results that may have been different with a lower inspiratory trigger pressure, such as —0.5 or —1.0 cm H20, may not be clinically important in our group of patients. (more…)

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  • They reported a statistically significant difference in the mean value of WOB with BiPAP S/T-D (mean ± SE) (1.04 ± 0.70 J/L) when compared with a conventional mechanical ventilator (0.63 ± 0.51 J/L). They attributed the difference in WOB to the higher tidal volume (599 ± 114 vs 467 ±112 mL) and minute ventilation (15.7 ± 5.8 vs 12.1 ± 3.6 L/min) with the BiPAP S/T-D. In our group of patients, tidal volume and minute ventilation were not statistically different between the BiPAP S/T-D and the Servo Ventilator 900C (Table 3). The higher tidal volume in their study could have resulted from inadequate emptying of tidal volume, which in turn could be caused by the single ventilation circuit with the Whisper Swivel, and a low level of EPAP (0 to 2 cm H20). (more…)

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  • Respiratory Muscle Performance, Pulmonary Mechanics, and Gas Exchange: ResultsThe mean values for respiratory rate, minute ventilation, auto-PEEP, duty cycle, and expiratory airway resistance during the two ventilatoiy modes are shown in Table 3. There was a statistically significant difference between the two ventilators in auto-PE EP, duty cycle, and expiratory airway resistance, but not in the respiratory rate and minute ventilation. There was a statistically significant difference in Pao2/Fio2, but not in Paco2, between the BiPAP S/T-D and the Servo Ventilator 900C. (more…)

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  • Data were sent from the pulmonary monitor to a PC via a serial port and stored in the PC using software provided by the manufacturer (Bicore; Irvine, CA). The pulmonary monitor provides a breath-by-breath, real-time display of the measured and/or calculated weaning parameters, including WOB and PTP; its reliability has been reported elsewhere. The patient’s WOB and PTP were calculated as derived in the Appendix. Data in the PC were analyzed using a Gaussian breath-elimina-tion method that we developed in order to omit breaths with artifactual changes in esophageal pressure due to nonrespiratory maneuvers.
    The WOB, in joules per minute, was calculated for each breath by our data analysis program by multiplying WOB per unit volume by the minute ventilation. (more…)

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  • Respiratory Muscle Performance, Pulmonary Mechanics, and Gas Exchange: Data Collection and AnalysisOxygen was bled in via the side port attached to the BiPAP S/T-D and was maintained constant with the help of an oxygen analyzer (5120 oxygen monitor; Ohmeda; Louisville, CO). IPAP and EPAP were chosen for the spontaneous mode setting and maintained by a pres sure-controlling valve. The difference between the inspiratoiy level and the expiratory level on the BiPAP S/T-D serves as an inspiratory pressure support, which is maintained throughout inspiration. For instance, with an inspiratory level of 10 cm H20 and an expiratory level of 5 cm H20, the actual inspiratory pressure support provided was 5 cm H20. (more…)

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  • The total WOB and the pressure-time product (PTP) have gained wide acceptance for the evaluation of respiratory muscle activity. When comparing ventilatory modes, this respiratory muscle activity is best evaluated during the terminal phase of the weaning process when the resistive work of the tracheal tube, the ventilatory circuit, and the breathing circuit are the major determinants of WOB.
    The BiPAP S/T-D has a single breathing circuit with a highly resistive valve, the Whisper Swivel, for expiration that may affect the pulmonary mechanics, gas exchange, and respiratory muscle performance. Recently, Ferguson and Gilmartin have shown that C02 rebreathing occurs using the single breathing circuit with the Whisper Swivel while operating the BiPAP S/T-D noninvasively through a nasal mask read more canadian health and care mall. Lofaso et al suggested that the use of low levels of expiratory airway pressure could eliminate the C02 rebreathing. To verify this, we measured arterial blood gas and pulmonary mechanics while using 5 cm H20 of EPAP on the BiPAP S/T-D and a similar level of PEEP on the Servo Ventilator 900C. (more…)

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