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- Rieger-Fackeldey, Esther, et al.
(författare)
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Bronchopulmonary C-fibers modulate the breathing pattern in surfactant-depleted juvenile cats
- 2008
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 160:3, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the influence of nonmyelinated C-fibers on the breathing pattern by cooling the vagal nerves to temperatures at which myelinated nerve transmission from pulmonary stretch receptors is blocked (+7 degrees C) and further at which nonmyelinated fiber input is blocked (0 degrees C), in anaesthetized spontaneously breathing juvenile cats with normal (L(N)), surfactant-depleted (L(D)) and surfactant-treated (L(T)) lungs. In L(N), vagal cooling from +7 to 0 degrees C decreased respiratory frequency (f(R); -8%; p < 0.01), and increased tidal volume (V(T); +40%; p < 0.01). In the presence of shallow fast breathing in L(D), f(R) decreased (+38 to +7 degrees C: -26%; p < 0.015 and +7 to 0 degrees C: -24%; p < 0.001) and V(T) increased (+37%; p < 0.049 and +88%; p < 0.016). In L(T), f(R) decreased (+7 to 0 degrees C: -21%; p < 0.001), whereas V(T) remained the same at 0 degrees C (+12%; NS). These findings show for the first time that the activity of bronchopulmonary C-fibers have a prominent role in modulating the breathing pattern in juvenile cats with surfactant-depleted lungs.
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| 2. |
- Rieger-Fackeldey, Esther, et al.
(författare)
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Inhibition of breathing after Surfactant Depletion is Achieved at a Higher Arterial PCO2 during Ventilation with Liquid than with Gas
- 2005
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 6, s. 24-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundInhibition of phrenic nerve activity (PNA) can be achieved when alveolar ventilation is adequate and when stretching of lung tissue stimulates mechanoreceptors to inhibit inspiratory activity. During mechanical ventilation under different lung conditions, inhibition of PNA can provide a physiological setting at which ventilatory parameters can be compared and related to arterial blood gases and pH.ObjectiveTo study lung mechanics and gas exchange at inhibition of PNA during controlled gas ventilation (GV) and during partial liquid ventilation (PLV) before and after lung lavage.MethodsNine anaesthetised, mechanically ventilated young cats (age 3.8 ± 0.5 months, weight 2.3 ± 0.1 kg) (mean ± SD) were studied with stepwise increases in peak inspiratory pressure (PIP) until total inhibition of PNA was attained before lavage (with GV) and after lavage (GV and PLV). Tidal volume (Vt), PIP, oesophageal pressure and arterial blood gases were measured at inhibition of PNA. One way repeated measures analysis of variance and Student Newman Keuls-tests were used for statistical analysis.ResultsDuring GV, inhibition of PNA occurred at lower PIP, transpulmonary pressure (Ptp) and Vt before than after lung lavage. After lavage, inhibition of inspiratory activity was achieved at the same PIP, Ptp and Vt during GV and PLV, but occurred at a higher PaCO2 during PLV. After lavage compliance at inhibition was almost the same during GV and PLV and resistance was lower during GV than during PLV.ConclusionInhibition of inspiratory activity occurs at a higher PaCO2 during PLV than during GV in cats with surfactant-depleted lungs. This could indicate that PLV induces better recruitment of mechanoreceptors than GV.
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| 4. |
- Rieger-Fackeldey, Esther, et al.
(författare)
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Pulmonary stretch receptor activity during partial liquid ventilation with different pressure waveforms
- 2020
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Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 276
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of the present study was to investigate pulmonary stretch receptor activity (PSR) under different peak inspiratory pressures (PIPs) and inspiratory pressure waveforms during partial liquid (PLV) and gas ventilation (GV).METHODS: PSR instantaneous impulse frequency (PSRfimp) was recorded from single fibers in the vagal nerve during PLV and GV in young cats. PIPs were set at 1.2/1.8/2.2/2.7 kPa, and square and sinusoidal pressure waveforms were applied.RESULTS: PSRfimp at the start of inspiration increased with increasing PIPs, and was steeper and higher with square than with sinusoidal waveforms (p < 0.05). Total number of impulses, peak and mean PSRfimp were lower during PLV than GV at the lowest and highest PIPs (p < 0.025). Time to peak PSRfimp was shorter with square than with sinusoidal waveforms at all pressures and ventilations (p < 0.005). Irrespective of waveform, lower PIPs yielded lower ventilation during PLV.CONCLUSION: As assessed by PSRfimp, increased PIPs do not expose the lungs to more stretching during PLV than during GV, with only minor differences between square and sinusoidal waveforms.
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| 5. |
- Rieger-Fackeldey, Esther, 1960-
(författare)
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Regulation of Breathing under Different Pulmonary Conditions
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The breathing pattern of preterm infants is immature and is associated with a variety of reflexes. In a patient on the ventilator these reflexes interfere with spontaneous breathing. A better understanding of the immature control of breathing could lead to further improvements in ventilatory techniques. This thesis concerns studies of pulmonary stretch receptor (PSR) and phrenic nerve activity as part of the regulation of breathing in an animal model.During assist/control ventilation with three different inspiratory pressure waveforms in animals with healthy lungs, squarewave pressure waveform strongly inhibits spontaneous inspiratory activity.During partial liquid ventilation (PLV) in animals with healthy lungs, all PSRs studied maintained their phasic character, with increased impulse frequency during inspiration. PSR activity was not higher during PLV than during gas ventilation (GV), indicating that there was no extensive stretching of the lung during PLV.During proportional assist ventilation (PAV) the applied airway pressure is servo-controlled proportionally to the ongoing breathing effort, thereby interacting with the activity of PSRs. Peak PSR activity was higher and occurred earlier during PAV than during CPAP. The regulation of breathing is maintained during PAV in surfactant-depleted animals before and early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP in both conditions.Both lung mechanics and gas exchange influence the regulation of breathing. Inhibition of inspiratory activity occurred at a lower arterial pH and a higher PaCO2 during PLV than during GV in animals with surfactant-depleted lungs, which might be related to recruitment of a larger number of pulmonary stretch receptors during PLV.In summary, selected aspects of the regulation of breathing were studied in an animal model with different ventilatory techniques under different lung conditions similar to those that can occur in infants.
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| 7. |
- Sindelar, Richard, et al.
(författare)
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Effects of the inspiratory pressure waveform during patient-triggered ventilation on pulmonary stretch receptor and phrenic nerve activity in cats
- 2001
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 29:6, s. 1207-1214
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Tidskriftsartikel (refereegranskat)abstract
- Objective:To examine the effects of square wave, sinusoidal, and linear inspiratory pressure waveforms during pressure-controlled assist/control ventilation on the firing pattern of pulmonary stretch receptors and phrenic nerve activity.Design:Experimental, comparative study.Setting:Research laboratory at a university biomedical center.Subjects:Nine anesthetized, endotracheally intubated young cats (2.5–3.4 kg).Intervention:With interposed periods of continuous positive airway pressure (0.2 kPa), each cat was exposed to periods of assist/control ventilation with three different pressure waveforms, where the peak inspiratory pressure (0.74 ± 0.13 kPa), end-expiratory pressure (0.2 ± 0.02 kPa), and tidal volume (14.9 ± 5.22 mL/kg) were kept constant. Preset controlled ventilator rate was set below the rate of spontaneous breathing, and the mechanical inflation time equaled the inspiratory time during spontaneous breathing on continuous positive airway pressure.Measurements and Main Results:Respiratory rate and arterial blood gases did not change between the three pressure waveforms during assist/control ventilation. Peak pulmonary stretch receptor activity was lower and mean phrenic nerve activity higher during continuous positive airway pressure than during assist/control ventilation (p < .05). Peak inspiratory pulmonary stretch receptor activity was the same with all three pressure waveforms (82 ± 17 impulses·sec-1) but occurred earlier with square wave than with sinusoidal or linear pressure waveforms (p < .05). The total number of impulses in the phrenic nerve activity burst was smaller with square wave than with the other two pressure waveforms (0.21 ± 0.17 vs. 0.33 ± 0.27 and 0.42 ± 0.30 arbitrary units;p < .05), and the phrenic nerve activity burst duration was shorter with square wave (1.10 ± 0.45 vs. 1.54 ± 0.36 and 1.64 ± 0.25 secs;p < .05).Conclusion:Square wave pressure waveform during pressure-controlled assist/control ventilation strongly inhibits spontaneous inspiratory activity in cats. One mechanism for this inhibition is earlier and sustained peak pulmonary stretch receptor activity during inspiration. These findings show that differences in inspiratory pressure waveforms influence the spontaneous breathing effort during assist/control ventilation in cats.
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| 8. |
- Sindelar, Richard, et al.
(författare)
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Maintained inspiratory activity during proportional assist ventilation in surfactant-depleted cats early after surfactant instillation : phrenic nerve and pulmonary stretch receptor activity.
- 2006
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Ingår i: Respir Res. - 1465-993X. ; 7, s. 38-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Inspiratory activity is a prerequisite for successful application of patient triggered ventilation such as proportional assist ventilation (PAV). It has recently been reported that surfactant instillation increases the activity of slowly adapting pulmonary stretch receptors (PSRs) followed by a shorter inspiratory time (Sindelar et al, J Appl Physiol, 2005 [Epub ahead of print]). Changes in lung mechanics, as observed in preterm infants with respiratory distress syndrome and after surfactant treatment, might therefore influence the inspiratory activity when applying PAV early after surfactant treatment. OBJECTIVE: To investigate the regulation of breathing and ventilatory response in surfactant-depleted young cats during PAV and during continuous positive airway pressure (CPAP) early after surfactant instillation in relation to phrenic nerve activity (PNA) and the activity of PSRs. METHODS: Seven anesthetized, endotracheally intubated young cats were exposed to periods of CPAP and PAV with the same end-expiratory pressure (0.2-0.5 kPa) before and after lung lavage and after surfactant instillation. PAV was set to compensate for 75% of the lung elastic recoil. RESULTS: Tidal volume and respiratory rate were higher with lower PaCO2 and higher PaO2 during PAV than during CPAP both before and after surfactant instillation (p < 0.05; both conditions). As an indicator of breathing effort, esophageal deflection pressure and PNA were lower during PAV than during CPAP in both conditions (p < 0.02). Peak PSR activity was higher and occurred earlier during PAV than during CPAP (p < 0.01), and correlated linearly with PNA duration in all conditions studied (p < 0.001). The inspiratory time decreased as tidal volume increased when CPAP was changed to PAV, with the highest correlation observed after surfactant instillation (r = -0.769). No apneic periods could be observed. CONCLUSION: PSR activity and the control of breathing are maintained during PAV in surfactant-depleted cats early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP.
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