Effect of negative-pressure inflation on pulmonary vascular flow.

Kira, Shiro; Hukushima, Yasunobu

doi:10.1152/jappl.1968.25.1.42

Cited by 5 publications

(2 citation statements)

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“…In addition to the changes in the hydrostatic pressure, the effects of lung inflation on transmural pressure distribution may also have an effect. Kira & Hukushima () demonstrated that when the vascular transmural pressure was approximately 5 cmH 2 O, a low‐pressure condition, the pulmonary vasculature resistance increased as the lung stretched. However, when the vascular pressure was high (11 cmH 2 O), the transmural pressure in small vessels remained high and the vasculature cross‐sectional area remained large.…”

Section: Discussionmentioning

confidence: 99%

“…However, when the vascular pressure was high (11 cmH 2 O), the transmural pressure in small vessels remained high and the vasculature cross‐sectional area remained large. Therefore, in the high transmural pressure condition, the reduction in vasculature cross‐sectional area due to axial stretch was a lesser influence and the vasculature resistance was virtually unchanged (Kira & Hukushima, ). Pulmonary vessels with low transmural pressures are predominantly located in the gravitationally non‐dependent region, while the high transmural vessels are located in the gravitationally dependent region of the lung.…”

Section: Discussionmentioning

confidence: 99%

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The effect of lung deformation on the spatial distribution of pulmonary blood flow

Arai

Theilmann

Sá

et al. 2016

The Journal of Physiology

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Tidal volume lung inflation results in structural changes in the pulmonary circulation, potentially affecting pulmonary perfusion. We hypothesized that perfusion is recruited to regions receiving the greatest deformation from a tidal breath, thus ensuring ventilation-perfusion matching. Density-normalized perfusion (DNP) magnetic resonance imaging data were obtained in healthy subjects (n = 7) in the right lung at functional residual capacity (FRC), FRC+500 ml, and FRC+1.0 l. Using deformable image registration, the displacement of a sagittal lung slice acquired at FRC to the larger volumes was calculated. Registered DNP images were normalized by the mean to estimate perfusion redistribution (nDNP). Data were evaluated across gravitational regions (dependent, middle, non-dependent) and by lobes (upper, RUL; middle, RML; lower, RLL). Lung inflation did not alter mean DNP within the slice (P = 0.10). The greatest expansion was seen in the dependent region (P < 0.0001: dependent vs non-dependent, P < 0.0001: dependent vs middle) and RLL (P = 0.0015: RLL vs RUL, P < 0.0001: RLL vs RML). Neither nDNP recruitment to RLL [+500 ml = -0.047(0.145), +1 litre = 0.018(0.096)] nor to dependent lung [+500 ml = -0.058(0.126), +1 litre = -0.023(0.106)] were found. Instead, redistribution was seen in decreased nDNP in the non-dependent [+500 ml = -0.075(0.152), +1 litre = -0.137(0.167)) and increased nDNP in the gravitational middle lung [+500 ml = 0.098(0.058), +1 litre = 0.093(0.081)] (P = 0.01). However, there was no significant lobar redistribution (P < 0.89). Contrary to our hypothesis, based on the comparison between gravitational and lobar perfusion data, perfusion was not redistributed to the regions of the most inflation. This suggests that either changes in hydrostatic pressure or transmural pressure distribution in the gravitational direction are implicated in the redistribution of perfusion away from the non-dependent lung.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The effect of lung deformation on the spatial distribution of pulmonary blood flow

Arai

Theilmann

Sá

et al. 2016

The Journal of Physiology

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Continuous Negative Chest‐wall Pressure Therapy for Assisting Ventilation in Older Children With Progressive Respiratory Insufficiency1

et al. 1977

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Continuous negative chest-wall pressure (CNP) was used to assist ventilation in 14 children, 6 months to 14 years of age, who had progressive respiratory insufficiency caused by diffuse bilateral alveolar disease. Before the start of CNP therapy, each child had a respiratory rate greater than 50/min, arterial oxygen tension (PaO2) less than 70 mmHg (FIO2 greater than or equal to 50%), and arterial carbon dioxide tension (PaCO2) less than 45 mmHg. The mean intrapulmonary right-to-left shunt was 28.7 +/- 3.8%. Within 6 hours after therapy was started, PaO2 increased from 55.4 +/- 15.9 to 81.6 +/-17.7 mmHg (p less than 0.005). This improvement was sustained and within 24 hours permitted a decrease in fractional concentration inspired oxygen (FIO2) from 51.8 +/- 6.2 to 41.0 +/- 8.4% (p less than 0.001) and in respiratory rate from 78.1 +/-23.0 to 56.4 +/- 21.3 (p less than 0.01). There was a concomitant decrease in intrapulmonary right-to-left shunt. Four of the 14 patients developed pneumothorax that was successfully decompressed. Ten patients survived. These observations establish CNP therapy as an effective means of improving arterial oxygenation in spontaneously breathing older children. Of added significance, this mode of therapy eliminates the need for endotracheal intubation and prolonged use of muscle relaxants and sedatives. It also minimizes exposure to high FIO2, thereby minimizing the hazards of pulmonary oxygen toxicity.

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Negative extrathoracic pressure in treatment of respiratory failure in infants and young children.

Samuels

Southall

1989

BMJ

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Objective-To assess the efficacy of a newly developed system for applying continuous or intermittent negative (subatmospheric) extrathoracic pressure in respiratory failure.Design Main outcome measures-Inspired oxygen concentration and carbon dioxide pressure before application of negative extrathoracic pressure and two and 48 hours afterwards; duration of treatment; and final outcome (discharge home or death).Results-While arterial oxygen saturation was maintained at constant values 75 infants showed reductions in inspired oxygen concentrations (range 4-50%, median 15%) two hours after starting treatment and 74 showed reductions at 48 hours (2-79%, median 20%). Of 59 infants who had carbon dioxide pressure measured before and after starting negative extrathoracic pressure, 21 showed a reduction (range 0*6-8*9 kPa, median 2.0), 30 no change (±0.5 kPa), and eight a rise (range 0-6-5-1 kPa, median 2.1).

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Effect of negative-pressure inflation on pulmonary vascular flow.

Cited by 5 publications

References 0 publications

The effect of lung deformation on the spatial distribution of pulmonary blood flow

The effect of lung deformation on the spatial distribution of pulmonary blood flow

Continuous Negative Chest‐wall Pressure Therapy for Assisting Ventilation in Older Children With Progressive Respiratory Insufficiency1

Negative extrathoracic pressure in treatment of respiratory failure in infants and young children.

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