Effects of Positive End-Expiratory Pressure (PEEP) on Bronchial Blood Flow

Agostoni, Piergiuseppe; Doria, Elisabetta; Pepi, Mauro; Tamborini, Gloria

doi:10.1007/978-1-4471-3782-5_9

Cited by 1 publication

(4 citation statements)

References 10 publications

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“…Also, the amount of Qbr(s-p) that we measure in our prep aration is similar to that reported by other investiga tors using different techniques of measurement and anesthesia in other animal species [14]. In any case, it must be recognized that the surgery involveld in our preparation would release vasoactice mediators that may increase the Qbr(s-p) [16]. However, these effects would be the same in the control and the experimental groups and therefore it would be reasonable to as sume that the observed effects are due to the experi mental interventions.…”

Section: Discussionsupporting

confidence: 85%

“…This has been shown in our preparation in which PEEP was applied only to the LLL without any detec table effect on systemic blood pressure [16]. The downstream pressure for Qbr(s-p) has been assumed to be either the mean alveolar pressure or the mean pulmonary capillary pressure [7,8,16]. Since the LLL airway pressure for a tidal volume of 150 ml cycled between 5 and 15 cm H20 and between 15 and 34 cm H20 with PEEP = 15 cm H20 , it would be reasonable to assume that the mean alveolar pressure and there fore the downstream pressure for Qbr(s-p) was about 7 cm H20 with PEEP = 5 and 19 cm H20 when PEEP = 15 cm H20 .…”

Section: Discussionsupporting

confidence: 59%

“…Mean aortic pressure was previously utilized as the upstream pres sure for calculating driving pressure and the changes in bronchial vascular resistance reported with PEEP [7][8][9]11]. Actually the upstream pressure is approxi mately 47 cm H20 [5] and does not change with PEEP [16]. This has been shown in our preparation in which PEEP was applied only to the LLL without any detec table effect on systemic blood pressure [16].…”

Section: Discussionmentioning

confidence: 54%

“…Actually the upstream pressure is approxi mately 47 cm H20 [5] and does not change with PEEP [16]. This has been shown in our preparation in which PEEP was applied only to the LLL without any detec table effect on systemic blood pressure [16]. The downstream pressure for Qbr(s-p) has been assumed to be either the mean alveolar pressure or the mean pulmonary capillary pressure [7,8,16].…”

Section: Discussionmentioning

confidence: 55%

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Vagal Cooling and Positive End-Expiratory Pressure Reduce Systemic to Pulmonary Bronchial Blood Flow in Dogs

1990

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Positive end-expiratory pressure (PEEP) reduces systemic to pulmonary bronchial blood flow [Qbr(s-p)] presumably because it increases bronchial vascular resistance. Since PEEP increases lung volume and thus could stimulate pulmonary stretch receptors, we investigated the hypothesis that the PEEP-related decrease in bronchial blood flow was due to a reflex mediated by the vagus. In open-chest dogs the left lower lobe (LLL) was isolated, independently ventilated, perfused in situ with a closed pulmonary vascular circuit and weighed continuously. Qbr(s-p) was measured as LLL vascular circuit overflow and changes in LLL weight. When LLL PEEP was increased from 5 to 15 cm H₂O in a group of 11 dogs Qbr(s-p) was reduced by half from 60.8 ± 10.5 to 31.6 ± 6.1 ml/min/100 g dry lobe weight. In another group of 7 dogs Qbr(s-p) was 46.5 ± 6.9 with PEEP = 5 cm H₂O; it decreased to 28.3 ± 6.8 with bilateral cervical vagal cooling (0–1.5 °C) and did not decrease further after increasing PEEP to 15 cm H₂O. We conclude that the effect of resting vagal tone is to increase Qbr(s-p) and that the effect of PEEP on Qbr(s-p) may be mediated at least partially by vagal influences

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Section: Discussionsupporting

confidence: 85%