Pulmonary effects of expiratory‐assisted small‐lumen ventilation during upper airway obstruction in pigs

Abstract

SummaryNovel devices for small-lumen ventilation may enable effective inspiration and expiratory ventilation assistance despite airway obstruction. In this study, we investigated a porcine model of complete upper airway obstruction. After ethical approval, we randomly assigned 13 anaesthetised pigs either to small-lumen ventilation following airway obstruction (n = 8) for 30 min, or to volume-controlled ventilation (sham setting, n = 5). Small-lumen ventilation enabled adequate gas exchange over 30 min. One animal died as a result of a tension pneumothorax in this setting. Redistribution of ventilation from dorsal to central compartments and significant impairment of the distribution of ventilation/perfusion occurred. Histopathology demonstrated considerable lung injury, predominantly through differences in the dorsal dependent lung regions. Small-lumen ventilation maintained adequate gas exchange in a porcine airway obstruction model. The use of this technique for 30 min by inexperienced clinicians was associated with considerable end-expiratory collapse leading to lung injury, and may also carry the risk of severe injury.

Random allogeneic blood transfusion in pigs: characterisation of a novel experimental model

“…Anesthesia and instrumentation procedure was previously described in detail in our former studies (Ziebart et al, 2015; Ziebart et al, 2018): Briefly, in each case two animals received an intramuscular injection of ketamine (8 mg kg −1 ) and midazolam (0.2 mg kg −1 ) followed by induction of general anesthesia via an ear vein cannula (propofol 4 mg kg −1 , and fentanyl 4 µg kg −1 , atracurium 0.5 mg kg −1 ), which was maintained by continuous infusion (propofol 8–12 mg kg −1 h −1 , fentanyl 0.1–0.2 mg h −1 ). After orotracheal intubation the animals were ventilated in volume-controlled mode (VCV; AVEA, CareFusion, USA): positive end-expiratory pressure (PEEP) five cmH 2 O, tidal volume 7 ml kg −1 , inspiration to expiration ratio 1:2, fraction of inspired oxygen (FiO 2 ) 0.4 and variable respiratory rate to achieve an end-tidal CO 2 <45 mmHg.…”

Peer Review #1 of "Bi-Level ventilation decreases pulmonary shunt and modulates neuroinflammation in a cardiopulmonary resuscitation model (v0.1)"

“…The right upper lobe was used for wet-todry ratio measurements. A previously established tissue damage score was used in investigator-blinded manner to quantify histologic injury as described before (13,14) .…”

Peer Review #2 of "Random allogeneic blood transfusion in pigs: characterisation of a novel experimental model (v0.1)"

“…Anesthesia and instrumentation procedure was previously described in detail in our former studies (Ziebart et al 2015;Ziebart et al 2018): Briefly, in each case two animals received an intramuscular injection of ketamine (8mg kg .1 ) and midazolam (0.2 mg kg -1 ) followed by induction of general anesthesia via an ear vein cannula (propofol 4 mg kg -1 , and fentanyl 4 µg kg -1 , atracurium 0.5 mg kg -1 ), which was maintained by continuous infusion (propofol 8-12 mg kg -1 h -1 , fentanyl 0.1-0.2 mg h -1 ). After orotracheal intubation the animals were ventilated in volumecontrolled mode (VCV; AVEA, CareFusion, USA): positive end-expiratory pressure (PEEP) 5 cmH 2 O, tidal volume 7 ml kg -1 , inspiration to expiration ratio 1:2, fraction of inspired oxygen (FiO 2 ) 0.4 and variable respiration rate to achieve an end-tidal CO 2 < 45 mmHg.…”

“…After finishing the protocol, the lung and the brain each were removed en-bloc. Manuscript to be reviewed embedding and hematoxylin/eosin staining the samples were analyzed in investigator-blinded manner by means of standardized scoring scheme (Ziebart et al 2015;Ziebart et al 2014).…”