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Rescue ventilation through a small-bore transtracheal cannula in severe hypoxic pigs using expiratory ventilation assistance.

Hamaekers AE, van der Beek T, Theunissen M, Enk D - Anesth. Analg. (2015)

Bottom Line: At lesser degrees of airway obstruction, the time to reoxygenation was delayed.Efficacy probably was limited when the airway was completely unobstructed, with 2 of 6 animals having a PaO2 <85 mm Hg even after 15 minutes of ventilation with EVA and a mean PaCO2 increased up to 90 mm Hg.Reoxygenation and ventilation were less efficient when the upper airway was completely unobstructed.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Anesthesiology and Pain Therapy, Maastricht University Medical Center, Maastricht, The Netherlands.

ABSTRACT

Background: Suction-generated expiratory ventilation assistance (EVA) has been proposed as a way to facilitate bidirectional ventilation through a small-bore transtracheal cannula (TC). In this study, we investigated the efficiency of ventilation with EVA for restoring oxygenation and ventilation in a pig model of acute hypoxia.

Methods: Six pigs (61-76 kg) were anesthetized and ventilated (intermittent positive pressure ventilation) via a cuffed endotracheal tube (ETT). Monitoring lines were placed, and a 75-mm long, 2-mm inner diameter TC was inserted. After the baseline recordings, the ventilator was disconnected. After 2 minutes of apnea, reoxygenation with EVA was initiated through the TC and continued for 15 minutes with the ETT occluded. In the second part of the study, the experiment was repeated with the ETT either partially obstructed or left open. Airway pressures and hemodynamic data were recorded, and arterial blood gases were measured. Descriptive statistical analysis was performed.

Results: With a completely or partially obstructed upper airway, ventilation with EVA restored oxygenation to baseline levels in all animals within 20 seconds. In a completely obstructed airway, PaCO2 remained stable for 15 minutes. At lesser degrees of airway obstruction, the time to reoxygenation was delayed. Efficacy probably was limited when the airway was completely unobstructed, with 2 of 6 animals having a PaO2 <85 mm Hg even after 15 minutes of ventilation with EVA and a mean PaCO2 increased up to 90 mm Hg.

Conclusions: In severe hypoxic pigs, ventilation with EVA restored oxygenation quickly in case of a completely or partially obstructed upper airway. Reoxygenation and ventilation were less efficient when the upper airway was completely unobstructed.

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Related in: MedlinePlus

The two functional modes of the DE 5. A, Device activated, insufflation: oxygen flows from the inlet (1) to the connecting tubing (3). The outlet (2) is occluded by finger. B, Device activated, expiratory ventilation assistance: oxygen flows from the inlet (1) to the outlet (2) entraining gas from the connecting tubing (3) by the Bernoulli effect.
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Figure 1: The two functional modes of the DE 5. A, Device activated, insufflation: oxygen flows from the inlet (1) to the connecting tubing (3). The outlet (2) is occluded by finger. B, Device activated, expiratory ventilation assistance: oxygen flows from the inlet (1) to the outlet (2) entraining gas from the connecting tubing (3) by the Bernoulli effect.

Mentions: Techniques proposed to facilitate the egress of gas through a small-bore cannula include applying thoracic and abdominal compression, inserting an additional cannula,15,16 or applying suction to the airway cannula during the expiratory phase.17,18 We have previously described a manually operated device (DE 5) that uses high-velocity gas flow to create suction by the Bernoulli effect during expiration. The DE 5 establishes not only flow-controlled inspiration but is also capable of actively supporting expiration (expiratory ventilation assistance [EVA]) (Fig. 1, A and B).19 In an artificial lung model, this emergency ventilation device achieved up to 8.3 L·min−1 of minute volume through a 2-mm ID transtracheal cannula (TC) with complete outflow obstruction.20 Although EVA in vitro appears promising, evaluation in vivo is mandatory. The primary aim of the present explorative study was to determine the efficiency of EVA regarding reoxygenation in an acute hypoxic pig model with an obstructed upper airway. In addition, we studied the influence of upper airway patency on reoxygenation and ventilation with EVA.


Rescue ventilation through a small-bore transtracheal cannula in severe hypoxic pigs using expiratory ventilation assistance.

Hamaekers AE, van der Beek T, Theunissen M, Enk D - Anesth. Analg. (2015)

The two functional modes of the DE 5. A, Device activated, insufflation: oxygen flows from the inlet (1) to the connecting tubing (3). The outlet (2) is occluded by finger. B, Device activated, expiratory ventilation assistance: oxygen flows from the inlet (1) to the outlet (2) entraining gas from the connecting tubing (3) by the Bernoulli effect.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4358705&req=5

Figure 1: The two functional modes of the DE 5. A, Device activated, insufflation: oxygen flows from the inlet (1) to the connecting tubing (3). The outlet (2) is occluded by finger. B, Device activated, expiratory ventilation assistance: oxygen flows from the inlet (1) to the outlet (2) entraining gas from the connecting tubing (3) by the Bernoulli effect.
Mentions: Techniques proposed to facilitate the egress of gas through a small-bore cannula include applying thoracic and abdominal compression, inserting an additional cannula,15,16 or applying suction to the airway cannula during the expiratory phase.17,18 We have previously described a manually operated device (DE 5) that uses high-velocity gas flow to create suction by the Bernoulli effect during expiration. The DE 5 establishes not only flow-controlled inspiration but is also capable of actively supporting expiration (expiratory ventilation assistance [EVA]) (Fig. 1, A and B).19 In an artificial lung model, this emergency ventilation device achieved up to 8.3 L·min−1 of minute volume through a 2-mm ID transtracheal cannula (TC) with complete outflow obstruction.20 Although EVA in vitro appears promising, evaluation in vivo is mandatory. The primary aim of the present explorative study was to determine the efficiency of EVA regarding reoxygenation in an acute hypoxic pig model with an obstructed upper airway. In addition, we studied the influence of upper airway patency on reoxygenation and ventilation with EVA.

Bottom Line: At lesser degrees of airway obstruction, the time to reoxygenation was delayed.Efficacy probably was limited when the airway was completely unobstructed, with 2 of 6 animals having a PaO2 <85 mm Hg even after 15 minutes of ventilation with EVA and a mean PaCO2 increased up to 90 mm Hg.Reoxygenation and ventilation were less efficient when the upper airway was completely unobstructed.

View Article: PubMed Central - PubMed

Affiliation: From the Department of Anesthesiology and Pain Therapy, Maastricht University Medical Center, Maastricht, The Netherlands.

ABSTRACT

Background: Suction-generated expiratory ventilation assistance (EVA) has been proposed as a way to facilitate bidirectional ventilation through a small-bore transtracheal cannula (TC). In this study, we investigated the efficiency of ventilation with EVA for restoring oxygenation and ventilation in a pig model of acute hypoxia.

Methods: Six pigs (61-76 kg) were anesthetized and ventilated (intermittent positive pressure ventilation) via a cuffed endotracheal tube (ETT). Monitoring lines were placed, and a 75-mm long, 2-mm inner diameter TC was inserted. After the baseline recordings, the ventilator was disconnected. After 2 minutes of apnea, reoxygenation with EVA was initiated through the TC and continued for 15 minutes with the ETT occluded. In the second part of the study, the experiment was repeated with the ETT either partially obstructed or left open. Airway pressures and hemodynamic data were recorded, and arterial blood gases were measured. Descriptive statistical analysis was performed.

Results: With a completely or partially obstructed upper airway, ventilation with EVA restored oxygenation to baseline levels in all animals within 20 seconds. In a completely obstructed airway, PaCO2 remained stable for 15 minutes. At lesser degrees of airway obstruction, the time to reoxygenation was delayed. Efficacy probably was limited when the airway was completely unobstructed, with 2 of 6 animals having a PaO2 <85 mm Hg even after 15 minutes of ventilation with EVA and a mean PaCO2 increased up to 90 mm Hg.

Conclusions: In severe hypoxic pigs, ventilation with EVA restored oxygenation quickly in case of a completely or partially obstructed upper airway. Reoxygenation and ventilation were less efficient when the upper airway was completely unobstructed.

Show MeSH
Related in: MedlinePlus