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Real-time ventilation and perfusion distributions by electrical impedance tomography during one-lung ventilation with capnothorax
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Thoracic Surgery.
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2015 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 59, no 3, 354-368 p.Article in journal (Refereed) Published
Abstract [en]

Background: Carbon dioxide insufflation into the pleural cavity, capnothorax, with one-lung ventilation (OLV) may entail respiratory and hemodynamic impairments. We investigated the online physiological effects of OLV/capnothorax by electrical impedance tomography (EIT) in a porcine model mimicking the clinical setting.

Methods: Five anesthetized, muscle-relaxed piglets were subjected to first right and then left capnothorax with an intra-pleural pressure of 19cm H2O. The contra-lateral lung was mechanically ventilated with a double-lumen tube at positive end-expiratory pressure 5 and subsequently 10cm H2O. Regional lung perfusion and ventilation were assessed by EIT. Hemodynamics, cerebral tissue oxygenation and lung gas exchange were also measured.

Results: During right-sided capnothorax, mixed venous oxygen saturation (P=0.018), as well as a tissue oxygenation index (P=0.038) decreased. There was also an increase in central venous pressure (P=0.006), and a decrease in mean arterial pressure (P=0.045) and cardiac output (P=0.017). During the left-sided capnothorax, the hemodynamic impairment was less than during the right side. EIT revealed that during the first period of OLV/capnothorax, no or very minor ventilation on the right side could be seen (33% vs. 97 +/- 3%, right vs. left, P=0.007), perfusion decreased in the non-ventilated and increased in the ventilated lung (18 +/- 2% vs. 82 +/- 2%, right vs. left, P=0.03). During the second OLV/capnothorax period, a similar distribution of perfusion was seen in the animals with successful separation (84 +/- 4% vs. 16 +/- 4%, right vs. left).

Conclusion: EIT detected in real-time dynamic changes in pulmonary ventilation and perfusion distributions. OLV to the left lung with right-sided capnothorax caused a decrease in cardiac output, arterial oxygenation and mixed venous saturation.

Place, publisher, year, edition, pages
2015. Vol. 59, no 3, 354-368 p.
National Category
Anesthesiology and Intensive Care
Identifiers
URN: urn:nbn:se:uu:diva-248178DOI: 10.1111/aas.12455ISI: 000349604000010PubMedID: 25556329OAI: oai:DiVA.org:uu-248178DiVA: diva2:802330
Note

De 2 första författarna delar förstaförfattarskapet.

Available from: 2015-04-12 Created: 2015-03-30 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Open lung concept in high risk anaesthesia: Optimizing mechanical ventilation in morbidly obese patients and during one lung ventilation with capnothorax
Open this publication in new window or tab >>Open lung concept in high risk anaesthesia: Optimizing mechanical ventilation in morbidly obese patients and during one lung ventilation with capnothorax
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Formation of atelectasis, defined as reversible collapse of aerated lung, often occurs after induction of anaesthesia with mechanical ventilation. As a consequence, there is a risk for hypoxemia, altered hemodynamics and impaired respiratory system mechanics. In certain situations, the risk for atelectasis formation is increased and its consequences may also be more difficult to manage. Anesthesia for bariatric surgery in morbidly obese patients and surgery requiring one-lung ventilation (OLV) with capnothorax are examples of such situations.

In Paper I (30 patients with BMI > 40 kg/m2 scheduled for bariatric surgery) a recruit­ment maneuver followed by positive end-expiratory pressure (PEEP) re­duced the amount of atelectasis and improved oxygenation for a prolonged period of time. PEEP or a recruitment maneuver alone did not reduce the amount of atelectasis.

In paper II we investigated whether it is possible to predict respiratory function impairment in morbidly obese patients without pulmonary disease from a preoperative lung function test. Patients with mild signs of airway obstruction (reduced end-expiratory flow) in the preoperative spirometry developed less atelectasis during anaesthesia.

In paper III we developed an experimental model of sequential OLV with capnothorax using electrical impedance tomography (EIT) that in real-time detected lung separation and dynamic changes in pulmonary ventilation and perfusion distributions. OLV to the left side caused a decrease in cardiac output, arterial oxygenation and mixed venous saturation.

In paper IV we used our model of OLV with capnothorax and applied a CO2-insufflation pressure of 16 cm H2O. We demonstrated that a PEEP level of 12-16 cm H2O is needed for optimal oxygenation and lowest possible driving pressure without compromising hemodynamic variables. Thus, the optimal PEEP was closely related to the level of the capnothorax insufflation pressure. With insufficient PEEP, ventilation/perfusion mismatch in the ventilated lung and redistribution of blood flow to the non-ventilated lung occurred.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 77 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1169
Keyword
Anaesthesia, mechanical ventilation, atelectasis, morbidly obese, one-lung ventilation, PEEP, recruitment maneuver, spirometry, EIT
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-268498 (URN)978-91-554-9440-7 (ISBN)
Public defence
2016-02-12, Grönwallssalen, Ing. 70, Akademiska sjukhuset, Uppsala, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2016-01-22 Created: 2015-12-06 Last updated: 2016-02-12

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Reinius, HenrikBorges, João BatistaFredén, FilipJideus, LenaHedenstierna, GöranLarsson, AndersLennmyr, Fredrik

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