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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

We present an ex vivo pig lung model for the demonstration of pulmonary mechanics and alveolar recruitment maneuvers for teaching purposes. The lungs can be used for more than one day (up to five days) with minimal changes in pulmonary mechanics variables.

Abstract

Mechanical ventilation is widely used and requires specific knowledge for understanding and management. Health professionals in this field may feel insecure and lack knowledge because of inadequate training and teaching methods. Therefore, the objective of this article is to outline the steps involved in generating an ex vivo porcine lung model to be used in the future, to study and teach lung mechanics. To generate the model, five porcine lungs were carefully removed from the thorax following the guidelines of the Animal Research Ethics Committee with adequate care and were connected to the mechanical ventilator through a tracheal cannula. These lungs were then subjected to the alveolar recruitment maneuver. Respiratory mechanics parameters were recorded, and video cameras were used to obtain videos of the lungs during this process. This process was repeated for five consecutive days. When not used, the lungs were kept refrigerated. The model showed different lung mechanics after the alveolar recruitment maneuver every day; not being influenced by the days, only by the maneuver. Therefore, we conclude that the ex vivo lung model can provide a better understanding of lung mechanics and its effects, and even of the alveolar recruitment maneuver through visual feedback during all stages of the process.

Introduction

Mechanical ventilation (MV) is widely used in intensive care units (ICUs) and surgical centers. Its monitoring is essential to help recognize asynchronies and prevent injuries for all patients, especially when the patient has serious lung injuries1,2,3,4,5,6. Monitoring respiratory mechanics can also contribute to the clinical understanding of the disease progression and therapeutic applications, such as the use of positive end-expiratory pressure (PEEP) or the alveolar re....

Protocol

The protocol was approved by the Animal Research Ethics Committee of our Institution (protocol no. 1610/2021).

1. Anesthesia and animal preparation

  1. Initially, place the animal on a scale and check the weight to adjust the medications and sedation necessary for the procedure.
  2. Administer ketamine 5 mg/kg and midazolam 0.25 mg/kg intramuscularly.
  3. Puncture the marginal ear vein with a 20 G venous catheter and administer intravenous propofol (5 mg/kg.......

Representative Results

We used five female pigs weighing between 23.4-26.9 kg and followed the described protocol for cardiopulmonary extraction and lung mechanics analysis. Our intention is that the model is useful for the study of lung mechanics by analyzing peak pressure, plateau pressure, resistance, driving pressure, and dynamic compliance variables collected directly from the mechanical ventilator screen. The model flowchart is shown in Figure 1.

The lungs were analyzed for five c.......

Discussion

The described protocol is useful for producing an ex vivo porcine lung model under positive-pressure MV. It can be used for studying and teaching lung mechanics through visual feedback from the lungs during recruitment and analysis of the curves and values projected on the device screen. To achieve this result, pilot studies are needed to understand the behavior of the lungs outside the rib cage and to identify the need for adaptations.

We identified that the critical point was the fo.......

Acknowledgements

We thank all colleagues and professionals who contributed to and supported the construction of this ex vivo porcine lung model protocol.

This study had no funding sources.

....

Materials

NameCompanyCatalog NumberComments
0.9% Saline solution2500ml
Anesthesia machine - PrimusDragerREF 8603800-18Anesthesia work station used in the procedure
AspiratorFor blood aspiration from thorax
Bedside Monitor - Life ScopeNihon KohdenBSM-7363Multiparameter monitor used during the procedure
Bonney Tissue ForcepsAny tissue forceps is suitable
Disposable scalper, #23Any scalper is suitable
Disposable syringe needles, 18G x 1 1/2", 23G x 1"BD302814Widely available
Disposable syringes, 10mlWidely available
Electrosurgical unit - SS-501WEMFor cutting and coagulation during thorax incision
Fentanyl10 mcg/kg bolus + 10 mcg/kg/hour continuous infusion
Finochietto retractorAny finochietto retractor is suitable
heparin3ml
Infusion setAny infusion set is suitable
Isoflurane1.5%
Kelly Forceps CurvedAny kelly forceps is suitable
Ketamine5mg/kg
Lactated Ringer solution500ml
Mechanical ventilator - Servo IMaquetREF 6449701Mechanical ventilator used in the procedure
Metzenbaum Scissor (Straight and curved)Any metzenbaum scissor is suitable
Midazolam0.25mg/kg
Orotracheal intubation cannula, #6.5Rusch112282Widely available
PlexiglassCustom made plexiglass box: 30x45x60cm
Polyester suture, 2-0Widely available
Potassium choride10 ml, 19.1% potassium chloride.
propofol5mg/kg
Three way stopcockWidely available
Venous catheter, G20 x 1"BD38183314Widely available

References

  1. Roberto, C., Carvalho, R., Toufen Jr, C., Franca, S. A. Mechanical Ventilation: Principles, graphic analysis and ventilation modalities. Jornal Brasileiro de Pneumologia. 33 (2), 54-55 (2007).
  2. Barbas, C. S. V., et al.

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