Method Article

Endotracheal Intubation Using a Flexible Intubation Endoscope as a Standardized Model for Safe Airway Management in Swine

DOI:

10.3791/63955

August 25th, 2022

In This Article

Erratum Notice

Important: There has been an erratum issued for this article. Read More ...

Erratum

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Formal Correction: Erratum: Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine
Posted by JoVE Editors on 4/03/2023. Citeable Link.

An erratum was issued for: Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine. The Protocol, Representative Results, and Discussion sections were updated.

In the Protocol, step 1.5 was updated from:

Disinfect the skin with a disinfectant (alcoholic) before inserting a peripheral vein cannula (22 G) into an ear vein. Spray the area, wipe once, then spray again, and allow the disinfectant to dry.

to:

Disinfect the skin with a disinfectant (alcoholic) before inserting a peripheral vein cannula (22 G) into an ear vein. Spray the area, wipe once, then spray again, and allow the disinfectant to dry. Secure the ear cannula with a band-aid (See Table of Materials).

In the Protocol, step 3.7 was updated from:

While maintaining the position of the endoscope, advance the endotracheal tube until it becomes visible in the camera image.
NOTE: If the endotracheal tube cannot be advanced through the glottic plane, there is a possibility that it has become caught on the arytenoid cartilage. In this case, the endotracheal tube must be withdrawn 1 cm and rotated by 90° before gently advancing again. If necessary, this maneuver can be repeated. Similar calibers of flexible intubation endoscope and endotracheal tube can minimize the risk of this issue occurring. If the endotracheal tube cannot be advanced despite this maneuver, it is likely that the subglottic narrowness-the narrowest part of the porcine larynx-cannot be passed. In this case, a smaller endotracheal tube size needs to be selected. Regular commercially available endotracheal tubes in sizes 6.5 cm or 7.0 cm ID should be able to pass the glottis as long as no anatomic abnormalities are present.

to:

While maintaining the position of the endoscope, advance the endotracheal tube until it becomes visible in the camera image.
NOTE: If the endotracheal tube cannot be advanced through the glottic plane, there is a possibility that it has become caught on the arytenoid cartilage. In this case, the endotracheal tube must be withdrawn 1 cm and rotated by 90° before gently advancing again. If necessary, this maneuver can be repeated. Similar calibers of flexible intubation endoscope and endotracheal tube can minimize the risk of this issue occurring. If the endotracheal tube cannot be advanced despite this maneuver, it is likely that the subglottic narrowness-the narrowest part of the porcine larynx-cannot be passed. In this case, a smaller endotracheal tube size needs to be selected. Regular commercially available endotracheal tubes in sizes 6.5 cm or 7.0 cm ID should be able to pass the glottis as long as no anatomic abnormalities are present. Endotracheal tube size requirements vary depending on the piglet size and breed.

In the Representative Results, the sixth paragraph was updated from:

Statistical analyses were performed using commercially available software (see Table of Materials). Normal distribution was examined using the Kolmogorov-Smirnoff test28. If a normal distribution was determined, group differences were analyzed using t-tests of independent samples29 or the Mann-Whitney U test30 for the non-parametric version. Data are presented as mean (± standard deviation). Correlations of ordinal-scale data were examined using Spearman's correlation coefficient31. A significance level of p < 0.05 was assumed.

to:

Statistical analyses were performed using commercially available software (see Table of Materials). Normal distribution was examined using the Kolmogorov-Smirnoff test28. If a normal distribution was determined, group differences were analyzed using t-tests of independent samples29 or the Mann-Whitney U test30 for the non-parametric version. Data are presented as mean (± standard deviation). Correlations of ordinal-scale data were examined using Spearman's correlation coefficient31. A significance level of p < 0.05 was assumed. All tests were performed with exploratory intention; therefore p-values are descriptive. Nevertheless, p < 0.05 was accepted as indicative of statistical significance.

In the Representative Results, the legend for figure 1 was updated from:

Figure 1: Number of intubation attempts in group comparison. For the group that was intubated using a flexible intubation endoscope, every intubation attempt was successful; in the group that was conventionally intubated, it took an average of 1.4 attempts before the endotracheal tube could be placed correctly. Error bars show the standard deviation. Please click here to view a larger version of this figure.

to:

Figure 1: Number of intubation attempts in group comparison. For the group that was intubated using a flexible intubation endoscope, every intubation attempt was successful; in the group that was conventionally intubated, it took an average of 1.4 attempts before the endotracheal tube could be placed correctly. Error bars show the standard deviation. n = 5 (for each group). Please click here to view a larger version of this figure.

In the Representative Results, figure 2 was updated from:

Seconds to CO2 detection; bar graph comparing FIE and CI methods; experimental result analysis.
Figure 2: Time until CO2 detection in group comparison. For the group that was intubated using a flexible intubation endoscope, it took significantly longer until end-tidal CO2 could be detected, depicted as mean and standard deviation. Please click here to view a larger version of this figure.

to:

Bar graph comparing CO2 detection time: FIE vs CI methods; data with error bars.
Figure 2: Time until CO2 detection in group comparison. For the group that was intubated using a flexible intubation endoscope, it took significantly longer until end-tidal CO2 could be detected, depicted as mean and standard deviation. n = 5 (for each group). Please click here to view a larger version of this figure.

In the Discussion, the fifth paragraph was updated from:

The increased duration had no clinical significance in this cohort. At no time was the termination criterion-a saturation of less than 93%-reached. This is shown in the results because a procedure change was unnecessary at any time. Prior adequate mask ventilation is a critical step to allow sufficient time for fiberoptic endotracheal tube placement to avoid rapid desaturation34. These results are consistent with previous studies comparing conventional intubation and endoscopically assisted intubations with inexperienced providers35.

to:

The increased duration had no clinical significance in this cohort. At no time was the termination criterion-a saturation of less than 93%-reached. This is shown in the results because a procedure change was unnecessary at any time. Prior adequate mask ventilation is a critical step to allow sufficient time for fiberoptic endotracheal tube placement to avoid rapid desaturation34. These results are consistent with previous studies comparing conventional intubation and endoscopically assisted intubations with inexperienced providers35. We attribute the prolonged duration of fiberoptic intubation to the fact that one must first reorient again after insertion, whereas with conventional intubation, one retains a view of the glottis. It is also important to avoid contact with the mucosa with the flexible intubation endoscope during advancement. This requires occasional corrective maneuvers. Last but not least, after successful placement, retraction of the relatively long endoscope is required, which increases the time to CO2 detection slightly.

Summary

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The use of pigs in research has increased in recent years. Nevertheless, pigs are characterized by difficult airway anatomy. By demonstrating how to perform endoscopically guided endotracheal intubation, the present protocol aims to further increase laboratory animals' safety to avoid animal suffering and unnecessary death.

Abstract

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Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures. Endotracheal intubation is a challenging skill, requiring a minimum number of successful endotracheal intubations to achieve a high success rate under optimal conditions, which is often unachievable for non-anaesthesiology researchers. Due to the specific porcine airway anatomy, a difficult airway can usually be assumed. The impossibility of establishing a secure airway can result in injury, adverse events, or death of the laboratory animal. Using a prospective, randomized, controlled evaluation approach, it has been shown that fiberoptic-assisted endotracheal intubation takes longer but has a higher first-pass success rate than conventional intubation without causing clinically relevant drops in oxygen saturation. This model presents a standardized regimen for endoscopically guided endotracheal intubation, providing a secured airway, especially for researchers who are inexperienced in the technique of endotracheal intubation via direct laryngoscopy. This procedure is expected to minimize animal suffering and unnecessary animal losses.

Introduction

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Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures (such as ventilation during cardiopulmonary resuscitation1 or acute respiratory distress syndrome2) or require that cerebral blood flow is not compromised through internal compression by supraglottic airway devices3, which are occasionally propagated as alternatives in the context of an anticipated difficult airway in pigs4,5.

Whil....

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Protocol

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The experiments in this protocol were approved by the State and Institutional Animal Care Committee (Landesuntersuchungsamt Rheinland-Pfalz, Koblenz, Germany; approval no. G20-1-135). The experiments were conducted following the ARRIVE guidelines. Overall, 10 anesthetized male pigs (Sus scrofa domestica) with a mean weight of 30 kg ± 2 kg and 12-16 weeks in age were used for the present study.

1. Animal preparation

  1. Maintain a normal environment for the animals to minimize stress. Withhold food 6 h before the scheduled experiment to lower the risk of aspiration, but allow access to water.
  2. ....

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Results

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Endotracheal intubation was performed on 10 male pigs (age 12-16 weeks, weight 30 kg ± 3 kg) in a prospective, randomized, controlled study setting. The pigs were randomized into two groups: one was conventionally laryngoscopically intubated (CI group), and the other group was intubated assisted via a flexible intubation endoscope as described in the protocol (FIE group). The group assignment was done by pulling sealed envelopes. The investigator was assigned randomly on a daily basis.

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Discussion

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In previous studies, our research group has already described specific details regarding the translational benefits of the porcine model2,27,32,33. Generally, reducing the stress level of the animal and unnecessary pain should be an integral part of any study protocol and is paramount for generating reliably reproducible data. Therefore, awake endoscopically guided intubation of the pig with an.......

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Disclosures

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The flexible intubation endoscope and its accessories have been provided unconditionally by the manufacturer for research purposes only. The authors declare no further financial or other conflicts of interest.

Acknowledgements

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The authors want to thank Dagmar Dirvonskis for her excellent technical support.

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
Ambu aScope RegularAmbu GmbH, Medizinprodukte, Bad Nauheim, GermanyDisposable fiber optic outer diameter 5 mm
Ambu aView MonitorAmbu GmbH, Medizinprodukte, Bad Nauheim, Germanymonitor
Atracurium Hikma 50 mg/5mLHikma Pharma GmbH, Martinsriedatracurium
Azaperone (Stresnil) 40mg/mLLilly Deutschland GmbH, Bad Homburg, Germanyazaperone
BD Discardit II Spritze 2, 5, 10, 20 mLBecton Dickinson S.A. Carretera, Mequinenza Fraga, Spainsyringe
BD Luer ConnectaBecton Dickinson Infusion Therapy, AB Helsingborg, Schweden3-way-stopcock
BD Microlance 3 20 GBecton Dickinson S.A. Carretera, Mequinenza Fraga, Spaincannula
Curafix i.v. classicsLohmann & Rauscher International GmbH & Co. KG, Rengsdorf, GermanyCannula retention dressing
Engström CarestationGE Heathcare, Madison USAventilator
Fentanyl-Janssen 0.05 mg/mLJanssen-Cilag GmbH, Neussfentanyl
Führungsstab, Durchmesser 4.3Rüschendotracheal tube introducer
IBM SPSS Statistics for Windows, Version 20IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp.)Statistical software
Incetomat-line 150 cmFresenius, Kabi Deutschland, GmbHperfusor line
Intrafix PrimelineB. Braun Melsungen AG, Melsungen, GermanyInfusion line
JOZA Einmal Nitril UntersuchungshandschuheJOZA, München, Germanydisposable gloves
Laryngoscope, 45.48.50, KL 2000MediconLaryngoscope handle
Littmann Classic III Stethoscope3M Deutschland GmbH, Neuss, Germanystethoscope
Luer LockB.Braun Melsungen AG, Germany
Maimed VlieskompresseMaimed GmbH, Neuenkirchen, GermanyFleece compress to fix the tongue
Masimo LNCS Adtx SpO2 sensorMasimo Corporation Irvine, Ca 92618 USAsaturation clip for the tail
Masimo LNCS TC-I SpO2 ear clip sensorMasimo Corporation Irvine, Ca 92618 USASaturation clip for the ear
Masimo Radical 7Masimo Corporation Irvine, Ca 92618 USAperiphereal oxygen saturation
Midazolam 15 mg/3 mLHameln Pharma GmbH, Hameln, Germanymidazolam
Midmark Canine Mask Small Plastic with Diaphragm FRSCM-0005Midmark Corp., Dayton, Ohio, USAdog ventilation mask
Octeniderm farblosSchülke & Mayr GmbH, Nordenstedt, GermanyAlcoholic disinfectant
Original Perfusor syringe 50 mLB.Braun Melsungen AG, Germanyperfusor syringe
Perfusor FM BraunB.Braun Melsungen AG, Germanysyringe pump
Propofol 2% 20 mg/mL (50 mL flasks)Fresenius, Kabi Deutschland, GmbHpropofol
RÜSCH Führungsstab für Endotrachealtubus (ID 5.6 mm)Teleflex Medical Sdn. Bhd, MalaysiaPVC coated tube guiding wire
Rüschelit Super Safety Clear >ID 6/6.5 /7.0 mmTeleflex Medical Sdn. Bhd, Malaysiaendotracheal tube
Stainless Macintosh Größe 4Welch Allyn69604blade for laryngoscope
SterofundinB.Braun Melsungen AG, Melsungen, GermanyBalanced electrolyte solution
Ultrastop Antibeschlagmittel bottle with dropper 25 mLSigmapharm Arzneimittel GmbH, Wien, AustriaAntifog agent
Vasofix Safety 22 G-16 GB.Braun Melsungen AG, Germanyvenous catheter
VBM Cuff ManometerVBM Medizintechnik GmbH, Sulz a.N., Germanycuff pressure gauge
ZeletteLohmann & Rauscher International GmbH & Co. KG, Rengsdorf, GermanyTissue swab

References

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  1. Kleinman, M. E., Oh, W., Stonestreet, B. S. Comparison of intravenous and endotracheal epinephrine during cardiopulmonary resuscitation in newborn piglets. Critical Care Medicine. 27 (12), 2748-2754 (1999).
  2. Rissel, R., et al.

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Tags

Endotracheal IntubationFlexible Intubation EndoscopeAirway ManagementSwine ModelDirect LaryngoscopyFiberoptic IntubationMechanical VentilationCapnography MonitoringCuff Pressure ControlPorcine Airway Anatomy

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