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Summary

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Medicine

A Simple Method of Mouse Lung Intubation

Published: March 21st, 2013

DOI:

10.3791/50318

1Department of Environmental Health Sciences, Program in Respiratory Biology and Lung Disease, Johns Hopkins Bloomberg School of Public Health, 2Department of Pediatrics, Oregon Health Sciences University

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

In 1999, Brown et al. published a paper describing a method for intubation of the mouse lung 1. Such a technique has considerable utility in doing repeat pulmonary function or bronchoalveolar lavage in individual mice in longitudinal studies 2. Since that original paper, there have been several other papers that have described different approaches to mouse intubation 3-9. While all of these methods can be used successfully, they usually require considerable training or cost. One of the main issues with such intubation is that as the intubation cannula approaches nears the trachea pending insertion, the cannula itself ....

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1. Preparing for the Procedure

One must first obtain and prepare the following items:

  1. The cannula. For intubation of 20-35 g mice, we use a 1 or 1.5 inch long, 20 gauge IV catheter (BD Insylte, Sparks, MD or Jelco Optiva, Carlsbad, CA). A new sterile catheter can be used for each mouse, but catheters can also be reused after sterilization by soaking in 70% ethanol overnight. Although neither the pharynx nor trachea of the mouse is sterile proper cleanliness proced.......

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As an evaluation of the method, we used four 20 week old male BALB/c mice with average weight (± SEM) of 27.7 ± 0.40 g. They were studied on five consecutive weeks, where the lung resistance was measured using a system as previously described 11. Each mouse was anesthetized with ketamine (100 μg/g BW) and xylazine (15 μg /g BW) in saline via IP injection. They were then intubated as described above. If there is any doubt whether the cannula is in the trachea and not the esophagus, this can .......

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The procedure described here has several advantages. First the apparatus is simple and relatively inexpensive.. The fabrication of the apparatus does not require any special tools or costly equipment. The use of a catheter introduces that also is the light source means that one never loses sight of the tracheal opening as the introducer approaches the tracheal opening. The use of a 0.5 mm introducer also serves to minimize trauma that might occur with an initial insertion of a larger cannula. We note here that a similar .......

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Supported by NIH HL-10342.

....

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Name Company Catalog Number Comments
Material Company Catalog # Comment
Intubation cannula BD Insylte, Sparks, MD or Jelco Optiva, Carlsbad, CA   1-in.-long, 20-gauge intravenous (IV) catheter
Fiber-optic cable Edmund Optics, Barrington, NJ #NT02-542 Approximately 2-ft length of 0.5-mm optical fiber (Communication grade plastic fiber). The edge of the fiber end that is inserted into the trachea should be gently rounded by holding the fiber ≈2 cm from the end and then making small circles while dragging the tip for a few seconds on 1,000-grit emory paper.
Light Source Volpi NCL-150 Although we use a 150-W halogen light source, any equivalent light source, even with much lower wattage can be used.
Silicone rubber stopper     A #1 silicone rubber stopper fits the light source used in this demonstration. Different light sources may require a different size.
Small silicone rubber tube Cole-Palmer EW-96410-13 A ≈1.5 cm piece of silicone rubber tubing (0.8 inner diameter, 4 mm outer diameter)
Angled support stand     Ours is constucted from plexiglass, but any material to which a thread or wire can be affixed to hold the mouse at an almost vertical angle can be used.

  1. Brown, R. H., Walters, D. M., Greenberg, R. S., Mitzner, W. A method of endotracheal intubation and pulmonary functional assessment for repeated studies in mice. J. Appl. Physiol. 87, 2362-2365 (1999).
  2. Walters, D. M., Wills-Karp, M., Mitzner, W. Assessment of cellular profile and lung function with repeated bronchoalveolar lavage in individual mice. Physiol. Genomics. 2, 29-36 (2000).
  3. Rivera, B., Miller, S., Brown, E., Price, R. A novel method for endotracheal intubation of mice and rats used in imaging studies. Contemporary Topics in Laboratory Animal Science / American Association for Laboratory Animal Science. 44, 52-55 (2005).
  4. Hamacher, J., et al. Microscopic wire guide-based orotracheal mouse intubation: description, evaluation and comparison with transillumination. Laboratory Animals. 42, 222-230 (2008).
  5. Spoelstra, E. N., et al. A novel and simple method for endotracheal intubation of mice. Laboratory Animals. 41, 128-135 (2007).
  6. Zhao, X., et al. A technique for retrograde intubation in mice. Lab Animal. 35, 39-42 (2006).
  7. Vergari, A., et al. A new method of orotracheal intubation in mice. European Review for Medical and Pharmacological Sciences. 8, 103-106 (2004).
  8. Vergari, A., Polito, A., Musumeci, M., Palazzesi, S., Marano, G. Video-assisted orotracheal intubation in mice. Laboratory Animals. 37, 204-206 (2003).
  9. Hastings, R. H., Summers-Torres, D. Direct Laryngoscopy in Mice. Contemporary Topics in Laboratory Animal Science / American Association for Laboratory Animal Science. 38, 33-35 (1999).
  10. MacDonald, K. D., Chang, H. Y., Mitzner, W. An improved simple method of mouse lung intubation. J. Appl. Physiol. 106, 984-987 (2009).
  11. Ewart, S. L., Levitt, R. C., Mitzner, W. Respiratory system mechanics in mice measured by end-inflation occlusion. Journal of Applied Physiology. 79, 560-566 (1995).
  12. MacDonald, K. D., McKenzie, K. R., Mitzner, W., Zeitlin, P. L. Lung Mechanics in Heterozygous CF Mice after Repeated LPS Dosing. Am. J. Respir. Crit. Care Med. 175 (4), A930 (2007).

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