Visible, Safe and Certain Endotracheal Intubation Using Endoscope System and Inhalation Anesthesia for Rats

Abstract

Anesthesia strongly influences laboratory animals, and it can also greatly affect the experimental data. Rats rank only second to mice in the number used in research fields, such as organ transplantation, regenerative medicine and imaging. Therefore, appropriate and effective anesthesia, including the protocol of the endotracheal intubation and inhalation anesthesia, is crucial. Hence, we evaluated these methods in this study. Twelve Wistar rats were intraperitoneally injected with M/M/B: 0.3/4/5, comprising of medetomidine, midazolam and butorphanol at a dose of 0.3 mg/kg + 4.0 mg/kg + 5.0 mg/kg body weight/rat, respectively. An endotracheal tube was then intubated into the trachea. After intubation, the rats were connected to the inhalation anesthesia circuit using isoflurane, and vital signs were measured until 30 min after connection. All intubations were successfully finished within 1 min, and the values of the vital signs were normal and stable. In addition, histopathological observation of the trachea and lungs showed no trauma. These results suggest that this visible endotracheal intubation method is simple, reliable, safe and favorable with regard to the rats’ welfare.

Effect of midazolam and butorphanol premedication on inhalant isoflurane anesthesia in mice

“…In mice, combination of midazolam and butorphanol, along with medetomidine was used as injectable anesthesia in mice [ 16 , 17 ]. Furthermore, recent rat study demonstrated that the combination of medetomidine, midazolam, and butorphanol can be used as anesthesia induction during tracheal intubation prior to inhalant anesthesia [ 18 ]. Considering these reports, we selected a combination of midazolam and butorphanol as the pre-anesthetic of isoflurane.…”

Different sensitivity to the suppressive effects of isoflurane anesthesia on cardiorespiratory function in SHR/Izm, WKY/Izm, and Crl:CD (SD) rats

“…After the recording under the set at 5%, the rat was relieved from anesthesia by removing the nose mask and observed until awakening. Endotracheal intubation in rats requires a certain amount of skill and endoscope for the successful intubation [20] and there were many reports using nose mask for isoflurane anesthesia in rats even in recent years [1, 2, 7, 40]. For practical data using nose mask, we used nose mask instead of endotracheal intubation in maintenance of isoflurane anesthesia.…”

Comparative analysis of lung function of rats using a new intubation technique and tracheostomy

“…However, it was demonstrated that the tracheal smooth muscle of rats submitted to the intubation procedure showed no histological signs of injury (KONNO et al, 2014). It seems that the relatively short period in which the animal is subjected to the procedure is not enough to cause damage to the tracheal smooth muscle.…”

“…Aiming at achieving intubation, several techniques are described in the literature, although some require more elaborate equipment specially developed (CLARY et al, 2004;KASTL et al, 2004;KONNO et al, 2014), requiring little prior training and generally achieving high success rates. Other simpler methods, not requiring specific materials, however, require more training and have questionable success rates, as well as injury history in the glottis, larynx and/or vocal cords of animals.…”

“…Other simpler methods, not requiring specific materials, however, require more training and have questionable success rates, as well as injury history in the glottis, larynx and/or vocal cords of animals. Among them can be mentioned: blind intubation (STARK et al, 1981), making a handmade laryngoscope (ABRÃO et al, 1994), use of a specially-developed fiber optic laryngoscope (LINDEN et al, 2000), insertion of wedge in the oral region (JOU et al, 2000), transillumination method (LIZIO et al, 2001), performing of videoendoscopy (KONNO et al, 2014) and use of perpendicular (HAMACHER et al, 2008) or inclined plaque (KASTL et al, 2004;ALZABEN et al, 2009) …”