Blind oral endotracheal intubation of rats using a ventilator to verify correct placement

Trigeminal nerve electrical stimulation: An effective arousal treatment for loss of consciousness

BACKGROUND

To determine if trigeminal nerve electrical stimulation (TNS) would be an effective arousal treatment for loss of consciousness (LOC), we applied neuroscientific methods to investigate the role of potential brain circuit and neuropeptide pathway in regulating level of consciousness.

METHODS

Consciousness behavioral analysis, Electroencephalogram (EEG) recording, Chemogenetics, Microarray analysis, Milliplex MAP rat peptide assay, Chromatin immune-precipitation (ChIP), Dual-luciferase reporter experiment, Western blot, PCR and Fluorescence in situ hybridization (FISH).

RESULTS

TNS can markedly activate the neuronal activities of the lateral hypothalamus (LH) and the spinal trigeminal nucleus (Sp5), as well as improve rat consciousness level and EEG activities. Then we proved that LH activation and upregulated neuropeptide hypocretin are beneficial for promotion of consciousness recovery. We then applied gene microarray experiment and found hypocretin might be mediated by a well-known transcription factor Early growth response gene 1 (EGR1), and the results were confirmed by ChIP and Dual-luciferase reporter experiment.

CONCLUSION

This study illustrates that TNS is an effective arousal strategy Treatment for LOC state via the activation of Sp5 and LH neurons and upregulation of hypocretin expression.

Improved blind tracheal intubation in rats: a simple and secure approach

Successful tracheal intubation is the prerequisite for open-chest models. Tracheal intubation in small animal such as the rat is often challenging due to the small size and special anatomy. We investigated whether endotracheal intubation can be performed safely and reliably in rats employing only gesture fixation and a catheter. Rats were randomly classified into three groups: Improved blind intubation (B group) was performed with gestures fixed intubation position. Transillumination intubation (T group) utilized light to locate the larynx. Incision intubation (I group) was intubated after trachea incision. The feasibility, difficulty, complications of the three groups were compared. B group was faster than the other two groups. Completion time of the operation was recorded as follows: B group: 35.00 ± 9.86 sec; T group: 57.12 ± 6.54 sec; I group: 184.33 ± 25.49 sec (P≤0.001). B group has fewer attempts than Group T (P=0.001). The operational success rates of all three groups (B group 14 (93.3%) vs. T group 12 (80.0%) vs. I group 13 (86.7%)) were similar (P>0.05). In terms of operation difficult and operational complications, the differences between the three groups were not significant. The rate of endometrial damage under microscope were no difference, too. The Improved blind endotracheal intubation is a simple method, with a comparable safety profile to that of the transillumination and incision intubaton.

Video laryngoscopic oral intubation in rats: a simple and effective method

Endotracheal intubation is a vital component of many rat in vivo experiments to secure the airway and allow controlled ventilation. Even in the hands of experienced researchers, however, the procedure remains technically challenging. The safest and most reliable way for human intubation is by video laryngoscopy. Previous attempts to apply this technique in rodents have been complicated and expensive. We, hereby, describe a novel, noninvasive method to safely intubate rats orally by video laryngoscopy, thus avoiding the need for a surgical tracheostomy. By repurposing a commercially available ear wax removal device, visualization of the rat larynx can be significantly enhanced. Because of its small diameter, integrated illumination, and a powerful camera with adequate focal length, the device has all of the necessary properties for exploring the upper airway of a rat. After identifying the vocal cords by video laryngoscopy, the insertion of an endotracheal tube (a 14G intravenous catheter) into the trachea under constant visual control is facilitated by using PE50 polyethylene tubing as a stylet (Seldinger technique). The procedure has been performed more than 60 times in our laboratory; all intubations were successful on the first attempt, and no adverse events were observed. We conclude that the described procedure is a simple and effective way to intubate a rat noninvasively, using inexpensive and commercially available equipment.

Impact of Stroke Therapy Academic Industry Roundtable (STAIR) Guidelines on Peri-Anesthesia Care for Rat Models of Stroke: A Meta-Analysis Comparing the Years 2005 and 2015

Numerous studies using rats in stroke models have failed to translate into successful clinical trials in humans. The Stroke Therapy Academic Industry Roundtable (STAIR) has produced guidelines on the rodent stroke model for preclinical trials in order to promote the successful translation of animal to human studies. These guidelines also underline the importance of anaesthetic and monitoring techniques. The aim of this literature review is to document whether anaesthesia protocols (i.e., choice of agents, mode of ventilation, physiological support and monitoring) have been amended since the publication of the STAIR guidelines in 2009. A number of articles describing the use of a stroke model in adult rats from the years 2005 and 2015 were randomly selected from the PubMed database and analysed for the following parameters: country where the study was performed, strain of rats used, technique of stroke induction, anaesthetic agent for induction and maintenance, mode of intubation and ventilation, monitoring techniques, control of body temperature, vascular accesses, and administration of intravenous fluids and analgesics. For each parameter (stroke, induction, maintenance, monitoring), exact chi-square tests were used to determine whether or not proportions were significantly different across year and p values were corrected for multiple comparisons. An exact p-test was used for each parameter to compare the frequency distribution of each value followed by a Bonferroni test. The level of significant set at < 0.05. Results show that there were very few differences in the anaesthetic and monitoring techniques used between 2005 and 2015. In 2015, significantly more studies were performed in China and significantly fewer studies used isoflurane and nitrous oxide. The most striking finding is that the vast majority of all the studies from both 2005 and 2015 did not report the use of ventilation; measurement of blood gases, end-tidal carbon dioxide concentration, or blood pressure; or administration of intravenous fluids or analgesics. The review of articles published in 2015 showed that the STAIR guidelines appear to have had no effect on the anaesthetic and monitoring techniques in rats undergoing experimental stroke induction, despite the publication of said guidelines in 2009.

Airway management using a supraglottic airway device without endotracheal intubation for positive ventilation of anaesthetized rats

Endotracheal intubation is often necessary for positive pressure ventilation of rats during open thoracic surgery. Since endotracheal intubation in rats is technically difficult and is associated with numerous complications, many techniques using various devices have been described in the scientific literature. In this study, we compared the effectiveness of airway management of a home-made supraglottic airway device (SAD), which is cheap to fabricate and easy to place with that of an endotracheal intubation tube in enflurane-anaesthetized rats. Twenty male Sprague-Dawley rats (200-300 g) were randomly assigned to two equal groups for positive pressure mechanical ventilation using either the SAD or an endotracheal intubation tube. The carotid artery of each rat was cannulated for continuous blood pressure measurements and obtaining blood samples for determination of oxygen tension, carbon dioxide tension, and blood acidity before, during and after SAD placement or endotracheal intubation. Proper placement of the SAD was confirmed by observing chest wall movements that coincided with the operation of the mechanical ventilator. No complications and adverse events were encountered in the rats in which the SAD was placed, during SAD placement and immediate removal, during their mechanical ventilation through the SAD, and one week after SAD removal. From the results of blood gas analyses, we conclude that anaesthetized rats can be successfully ventilated using an SAD for open thoracic surgery.

Assisted ventilation without endotracheal intubation in rats

This technique was performed to allow for an additional approach to assist in ventilation. A modified ventilation nose cone was placed over the nose, which allowed the animal to not require endotracheal intubation. This method was effective in ventilating the animals during thoracic and abdominal procedures without requiring endotracheal intubation.

Lung injury induced by the pulmonary instillation of povidone-iodine in rats

PURPOSE

Povidone-iodine (polyvinylpyrrolidone iodine, PI), which is commonly used as a pre- and postoperative oral antiseptic, has been reported to cause pneumonia secondary to its pulmonary aspiration. Because no studies have yet investigated the underlying mechanisms of PI-induced pneumonia, we conducted an animal study to analyze the effect of PI on the lung following its pulmonary instillation.

METHODS

The lungs of 61 male Sprague-Dawley rats (150-250 g) were instilled with varying volumes of either phosphate-buffered saline or PI solutions varying in strength from 0.01% to 10%. The lungs were harvested from the rats 1 h or 1, 3, 5, 7, 14, or 21 days after instillation for radiologic examination, macroscopic and light and scanning electron microscopic assessment, and an assessment of pulmonary toxicity using an MTT-based cytotoxicity assay.

RESULTS

Macroscopically, atelectasis was the primary pulmonary lesion after PI instillation. The primary light and scanning electron microscopic findings were an initial inflammatory phase with edema, alveolar rupture, and leukocyte infiltration into the pulmonary interstitium, which progressed into a phase of lung parenchyma loss, and then resolved itself with scar tissue formation. Lung tissue viability following 1-day exposure to 0.01%, 0.1%, 1%, or 5% PI progressively decreased in a significant dose-dependent manner.

CONCLUSIONS

PI aspiration can cause lung injury, including pulmonary fibrosis.