This work was supported in part by R01HD090887-01A1 from NICHD to AH. The authors also acknowledge the facilities provided by Dr. Peter Mc Farlane&#39;s lab such as inhalation anesthesia/ heating pad system. Ms. Catherine Mayer&#39;s valuable assistance in setting up of the system is appreciated. No role was played by the funding body in the design of the study, collection, analysis and interpretation of data or in writing the manuscript.

All experiments were approved by the Institutional Animal Care and Use Committee (protocol # 2020-0035) at the Case Western Reserve University. All animals were treated in accordance with the NIH guidelines for the care and use of laboratory animals.
1. Animals
<ol>
	<li>Commercially obtain pregnant Sprague Dawley rats.</li>
	<li>Maintain animals at an approved veterinary facility with 14 h/10 h light-dark cycle and 45-60% relative humidity.</li>
</ol>
2. Preparation of test compound
<ol>
	<li>Use Evans blue dye as the test compound to assess the efficacy of the intratracheal instillation procedure.</li>
	<li>Prepare a 0.25% (w/v) solution of the dye in phosphate-buffered saline (pH 7.2) and filter sterilize using a 0.45 &#181;m syringe filter.</li>
</ol>
3. Administration of anesthesia
<ol>
	<li>Anesthetize rat pups using gas anesthesia (3% isoflurane in 100% oxygen), using a modified delivery system adapted for small rat neonates.</li>
	<li>Check for the loss of tail and pedal reflexes and shallow breathing to ensure the proper depth of anesthesia for carrying out the procedure.</li>
</ol>
4. Intratracheal instillation (ITI)
<ol>
	<li>Use rat pups at post-natal day 5 (PN 5) for the ITI. Average weight of a PN 5 rat pup is 12 grams.</li>
	<li>Restrain the anesthetized rat pup on an inclined flat platform using laboratory labelling tape. The pup is restrained at an angle of about 45&#176; in the supine position.</li>
	<li>Open the mouth of the neonate, and gently pull the tongue out to one side using a blunt forceps.</li>
	<li>Use a small otoscope speculum of 2 mm diameter connected to the otoscope to hold the tongue gently and for proper visualization of the larynx.</li>
	<li>Use the throat illuminator system i.e., the operating otoscope, and the magnifying lens for proper visualization of vocal cords (Figure 1).</li>
	<li>Position&#160;the animals at an angle of 45&#176; in an inclined plane. The wired bar lids of mouse cages are used (Figure 2). 
	NOTE: Positioning the animal at an angle of 45&#176; provides better visualization of tracheal opening without the interference of the epiglottis.</li>
	<li>Take a long-angled pipette tip which is used for loading western blot gels. Cut the base of the pipette tip using a surgical blade so that it fits well into the tip of 1 cc syringe.</li>
	<li>Use the sterile 1 mL syringe fitted into a long-angled pipette tip to deliver 30-50 &#181;L of the substance into the lung. Invert the syringe and aspirate nearly 0.9 cc air into the 1 mL syringe connected to the pipette tip followed by the dye or the substance to be delivered. This allows the air behind the dye to be pushed into the trachea after the dye is administered as shown in Figure 3. The intratracheal administration is achieved by visualizing the laryngeal lumen (vocal cords) and inserting the pipette tip fitted to a syringe into the tracheal lumen.</li>
	<li>Use the speculum of the otoscope to hold the tongue and expose the vocal cords. Speculum serves the role of the blade of a laryngoscope. Bend the pipette tip to an angle of 30&#176; to facilitate easy introduction of the agent through the cone-shaped speculum into the tracheal opening.</li>
	<li>Introduce the pipette tip into the tracheal opening to the point of about 2 mm beyond the vocal cords. Push the piston of the syringe to administer the dye or the drug through the speculum of the operating otoscope as shown in Figure 3. The introduction of air into the lung soon after the administration of the agent prevents the substance from coming back to the laryngeal cavity.</li>
	<li>After administering the pup with the dye or normal saline, place the pups on an integrated circulating fluid heating pad (38&#176;C) until their respiratory movements are regular. After complete recovery from anesthesia, reunite the pups with the dam.</li>
</ol>
5. Characterization of ITI delivery
<ol>
	<li>After ITI, euthanize the rat pups by giving excessive anesthesia (Ketamine 100 mg/kg and Xylazine 10 mg/kg) / thiopentone followed by exsanguination at an appropriate time post-administration. Euthanasia was performed as part of the experiment to collect lung tissue to demonstrate the efficacy.</li>
	<li>Secure the euthanized rat pup on a dissection board and wipe the chest and abdomen with 70% ethyl alcohol.</li>
	<li>For evaluating the distribution of the dye throughout the lung, remove the lungs from the animal using sterile technique and display the lungs as appropriate for imaging (Figure 4A,B).</li>
</ol>

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The authors have nothing to disclose.

Intratracheal instillation is an excellent method that offers several advantages over the existing methods for respiratory disease interventions as well as disease model development. It is a quick method and with experience, can be performed with an average speed of 2-3 minutes per animal. The key considerations for a successful intubation are proper sedation of the animal, it&#39;s correct positioning, especially the head, as well as accurate depth of placement/ size of the specula in the oropharynx. Proper sedation wou...

Neonates born prematurely have poorly developed lungs requiring many interventional therapies such as long-term ventilation. These interventions place the surviving neonates at a high risk of subsequent sequelae1. Experimental animal models serve as an important tool in simulating various disease conditions, studying the pathobiology of diseases, and evaluating therapeutic interventions. Even though a broad range of animal models from mice, rat, and rabbit to pre-term lambs and pigs are available, mice and rat are the most used. 
The primary advantage of using mice and rats are the relatively short gestation period and reduced cost. They are also readily available, easy to maintain in disease-free environments, genetically homogeneous and have relatively less ethical concern2,3. Another major advantage of the rodent model is that at birth the neonatal pup is at late canalicular/early saccular stage of lung development which is morphologically equivalent to the lung of a 24-week preterm neonatal human infant going on to develop bronchopulmonary dysplasia4. In addition, as their lung development rapidly progresses to completion within the first 4 weeks of life, it is feasible to study the post-natal lung maturation in a reasonable time frame4. Despite these advantages, the small size of the mice and rat pups is a source of concern for various interventions, which compels most researchers to use adult animals rather than pups5. Neonatal lungs are in a developmental stage and the response of a neonate to an inciting agent differs from that of an adult. This makes it appropriate to use neonatal animal models to study human neonatal disease conditions.
There are different methods to administer drugs/ biological agents to the lung. This includes intranasal6,7 or intratracheal8,9,10 instillation as well as aerosol inhalation11,12. Each approach has its own technical challenges, advantages, as well as limitations13. Intratracheal route of administration of therapeutic agents is preferred to study the direct therapeutic impact in the organ bypassing the systemic effects. This route could also be used to study lung pathology caused by inciting agents. There are both invasive and minimally invasive techniques to do this and is easy to perform in adults. However, in pups, because of the small size of the animal, there are technical challenges associated with the intubation process. The current study presents a simple, consistent, non-surgical intratracheal instillation (ITI) method in rat pups that could be used to study the efficacy of various neonatal therapeutic interventions as well as to generate animal models simulating neonatal respiratory diseases.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Evans Blue dye</td>
			<td>Sigma-Aldrich, St Louis, MO, USA</td>
			<td>314-13-6</td>
			<td>Confirmation of drug administration into lungs</td>
		</tr>
		<tr>
			<td>Ketamine Hydrochloride</td>
			<td>Hospira. Inc, Lake Forest, IL, USA</td>
			<td>Dispensed from Animal care facility</td>
			<td>For sedation</td>
		</tr>
		<tr>
			<td>Operating Otoscope</td>
			<td>Welch Allyn, Hillrom, Chicago, IL, USA</td>
			<td>21770- 3.5V</td>
			<td>For visualization of vocal cords</td>
		</tr>
		<tr>
			<td>Otoscope Rechargeable Handle</td>
			<td>Welch Allyn, Hillrom, Chicago, IL, USA</td>
			<td>71050-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tip (Gel loading)</td>
			<td>Fisherbrand</td>
			<td>02-707-139</td>
			<td>Administering the drug</td>
		</tr>
		<tr>
			<td>Platform for restraining (inclined plane)</td>
			<td>Animal care facility</td>
			<td>Dispensed from Animal care facility</td>
			<td>Wired roof of mice cage can be used</td>
		</tr>
		<tr>
			<td>3M Micropore Surgical White Paper (sticking tape)</td>
			<td>3M, St. Paul, MN, USA</td>
			<td>1530-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Luer Lock SyringeSyringes (1 ml)</td>
			<td>BD Franklin Lakes, NJ , USA</td>
			<td>NBD2515</td>
			<td>Administering the drug</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Hospira. Inc, Lake Forest, IL, USA</td>
			<td></td>
			<td>For sedation</td>
		</tr>
	</tbody>
</table>

a minimally invasive method for intratracheal instillation of drugs in neonatal rodents to treat lung disease

Treatment of neonatal rodent with drugs instilled directly into the trachea could serve as a valuable tool to study the impact of a locally administered drug. This has direct translational impact because surfactant and drugs are administered locally into the lungs. Though the literature has many publications describing minimally invasive transoral intubation of adult mice and rats in therapeutic experiments, this approach in neonatal rat pups is lacking. The small size of orotracheal region/pharynx in the pups makes visualization of laryngeal lumen (vocal cords) difficult, contributing to the variable success rate of intratracheal drug delivery. We hereby demonstrate effective oral intubation of neonatal rat pup - a technique that is non-traumatic and minimally-invasive, so that it can be used for serial administration of drugs. We used an operating otoscope with an illumination system and a magnifying lens to visualize the tracheal opening of the rat neonates. The drug is then instilled using a 1 mL syringe connected to a pipette tip. The accuracy of the delivery method was demonstrated using Evans blue dye administration. This method is easy to get trained in and could serve as an effective way to instill drugs into trachea. This method could also be used for administration of inoculum or agents to simulate disease conditions in animals and, also, for cell-based treatment strategies for various lung diseases.

The instillation of Evans blue revealed multifocal distribution of the dye involving all pulmonary lobes (Figure 4A,B). Our result as shown in Figure 4 demonstrates efficacy of distribution to all lobes. The picture is taken immediately after ITI of the dye into the trachea. 100% efficacy was achieved in instilling the dye into the trachea followed by its spread into all the lobes on both sides. It is expected that the dye would spread further w...

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A Minimally Invasive Method for Intratracheal Instillation of Drugs in Neonatal Rodents to Treat Lung Disease

This technique of instilling drugs directly into the trachea of neonatal rodents is important in studying the impact of locally administered drugs or biologicals on neonatal lung diseases. Additionally, this method can also be used for inducing lung injury in animal models.

Treatment of neonatal rodent with drugs instilled directly into the trachea could serve as a valuable tool to study the impact of a locally administered ...

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5.6K Views.  Case Western Reserve University. This technique of instilling drugs directly into the trachea of neonatal rodents is important in studying the impact of locally administered drugs or biologicals on neonatal lung diseases. Additionally, this method can also be used for inducing lung injury in animal models. 

Video: A Minimally Invasive Method for Intratracheal Instillation of Drugs in Neonatal Rodents to Treat Lung Disease

A Simple Method of Mouse Lung Intubation

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.

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  ...

Intubation-mediated Intratracheal (IMIT) Instillation: A Noninvasive, Lung-specific Delivery System

Respiratory disease studies typically involve the use of murine models as surrogate systems. However, there are significant physiologic differences between the murine and human respiratory systems, especially in their upper respiratory tracts (URT). In some models, these differences in the murine nasal cavity can have a significant impact on disease progression and presentation in the lower respiratory tract (LRT) when using intranasal instillation techniques, potentially limiting the usefulness of the mouse model to study these diseases. For these reasons, it would be advantageous to develop a technique to instill bacteria directly into the mouse lungs in order to study LRT disease in the absence of involvement of the URT. We have termed this lung specific delivery technique intubation-mediated intratracheal (IMIT) instillation. This noninvasive technique minimizes the potential for instillation into the bloodstream, which can occur during more invasive traditional surgical intratracheal infection approaches, and limits the possibility of incidental digestive tract delivery. IMIT is a two-step process in which mice are first intubated, with an intermediate step to ensure correct catheter placement into the trachea, followed by insertion of a blunt needle into the catheter to mediate direct delivery of bacteria into the lung. This approach facilitates a &#62;98% efficacy of delivery into the lungs with excellent distribution of reagent throughout the lung. Thus, IMIT represents a novel approach to study LRT disease and therapeutic delivery directly into the lung, improving upon the ability to use mice as surrogates to study human respiratory disease. Furthermore, the accuracy and reproducibility of this delivery system also makes it amenable to Good Laboratory Practice Standards (GLPS), as well as delivery of a wide range of reagents which require high efficiency delivery to the lung.

Intubation-mediated Intratracheal IMIT Instillation: A Noninvasive, Lung-specific Delivery System

Intubation-mediated intratracheal (IMIT) instillation of reagents is an excellent, noninvasive method for studying respiratory disease, as well as a method for instilling therapeutic reagents directly into the lung. It is a rapid and highly reproducible method which is suitable for preclinical testing.

Respiratory disease studies typically involve the use of murine models as surrogate systems. However, there are significant physiologic differences ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

This protocol describes a minimally invasive osteosynthesis technique using an intramedullary screw for standardized stabilization of femur fractures, which can be used to analyze endochondral bone healing in mice.

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an ...

A Pleural Effusion Model in Rats by Intratracheal Instillation of Polyacrylate/Nanosilica

Pleural effusion is a prevalent clinical finding of many pulmonary diseases. Having a useful animal pleural effusion model is very important to study these pulmonary diseases. Previous pleural effusion models paid more attention to biological factors rather than nanoparticles in the environment. Here, we introduce a model to make pleural effusion in rats by intratracheal instillation of polyacrylate/nanosilica, and a method of nanoparticle isolation in the pleural effusion. By intratracheal instillation of polyacrylate/nanosilica with concentrations of 3.125, 6.25 and 12.5 mg/kg&#8729;mL, the pleural effusion in rats presented on day 3, peaked at days 7-10 in 6.25 and 12.5 mg/kg&#8729;mL groups, then slowly decreased and disappeared on day 14. When the concentration of polyacrylate/nanosilica increased, the pleural effusion is produced more and faster. This pleural fluid was detected by ultrasound examination or CT chest scanning and confirmed by dissection of rats. Silica nanoparticles were observed in the rats' pleural effusion by transmission electron microscope. These results showed that the exposure to polyacrylate/nanosilica leads to the induction of pleural effusion, which was consistent with our previous report in humans. Additionally, this model is beneficial for the further study of nanotoxicology and the pleural effusion diseases.

Here, we present a protocol to construct a pleural effusion model in rats by intratracheal instillation of polyacrylate/nanosilica.

Pleural effusion is a prevalent clinical finding of many pulmonary diseases. Having a useful animal pleural effusion model is very important to study ...

Inducing Acute Lung Injury in Mice by Direct Intratracheal Lipopolysaccharide Instillation

Airway administration of lipopolysaccharide (LPS) is a common way to study pulmonary inflammation and acute lung injury (ALI) in small animal models. Various approaches have been described, such as the inhalation of aerosolized LPS as well as nasal or intratracheal instillation. The presented protocol describes a detailed step-by-step procedure to induce ALI in mice by direct intratracheal LPS instillation and perform FACS analysis of blood samples, bronchoalveolar lavage (BAL) fluid, and lung tissue. After intraperitoneal sedation, the trachea is exposed and LPS is administered via a 22 G venous catheter. A robust and reproducible inflammatory reaction with leukocyte invasion, upregulation of proinflammatory cytokines, and disruption of the alveolo-capillary barrier is induced within hours to days, depending on the LPS dosage used. Collection of blood samples, BAL fluid, and lung harvesting, as well as the processing for FACS analysis, are described in detail in the protocol. Although the use of the sterile LPS is not suitable to study pharmacologic interventions in infectious diseases, the described approach offers minimal invasiveness, simple handling, and good reproducibility to answer mechanistic immunological questions. Furthermore, dose titration as well as the use of alternative LPS preparations or mouse strains allow modulation of the clinical effects, which can exhibit different degrees of ALI severity or early vs. late onset of disease symptoms.

Presented here is a step-by-step procedure to induce acute lung injury in mice by direct intratracheal lipopolysaccharide instillation and to perform FACS analysis of blood samples, bronchoalveolar lavage fluid, and lung tissue. Minimal invasiveness, simple handling, good reproducibility, and titration of disease severity are advantages of this approach.

Airway administration of lipopolysaccharide (LPS) is a common way to study pulmonary inflammation and acute lung injury (ALI) in small animal models. ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...

Intratracheal Instillation of Stem Cells in Term Neonatal Rats

Prolonged exposure to high concentrations of oxygen leads to inflammation and acute lung injury, which is similar to human bronchopulmonary dysplasia (BPD). In premature infants, BPD is a major complication despite early use of surfactant therapy, optimal ventilation strategies, and noninvasive positive pressure ventilation. Because pulmonary inflammation plays a crucial role in the pathogenesis of BPD, corticosteroid use is one potential treatment to prevent it. Nevertheless, systemic corticosteroid treatment is not usually recommended for preterm infants due to long-term adverse effects. Preclinical studies and human phase I clinical trials demonstrated that use of mesenchymal stromal cells (MSCs) in hyperoxia-induced lung injuries and in preterm infants is safe and feasible. Intratracheal and intravenous MSC transplantation has been shown to protect against neonatal hyperoxic lung injury. Therefore, intratracheal administration of stem cells and combined surfactant and glucocorticoid treatment has emerged as a new strategy to treat newborns with respiratory disorders. The developmental stage of rat lungs at birth is equivalent to that in human lungs at 26&#8722;28 week of gestation. Hence, newborn rats are appropriate for studying intratracheal administration to preterm infants with respiratory distress to evaluate its efficacy. This intratracheal instillation technique is a clinically viable option for delivery of stem cells and drugs into the lungs.

Described is a protocol for performing intratracheal transplantation of mesenchymal stromal cells (MSCs) through intratracheal injection in term neonatal rats. This technique is a clinically viable option for delivery of stem cells and drugs into neonatal rat lungs to evaluate their efficacy.

Prolonged exposure to high concentrations of oxygen leads to inflammation and acute lung injury, which is similar to human bronchopulmonary dysplasia ...

Evaluation of Capnography Sampling Line Compatibility and Accuracy when Used with a Portable Capnography Monitor

Capnography is commonly used to monitor patient&#8217;s ventilatory status. While sidestream capnography has been shown to provide a reliable assessment of end-tidal CO2 (ETCO2), its accuracy is commonly validated using commercial kits composed of a capnography monitor and its matching disposable nasal cannula sampling lines. The purpose of this study was to assess the compatibility and accuracy of cross-paired capnography sampling lines with a single portable bedside capnography monitor. A series of 4 bench tests were performed to evaluate the tensile strength, rise time, ETCO2 accuracy as a function of respiratory rate, and ETCO2 accuracy in the presence of supplemental O2. Each bench test was performed using specialized, validated equipment to allow for a full evaluation of sampling line performance. The 4 bench tests successfully differentiated between sampling lines from different commercial sources and suggested that due to increased rise time and decreased ETCO2 accuracy, not all nasal cannula sampling lines provide reliable clinical data when cross-paired with a commercial capnography monitor. Care should be taken to ensure that any cross-pairing of capnography monitors and disposable sampling lines is fully validated for use across respiratory rates and supplemental O2 flow rates commonly encountered in clinical settings.

The goal of this study was to evaluate the accuracy of capnography sampling lines used in conjunction with a portable bedside capnography monitor. Sampling lines from 7 manufacturers were evaluated for tensile strength, rise time, and ETCO2 accuracy as a function of respiratory rate or supplemental oxygen flow rate.

Capnography is commonly used to monitor patient&#8217;s ventilatory status. While sidestream capnography has been shown to provide a reliable assessment ...

Ascending Aortic Banding for Studying Pressure-Overload Induced Heart Failure

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...