Getting Back to Basics: Surgical Monitoring in Rodents for Better Experiments

Clinical advancements in the diagnosis and treatment of cardiovascular disease stem from essential pre-clinical research.  Small animal models, such as rodents, are used to study the pathophysiology of disease as well as the effects of pharmacologic interventions.  In some cases, surgical methods are required to generate a disease model, such as transverse aortic constriction to mimic pressure overload-induced hypertrophy and heart failure.   The genetic and molecular factors underlying pathophysiology, as well as the novel therapeutic agents being investigated advance our understanding of disease and eventually translate to the clinic. However, these outcomes rely on accurate and consistent lab work, especially small animal surgeries.


Why is surgical monitoring important?

Monitoring animal vital signs during a procedure provides insight into animal health and enables the researcher to identify and intervene when problems arise, resulting in more consistent surgeries.

Anesthetics induce central nervous system, cardiovascular system and respiratory depression in animals. Without careful monitoring, cardiac output and respiration may be lost.  Anesthetics also inhibit temperature regulation centers in the brain, and hypothermia reduces platelet function, lowers cardiac output and enhances bradycardia and cardiac respiratory depression.  Monitoring vital signs such as heart rate, core temperature and respiration rate are essential to animal wellbeing, especially to ensure full recovery from a surgery.

These physiological parameters may also influence the quality of data collected during an experiment.  For example, vascular and ventricular pressure measured with catheters can be compromised if animal physiology changes due to the surgical intervention.  Monitoring vital signs can ensure the animal is in stable condition prior to initiating data collection.

Identifying vital sign abnormalities also enables researchers to intervene when problems arise and improve surgical outcomes.  For example, a sudden increase in respiration rate or heart rate can be a cue the animal is not sufficiently anesthetized, and ECG abnormalities may indicate infarction. When this data is available, the researcher can take steps to restore physiological function and reduce complications.


Key vital signs to monitor

  • Respiration: a high respiratory rate may indicate the animal is not adequately anesthetized, or that it is experiencing some discomfort. A very low respiratory rate may indicate respiratory depression and may require reducing the anesthetic delivery.
  • ECG: provides information pertaining to heart rate, rhythm, and ischemia or infarction. ECG monitoring provides valuable data during surgery and can also be reviewed following an unsuccessful procedure to assess the cause.
  • Heart rate: is a rapid way to ensure normal cardiovascular function.
  • Temperature: several factors such as anesthetic agents, hair clipping, and evaporation of aseptic preparation solutions drive heat loss during surgery. Falling core temperature results in reduced metabolism and deeper anesthesia.
  • Pulse oximetry: provides a simple, noninvasive method to assess blood oxygenation.



How to create your optimal surgical workspace

When designing a surgical workspace, it is important to factor in animal and researcher wellbeing.  There are numerous guidelines and protocols in place to ensure animal health, but very few pertaining to user safety when working with gas anesthesia.  Short term user exposure can cause eye irritation, headache, cough, dizziness, etc. Thus, ensuring appropriate ventilation and gas scavenging is essential.  Here are a few things to keep in mind when assembling your workspace:

  • Ensure you have enough space for microscopes, surgical lighting, and supplies.
  • Keep sterilizing solutions and autoclave packages stocked and easy to locate.
  • Consider access to electrical outlets for various instruments.
  • Ensure the surgical field includes a heating device as well as a surgical monitoring system to ensure animal vitals are maintained during the procedure.
  • If working in a fume hood is not possible, ensure the gas anesthesia system has appropriate active scavenging capabilities. This consists of connecting to a central exhaust system or using an active gas scavenging unit with a charcoal filter.

By implementing good monitoring practices, a laboratory can enhance the success of their experiments by improving surgical consistency and generation of accurate disease models. Monitoring can also help to reduce the number of animals lost to unsuccessful procedures by spotting problems sooner and ensuring there were no surgical complications.  Using surgical monitoring devices can also reduce the cost of personnel involved in monitoring during procedures as well as streamline record keeping and reporting.  Returning to the fundamental principles of surgical monitoring can enable consistent experiments and exiting new discoveries.

Scintica Instrumentation offers surgical monitoring and anesthesia solutions. Click to learn more about our Rodent Surgical Monitor+ and our UNO BV anesthesia solutions.  Questions? Feel free to send us a message ( or call our applications specialists (+1 519 914 5495).

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