In April of 2017 I started a new job at a small animal practice that also employed a visiting boarded surgeon. On my second day on the job a 9-month-old French bulldog puppy presented with trouble breathing (shocking, I know)! After a few diagnostics it was determined that this Frenchie pup would need a lung lobectomy and thoracotomy. No problem, right? Well at this vet hospital I knew things were about to get interesting because they did not have a mechanical ventilator. So, for the almost 90 minutes of surgery, I became the mechanical ventilator. Has this ever happened to you?
In small animal veterinary medicine, anesthesia plays a crucial role in performing surgical procedures and diagnostic tests. Depending on the anesthetic agents used we can see variations from mild sedation to full-blown unconsciousness. When patients become unconscious many anesthetics can depress the natural process of ventilation, leading to potential complications such as hypoventilation and hypoxemia. During surgical and dental procedures requiring general anesthesia, these are everyday concerns. To address this, anesthetic ventilators have become an indispensable tool in veterinary practice, facilitating controlled and precise ventilation during anesthesia. Let's explore the significance of anesthetic ventilators in small animal veterinary medicine, highlighting the necessity of their use for safe and effective anesthesia in every veterinary practice (yes, even the GPs).
Understanding Ventilation
Ventilation, in the context of anesthesia, refers to the process of moving air in and out of the animal's lungs, facilitating the exchange of oxygen and carbon dioxide. This exchange is essential for maintaining optimal blood gas levels, ensuring the delivery of oxygen to tissues, and removing carbon dioxide, a waste product of metabolism. In conscious animals, the process of ventilation is automatic and involuntary, regulated by the brainstem in response to changes in oxygen and carbon dioxide levels.
Why Anesthetics Depress Ventilation
When an animal is administered anesthetic agents, these drugs act on the central nervous system, resulting in reversible loss of consciousness. While this state is necessary for pain-free surgery, it can also cause several physiological changes, including the depression of respiratory centers in the brainstem.
Anesthetic agents, such as inhalation anesthetics and certain injectable drugs like combinations of high-dose opioids and ketamine or induction agents such as propofol, can reduce the responsiveness of the respiratory centers to carbon dioxide levels. As a result, the animal's respiratory drive may be compromised, leading to shallow breathing or, in some cases, respiratory arrest. This is a reason you should always be prepared with intubation materials for patients that have had heavy sedation. Additionally, anesthetics can cause muscle relaxation, including the muscles responsible for breathing, further impeding ventilation. If you are at a practice that utilizes NMBA's a mechanical ventilator is an absolute must!
As the anesthesia technician monitoring the case, it's important to pay attention to your patient's breathing and end-tidal CO2 waveform. If your patient is hypoventilating or becomes hypoxemic some corrections can be made with intermittent positive pressure ventilation (IPPV). However, many procedures are lengthy (such as dentistry procedures) and due to the patient's positioning or body confirmation, a mechanical ventilator gives you the best way to easily maintain oxygenation and removal of carbon dioxide.
Here are Some of the Reasons You Should Invest in a Mechanical Ventilator
1. Maintaining Adequate Oxygenation
Anesthetic ventilators ensure that animals receive a consistent supply of oxygen during anesthesia. By precisely controlling the delivery of oxygen, ventilators help prevent hypoxemia (low blood oxygen levels) and its associated complications, such as tissue damage and organ failure.
2. Eliminating Exhaled Carbon Dioxide
Anesthetic ventilators effectively remove carbon dioxide from the animal's body, preventing its accumulation in the bloodstream, which can lead to respiratory acidosis and other detrimental effects.
3. Adjusting Ventilation Parameters
Each animal's respiratory needs may vary based on factors such as size, age, and overall health. Anesthetic ventilators allow you to customize ventilation parameters, including tidal volume and respiratory rate, to suit the specific requirements of the patient, ensuring optimal gas exchange. If you are in a practice that may do the occasional thoracotomy, a ventilator that can switch between pressure control mode and volume mode is a must.
4. Enhancing Anesthetic Safety
By providing precise control over ventilation, anesthetic ventilators reduce the risk of respiratory complications, such as atelectasis (collapsed lung regions) and hypoxemia. Many modern mechanical ventilators allow you to provide Positive End Expiratory Pressure (PEEP). So, what does PEEP do? Well, it helps maintain the lung's volume and prevents the alveoli from deflating completely during exhalation. By keeping the alveoli open, PEEP improves gas exchange, meaning oxygen can get into the bloodstream better, and carbon dioxide can be expelled more effectively. This enhances the overall safety of anesthesia, particularly in high-risk patients and prolonged procedures.
5. Monitoring Capabilities
Advanced anesthetic ventilators come equipped with sophisticated monitoring systems that provide real-time data on various parameters, including tidal volume, peak inspiratory pressure, end-tidal carbon dioxide levels, as well as measuring anesthetic gas agents. These measurements aid veterinary technicians who are monitoring physical parameters as well as assessing the animal's respiratory status and making timely adjustments if needed.
In small animal veterinary medicine, anesthetic ventilators play a critical role in ensuring the safety and efficacy of anesthesia.
Every practice, especially the ones performing dentistry procedures on higher-risk patients can benefit from understanding and properly using a mechanical ventilator. By addressing the inherent risks of respiratory depression associated with anesthetic agents, these devices maintain adequate ventilation, oxygenation, and carbon dioxide elimination during the perioperative period. Veterinary professionals rely on anesthetic ventilators to deliver tailored respiratory support, allowing for successful surgical procedures and a faster, smoother recovery for their patients. As technology continues to advance, anesthetic ventilators are expected to further evolve, contributing to improved outcomes and better patient care in small animal veterinary practice.