How dare we mention the words anesthetic complications. Just the mere thought of those two words can turn a good day bad. In this article, let’s focus on early warnings of trouble!
What is instructive in terms of gained knowledge in anesthetic complications are the differing safety measures and monitors available for use in applications where animals undergo anesthetic procedures. We often ask ourselves, what could we have done? What can we do? What tools are available?
Clinical judgment is the most important component of intraoperative monitoring. Any instrumentation used for intraoperative monitoring should always be in addition to the clinical judgment of competent veterinarians and veterinary anesthesia nurses. Typical standards are monitoring for oxygen saturation by pulse oximeter. This monitor measures blood hemoglobin oxygen saturation. In patients receiving supplemental oxygen, this parameter drops only when the patient’s circulation / ventilation is jeopardized. Many veterinary anesthesiologists believe in raising this standard to include monitoring for the presence of exhaled carbon dioxide using a capnograph. A capnograph like the Vetcorder Airmate™ can provide an extra level of patient safety by monitoring the adequacy of ventilation.
Let’s compare a Capnograph to a Pulse Oximeter:
Capnography and pulse oximetry measure two different physiologic processes – ventilation and oxygenation, respectively.
- Capnography measures EtCO2, which reflects ventilation – a capnograph can tell us how well a patient is managing their breathing while intubated.
- Pulse Oximetry reflects oxygen saturation in the blood. How much oxygen is getting into the blood after going through the lungs? While a low SpO2 can alert you to a ventilation problem, it is a relatively late alert. Unfortunately, many times too late.
Many board-certified anesthesiologists believe pulse oximetry is no substitute for capnography. In patients receiving supplemental oxygen, we often see an elevated SpO2 reading however it is artificial and could be potentially be masking a compromised ventilation. Relying on pulse oximetry alone can be misleading and even dangerous, giving a false sense of security that your patient is ventilating well.
Studies have validated that capnography is more effective than pulse oximetry in detecting early signs of respiratory complication.
Using a capnograph like the Vetcorder Airmate™ can also provide you with key information about the animal’s circulatory status, such as whether they have adequate cardiac output and are perfusing well. In addition, it provides anesthesia nurses key information about the patient’s metabolic status.
It is also important to understand the numerical readings and graphic waveforms to use a capnograph effectively. The numerical readings are derived from the respiratory cycle known as the end tidal CO2 (EtCO2). This is the point at the end of the exhale when the carbon dioxide reaches its highest level – this level is generally in the range of 35-45 mmHg. An elevated CO2 level is typically an indication of hypoventilation or increased metabolic activity. A low exhaled CO2 level may be indicative of hyperventilation, decreased cardiac output or poor pulmonary perfusion.
Should you be using a capnograph on every patient?
Consider this analogy – Would you be comfortable boarding a plane without radar capability? This is equivalent to performing a procedure requiring anesthesia without using a capnograph for patient monitoring. Protect patients every time with the Vetcorder Airmate™ Capnograph.