Patient Monitoring – Anesthetic Systems

00:00 So, all of the alarms we've talked about are on the anesthetic machines, and that's part of the standard monitoring system in an operating room. In addition to that, every patient gets an electrocardiogram.

00:17 And most of us use a 5 lead electrocardiogram, because this is a much more sensitive way of measuring for coronary ischemia, lack of oxygen supply to the heart, than just a 3 lead. We all use automatic, and hopefully properly calibrated, blood pressure cuffs. There's automatically, on every patient, an oxygen saturation monitor, an oximeter. The introduction of the oximeter in the late 1980's, revolutionized the way we treat patients and improved care exponentially.

00:53 On the machine, there is end-tidal carbon dioxide monitoring, so that we always know that we're connected to the patient, and that the patient is producing carbon dioxide, and it also allows us to adjust ventilation, to make sure the carbon dioxide level is within what we considered to be a safe and normal range. We constantly monitor tidal volume and airway pressure through the machine as well, it's all done on every anesthetic machine virtually seamlessly.

01:23 Then, at the discretion of the anesthesiologist, there are additional monitors that can be put in place. The peripheral nerve stimulator can monitor muscle relaxant status, and we can actually determine when it's possible to reverse a muscle relaxant, by using this device.

01:41 Or we can determine that maybe the surgeon's right, that the patient isn't adequately paralyzed, and it's time to give more muscle relaxant. Temperature monitoring is mandatory in the United States, but is immediately available in most places.

01:59 Initially it was introduced as a way to monitor for malignant hyperthermia, which we will talk about in more detail in a later lecture, but it turns out that temperature changes are a late indicator of that disorder. So, monitoring temperature for that disorder is probably not an important feature of temperature monitoring, but operating rooms tend to be cold, and people lose heat in operating rooms. And there's danger in losing heat and becoming hypothermic.

02:29 So most of us measure temperature on a regular basis as well. Modern anesthetic machines also tell us exactly how much vapour the patient is receiving on inspiration, and more importantly, from the perspective of knowing how deep our anesthetic is, shows us what their end-tidal vapour level is. So their expired vapour at the end of a breath. We know exactly how much is returning to the machine, and whether the patient is retaining enough to maintain anesthesia. We also can use ultrasound transthoracically across the thoracic wall, or transabdominally to look for evolving problems in the chest or in the abdomen. There are a number of invasive monitors that are used