Routine monitors include blood pressure cuff, heart monitor, and pulse oximeter. Every patient wears these during surgery. Some situations call for special monitors during surgery. Either special aspects of a surgical procedure, or special medical conditions existing in a patient may call for special monitors. Likewise some situations will require a urinary catheter or nasogastric tube. Occasionally patients appear to think their anesthesiologist is being unkind to trouble them with these devices. Please be assured that in each case where they are used the anesthesiologist believes that any risks or discomfort associated with them are far overshadowed by potential benefit. These are the tools anesthesiologists use to provide better outcome for patients who need them.
A urinary catheter, also often called a Foley catheter, is a tube inserted into the bladder during anesthesia to drain urine both during and after surgery. Sometimes after surgery, patients have trouble getting their urine out. This device solves that problem. Also, it allows the anesthesiologist to measure urine output during surgery. This helps him gauge the proper amount of fluid to provide for the patient during surgery.
A nasogastric tube is a soft plastic tube, of diameter about that of a pencil, which is inserted through the nose into the stomach during anesthesia. Most commonly it is used in intraabdominal surgery. When the surgeon works in the abdomen, the bowel is manipulated. After being manipulated, it often stops working for several days. The bowel normally moves fluids through the digestive system. When it ceases to perform this function, fluids accumulate, and having no other way out, are expelled as vomiting. Wearing a nasogastric tube is uncomfortable - it often causes sore nose and throat. But the alternative of continuous vomiting is even more unpleasant.
One special monitor is an arterial line. An arterial line is a small plastic tube inserted into an artery, usually the artery at your wrist called the radial artery. The small tube is the same kind that is used to put in a vein to start an intravenous. It is attached to devices which allow display of a continuous tracing of blood pressure on a screen like a heart monitor tracing, but for blood pressure. The arterial line allows the anesthesiologist to measure blood pressure continuously and to withdraw samples of arterial blood without making new punctures.
The arterial line is inserted in the operating room by the anesthesiologist. Sometimes it is best put in before starting anesthesia, sometimes after the patient is asleep. When it is put in while the patient is awake, the experience is similar to having an intravenous started. Rarely is it significantly uncomfortable. The arterial line may be removed at the end of surgery, in the recovery room, or it may stay in a day or more.
Another special monitor is a central venous pressure line, also called simply a central line or a CVP. To establish this monitor a special intravenous tube is inserted in to the side of the neck into the jugular vein or under the collar bone into the subclavian vein. The tip of the catheter is inserted down toward, but not into the heart. This monitor helps to guide the accurate replacement of fluid and blood. It also provides a route for rapid replacement of fluid and blood. It is sometimes used to provide intravenous feeding of patients after surgery. It is sometimes used to provide an intravenous route for patients whose arm and leg veins are inaccessible.
The CVP is usually inserted with the patient asleep. It may be removed at the end of surgery, or remain for some days after surgery.
A third special monitor is the pulmonary artery catheter. This device is another special intravenous, inserted like the CVP through the jugular vein or subclavian vein and passed through the right heart into the pulmonary artery. This device is usually employed in patients with more advanced forms of heart disease or in surgery where the chances of blood loss are increased. It provides the best possible information to guide fluid administration for optimizing heart function.
pulmonary artery catheter