Anesthesia Monitoring

Patient in a surgical setting wearing a cap and receiving ventilation or anesthesia via a face mask held by a gloved healthcare provider.

Monitoring the patient during anesthesia is now a standard part of any surgical procedure. This not only ensures patient safety, but also protects medical staff in the event of emissions of anesthetic gases.

The number of surgeries performed is steadily increasing with each passing year. The WHO estimates that more than 300 million operations were performed worldwide in 2012, an increase of more than 38% compared to 2004. The reasons for this are manifold: from improved treatment options for diseases to financial incentives in the accounting system in certain countries. Regardless of the reasons the safety of patients and medical staff is paramount. To guarantee a safe environment it is important to be able to dose anesthetic agents precisely, monitor them and adjust them according to the situation.

Holistic Monitoring for Optimal Anesthesia

Even though anesthesia is generally considered safe today, it is still a medical procedure that involves risks. The level of risk depends on the age and condition of the patient in question.

Clinician operates an anesthesia machine and ventilator, monitoring and adjusting settings while manually ventilating a patient during surgery.

To minimize the risk to the patient as much as possible, many parameters must be monitored during anesthesia. The most informative vital parameters here are monitoring of the heartbeat by means of ECG and measurement of pulse and blood pressure. But carbon dioxide (CO₂) and oxygen (O₂) as relevant respiratory gases also provide valuable data. In order to be able to adjust the anesthesia to all these parameters correctly, it is also important to measure the anesthetic gases themselves. During delivery to the patient, defined gas mixtures are controlled by means of flow sensors. However, how well the respective anesthetics are metabolized by the patient can only be determined by the exhaled air. The technique of infrared spectroscopy has been used successfully here for a long time.

Flexible Measurement Technology for High Demands in Anesthesia

n addition to nitrous oxide (N₂O) and halothane, fluranes in particular are used nowadays for inhalation anesthesia. Since most anesthetic gases mainly have a hypnotic effect on the human body, they are combined with pain-relieving substances.

Close-up of anesthesia or ventilator machine panel with dials and digital displays in a surgical operating room, surgical team working in the background.

Due to its pleasant odor, only sevoflurane is also suitable for induction of anesthesia; all other gases are mainly used for its perpetuation. In addition to these anesthetic gases, CO₂ must also be measured simultaneously in the exhaled air. Therefore, the infrared spectrometers used have detectors for up to 7 different gases. A broadband infrared source such as the EMIRS from Axetris with a high emission power over the entire, relevant spectral range is particularly important for this application. Real-time measurement enables the gases used to be adapted to a changing situation at any time.

Infrared Spectroscopy for a Safe Workplace

In addition to patients, medical personnel are also exposed to anesthetic gas. Admittedly in much lower concentrations, but overall over a much longer period in the course of their professional lives.

Medical professional in surgical attire, mask, and hair cover is adjusting settings on a device, likely an anesthesia or patient monitoring system, in a clinical environment.

Therefore, from an occupational safety perspective, it makes sense to also monitor emissions and possible leaks of anesthetic gases. The exact limits for the anesthetic gas in each case vary, but they are always in the lower ppm range. In addition to special leakage measuring devices, measuring techniques can also be used to monitor the room air. These are mostly based on the technique of infrared spectroscopy. A significant advantage of this measuring technique is that they can measure all common inhalation anesthetics simultaneously. Therefore, they can be used flexibly and do not have to be replaced depending on the anesthetic gas used. In contrast to gas chromatography, these devices are also significantly less expensive and can measure in real time during surgery.