Sevoflurane: An Ideal Inhalation Anaesthetic for Surgeries

 

Sevoflurane

Sevoflurane is a widely used inhalation anesthetic for general anesthesia. It has certain properties that make it an ideal choice for carrying out surgical procedures smoothly.

Physical and Chemical Properties

Sevoflurane is a haloether that is clear, colorless, and nonflammable liquid at room temperature. Its chemical formula is C4H3F7O and molecular weight is 200. Its boiling point is 58°C which allows it to vaporize quickly from the vaporizer into the carrier gas. Some key physical properties that make it suitable for anesthesia include low solubility in blood and tissues, nonpungency, and negligible metabolism. These ensure a rapid onset and offset of anesthesia.

Rapid Onset and Offset of Action

Due to its low solubility, Sevoflurane produces anesthesia very quickly after inspiration. This property allows fast induction of anesthesia as the patient loses consciousness within 2-3 minutes of starting sevoflurane inhalation. Similarly, when administration is discontinued, sevoflurane is rapidly eliminated from the body through expiration. Patients regain consciousness quickly within 5-10 minutes,Resume pre-anesthesia level of consciousness. This rapid offset of action makes sevoflurane ideal for short outpatient surgeries as it allows speedy recovery and discharge.

Hemodynamic Stability

During induction and maintenance of anesthesia, sevoflurane does not cause significant changes in heart rate and blood pressure as compared to other gases. This hemodynamic stability is beneficial for patients with cardiovascular diseases. The stable cardiovascular function also makes sevoflurane suitable for surgeries involving minimal blood loss like laparoscopic procedures.

Minimal Respiratory Depression

Sevoflurane exerts less depressing effect on respiration compared to older halogenated gases. It produces minimal reductions in tidal volume, respiratory rate, and minute volume especially at 1-2 MAC concentrations required for surgery. This characteristic reduces the need for mechanical ventilation in minor procedures.

Nausea and Vomiting

Postoperative nausea and vomiting (PONV) is an unpleasant complication of anesthesia. Sevoflurane, when used as the sole anesthetic, is associated with a low incidence of PONV. This favorable side effect profile and early recovery enhances patient satisfaction in the postoperative period.

Advantages over Other Agents

In this section, we will compare sevoflurane with other commonly used inhalation anesthetics to highlight its advantages:

Comparison with Isoflurane

Both isoflurane and sevoflurane are highly volatile ethers used for inhalation-based general anesthesia. However, sevoflurane has a lower blood-gas partition coefficient than isoflurane which allows faster induction and emergence. Additionally, sevoflurane provides more hemodynamic stability and fewer reports of exciting emergence phenomena like involuntary muscle movements.

Comparison with Desflurane

Desflurane is another low-solubility gas used for rapid-sequence inductions. Though desflurane has a faster emergence than sevoflurane, its high volatility increases operating room expenditures due to increased gas consumption. Sevoflurane consumption is lower making it more cost-effective compared to desflurane, especially for prolonged procedures.

Comparison with Nitrous Oxide

Nitrous oxide (N2O) is used as an adjunct to other inhalational agents, but its sole use as anesthetic has been limited. Sevoflurane does not require N2O for favorable anesthetic profiles, making it safer for procedures like abdominal/neurosurgeries where N2O is best avoided. It also obviates the need for N2O scavenging systems.