Total intravenous anaesthesia

Total Intravenous Anaesthesia (TIVA) is a technique of anesthesia that involves the exclusive use of intravenous drugs to induce and maintain general anesthesia without the use of inhalational anaesthetics. TIVA is commonly used for surgeries where maintaining a stable respiratory and cardiovascular system is crucial, and for patients where inhalational anaesthetics are contraindicated.

Indications

TIVA is indicated in a variety of surgical procedures, particularly those involving the airway, such as ENT surgery, and in patients where the use of gas anaesthetics might increase the risk of complications, such as those with a history of malignant hyperthermia. It is also preferred in procedures where minimal post-operative nausea and vomiting (PONV) is desired and in situations where the precise control of the anaesthetic depth is required, such as neurosurgery.

Drugs Used

The most commonly used drugs for TIVA include propofol, which is used for induction and maintenance of anesthesia, and opioids such as remifentanil or fentanyl for analgesia. Benzodiazepines may also be used for their anxiolytic and amnesic properties. The choice of drugs and their dosages depends on the patient's health, the duration of the surgery, and the specific requirements of the procedure.

Advantages

TIVA has several advantages over inhalational anaesthesia, including a lower risk of PONV, faster recovery times, and less impact on the environment due to the absence of greenhouse gas emissions. It also allows for a more stable hemodynamic profile during surgery and reduces the risk of airway irritation.

Disadvantages

However, TIVA requires sophisticated infusion devices and continuous monitoring of the patient's depth of anesthesia, which can be challenging. There is also a risk of awareness during surgery if the anesthesia is inadequately managed. Additionally, the lack of a gas mixture means that TIVA cannot be used to manage the patient's ventilation.

Techniques

The administration of TIVA typically involves the use of programmable infusion pumps that allow for the continuous and controlled delivery of anaesthetic agents. The Target-Controlled Infusion (TCI) technique is often used, where the infusion rate is adjusted based on the desired target concentration of the drug in the patient's brain.

Monitoring

Monitoring during TIVA is critical and includes standard anesthesia monitoring protocols such as electrocardiogram (ECG), blood pressure, and oxygen saturation. Additionally, the depth of anesthesia is often monitored using bispectral index (BIS) or similar neurophysiological monitoring techniques to ensure the patient remains unconscious and does not experience awareness during the procedure.

Conclusion

Total Intravenous Anaesthesia is a versatile and effective method for inducing and maintaining general anesthesia, particularly suited to certain patient groups and surgical procedures. Its success relies on the careful selection of drugs, sophisticated infusion systems, and diligent monitoring of the patient throughout the surgical process.