Total intravenous anaesthesia (TIVA) is a technique of anaesthesia which involves use ofintravenous drugs to anaesthetize the patient without the use of inhalational agents. TIVAis getting popular mode of anaesthesia in otolaryngological surgeries. This article reviewsthe entire procedure of TIVA from otolaryngologist’s perspective. TIVA is really useful toanaesthetize patients during functional endoscopic sinus surgeries due to its ability toproduce controlled hypotension, and post-operative vomiting free recovery.
Introduction:TIVA is defined as a technique of general anaesthesia which involves use of intravenous drugs to anaesthetize the patient without the use of inhalational agents. In fact chloral hydrate1 was the first anaesthetic agent to be introduced intravenously way back in 1870.Introduction of Propofol in 1986 gave a new lease of life to TIVA.It was Sigismund Elsholtz who first attempted intravenous anaesthesia in 16652 . Real advance in intravenous anaesthesia took place during 1921 when Daniel and Gabriel Bardet published their experiences using somnifaine. Fredet and Perlis combined somnifaine withsubcutaneous injection of morphine to supplement the effects of somnifaine. To begin with a Vann’s 10 ml syringe was used for this purpose. To facilitate continuous intravenous infusion Abel’s syringe3 was used.The current popularity of TIVA has been attributed to the pharmacokinetic and pharmacodynamics properties of Propofol and opioids. These drugs are ultra-short acting and hence suitable for continuous infusion. With the advent of advanced computer based drug administration system intravenous drug administration has become safer and predictable. The currently available intravenous drug delivery system allows the anaesthetists of vary the depth of anaesthesia by just controlling the infusion rate of thedrug. This is in fact similar to that of conventional inhalational systems currently available.
Advantages of TIVA 4 :
1. Recovery is smooth and predictable2. No post-operative vomiting3. There is no pollution4. Allows high dose of oxygen to be inspired5. There is virtually no bowel distention6. Reduced requirement for muscle relaxants7. Intraocular pressure is reduced8. Malignant hyperthermia is virtually unknown9. Controlled hypotension is possible10. Produces adequate amnesia11. Produces adequate analgesia12. Less neuro humoral responseDrug pharmacokinetics:This is actually the use of mathematics to describe how body handles a certain drug. This is in a nutshell a calculation of the mathematical relationship between the administered dose of drug and the resulting observed changes in its plasma concentration. This is very important in deciding which drug / drug combinations can be safely used to administerTIVA.
Goals of TIVA:1. Smooth induction2. Reliable and titratable maintenance of anaesthesia3. Rapid emergence out of the effects of infused drug as soon as the infusion is terminatedDrug combinations used in TIVA:1. Propofol with remifentanil2. Propofol with sufentanil3. Midazolam with sufentanil 5 (used in patients susceptible to hyperthermia)Only flip side to TIVA is the expense involved. The newer drugs are highly expensive and coupled with the cost of computerized delivery system adds to the cost.
Target controlled infusion:This is the basis of TIVA. This system calculates the drug concentration, the delay in the transfer of blood brain barrier. Drugs like Propofol affects its own pharmacokinetics, probably by decreasing cardiac output and also by decreasing hepatic blood flow4 . Target controlled infusion is performed using a syringe pump.
Important functions of syringe pump include5 :1. Bolus – This gives the ability to rapidly increase plasma concentration of the drug administered2. Flow rate – The pump should be able to function accurately even at low flow rates3. Alarms – Facilitates identification of improper positioning of syringe in the pump4. Tight syringe fitting – This prevents syringe from moving when the pump is in action5. Battery indicator
Precautions that should be taken while using syringe pump:1. High concentration of drugs that run at slow speed should be avoided2. The syringe pump should be connected close to the patient3. Vasoactive drugs should not be combined with the primary drug4. Pump should not be placed above the level of the patientOtolaryngological surgeries where TIVP is preferred:1. Functional endoscopic sinus surgery 62. Thyroid surgeries where recurrent laryngeal nerve monitoring is needed3. Advanced endoscopic surgical procedures involving skull base where hypotensive anaesthesia is needed to control bleeding
Propofol:This drug is GABA receptor agonist. This drug produces deep state of unconsciousness within 30 seconds of administration of loading dose (1.5-2.5 mg/kg body weight). It is also known to cause respiratory depression in 90% of patients. Effects of this drug wanes within5 minutes of administration due to redistribution of the drug. This drug causes lower incidence of post-operative vomiting. Liver plays a vital role in elimination of Propofol.Opioids:Total intravenous anaesthesia (TIVA) is a technique of anaesthesia which involves use of intravenous drugs to anaesthetize the patient without the use of inhalational agents. TIVA is getting popular mode of anaesthesia in otolaryngological surgeries. This article reviews the entire procedure of TIVA from otolaryngologist’s perspective. TIVA is really useful toanaesthetize patients during functional endoscopic sinus surgeries due to its ability to produce controlled hypotension, and post-operative vomiting free recovery.
Commonly used opioids in TVIP include:MorphineFentanyl – 100 times more potent than morphineRemifentanyl – Short half lifeSufentanyl – Ultra short half lifeCurrently only Remifentanyl / Sufentanyl is being used.
- JARMAN, R., and ABEL, A. L. (I936), "Pentothal Sodium, Intravenous Anaesthesia," Lancet, 1, 42.
- An introduction to Intravenous anaesthesia Gordon Yuill, Milda Simpson British Journal of Anaesthesia volume 2 Number 1 2002
- Tirelli G, Bigarini S, Russolo M, Lucangelo U, Gullo A. Total intravenous anaesthesia in endoscopic sinus-nasal surgery. Acta Otorhinolaryngol Ital. 2004;24:137–44. [PubMed]