Total intravenous anaesthesia: An overview

Mohamed Najibullah*

Consultant Anaesthesiologist, Kauvery Hospital, Chennai

*Correspondence: [email protected]

Abstract

The objective of this article is to present an overview of a novel technique in anaesthesia known as Total Intravenous Anaesthesia (TIVA), its goals, advantages, disadvantages, different drugs and techniques used. Total Intravenous Anaesthesia (TIVA) refers to the technique of anaesthetising a patient using only intravenous agents without the use of volatile agents, using short-acting drugs like propofol, fentanyl, dexmedetomidine, etc. TIVA is useful in certain conditions and surgeries where the use of inhalational agents and neuromuscular blockade is a contraindicated or undesirable. It needs a thorough understanding of the pharmacokinetic profile of each drug used, their interactions with the patient and between themselves. Although it is possible to implement TIVA using pumps with the infusion rate controlled manually, the advent of pumps programmed with pharmacokinetic information has facilitated its use nowadays.

Keywords: Total intravenous anaesthesia (TIVA), propofol, fentanyl, dexmedetomidine, target-controlled infusion (TCI) pump, processed electroencephalogram (pEEG)

Background

What is TIVA?

Total Intravenous Anesthesia (TIVA) is a technique of general anesthesia which uses a combination of intravenous anaesthetic agents given via a syringe pump exclusively by the intravenous route without the use of inhalation agents [1].

Goals of TIVA:

The overall goals of TIVA include:

  1. Smooth induction of anaesthesia
  2. Reliable and measurable maintenance of anaesthesia
  3. Rapid emergence out of the effects of infused drugs as soon as the infusion is terminated.

When and why do we use TIVA?

  1. The use of TIVA is justified in cases where the delivery of inhaled anesthetics is not possible or undesirable , or in scenarios where traditional anaesthetic delivery systems may be unavailable or impractical.
  2. In certain cases where the use of TIVA could make the process more efficient and advantageous for the patient.

Knowledge required by the anaesthesiologist before administering TIVA

  1. The principles behind achieving and maintaining an appropriate plasma and brain concentration of the i.v. anaesthetic drug
  2. The factors determining the appropriate target drug concentration to aim for, and how to adjust this in the light of the patient’s response
  3. Practical aspects involved in ensuring that the intended dose of drug is delivered to the patient;
  4. Monitoring of the patient receiving TIVA including the use and interpretation of pEEG monitors.

Specific situations where TIVA is useful

  1. Patients with risk of Malignant hyperthermia
  2. Long QT syndrome (QTc ≥ 500 ms)
  3. History of severe Postoperative nausea and vomiting (PONV)
  4. ‘Tubeless’ ENT and thoracic surgery
  5. Patients with anticipated difficult intubation/extubation
  6. Neurosurgery-to limit intracranial volume
  7. Surgery requiring neurophysiological monitoring- brachial plexus injuries, spinal cord tumours, etc.
  8. Myasthenia gravis/neuromuscular disorders, and situations where neuromuscular blockers (NMBs) are of disadvantage
  9. Anaesthesia in non-theatre environments
  10. Transfer of an anaesthetised patient between environments
  11. Daycare surgery
  12. Patient choice

Advantages

Compared to traditional volatile anaesthetic techniques, TIVA offer several potential advantages. These include:

  1. Reduced incidence of post-operative nausea and vomiting [3]
  2. Better postoperative recovery [4]
  3. Greater hemodynamic stability [5]
  4. Lesser incidence of bradycardia and hypotensive episodes [6]
  5. Better intubation conditions [6]
  6. Better cerebral auto regulation
  7. Reduced stress response
  8. No risk of environmental pollution with anaesthetic gases

Disadvantages

  1. A slightly increased risk of awareness
  2. Hemodynamic instability in the setting of severe blood loss
  3. No accurate method to monitor drug concentration in real time
  4. More challenging to titrate drug dosage in patients with opioid or benzodiazepine tolerance
  5. More time-consuming
  6. Risk of inadequate delivery of drugs due to equipment malfunction/disconnection of tubings.
  7. Need for special equipment like syringe pumps, target-controlled infusion (TCI) pumps, invasive monitoring, etc

Drugs used in TIVA

Propofol

  1. Most commonly used drug in TIVA because of its rapid onset and offset, beneficial properties and few adverse effects
  2. Its rapid onset of action is due to its high lipid-solubility , rapid redistribution from the brain to other parts of the body, and rapid clearance.
  3. Propofol is conjugated in the liver with pharmacologically inactive metabolites. (7)
  4. Dosage: 1-2.5mg/kg bolus followed by maintenance infusion of 25-200mcg/kg/hr

Fentanyl

  1. Most commonly used opioid due to its rapid onset (3-5 min), short duration (30-60 min) & rapid elimination by the liver into inactive metabolites
  2. Dosage: 1-2 mcg/kg bolus followed by maintenance infusion of 1-2 mcg/kg/hr
  3. Potent analgesic. It is 100 times more potent than morphine
  4. It reduces autonomic responses to airway manipulation, provides hemodynamic stability and lesser respiratory depression [8]

Dexmedetomidine

  1. Non-selective alpha2 agonist having sympatholytic, sedative & analgesic properties
  2. Elimination half-life of 2-3 hours with a context-sensitive half-life of 250 min after an 8-hour infusion
  3. Dosage: 1 mcg/kg bolus over 10 min followed by maintenance infusion of 0.2-0.7 mcg/kg/hr

Other drugs

  1. Other drugs which are sometimes used in TIVA include Etomidate, Ketamine, Midazolam, etc
  2. Etomidate and Ketamine are useful in hemodynamically unstable patients but their use is limited because of adverse side effects like cortical suppression in the case of Etomidate & sympathetic stimulation in the case of Ketamine, etc.
  3. Midazolam is nowadays not used due to its propensity to cause respiratory depression.

How is TIVA administered

Administering TIVA can be done in two ways:

  1. Manual dosing – giving a bolus and setting an infusion rate (ml/h). This is the easiest and most commonly used method.
  2. Target controlled Infusion (TCI) – this is the preferred and recommended option.

Manual dosing

  1. When TIVA is administered manually (i.e. without a TCI pump), a thorough understanding of the pharmacokinetics of the drugs being used is necessary.
  2. There is considerable variation between patients in the brain propofol concentration required for anaesthesia [9].
  3. In general, older patients require a lower brain anaesthetic drug concentration than younger patients, but there is considerable variation between individuals of the same age and overlap between patients of different ages [10].
  4. The ‘Roberts’ (or Bristol) regimen for Propofol has been commonly used. It involves a loading bolus of 1 mg.kg-1 followed by a step-down infusion scheme (10 mg/kg/h for the first 10 min, 8 mg/kg/h for the next 10 min, and then 6 mg/kg/h) [11].

Target-Controlled Infusion (TCI)

  1. TCI is achieved by the use of dedicated pumps
  2. TCI pump contains a micropressor programmed with pharmacokinetic models for relevant drugs
  3. Various pre-programmed pharmacokinetic models have been developed to achieve desired drug concentration in TIVA.
  4. Some of the most commonly used models are

Adults

  1. Kataria
  2. Paedfusor
  3. Eleveld

Paediatrics

  1. Kataria
  2. Paedfusor
  3. Marsh
Total-intravenous-anaesthesia-1
Total-intravenous-anaesthesia-2

Monitoring during TIVA

In addition to the routinely used monitors during general anaesthesia such as ECG, pulse oximetry, NIBP, PR, etc. the following monitors are commonly used during TIVA….

  1. Intra-arterial BP: To look for hemodynamic fluctuations
  2. Processed EEG: to look for awareness during anaesthesia. Recommended but not available in all centers.
Total-intravenous-anaesthesia-3

Guidelines for safe administration of TIVA

  1. The Society for Intravenous Anaesthesia (SIVA) and the Association of Anaesthetists have come out with specific guidelines to be followed while administering TIVA
  2. These have been made in response to the recommendations made by the 5th national Audit project (NAP5) on accidental awareness during TIVA.

Our experience with TIVA at Kauvery Hospital Chennai

  1. At Chennai Kauvery Hospital, we have successfully administered TIVA to 110 patients since 2019
  2. Surgeries done under TIVA included a wide range of spinal cord tumors, brachial plexus injuries, cord decompressions, etc which were done under neuromuscular monitoring without the use of inhalational agents or neuromuscular blockade.
  3. Age of the patients varied from 6 to 78 years.
  4. All the surgeries were completed successfully under TIVA without the need to convert to full General anaesthesia with volatile anaesthesia and muscle relaxants.

Conclusion

TIVA has many potential benefits and it is important for anaesthetists to be equally competent in intravenous anaesthesia as they are with inhalational anaesthesia

Having an understanding of the pharmacokinetic principles and pharmacodynamic effects of different TIVA drugs as well as different co-administration drugs will help to select the safest doses for induction and maintenance.

Consider the patient as a whole – age, clinical status, co-administration drugs, type of surgery have an effect on the drug dosage and action

The use of pEEG is recommended during TIVA especially when neuromuscular blockage is used.

References

  1. Total Intravenous Anesthesia using a target controlled infusion – A pocket reference’, College of Anesthesiologists, Academy of Medicine Malaysia (retrieved 07.10.15).
  2. Yuill G, et al. An introduction to total intravenous anaesthesia. BJA CEPD Rev. 2002;2(1):24-26.
  3. Ozkose Z, et al. Inhalation versus total intravenous anesthesia for lumbar disc herniation: comparison of hemodynamic effects, recovery characteristics, and cost. J Neurosurg Anesthesiol. 2001;13(4):296-302.
  4. Lee WK, et al. Type of anaesthesia and patient quality of recovery: a randomized trial comparing propofol-remifentanil total i.v. anaesthesia with desflurane anaesthesia. Br J Anaesth 2015;114(4):663-668.
  5. Wang Y, et al. A randomized comparison of target-controlled infusion of remifentanil and propofol with desflurane and fentanyl for laryngeal surgery. J Otorhinolaryngol Relat Spec. 2011;73(1):47-52.
  6. Godet G, et al. A comparison of sevoflurane, target-controlled infusion propofol, and propofol/isoflurane anesthesia in patients undergoing carotid surgery: a quality of anesthesia and recovery profile. Anesth Analg 2001;93(3):560-565.
  7. McGrenaghan E, et al. Total intravenous anaesthesia. Anaesth Intens Care Med. 2019;20(2):130-5.
  8. Murat I, et al. Effects of fentanyl on baroreceptor reflex control of heart rate in newborn infants. Anesthesiol. 1988;68:712-22.
  9. Absalom A, et al. ‘Paedfusor’ pharmacokinetic data set. Br J Anaesth 2019;95:110.
  10. Minto CF, et al. Influence of age and gender on the pharmacokinetics and pharmacodynamics of remifentanil. I. Model development. Anesthesiol. 1997;86:10-23.
  11. Roberts FL, et al. Induction and maintenance of propofol anaesthesia. A manual infusion scheme. Anaesth. 1988;43:S14-S17.

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