THIEME Review Article 141 Total Intravenous Anesthesia in Neurosurgery Narmadhalakshmi Kannabiran1 Prasanna Udupi Bidkar2 1Department of Neuroanaesthesiology, Jawaharlal Institute Address for correspondence Prasanna Udupi Bidkar, MBBS, MD of Postgraduate Medical Education and Research (JIPMER), (Anesthesiology), DNB (Anesthesiology), DM (Neuroanesthesiology) Pondicherry, India MNAMS, MBA, Division of Neuroanaesthesia, Department 2Division of Neuroanaesthesia, Department of Anaesthesiology of Anaesthesiology and Critical Care, Jawaharlal Institute of and Critical Care, Jawaharlal Institute of Postgraduate Medical Postgraduate Medical Education and Research (JIPMER), Pondicherry Education and Research (JIPMER), Pondicherry, India 605006, Tamil Nadu, India (e-mail: [email protected]). J Neuroanaesthesiol Crit Care 2018;5:141–149 Abstract In recent years, neurosurgical anesthesia has been rapidly evolving in the fields of pharmacotherapy and techniques to administer safe anesthesia. Intravenous (IV) anesthetic agents reduce both cerebral blood flow and intracranial pressure besides maintaining flow–metabolism coupling in contrast to inhalational agents. In neuro- anesthesia, the technique and choice of drugs directly influence the outcome of the patients. The purpose of this review is to provide the updated information of total intravenous anesthesia (TIVA) in neuroanesthesia. Administration of TIVA using tar- get-controlled infusion technique is emerging as a standard method to administer safe anesthesia in neurosurgical patients. The propofol–remifentanil combination has Keywords become very popular due to their favorable pharmacokinetic and pharmacodynamic ► neurosurgery properties for neurosurgery cases. Plasma-effect site concentration monitoring from ► TIVA target TCI devices together with electroencephalogram or bispectral index monitors ► propofol allows easy titration of anesthetic agents to ensure adequate depth of anesthesia ► remifentanil depending upon the nociceptive stimulus. TIVA is associated with smooth induction ► dexmedetomidine and rapid emergence with less postoperative nausea and vomiting. Introduction of adequate cerebral perfusion pressure (CPP), avoidance of intracranial hypertension, and the provision of optimal sur- Neuroanesthesia has been rapidly evolving over the decades. gical conditions to avoid further progression of the pre-exist- Anesthesia for neurosurgical procedures requires an under- ing neurological insult.1 The aforementioned conditions can standing of cerebral anatomy, physiological cerebral flow be achieved by both inhalational and total intravenous anes- dynamics, and the likely changes that occur in response to thesia (TIVA).2 However, in certain circumstances, TIVA has the pathological rise in intracranial pressure (ICP). With the edge over the other technique, as the evidence is weak the development of safer and faster acting inhalational and for inhalational agents, and affirmation on TIVA also needs intravenous (IV) anesthetic agents, a balanced anesthesia is to be established. widely provided in a variety of neurosurgical cases. But, it The IV thiopental was introduced into clinical practice in is always challenging to provide optimal anesthesia during 1934 and was widely used during world war II,3 but its pop- perioperative period. ularity fell soon after the attack on Pearl Harbor when sol- We cannot deny the fact that IV anesthesia is widely used diers died after the administration of thiopental in patients in neurosurgical anesthesia. The drugs and techniques of with hypovolemic shock. Since the introduction of propofol neuroanesthesia will directly influence the perioperative in 1986, it has largely replaced thiopental and has become an surgical outcome of patients. In addition to balanced anes- induction agent of choice.4 It has become a key component of thesia with smooth induction and emergence, the funda- TIVA nowadays. mental necessities in neuroanesthesia include maintenance received DOI https://doi.org/ Copyright ©2018 Indian Society of July 1, 2018 10.1055/s-0038-1673544 Neuroanaesthesiology and Critical accepted after revision ISSN 2348-0548. Care August 21, 2018 published online October 24, 2018 142 TIVA in Neurosurgery Kannabiran, Bidkar Ideal Anesthetic Agent for Neuroanesthesia as is a shorter acting drug, a property which facilitates rapid tracheal intubation and smooth emergence during recovery, The choice of the anesthetic agent can have a significant which is crucial for monitoring neurosurgical patients. impact on neurological outcome in neurosurgical operations. The ideal anesthetic agent in neurosurgery should have the following properties: rapid onset and rapid emergence for Which is Better? neurological assessment, hemodynamic stability, and ICP Is Anesthesia for Elective and Emergency Neurosurgery 5 reduction. Cases Different? Cerebral blood flow (CBF) and cerebral metabolic rate Though inhalational anesthetic agents and TIVA have been of oxygen (CMRO ) are interdependent. Any increase or 2 used successfully, there is no sufficient evidence to prove decrease in cerebral metabolic oxygen demand will increase the superiority of one over the other. Todd et al compared or decrease the CBF, respectively, and this phenomenon is propofol–fentanyl-, isoflurane–nitrous oxide-, and fentan- known as flow–metabolism coupling. As the skull is a closed yl–nitrous oxide-based anesthesia techniques in 121 patients space, any increase in CBF will increase ICP, which may undergoing supratentorial tumor surgeries.10 ICP was com- affect CPP. parable in all the three groups. Fentanyl–nitrous oxide group Inhalational anesthetic agents tend to affect this flow– had slightly faster recovery (5 minutes vs. 10 minutes in 6 metabolism coupling in a dose-dependent manner. At con- other group). But early postoperative nausea and vomiting centrations of ≤1 minimum alveolar concentrations (MAC), (PONV) were significantly higher in fentanyl–nitrous oxide there will be a minimum increase in CBF and reduction in patients (17%) compared with only 2.5% and 5% in patients the CMRO . However, at >1 MAC inhaled concentrations, 2 in propofol–fentanyl and isoflurane–nitrous oxide group there will be an increase in CBF, which, in turn, increases ICP (p = 0.03). The study concluded that the short-term outcomes and causes flow–metabolism uncoupling (►Table 1). The such as new postoperative deficits, total hospital stay, or cost vasodilation caused by inhalational agents is managed by were similar, and all the three techniques were acceptable for hyperventilating the patient to vent off the carbon dioxide supratentorial tumor surgeries. (CO ), but moderate-to-severe hyperventilation can induce 2 Petersen et al studied three groups: propofol–fentanyl cerebral ischemia due to vasoconstriction of cerebral vessels (TIVA), isoflurane–fentanyl, and sevoflurane–fentanyl in a patient whose CPP is low due to raised ICP. anesthesia techniques to assess its effects on ICP and cere- In contrast to inhalational agents, IV agents, such as propo- bral hemodynamics before and during hyperventilation in fol, reduce both CBF and CMRO lower ICP, improve CPP, and 2, 117 patients undergoing elective craniotomy surgeries.7 provide adequate neuroprotective effect during cerebral isch- Subdural ICP and jugular venous oxygen saturation (SJVO ) 7–9 2 emia (►Table 2). Besides, propofol has rapid onset as well were significantly lower in the TIVA group compared Table 1 Effect of inhaled agents on cerebral dynamics Inhaled agents MAP CBF CPP ICP CMRO2 Halothane ↓↓ ↑↑↑ ↓↓ ↑↑ ↓↓ Isoflurane ↓↓ ↑ ↓↓ ↑ ↓↓↓ Sevoflurane ↓↓ ↑ ↑ 0–↑ ↓↓↓ Desflurane ↓↓ ↑ ↑ ↑ ↓ Nitrous oxide 0–↓ ↑–↑↑ ↓ ↑–↑↑ ↓↑ Abbreviations: CBF, cerebral blood flow; CMRO2, cerebral metabolic rate of oxygen; CPP, cerebral perfusion pressure; ICP, intracranial pressure; MAP, mean arterial pressure. (↓) Decrease and (↑) increase. Table 2 Effects of intravenous agents on cerebral dynamics Intravenous agents MAP CBF CPP ICP CMRO2 Thiopentone ↓↓ ↓↓↓ ↑↑↑ ↓↓↓ ↓↓↓ Propofol ↓↓↓ ↓↓↓ ↑↑ ↓↓ ↓↓↓ Etomidate 0–↓ ↓↓↓ ↑↑ ↓↓↓ ↓↓↓ Ketamine ↑↑ ↑↑↑ ↓ ↑↑↑ ↑ Benzodiazepines 0–↓ ↓↓ ↑ 0 ↓↓ Opioids 0–↓ ↓ 0–↓ 0–↓ ↓ Abbreviations: CBF, cerebral blood flow; CMRO2, cerebral metabolic rate of oxygen; CPP, cerebral perfusion pressure; ICP, intracranial pressure; MAP, mean arterial pressure. (↓) Decrease and (↑) increase. Journal of Neuroanaesthesiology and Critical Care Vol. 5 No. 3/2018 TIVA in Neurosurgery Kannabiran, Bidkar 143 with patients in the inhalational agents’ group (p < 0.05), of drugs facilitate smoother induction, with smaller doses, whereas mean arterial pressure and CPP were found and slower infusion rates thereby prevent fall in mean arte- higher in patients receiving propofol–fentanyl (TIVA) com- rial pressure, which is often associated with the manual pared with patients receiving isoflurane and sevoflurane administration of IV drugs during induction.12 Thiopentone, (p < 0.05). They concluded that favorable cerebral hemody- propofol, ketamine, and etomidate all have been used for namics from propofol group resulted in decreased cerebral the induction in patients with raised ICP.13,14 The property swelling after dural opening. of ketamine to raise ICP has been challenged and has been In the meta-analysis by Prabhakar et al, TIVA and the found to have beneficial effects on ICP.13 Propofol, when giv- inhalational-based anesthesia techniques were compared en in bolus doses, will cause fall in mean arterial pressure, to assess the rapid emergence from anesthesia.11 They