Brain relaxation score on craniotomy brain tumour removal with adjuvant thiopental and dexmedetomidine: A case report ‎

Dewi Yulianti Bisri^1*, Ignatia Karina Hallis¹,Tengku Addi Saputra¹, Tatang Bisri²

¹Departement of Anesthesiology and Intensive Care, Medical Faculty Universitas Padjadjaran/Dr. Hasan Sadikin Hospital-Bandung Indonesia. ²Departement of Anesthesiology and Intensive Care, Medical Faculty Universitas Jenderal Achmad Yani Cimahi/Santosa Bandung Central Hospital Indonesia.

Correspondence: Dewi Yulianti Bisri, Departement of Anesthesiology and Intensive Care, Medical Faculty Universitas Padjadjaran/Dr. Hasan Sadikin Hospital-Bandung Indonesia. [email protected]

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ABSTRACT

The term ‘brain relaxation’ is frequenly used to describe the tension of brain tissue during craniotomy. The relaxation status of brain is an essential element of neuroanesthesia practice and is relevant to surgical condition, retractive injuries, and patient outcomes. The beneficial and detrimental effects of various interventions for brain relaxation should be considered in zpatient management.

A 63-year-old woman with a supratentorial tumor who weighed 70 kg and was 164 cm tall complained of a decrease in consciousness three days before hospital admission, and partial left-body paralysis for the last two months. The patient’s Glasgow Coma Scale (GCS) score was 12, feeling headache, nausea, vomiting, but not seizures.  Blood pressure was 146/79 mmHg, mean arterial pressure (MAP) was 99 mmHg, pulse rate was 87 x/min, respiratory rate was 20 x/min, temperature was 36.9⁰C, and SpO₂ was 97% with air. She was induced with dexmedetomidine, followed by thiopental, vecuronium bromide, fentanyl, lidocaine, ventilation with 100% oxygen, and sevoflurane 2 vol%. Before intubation, a repeat dose of thiopental was given at half the initial dose. Dexamethasone and mannitol were administered, thiopental was continued, and the dose was then lowered to 1-3 mg/kg BW, sevoflurane 1-2 vol%, oxygen/air, and continuous vecuronium bromide were also given. A slack brain with a brain relaxation score of 1 was obtained. The operation lasted 5.5 hours. Using a drug combination from the neuroanesthesia drug club, a slack brain was achieved, allowing the tumor to be entirely removed, with minimal bleeding and without the need for blood transfusions‎.

 

Keywords: Adjuvant anesthesia, Brain tumor, Brain relaxation score, Craniotomy, Dexmedetomidine, Thiopental

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a)

b)

Figure 4. This picture illustrates slack brain condition

 

Figure 5. Tumor mass: the tumor was 100% removed.

Postoperative at ICU

 

Day 1

Figure 6. Postoperative Monitoring Hemodynamic at ICU Note: SBP = systolic blood pressure; DBP = diastolic blood pressure; MAP = mean arterial pressure; SpO2 = saturation peripheral oxygen

 

Table 2. Postoperative lab test
Hemoglobin	13,4 g/dl
Haematocrit	42 %
Leucocyte	7.340 uL
Thrombocyte	205.000/ uL
Ureum	19 mg/ dl
Creatinin	0,42 mg/dl
Natrium	134 mEq/ L
Kalium	4,2 mEq/ L
Chloride	105 mEq/ L
Magnesium	2,24 mEq/ L
Calcium ion	1,31 mEq/ L

 

In the ICU, the patient was positioned head-up at 30 degrees, neutral. The drug given in the ICU was a thiopental sedative of 0.5 mg/kg/hour because the patient was still under ventilator and intravenous fluid maintenance with a balanced solution of ringerfundin (30 mL/kgBW/24 hours). Postoperative Hb was 13.4 g/dL, so no blood transfusion was required.

Results and Discussion

Experienced  neuro anesthesiologists and surgeons regularly integrate the concept of ‘brain relaxation’ into perioperative communication. After the opening of the skull and dura, surgeons frequently assess how tight or relaxed the brain is. If the brain is tight or enlarges, various maneuvers are performed to soften in to enhance operating conditions and to protect the brain from retraction injuries and ischemia caused by compression [4, 8-10].

Brain relaxation is a term specifically used to describe the brain condition during craniotomy; however, the concept of brain relaxation has expanded over time to integrate avariety of terms. Additionally, the term, such as, brain relaxation, brain bulging, and brain herniation have been use. The term brain relaxation should be used to describe clinical entities that have anesthetic, surgical, physiological and outcome implication. When the skull and dura are opened by the neurosuegeon, brain relaxation defines the rlationship between the volume of intracranial contents and the capacity of the intracranial space. Therefore,it is a concept that must be applied specifically during intracranial procedures when direct assasment of content-space relationships is possible.If the volume of intracranial content is equal to or less than the capacity of the intracranial space, then relaxation of the brain is adequate. However, if the volume of crebral content in connection with the capacity of the intracranial space that gives the best operating circumstances for open intracranial surgery and patient outcomes should be described as the current nation of brain relaxation.  Relaxation of the brain is sufficient if the volume of intracranial content is equivalent to or smaller than the capacity of the intracranial space. The modern concept of brain relaxation should be defined as the ideal volume of intracranial contents in conjuction with the capacity of the intracranial space that provides optimal operating conditions during open intracranial surgery and patient outcomes [4, 8, 9].

It is important to distinguish the concept of brain relaxation from the practice of measuring intracranial pressure (ICP). Intracranial pressure is pressure with a closed skull, that is measured objectively by a transducer. Brain relaxation, by contrast, is a more subjective assesment by surgeons primaly based on intracranial content-space relationship when the skull and dura are opened. Intracranial pressure decrease to the atmospheric level (referre to as zero) when the dura is opened, but the degree of relaxation of tge brain may not change, or may worsen if brain tissue suddenly expands. ICP Physically result from the pressure that intracranial contents place on the skull’s walls. It makes sense that the ICP would be higher and vice versa, depending on how much cerebral space was accupied by intracranial substances. Research demonstating a link between raised ICP and a greater frequency of clinical brain edema following dural opening supports this connection. Physically, ICP is the result of the force exerted by intracranial content on walls of cranium. Intuitively, the greater the volume of intracranial space, the higher the ICP, and vice versa. This association is confirmed by research showing that eleveted ICP correlates with a higher incidence of clinical brain swelling after dural opening [4, 8, 9].

 

The Chemical Brain Retractor concept for obtaining a slack brain is:

Mild hyperosmolality (use NaCl 0.9% [304 mOsm/kg] as baseline infusion; give 20% mannitol [1245mOsm/kg] 0.5 to 0.75g/kg or hypertonic saline [7.5%, 2498mOsm/kg] 2 to 4mL/kg before bone flap removal) Intravenous anesthetic agent (propofol), adequate depth of anesthesia Mild hyperventilation, mild hyperoxygenation Mild controlled hypertension: mean arterial blood pressure maintained around 100 mmHg to decrease cerebral blood volume and intracranial pressure Normovolemia; no vasodilators Mild hyperoxia   Together with: Head-up positioning with unimpeded cerebral venous drainage; no compression of the jugular veins Minimal positive end-expiratory pressure Adequate anesthetic depth or muscle relaxant to prevent bucking on the ventilator Lumbar drainage Avoidance of brain retractors

Picture. The Chemical Brain Retractor concept [6].

 

Propofol-based intravenous anesthesia has been used with positive results [8]. As well as the combination of the inhalation anesthetic sevoflurane with propofol [5]. The use pharmacological brain retraction, such as perioperative dexamethasone, was associated with improved brain relaxation, however, the presence of a preoperative middle shift and a higher haemoglobin level were was associated with poor brain relaxation [6].

In this case, thiopental, fentanyl, sevoflurane, vecuronium, mannitol, and dexamethasone were used as anesthetic drugs and adjuvants. The effects of anesthetics on Cerebral Blood Flow (CBF), cerebral metabolic rate (CMRO2), and intracranial pressure (ICP) are illustrated in the table below.

 

Table 3. The effects of anesthetics on Cerebral Blood Flow (CBF), Cerebral Metabolic Rate (CMRO2), and Intracranial Pressure (ICP) [7-12].
Drugs used in this patients	CBF	CMRO2	ICP
Thiopentone	Decrease	Decrease	Decrease
Fentanyl	0/Decrease	0/Decrease	0/Decrease
Vecuronium	0	0	0/Decrease
Lidocaine	Decrease	Decrease	Decrease
Sevoflurane	Increase	Decrease	Increase
Mannitol	0/increase	-	Decrease
Dexamethasone	0	-	Decrease
Dexmedetomidine	Decrease	-	Decrease

Note: CBF = cerebral blood flow, CMRO₂ = cerebral metabolic rate for oxygen, ICP = intracranial pressure

 

In this case, a dose of 0.5 g/kg BW of mannitol as a standard osmotic diuretic was given within 20 minutes.

The incidence of poor intraoperative brain relaxation, as is manifested by brain oedema (the brain swelling). A spectrum review of elective neurosurgery patients found an incidence of 0.7% to 6.1% of severe brain swelling. Mild and moderate brain enlargement is relatively common, occurring in nearly 30% of patients undergoing supratentorial brain tumor resection [4]. In this case, although the brain tumor was large, 100% of the tumor could be removed because the brain slack was achieved.

The main cause of tight brain is the excessive volume of intracranial contents. Various brain lession, such as tumor,cyst,hematomas, and traumatic injuries, together with cerebral oedema, enlarge the volume of intracranial contents without changing the capacity of the intracranial space, leading  to a s023pace-content mismatch. Other factors that contribute to brain tightness include excessive cerebrospinal fluid (CSF,e.g., hydrochepalus), increased cerebral blood volume (CBV). Eleveted CBV may result from increased CPF (e.g., hypercapnia, high minimum alveolar concentration (MAC) of Voatile anesthetic agents) or reduced cerebral venous drainage (e.g., headward tilt, extreme head/neck rotation, neck copression) [4, 7, 9, 12, 13]. In this case, the problems of CBF, CBV, patient position, fluid intake, and anesthetic effects on cerebral dynamics were calculated.

Conclusion

Brain relaxation during a surgical removal of brain tumor plays an important role in the success of of procedure. The combination of sevoflurane < 1.5 MAC, oxygen/air, dexmedetomidine, and the thiopental adjuvant produced a slack brain with a brain relaxation score of 1 so that brain tumor removal could be performed in a relatively short time. 100% of the tumor was removed and the amount of bleeding was so minimum that it did not require a blood transfusion.

Acknowledgments: None

Conflict of interest: None

Financial support: None

Ethics statement: None

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