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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.56 no.6 Campinas Nov./Dec. 2006
Use of the lateral approach for laryngeal mask insertion during awake craniotomy. Case report*
Uso del abordaje lateral para la introducción de máscara laríngea durante craniotomía en paciente despierto. Relato de Caso
Mirna Bastos MarquesI; Carlos Henrique Vianna de Castro, TSAII; Dener Augusto Diniz, TSAI; Ana Tereza Moreira Dantas de Andrade Pinto, TSAI; Marcello Penholate FariaIII
do Hospital Lifecenter
IIDiretor Clínico e Anestesiologista do Hospital Lifecenter
IIINeurocirurgião do Hospital Lifecenter
CASE REPORT: The case of a patient who underwent resection of a tumor in the left temporal lobe, in the Wernicke gyrus, with clinical signs of difficult airway is reported. The "asleep-awake-asleep" anesthetic technique, with continuous infusion of propofol and remifentanil, was used. A laryngeal mask, inserted by the lateral approach, was used to keep the airways patency.
CONCLUSIONS: The technique used was effective in obtaining an intraoperative awake and cooperative patient, and the airways were maintained patent with a laryngeal mask. Insertion of this device by the lateral approach is especially interesting since this was a patient who presented difficult airway and underwent a surgical procedure in which in which the patient must remain immobile and the surgical field cannot be contaminated.
RELATO DEL CASO: Se ha descrito el caso de un paciente sometido a la resección de un tumor en el lobo temporal izquierdo, en el giro de Wernicke, con señales clínicos de vía aérea difícil. Fue utilizada la técnica "durmiendo-despierto-durmiendo", con infusión continua de propofol y remifentanil. La vía aérea se mantuvo con el uso de la máscara laríngea, a través de abordaje lateral.
CONCLUSIONES: La técnica utilizada fue eficaz para la obtención de un paciente despierto y cooperativo en el intraoperatorio, habiendo sido asegurada la permeabilidad de la vía aérea con el uso de la máscara laríngea. La inserción de ese dispositivo a través del abordaje lateral es de especial interés por tratarse de un paciente con una posible dificultad de acceso a la vía aérea, en procedimiento quirúrgico en que era necesario evitar desplazamiento del paciente y contaminación del campo quirúrgico.
Intraoperative mapping with the patient awake is the most effective method to localize and preserve the eloquent cortex during resection of brain tumors, especially of low-grade gliomas 1. For surgeries in the dominant cerebral hemisphere, this technique allows for a safe extension of resections close to the language center, reducing the risk of lesions to this area and the disturbs that follow 2.
During the Aachen Aphasia test 3,4, in which the patient must recognize and name figures, the patient should be completely alert, calm, and cooperative.
The objective of this report was to present a case of awake craniotomy using the "asleep-awake-asleep"4 anesthetic technique in a patient who presented stigmata of difficult airway.
A man patient, 56 years old, who underwent resection of a left temporal lobe resection in the Werniecke gyrus is reported. His comorbidities included hypertension, treated with enalapril (10 mg.day-1) and atenolol (50 mg.day-1), without past history of allergies or addictions.
On physical exam, his blood pressure was 140 x 80 mmHg, without any other changes. The exam of the airways showed a mentothyroid distance < 6 cm, mouth opening > 4 cm, cervical mobility > 2.5 cm, incisive teeth were not protruded, without dental prosthesis, and Mallampati III. Laboratory work did not show evidence of end-organ lesion secondary to hypertension. The echodopplercardiogram showed mild diastolic dysfunction. The patient and his family received detailed information on the surgical and anesthetic procedures, emphasizing the awaken phase and the test of recognition of figures. Twelve hours before the procedure, oral bromazepam (3 mg) was administered as premedication. The "asleep-awake-asleep" anesthetic technique with remifentanil, propofol, and laryngeal mask was chosen.
In the surgical room, the patient was comfortably positioned in order to avoid peripheral nerve lesion. Surgical fields were adjusted to maintain the airways and eyes easily visible.
Monitoring included an electrocardiogram with continuous analysis of the ST segment, pulse oxymetry, non-invasive blood pressure, capnograph, blood analyzer, nasopharyngeal temperature, arterial ABGs, glucose level, urine output, and ionogram. Intravenous phenytoin (750 mg) and prophylactic antibiotics were administered.
Continuous intravenous administration of remifentanil (0.05 to 0.3 µg.kg-1.min-1) and target-controlled infusion of propofol (1.5 to 3 µg-1.mL-1) were done. A classical laryngeal mask number 4 and lubricant were used to maintain the airways patency. The patient was maintained normocapnic (PaCO2 from 32 to 36) and normoglycemic (70 to 140 mg.dl-1). The hemicranial field was blocked with 0.5% ropivacaine (2.8 mg.kg-1). Hemodymanic parameters and temperature remained normal and the patient maintained a urine output of 0.5 mL.kg-1.h-1. Serum sodium level was 139 mEq.L-1.
After opening the dura mater, the infusion of remifentanil and propofol was discontinued. The patient woke up, reaching a Ramsay score of 2 after 11 minutes. The laryngeal mask was then removed, and the patient did not present coughing, laryngospasm, and remained immobile. When questioned, the patient, through the visual analogic scale (VAS= 0), said he was not experiencing any pain. The Aachen Aphasia Test was performed during electrical stimulation, with stimuli of 2 to 6 µA, to map the lesion.
At this moment, there was an increase in heart rate and mean arterial pressure, and 15 mg of metoprolol were administered intravenously.
At the end of the mapping, the infusion of propofol and remifentanil was reinitiated, the laryngeal mask was reintroduced by the lateral approach using the thumb as a guide. In the second phase of the surgical procedure, continuous infusion of propofol and remifentanil were maintained associated with 0.8% isofluorane. Intravenous mannitol (50 g) and furosemide (20 mg) were also administered. The lowest serum potassium level was 3.7 mEq.L-1.
The second phase of the surgery lasted 3 hours and 30 minutes, and the patient had focal seizure affecting the left upper limb, which was controlled immediately with 10 mg intravenous diazepam.
The laryngeal mask was removed when the surgery was over. The patient was discharged from the ICU 16 hours later, and did not present complications.
Target-controlled infusion of propofol and remifentanil for awake craniotomy has been widely described 6,7. With this technique, the length of time necessary to regain consciousness was compatible with that reported in the literature 2. The patient was hemodynamically stable during the infusion of remifentanil and propofol. After it was discontinued, it was necessary to administer metoprolol to control the heart rate. Excluding hypercapnia, pain, and hyperthermia, the episode of tachycardia was attributed to a probable rebound effect due to the irregular use of the beta-adrenergic blocker.
It is known that dexmedetomidine associated with regional anesthesia causes sedation, analgesia, and hemodynamic stability without respiratory depression, allowing the neurological evaluation in awake craniotomy 8-11 and carotid endarterectomy 12. However, the effects of dexmedetomidine on brain blood flow in these two populations are still to be determined.
The blockade of the hemicranial field with 0.5% ropivacaine, 2.8 mg.kg-1, is safe, but one should avoid exceeding a plasma level of 4.300 ± 500 ng.mL-1 13. Note that the absorption of ropivacaine in the scalp is very fast, with a T½ of 3 minutes and peak plasma level 134 minutes after the infiltration is initiated. Even though ropivacaine has intrinsic vasoconstrictor properties, adding epinephrine (5 µg.mL-1) seems to decrease its systemic absorption and prevent neurological symptoms 14.
In this case, we considered especially interesting the insertion of the laryngeal mask by the lateral approach. The thumb was used as a guide, squeezing the tube of the mask against the palate while introducing it with the other hand. In this case, the contamination of the surgical field was avoided and the insertion was successful in the first attempt, although it is considered more difficult than the cephalic approach 15,16.
The use of the "awake-asleep-awake" anesthetic technique with continuous infusion of remifentanil and propofol provided hemodynamic stability, complete awakening in a short time, and the patient remained cooperative for the aphasia test. The insertion of the laryngeal mask by the lateral approach avoided contamination of the surgical field and assured the control of the airways in a patient with clinical signs suggestive of difficult airway.
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Dra. Mirna Bastos Marques
Rua Santa Rita Durão, 865/1303 - Savassi
30140-111 Belo Horizonte, MG
Submitted for publication
28 de novembro de 2005
Accepted for publication 30 de agosto de 2006
* Received from Departamento de Anestesiologia do Hospital Lifecenter, Belo Horizonte, MG