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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.55 no.2 Campinas Mar./Apr. 2005
Dexmedetomidine in general anesthesia for surgical treatment of cerebral aneurysm in pregnant patient with specific hypertensive disease of pregnancy. Case report*
Uso de dexmedetomidina en anestesia general para tratamiento quirúrgico de aneurisma cerebral, en paciente embarazada, portadora de enfermedad hipertensiva específica del embarazo. Relato de caso
Kleber Machareth de Souza, M.D.I; Luiz César Anzoategui, TSA, M.D.II; Washington Cássio Justino Pedroso, TSA, M.D.I; Werner Alfred Gemperli, TSA, M.D.I
IAnestesiologista do Serviço de Anestesiologia
da Santa Casa de Campo Grande
IIAnestesiologista Responsável pelo CET da Santa Casa de Campo Grande
BACKGROUND AND OBJECTIVES: The incidence
of non-obstetrical surgeries in pregnant patients is about 0.36% to 2%. However,
surgeries aiming at surgical treatment of cerebral aneurysm in pregnant women
are extremely rare. Specific hypertensive disease of pregnancy, shows clinical
prevalence of 10%. It is a disease with high clinical complexity compromising
multiple organs and systems. Dexmedetomidine, a2-adrenoceptor
agonist drug, in therapeutic clinical doses has major selectivity for these
receptors and promotes suitable hemodynamic stability if used in the preoperative
period. The purpose of this report was to present an anesthetic technique able
to provide adequate maintenance of maternal homeostasis, preserving to the highest
level uterus-placental blood flow and fetal vitality, without neglecting fundamental
aspects regarding the optimization of brain oxygen supply/demand ratio and favorable
brain tissue conditions for surgical management.
CASE REPORT: Pregnant patient, 19 years old, 27 weeks of gestation, was referred to the operating room for surgical treatment of cerebral aneurysm. In the preoperative period she was conscious, oriented, eupneic but with left side motor deficit and clinical signs compatible with toxemia of pregnancy. Dexmedetomidine (1 µg.kg-1.h-1) was administered in 20 minutes, followed by anesthetic induction with propofol (2.5 mg.kg-1), fentanyl (7.5 µg.kg-1), lidocaine (1 mg.kg-1) and rocuronium (1.2 mg.kg-1) in rapid sequence. Anesthesia was maintained with propofol (50 µg.kg-1.min-1), alfentanil (1 µg.kg-1.min-1) and dexmedetomi- dine (0.7 µg.kg-1.h-1). Surgical procedure went on with no complications, including brain sequelae.
CONCLUSIONS: This case report has shown that dexmedetomidine made possible the handling of hemodynamic responses, keeping optimized uterus-placental blood flow and fetal vitality. Adequate conditions of surgical brain tissue manipulation and the absence of influence in postoperative morbidity are also emphasized.
Key words: ANESTHESIA, General; DISEASES: specific hypertensive pregnancy; DRUGS: dexmedetomidine; SURGERY, Neurosurgical: aneurysm
JUSTIFICATIVA Y OBJETIVOS: La incidencia
de cirugías no obstétricas en pacientes embarazadas es del 0,36% a 2%. Sin embargo,
cirugías con la finalidad de tratamiento quirúrgico de aneurisma cerebral en
embarazadas son extremadamente raras. La enfermedad hipertensiva específica
de la gestación, presenta superioridad clínica del 10% en la población gestante.
Se trata de una enfermedad de elevada complejidad clínica, acometiendo múltiples
órganos y sistemas. La dexmedetomi- dina, fármaco agonista a-2,
presenta importante selectividad para estos receptores cuando utilizada en dosis
clínicas terapéuticas y promueve adecuada estabilidad hemodinámica cuando empleada
en el período peri-operatorio. El objetivo de este relato fue presentar una
técnica con la cual hubiera sido posible el mantenimiento de la homeostasis
materna, preservando al máximo el flujo sanguíneo útero-placentario y la vitalidad
fetal, sin dejar de lado aspectos fundamentales relativos a la optimización
de la relación oferta/demanda de oxígeno cerebral y adecuación de las condiciones
del tejido cerebral propicias al manoseo quirúrgico.
RELATO DEL CASO: Embarazada con 19 años encaminada para tratamiento quirúrgico de aneurisma cerebral, en la vigésima séptima semana de embarazo. En el pre-operatorio, se presentaba consciente, orientada, con presencia de déficit a la izquierda y cuadro clínico compatible con toxemia gravídica. Fue administrada dexmedetomidina (1 µg.kg-1) en 20 minutos, seguida de inducción anestésica con propofol (2,5 mg.kg-1), fentan il (7,5 µg.kg-1), lidocaína (1 mg.kg-1) y rocurônio (2 mg.kg-1) en secuencia rápida. El mantenimiento de la anestesia fue lograda con propofol (50 µg.kg-1.min-1), alfentanil (1 µg.kg-1.min-1) y dexmedetomidina (0,7 µg.kg-1.min-1). La cirugía fue realizada sin cualquier acontecimiento, no habiendo secuela neurológica subyacente.
CONCLUSIONES: El presente caso mostró que el uso de la dexmedetomidina posibilitó un adecuado manoseo hemodinámico, manteniendo optimizado el flujo sanguíneo útero-placentario y la vitalidad fetal. Se resaltan aún las condiciones adecuadas de manipulación quirúrgica del tejido cerebral, así como la ausencia de influencia en la morbidad después del procedimiento anestésico-quirúrgico.
Surgical treatment of neurological diseases during pregnancy is extremely uncommon. Gestation and related physiological changes per se require special care. The association of specific hypertensive disease of pregnancy is an additional challenge in terms of anesthetic management of these patients.
In the international literature, specific hypertensive disease of pregnancy is manifested in 7% to 10% of all pregnant population and may be classified as mild or severe. Strokes are among major causes of morbidity/mortality 1.
Clinically, it is characterized by generalized vasoconstriction and hypoperfusion, with sodium and water retention and edema. Intravascular space, however, is decreased. The level of hemodynamic impairment characterizes the severity of the disease; hypertension, increased heart rate and peripheral vascular resistance are present in different levels. There may be uterus-placental, liver, renal and central nervous system blood flow impairment being proteinuria a typical finding of the disease. So, it is a systemic change with complex clinical control1. Hemodynamic stability, rigorous control of intracranial pressure, brain protection with adequate oxygen supply/demand ratio, maintenance of adequate brain tissue compliance during surgical procedure and early postoperative emergence - if possible - allowing for early neurological evaluation, are major objectives of neurosurgical anesthetic techniques 2.
Dexmedetomidine, an a2 adrenoceptor agonista drug with sedative and analgesic properties and introduced in the clinical practice as adjuvant analgesic, hypnotic and sedative agent, is able to promote efficient hemodynamic stability, decrease anesthetic consumption and promote early and smooth emergence with lower respiratory depression risk, thus preventing CO2 retention and, as a consequence, increased PaCO2, which is undesirable during neurosurgical postoperative period 3,4.
This report aimed at presenting the clinical case of a pregnant patient (27 weeks), with specific hypertensive disease of pregnancy, to be submitted to surgical treatment of cerebral aneurysm.
Female patient, 19 years old, 58 kg, 168 cm, 27 weeks of gestation, with clinical symptoms compatible with specific hypertensive disease of pregnancy. Patient was referred to the operating room with left side motor deficit caused by hemorrhagic stroke in posterior communicating artery, however conscious, oriented and without any other neurological sign. Patient also presented blood pressure = 170 x 110 mmHg, heart rate = 128 beats per minute and lower limbs edema ++/++++. Additional tests have shown 4.5 g.24h-1 proteinuria with normal blood biochemistry and liver function. Patient was monitored with ECG at DII lead, pulse oximetry, capnography, invasive blood pressure in left radial artery and central venous pressure. Patient was premedicated with dexmedetomidine (1 µg.kg-1) in 20 minutes. Anesthesia was induced with propofol (2.5 mg.kg-1), fentanyl (7.5 µg.kg-1), lidocaine (1 mg.kg-1) and rocuronium (1.2 mg.kg-1) in rapid sequence under Sellick's maneuver until tracheal intubation. Anesthesia was maintained with propofol (50 µg.kg-1.min-1), alfentanil (1 µg.kg-1.min-1), rocuronium (6 µg.kg-1.min-1) and dexmedetomidine (0.7 µg.kg-1.h-1). Dexmedetomidine infusion was gradually decreased to 0.4 µg.kg-1.h-1, according to evaluated parameters (invasive mean blood pressure and heart rate).
Intraoperative hydration was achieved with saline at the rate of 6 mL.kg-1.h-1, after preoperative fast replacement. Arterial gases and blood biochemistry were analyzed every 60 minutes. Patient was maintained in slight left lateral position during surgery and fetal heart rate was periodically monitored by sonar. Patient was maintained hemodynamically stable (blood pressure around 110 x 60 mmHg and mean blood pressure around 76 mmHg) during the 320 minutes of procedure, with good conditions for surgical brain tissue manipulation.
Patient was referred to the ICU at procedure completion and was extubated 90 minutes after surgery without intercurrences or underlying neurological sequelae. Fetal vitality was maintained unchanged throughout the period. Patient was submitted to Cesarean section 10 weeks later without any intercurrence both for mother and fetus.
This report aimed at presenting an anesthetic technique able to preserve maternal homeostasis, to favor fundamental aspects inherent to neurosurgical technique with maintenance of brain oxygen supply/demand ratio and, whenever possible 1, to preserve at the utmost uterus-placental blood flow.
Dexmedetomidine, a2 adrenoceptor agonist used as adjuvant to anesthetic agents, has provided major hemodynamic stability 3. Relatively recent studies have shown that dexmedetomidine is able to decrease circulating plasma norepinephrine and epinephrine concentration in approximately 50% 4. Some studies have shown that dexmedetomidine decreases brain blood flow by directly acting on post-synaptic a2 receptors 5,6, in addition to its intrinsic ability to decrease CSF pressure 7. When its hemodynamic effects and action on brain vascularization are indirectly assumed, one may admit that this drug is able to effectively decrease brain metabolism and intracranial pressure 8,9. Dexmedetomidine ability to decrease brain metabolism in humans is still not well established by the literature. Recent animal studies have shown that dexmedetomidine is able to decrease blood flow in up to 45% without ischemic suffering 10. Other studies have shown that dexmedetomidine is able to decrease injury caused by focal ischemia 11.
More consistent studies on possible dexmedetomidine neuroprotective effect in humans, as well as its joint pharmacological action on the binomial mother-fetus are still needed 12. However, its benefits in this case report by promoting adequate hemodynamic stability (MBP = 76 mmHg ± 10 mmHg and HR = 75 bpm ± 10 bpm) and decreasing anesthetic drugs consumption are undoubtedly apparent.
There has been 70% decrease in alfentanil initial values and 50% in propofol initial values, associated to 43% decrease in dexmedetomidine infusion rate (0.7 µg.kg-1.min-1 to 0.4 µg.kg-1.min-1)
This case has shown that dexmedetomidine has allowed for adequate hemodynamic handling, optimized surgical handling of brain tissue, as well as the absence of influence in morbidity of the binomial mother-fetus after the anesthetic-surgical procedure.
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Dr. Kleber Machareth de Souza
Address: Rua Pernambuco, 946/403 Bairro Monte Castelo
ZIP: 79010-040 City: Campo Grande, Brazil
Submitted for publication April 26, 2004
Accepted for publication December 8, 2004
* Received from CET da Santa da Casa de Campo Grande, MS