Dexmedetomidine as a total intravenous anesthetic agent,”

DEXMEDETOMIDINE is a highly selective ␣ 2 adrenoceptor agonist that has sedative and analgesic properties with associated reduction in opioid and anesthetic requirements. 1-11 One significant advantage of dexmedetomidine is that in the clinical dose range there is no respiratory depression. Case Reports Case 1 A 66-yr-old, 85-kg woman presented with inspiratory stridor and was found to have a severe subglottic stenosis of her trachea. The stenosis was measured to be 1.5 cm below the vocal cords and to have a lumen diameter of 4 mm. Neodymium:yttrium-aluminum-garnet laser destruction of the tracheal stenosis was scheduled emergently. The patient was brought to the operating room and peripheral intravenous and arterial cannulae were inserted and electrocardiogram electrodes and pulse oximetry sensor were applied. A loading dose of dexmedetomidine 1 g/kg was infused over 10 min and then an infusion of 0.7 g·kg Ϫ1 ·h Ϫ1 was delivered but rapidly increased over 10 min to 10 g·kg Ϫ1 ·h Ϫ1 to attain an acceptable level of anesthesia that would allow the airway to be instrumented by direct laryngoscopy. Topical lidocaine was applied to the nasal mucosa, the back of the pharynx, and the upper surface of the glottis. A fiberoptic bronchoscope was passed through the nose and the tracheal stenosis was visualized. No supplemental oxygen was supplied. When the patient was completely unresponsive approximately 20 min after induction the laser was powered and the tracheal stenosis was ablated. The procedure took 30 min and during that time the airway had to be supported with a chin lift. The blood pressure declined from 150/80 mm Hg to 110/60 mm Hg and pulse rate was maintained between 70 and 75 beats/min. (figs. 1 and 2) After 20 min the infusion of dexmedetomidine was reduced to 5 g·kg , but the patient began to exhibit signs of lightening from anesthesia and so the infusion was increased back to 10 g·kg Ϫ1 ·h Ϫ1 . The oxygen saturations were maintained at greater than 90% except when the upper airway was obstructed and a chin lift was necessary. Case 2 A 65-yr-old, 50-kg man was admitted with acute exacerbation of chronic respiratory failure secondary to emphysema. He required mechanical ventilation for 5 days and was then weaned to spontaneous ventilation and the endotracheal tube was removed. While breathing room air, his arterial PaO 2 was 55 mm Hg and PaCO 2 was 60 mm Hg. He was then scheduled to have extensive resections of facial skin cancers with full-thickness skin graft reconstruction. The patient arrived in the operating room tachycardic and hypertensive and vigorously refused local anesthesia. Sedation with dexmedetomidine was attempted with a loading dose of 1 g/kg followed by an infusion of 0.7 g·kg Ϫ1 ·h Ϫ1 . This did not provide adequate anesthesia so the infusion was increased to 5 g·kg Ϫ1 ·h Ϫ1 , and after a further 10 min the patient was anesthetized deeply enough to allow the surgery to take place. No supplemental oxygen was administered because of the close proximity of the electrical cautery. Hemodynamically he became stable with heart rate slowing from 120 beats/minute to 65 beats/minute and blood pressure declining from 220/120 mm Hg to 120/65 mm Hg. Oxygen saturation, measured by a pulse oximeter, was maintained above 90% and respiratory rate declined from 30 breaths/min to 16 breaths/min. At the conclusion of the procedure local anesthesia was infiltrated into the surgical sites. The patient required no analgesia in the postanesthesia recovery unit and remained hemodynamically stable. He was discharged from the unit 2 h postoperatively

Dexmedetomidine as a total intravenous anesthetic agent

DEXMEDETOMIDINE is a highly selective ␣ 2 adrenoceptor agonist that has sedative and analgesic properties with associated reduction in opioid and anesthetic requirements. 1-11 One significant advantage of dexmedetomidine is that in the clinical dose range there is no respiratory depression. Case Reports Case 1 A 66-yr-old, 85-kg woman presented with inspiratory stridor and was found to have a severe subglottic stenosis of her trachea. The stenosis was measured to be 1.5 cm below the vocal cords and to have a lumen diameter of 4 mm. Neodymium:yttrium-aluminum-garnet laser destruction of the tracheal stenosis was scheduled emergently. The patient was brought to the operating room and peripheral intravenous and arterial cannulae were inserted and electrocardiogram electrodes and pulse oximetry sensor were applied. A loading dose of dexmedetomidine 1 g/kg was infused over 10 min and then an infusion of 0.7 g·kg Ϫ1 ·h Ϫ1 was delivered but rapidly increased over 10 min to 10 g·kg Ϫ1 ·h Ϫ1 to attain an acceptable level of anesthesia that would allow the airway to be instrumented by direct laryngoscopy. Topical lidocaine was applied to the nasal mucosa, the back of the pharynx, and the upper surface of the glottis. A fiberoptic bronchoscope was passed through the nose and the tracheal stenosis was visualized. No supplemental oxygen was supplied. When the patient was completely unresponsive approximately 20 min after induction the laser was powered and the tracheal stenosis was ablated. The procedure took 30 min and during that time the airway had to be supported with a chin lift. The blood pressure declined from 150/80 mm Hg to 110/60 mm Hg and pulse rate was maintained between 70 and 75 beats/min. (figs. 1 and 2) After 20 min the infusion of dexmedetomidine was reduced to 5 g·kg , but the patient began to exhibit signs of lightening from anesthesia and so the infusion was increased back to 10 g·kg Ϫ1 ·h Ϫ1 . The oxygen saturations were maintained at greater than 90% except when the upper airway was obstructed and a chin lift was necessary. Case 2 A 65-yr-old, 50-kg man was admitted with acute exacerbation of chronic respiratory failure secondary to emphysema. He required mechanical ventilation for 5 days and was then weaned to spontaneous ventilation and the endotracheal tube was removed. While breathing room air, his arterial PaO 2 was 55 mm Hg and PaCO 2 was 60 mm Hg. He was then scheduled to have extensive resections of facial skin cancers with full-thickness skin graft reconstruction. The patient arrived in the operating room tachycardic and hypertensive and vigorously refused local anesthesia. Sedation with dexmedetomidine was attempted with a loading dose of 1 g/kg followed by an infusion of 0.7 g·kg Ϫ1 ·h Ϫ1 . This did not provide adequate anesthesia so the infusion was increased to 5 g·kg Ϫ1 ·h Ϫ1 , and after a further 10 min the patient was anesthetized deeply enough to allow the surgery to take place. No supplemental oxygen was administered because of the close proximity of the electrical cautery. Hemodynamically he became stable with heart rate slowing from 120 beats/minute to 65 beats/minute and blood pressure declining from 220/120 mm Hg to 120/65 mm Hg. Oxygen saturation, measured by a pulse oximeter, was maintained above 90% and respiratory rate declined from 30 breaths/min to 16 breaths/min. At the conclusion of the procedure local anesthesia was infiltrated into the surgical sites. The patient required no analgesia in the postanesthesia recovery unit and remained hemodynamically stable. He was discharged from the unit 2 h postoperatively