Serious cardiac complications occurring during noncardiac surgery in a young and otherwise normal... more Serious cardiac complications occurring during noncardiac surgery in a young and otherwise normal person can be quite alarming for the anesthesiologist. We report here the case of a young, healthy woman who immediately after an uncomplicated spinal surgery developed a clinical picture suggestive of an acute myocardial infarction (MI) with positive relevant investigations. However, she had an abrupt and full clinical recovery and complete normalization of her cardiac investigations within a few days of this event and thereafter continued to lead a normal, symptom-free life unlike the usual course in an MI; her coronary angiography was also normal. A diagnosis of perioperative stress-induced cardiomyopathy or Takotsubo cardiomyopathy was subsequently made. This condition is characterized by a rapid, severe, but reversible, cardiac dysfunction triggered by physical or mental stress. Awareness of this entity should help anesthesiologists manage better this infrequent, but potentially li...
SIR—We read with interest, the airway management of an infant with a giant occipital encephalocel... more SIR—We read with interest, the airway management of an infant with a giant occipital encephalocele (GOE) and the use of preoperative decompression of the encephalocele sac to help achieve tracheal intubation in the supine position (1). Securing the airway is often a challenge in these patients, because the enormous, occipitally located encephalocele prevents proper positioning by restricting the movement of the head at the atlantooccipital joint. The authors have mentioned various modifications for anesthetic induction in the supine position; however, they have expressed their apprehensions with the use of the lateral position, due to unavailability of advanced pediatric airway equipment. We routinely use the lateral position for airway control of such infants and would like to mention that no advanced airway equipment such as a pediatric video-laryngoscope is required, as suggested by the authors (1). This position is considered to be safer than the supine position, because the weight of the head is not transmitted to the encephalocele sac; this eliminates the risk of compression-related preoperative rupture of the GOE, or an inadvertent increase in the intracranial pressure (2,3). These children also, mostly, remain in a lateral rather than a supine position (due to weight of the GOE) and are therefore more comfortable during the anesthetic induction. No special equipment is required for positioning; however, anesthetists often modify the position of the GOE relative to the head, after anesthetic induction. This helps to improve the degree of head extension the atlanto-occipital joint and obtain a nearoptimal tracheal intubating condition. Usually, gentle manipulation and caudal displacement of the GOE suffices however, this maneuvre warrants caution as it can cause an inadvertent rupture of the GOE. It is best performed in the lateral position, as the optimal extent of manipulation and caudal displacement of the GOE can be directly observed and controlled. Laryngoscopy does cause a mild inconvenience, because the anesthetist has to bend laterally to visualize the larynx; however, we usually offset it by giving a 30–40 degree, counter-lateral tilt to the operating table, for example a left lateral table tilt, for a right lateral decubitus position, and vice versa. A difficult airway situation is not uncommon during the anesthetic management of infants with GOE, and anesthetists usually have an alternate airway management plan in place. Although the decision of lateral or supine position for tracheal intubation is largely a matter of personal choice and experience, we believe that familiarity with both the positions definitely gives an edge. After all, ‘birds in the hand’ are definitely better than those ‘in the bush’.
A primigravida at 28 weeks of gestation was diagnosed with a left internal carotid artery aneurys... more A primigravida at 28 weeks of gestation was diagnosed with a left internal carotid artery aneurysm with subarachnoid hemorrhage, World Federation of Neurosurgical Societies (WFNS) Grade-2, necessitating urgent aneurysm clipping. Relevant preoperative checkup included no apparent history of syncopal episodes, a BP of 90/60 mm of Hg, a heart rate of 41 beats/min, a CHB on ECG and no evidence of underlying cardiac disease on echocardiography. The patient was paced with a temporary transvenous pacemaker at a rate of 80 beats/ min; her post-pacing BP was 118/72 mm of Hg. During surgery, the patient’s BP fell abruptly to 82/56 mm of Hg which was normalized by resetting the pacemaker rate at 90 beats/min. Repeated pacemaker adjustments became necessary in the postoperative period to maintain stable post-clipping systolic BP in the range of 140-160 mmHg; a permanent pacemaker was then inserted in her.
Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder characterized by prem... more Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder characterized by premature ageing, severe growth failure, and very early onset atherosclerosis. Psychologically and emotionally child-like, these patients suffer from physiological changes of old age. Early and progressive atherosclerosis of intra-cranial vessels in HGPS patients, along with a thin skin and fragile vessels, make these patients susceptible to intra-cranial hematomas following relatively trivial injuries and to severe intra-cranial disease. Anesthetizing HGPS patients for surgery can be challenging due to the presence of a possible difficult airway, multi-system derangements, and associated skin, bone and joint disease. We report here one such child with HGPS who underwent craniotomy and evacuation of an extradural hematoma that developed after minor head trauma. Securing his airway during surgery was difficult.
Mitral valve disease in patients undergoing posterior fossa surgery enhances the inherent risk of... more Mitral valve disease in patients undergoing posterior fossa surgery enhances the inherent risk of the procedure and can complicate the anesthetic management. A great challenge for the anesthesiologist is to choose the most appropriate perioperative technique that balances the specific anesthetic considerations of both the cardiac and the neurologic diseases. The authors describe the anesthetic management of a patient with a meningioma in the posterior fossa requiring craniectomy and tumor decompression. She was also diagnosed with severe mitral regurgitation and moderate mitral stenosis.
Journal of Anaesthesiology Clinical Pharmacology, 2014
Preoperative thrombocytosis, often detected incidentally in surgical patients and inadvertently o... more Preoperative thrombocytosis, often detected incidentally in surgical patients and inadvertently overlooked, has important implications for the anesthesiologists. The primary form is a chronic clonal myeloproliferative disorder usually affecting adults while the secondary type is a benign reactive disease commonly found in children. Serious perioperative hemostatic complications are reported in primary thrombocytosis and hence, a detailed preoperative evaluation and initiation of therapy to lower the platelet count (PC) is required before undertaking surgery. Patients with reactive thrombocytosis however, usually have complicationfree surgeries, and if there is no prior evidence of hemostatic complications and the reactive cause can be identified, no specific perioperative intervention may be required. A thorough preanesthetic checkup and implementation of basic thrombo-prophylaxis measures in all patients with a raised PC is advocated. We present here our experience with three infants diagnosed with high preoperative PC, presumably due to reactive causes, who underwent uneventful neurosurgeries at our institution.
ABSTRACT Determining the proper dosage of protamine for heparin reversal in open-heart surgery is... more ABSTRACT Determining the proper dosage of protamine for heparin reversal in open-heart surgery is often arbitrary and both under-and overdosing are possible. We describe here a method of protamine administration that was studied in 50 patients undergoing open heart surgery. Protamine was given as a slow, controlled infusion guided by repeated activated clotting time measurements till the earliest return of these values to base-line levels. Using this technique, 39 (78%) patients had an adequate heparin reversal at the end of surgery, at doses of protamine less than those used conventionally. There was no unusual increase in 24-hour chest tube drainage in these patients. The method appears to be a safe and effective alternative to traditional protocols of heparin neutralisation.
Prolongation of the neuromuscular blocking effect of vecuronium with intravenous preparations of ... more Prolongation of the neuromuscular blocking effect of vecuronium with intravenous preparations of cyclosporine has been described, t.2 We observed this interaction in a 36-yr-old man two months after renal transplant receiving oral cyclosporine when he returned for internal urethrotomy. He was taking oral cyclosporine 180 mg bid, and azathioprine 75 mg and prednisolone 30 mg od. Physical examination and preoperative investigations were normal. On the morning of the operation, he took one dose of each of the three immunosuppressives. Premedication was with pentazocine 20 mg and phenergan 20 mg im and anaesthesia was induced with thiopentone 5 mg-kg -l followed by vecuronium 0.08 mg. kg -l/v, O2 + N20 (40:60) and halothane 0.5%. Neuromuscular function was assessed continuously. Haemodynamic stability was maintained throughout the one-hour operation. No additional vecuronium was given. Neuromuscular blockade was reversed with neostigmine 0.05 mg. kg -I and atropine 0.02 mg. kg -~/v after two definite and a faint third response to train-of-four stimulation were observed. Though the patient was awake and cooperative, incoordinate body movements, inability to sustain head lift, inadequate respiratory efforts and poorly sustained 50 Hz tetanus suggested residual neuromuscular blockade. The patient's temperature, serum electrolytes and arterial blood gas analysis were normal. Further neostigmine 1.0 mg and atropine 0.5 mg after ten minutes had no effect. Positive-pressure ventilation was continued for about three hours after which a satisfactory return of the neuromuscular function enabled extubation. In the absence of obvious renal, hepatic or metabolic derangement in this patient, the prolonged neuromuscular blocking effect of vecuronium was probably due to drug interaction. While azathioprine 3 and chronic steroid therapy 4 antagonize non-depolarizing neuromuscular blockade, cyclosporine appears to prolong it. 1,2,s Intravenous preparations of cyclosporine, however, contain cremophor as solvent, which may potentiate vecuronium-induced blockade s and thus be partly responsible for this interaction. Oral eyelosporine (Sandimmum, Sandoz) does not contain cremophor. Thus, in light of the above interaction, continuous monitoring of neuromuscular block in post-transplant patients is reemphasized.
Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF).... more Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF). However, few studies have investigated the action of dexmedetomidine on the cerebral microcirculation. This investigation examined the effects of dexmedetomidine on (1) regional CBF in the rat cerebral cortex using laser-Doppler flowmetry and (2) on pial arteriolar diameter. Methods Halothane-anesthetized rats were fitted with instruments to measure CBF as determined by laser-Doppler flow (CBFldf) or to measure pial arteriolar diameter by preparing a cranial hollow deepened until a translucent plate of skull remained, thereby maintaining the integrity of the cranial vault. In both groups, 20 microg/kg dexmedetomidine was infused intravenously. Thirty minutes later, the mean arterial pressure was restored to control values with an infusion of phenylephrine (0.5 to 5 microg/kg/min). Results Administration of dexmedetomidine was associated with decreases in end-tidal and arterial carbon di...
ABSTRACT The sedative and anesthetic-sparing ability of the alpha2-adrenergic agonist dexmedetomi... more ABSTRACT The sedative and anesthetic-sparing ability of the alpha2-adrenergic agonist dexmedetomidine is well documented. In this study, we identified the effects of halothane, with and without dexmedetomidine, on hemodynamic and electroencephalographic (EEG) variables and quantified the concentration of halothane resulting in various anesthetic depth indices mediated through the central nervous system (CNS) in chronically instrumented cats. Halothane was given alone or after dexmedetomidine (15 microg/kg p.o.). In both groups, four indices of anesthetic depth--minimum alveolar anesthetic concentration (MAC; no movement to noxious stimuli), MAC(BAR) (no autonomic response to noxious stimuli), MAC(BS) (EEG burst suppression), and MAC(ISOELECTRIC) (EEG isoelectricity)--were determined. Halothane decreased arterial blood pressure, heart rate, and higher frequency components of the EEG before the onset of burst suppression and isoelectricity. Dexmedetomidine pretreatment augmented the actions of halothane on arterial pressure, heart rate, and the EEG. Dexmedetomidine reduced the halothane concentrations resulting in MAC (from 1.22% +/- 0.06% to 0.89% +/- 0.08%) and MAC(BAR) (from 1.81% +/- 0.05% to 1.1% +/- 0.10%), but not those resulting in MAC(BS) (3.01% +/- 0.17% vs 3.14% +/- 0.10%) or MAC(ISOELECTRIC) (4.39% +/- 0.26% vs 4.65% +/- 0.12%). These results suggest that dexmedetomidine does not alter various CNS-mediated indices of anesthetic action to equivalent degrees and that there are dissimilar degrees of an anesthetic-sparing action at different levels of the neuraxis. IMPLICATIONS: The anesthetic adjuvant dexmedetomidine seems to differentially alter central nervous system-mediated indices of anesthetic action. Lower brainstem or spinal determinants of anesthetic depth (movement and hemodynamic responses) are more attenuated than those of higher brain functions, such as the electroencephalogram.
We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applic... more We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus,`strange feelings' and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.
Serious cardiac complications occurring during noncardiac surgery in a young and otherwise normal... more Serious cardiac complications occurring during noncardiac surgery in a young and otherwise normal person can be quite alarming for the anesthesiologist. We report here the case of a young, healthy woman who immediately after an uncomplicated spinal surgery developed a clinical picture suggestive of an acute myocardial infarction (MI) with positive relevant investigations. However, she had an abrupt and full clinical recovery and complete normalization of her cardiac investigations within a few days of this event and thereafter continued to lead a normal, symptom-free life unlike the usual course in an MI; her coronary angiography was also normal. A diagnosis of perioperative stress-induced cardiomyopathy or Takotsubo cardiomyopathy was subsequently made. This condition is characterized by a rapid, severe, but reversible, cardiac dysfunction triggered by physical or mental stress. Awareness of this entity should help anesthesiologists manage better this infrequent, but potentially li...
SIR—We read with interest, the airway management of an infant with a giant occipital encephalocel... more SIR—We read with interest, the airway management of an infant with a giant occipital encephalocele (GOE) and the use of preoperative decompression of the encephalocele sac to help achieve tracheal intubation in the supine position (1). Securing the airway is often a challenge in these patients, because the enormous, occipitally located encephalocele prevents proper positioning by restricting the movement of the head at the atlantooccipital joint. The authors have mentioned various modifications for anesthetic induction in the supine position; however, they have expressed their apprehensions with the use of the lateral position, due to unavailability of advanced pediatric airway equipment. We routinely use the lateral position for airway control of such infants and would like to mention that no advanced airway equipment such as a pediatric video-laryngoscope is required, as suggested by the authors (1). This position is considered to be safer than the supine position, because the weight of the head is not transmitted to the encephalocele sac; this eliminates the risk of compression-related preoperative rupture of the GOE, or an inadvertent increase in the intracranial pressure (2,3). These children also, mostly, remain in a lateral rather than a supine position (due to weight of the GOE) and are therefore more comfortable during the anesthetic induction. No special equipment is required for positioning; however, anesthetists often modify the position of the GOE relative to the head, after anesthetic induction. This helps to improve the degree of head extension the atlanto-occipital joint and obtain a nearoptimal tracheal intubating condition. Usually, gentle manipulation and caudal displacement of the GOE suffices however, this maneuvre warrants caution as it can cause an inadvertent rupture of the GOE. It is best performed in the lateral position, as the optimal extent of manipulation and caudal displacement of the GOE can be directly observed and controlled. Laryngoscopy does cause a mild inconvenience, because the anesthetist has to bend laterally to visualize the larynx; however, we usually offset it by giving a 30–40 degree, counter-lateral tilt to the operating table, for example a left lateral table tilt, for a right lateral decubitus position, and vice versa. A difficult airway situation is not uncommon during the anesthetic management of infants with GOE, and anesthetists usually have an alternate airway management plan in place. Although the decision of lateral or supine position for tracheal intubation is largely a matter of personal choice and experience, we believe that familiarity with both the positions definitely gives an edge. After all, ‘birds in the hand’ are definitely better than those ‘in the bush’.
A primigravida at 28 weeks of gestation was diagnosed with a left internal carotid artery aneurys... more A primigravida at 28 weeks of gestation was diagnosed with a left internal carotid artery aneurysm with subarachnoid hemorrhage, World Federation of Neurosurgical Societies (WFNS) Grade-2, necessitating urgent aneurysm clipping. Relevant preoperative checkup included no apparent history of syncopal episodes, a BP of 90/60 mm of Hg, a heart rate of 41 beats/min, a CHB on ECG and no evidence of underlying cardiac disease on echocardiography. The patient was paced with a temporary transvenous pacemaker at a rate of 80 beats/ min; her post-pacing BP was 118/72 mm of Hg. During surgery, the patient’s BP fell abruptly to 82/56 mm of Hg which was normalized by resetting the pacemaker rate at 90 beats/min. Repeated pacemaker adjustments became necessary in the postoperative period to maintain stable post-clipping systolic BP in the range of 140-160 mmHg; a permanent pacemaker was then inserted in her.
Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder characterized by prem... more Hutchinson-Gilford progeria syndrome (HGPS) is a very rare genetic disorder characterized by premature ageing, severe growth failure, and very early onset atherosclerosis. Psychologically and emotionally child-like, these patients suffer from physiological changes of old age. Early and progressive atherosclerosis of intra-cranial vessels in HGPS patients, along with a thin skin and fragile vessels, make these patients susceptible to intra-cranial hematomas following relatively trivial injuries and to severe intra-cranial disease. Anesthetizing HGPS patients for surgery can be challenging due to the presence of a possible difficult airway, multi-system derangements, and associated skin, bone and joint disease. We report here one such child with HGPS who underwent craniotomy and evacuation of an extradural hematoma that developed after minor head trauma. Securing his airway during surgery was difficult.
Mitral valve disease in patients undergoing posterior fossa surgery enhances the inherent risk of... more Mitral valve disease in patients undergoing posterior fossa surgery enhances the inherent risk of the procedure and can complicate the anesthetic management. A great challenge for the anesthesiologist is to choose the most appropriate perioperative technique that balances the specific anesthetic considerations of both the cardiac and the neurologic diseases. The authors describe the anesthetic management of a patient with a meningioma in the posterior fossa requiring craniectomy and tumor decompression. She was also diagnosed with severe mitral regurgitation and moderate mitral stenosis.
Journal of Anaesthesiology Clinical Pharmacology, 2014
Preoperative thrombocytosis, often detected incidentally in surgical patients and inadvertently o... more Preoperative thrombocytosis, often detected incidentally in surgical patients and inadvertently overlooked, has important implications for the anesthesiologists. The primary form is a chronic clonal myeloproliferative disorder usually affecting adults while the secondary type is a benign reactive disease commonly found in children. Serious perioperative hemostatic complications are reported in primary thrombocytosis and hence, a detailed preoperative evaluation and initiation of therapy to lower the platelet count (PC) is required before undertaking surgery. Patients with reactive thrombocytosis however, usually have complicationfree surgeries, and if there is no prior evidence of hemostatic complications and the reactive cause can be identified, no specific perioperative intervention may be required. A thorough preanesthetic checkup and implementation of basic thrombo-prophylaxis measures in all patients with a raised PC is advocated. We present here our experience with three infants diagnosed with high preoperative PC, presumably due to reactive causes, who underwent uneventful neurosurgeries at our institution.
ABSTRACT Determining the proper dosage of protamine for heparin reversal in open-heart surgery is... more ABSTRACT Determining the proper dosage of protamine for heparin reversal in open-heart surgery is often arbitrary and both under-and overdosing are possible. We describe here a method of protamine administration that was studied in 50 patients undergoing open heart surgery. Protamine was given as a slow, controlled infusion guided by repeated activated clotting time measurements till the earliest return of these values to base-line levels. Using this technique, 39 (78%) patients had an adequate heparin reversal at the end of surgery, at doses of protamine less than those used conventionally. There was no unusual increase in 24-hour chest tube drainage in these patients. The method appears to be a safe and effective alternative to traditional protocols of heparin neutralisation.
Prolongation of the neuromuscular blocking effect of vecuronium with intravenous preparations of ... more Prolongation of the neuromuscular blocking effect of vecuronium with intravenous preparations of cyclosporine has been described, t.2 We observed this interaction in a 36-yr-old man two months after renal transplant receiving oral cyclosporine when he returned for internal urethrotomy. He was taking oral cyclosporine 180 mg bid, and azathioprine 75 mg and prednisolone 30 mg od. Physical examination and preoperative investigations were normal. On the morning of the operation, he took one dose of each of the three immunosuppressives. Premedication was with pentazocine 20 mg and phenergan 20 mg im and anaesthesia was induced with thiopentone 5 mg-kg -l followed by vecuronium 0.08 mg. kg -l/v, O2 + N20 (40:60) and halothane 0.5%. Neuromuscular function was assessed continuously. Haemodynamic stability was maintained throughout the one-hour operation. No additional vecuronium was given. Neuromuscular blockade was reversed with neostigmine 0.05 mg. kg -I and atropine 0.02 mg. kg -~/v after two definite and a faint third response to train-of-four stimulation were observed. Though the patient was awake and cooperative, incoordinate body movements, inability to sustain head lift, inadequate respiratory efforts and poorly sustained 50 Hz tetanus suggested residual neuromuscular blockade. The patient's temperature, serum electrolytes and arterial blood gas analysis were normal. Further neostigmine 1.0 mg and atropine 0.5 mg after ten minutes had no effect. Positive-pressure ventilation was continued for about three hours after which a satisfactory return of the neuromuscular function enabled extubation. In the absence of obvious renal, hepatic or metabolic derangement in this patient, the prolonged neuromuscular blocking effect of vecuronium was probably due to drug interaction. While azathioprine 3 and chronic steroid therapy 4 antagonize non-depolarizing neuromuscular blockade, cyclosporine appears to prolong it. 1,2,s Intravenous preparations of cyclosporine, however, contain cremophor as solvent, which may potentiate vecuronium-induced blockade s and thus be partly responsible for this interaction. Oral eyelosporine (Sandimmum, Sandoz) does not contain cremophor. Thus, in light of the above interaction, continuous monitoring of neuromuscular block in post-transplant patients is reemphasized.
Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF).... more Background The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF). However, few studies have investigated the action of dexmedetomidine on the cerebral microcirculation. This investigation examined the effects of dexmedetomidine on (1) regional CBF in the rat cerebral cortex using laser-Doppler flowmetry and (2) on pial arteriolar diameter. Methods Halothane-anesthetized rats were fitted with instruments to measure CBF as determined by laser-Doppler flow (CBFldf) or to measure pial arteriolar diameter by preparing a cranial hollow deepened until a translucent plate of skull remained, thereby maintaining the integrity of the cranial vault. In both groups, 20 microg/kg dexmedetomidine was infused intravenously. Thirty minutes later, the mean arterial pressure was restored to control values with an infusion of phenylephrine (0.5 to 5 microg/kg/min). Results Administration of dexmedetomidine was associated with decreases in end-tidal and arterial carbon di...
ABSTRACT The sedative and anesthetic-sparing ability of the alpha2-adrenergic agonist dexmedetomi... more ABSTRACT The sedative and anesthetic-sparing ability of the alpha2-adrenergic agonist dexmedetomidine is well documented. In this study, we identified the effects of halothane, with and without dexmedetomidine, on hemodynamic and electroencephalographic (EEG) variables and quantified the concentration of halothane resulting in various anesthetic depth indices mediated through the central nervous system (CNS) in chronically instrumented cats. Halothane was given alone or after dexmedetomidine (15 microg/kg p.o.). In both groups, four indices of anesthetic depth--minimum alveolar anesthetic concentration (MAC; no movement to noxious stimuli), MAC(BAR) (no autonomic response to noxious stimuli), MAC(BS) (EEG burst suppression), and MAC(ISOELECTRIC) (EEG isoelectricity)--were determined. Halothane decreased arterial blood pressure, heart rate, and higher frequency components of the EEG before the onset of burst suppression and isoelectricity. Dexmedetomidine pretreatment augmented the actions of halothane on arterial pressure, heart rate, and the EEG. Dexmedetomidine reduced the halothane concentrations resulting in MAC (from 1.22% +/- 0.06% to 0.89% +/- 0.08%) and MAC(BAR) (from 1.81% +/- 0.05% to 1.1% +/- 0.10%), but not those resulting in MAC(BS) (3.01% +/- 0.17% vs 3.14% +/- 0.10%) or MAC(ISOELECTRIC) (4.39% +/- 0.26% vs 4.65% +/- 0.12%). These results suggest that dexmedetomidine does not alter various CNS-mediated indices of anesthetic action to equivalent degrees and that there are dissimilar degrees of an anesthetic-sparing action at different levels of the neuraxis. IMPLICATIONS: The anesthetic adjuvant dexmedetomidine seems to differentially alter central nervous system-mediated indices of anesthetic action. Lower brainstem or spinal determinants of anesthetic depth (movement and hemodynamic responses) are more attenuated than those of higher brain functions, such as the electroencephalogram.
We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applic... more We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus,`strange feelings' and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.
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