Spontaneous acute thoracic epidural hematoma causing paraplegia in a patient with severe preeclampsia in early labor.

This is a case of acute spontaneous thoracic epidural hematoma in a laboring patient at term who presented with severe preeclampsia and acute spinal cord compression, paraplegia, and sensory loss below T8. In early labor, at home, the patient experienced sudden lumbar back pain that progressed to mid-scapular pain leading to paraplegia and T8 sensory loss within one hour of onset of pain. Her symptoms were caused by a spontaneous thoracic epidural hematoma. Upon arrival at the first hospital, the correct presumptive diagnosis was made in the emergency room, magnesium sulfate was administered, and the patient was transferred to our medical center. Her hypertension was not treated despite severe preeclampsia in order to maintain spinal cord perfusion pressure. Following cesarean section under general anesthesia, thoracic laminectomy was performed and an epidural hematoma compressing the spinal cord to 2-3 mm was evacuated 13 h after the onset of symptoms. After approximately three months of paraplegia, five months with quad-walker and cane use, the patient can now walk with a cane or other minimal support but has remaining bowel and bladder problems. The conflicting anesthetic management objectives of severe preeclampsia and acute paraplegia secondary to spinal epidural hematoma required compromise in the management of her preeclampsia in order to preserve spinal cord perfusion.

Microemboli detected by transcranial Doppler monitoring in patients during carotid angioplasty versus carotid endarterectomy.

UNLABELLED: Microemboli, as detected by transcranial Doppler monitoring, have been shown to be a potential cause of strokes after carotid endarterectomy. We retrospectively reviewed 105 patients who underwent transcranial Doppler monitoring during 112 procedures for the treatment of 115 carotid bifurcation stenoses: 40 by percutaneous angioplasty with stenting and 75 by carotid endarterectomy. In PTAS procedures (n = 40), there was a mean of 74.0 emboli per stenosis (range 0-398, P = 0.0001) with 4 neurologic events per patient (P = 0.08). In CEA procedures (n = 76), there was a mean of 8.8. emboli per stenosis (range 0-102, P= 0.0001) with 1 neurologic event per patient (P = 0.08). The post-procedural neurological events in the percutaneous angioplasty with stenting population included two strokes (5.6%) and two transient ischemia attacks (5.6%). Microemboli for each of these cases totalled 133, 17, 29 and 47 (with one shower), respectively. One postoperative carotid endarterectomy patient was noted to have a stroke (1.4%), with 48 microemboli noted during that procedure. The mean emboli rate for percutaneous angioplasty with stenting patients with neurological events was 59.0: without complications it was 85.1. The mean emboli rate for carotid endarterectomy patients without complications was 8.3. Three percutaneous angioplasty with stenting patients had no emboli (7.5%), whereas 29 carotid endarterectomy patients had no emboli (38.7%). CONCLUSION: The percutaneous angioplasty with stenting procedure is associated with more than eight times the rate of microemboli seen during carotid endarterectomy when evaluated with transcranial Doppler monitoring. Larger patient groups are needed to determine if this greater embolization rate has an associated risk of higher morbidity or mortality.

Design considerations for a transcranial Doppler coupled to a stereotactic position arm.

We present the localization error analysis for a stereotactic positioning arm, transcranial Doppler (TCD) system. Localization displacement errors were determined with a custom phantom head. A bubble apparatus was built to measure sample volume (SV). From interface plane relationships, biological material properties, and human computerized tomography (CT) scan data, an algorithm for computing the actual TCD signal path was developed. Localization resolution was diminished by constraints intrinsic to the TCD instrument (+/-1 mm) and the positioning arm (1.9+/-0.9 mm). The overall SV localization error ranged from 3.3 mm from the target, to complete signal loss at a critical cumulative angle of 31, one third of which may be reached at the TCD probe/skin interface. Any stereotactic ultrasound system must include correction for the beam path. The "failed ultrasound window," may be predicted by signal loss based on refraction alone. The use of stereotactic TCD may enhance the clinical applications of TCD.

Predicting the effect of carotid artery occlusion during carotid endarterectomy: comparing transcranial doppler measurements and cerebral angiography.

BACKGROUND AND PURPOSE: We correlated the mean transcranial Doppler blood flow velocity (FVm) during carotid endarterectomy with the functional collateral pathway(s) documented by angiography. METHODS: Three patient groups were established: group 1 was dependent on the anterior communicating artery, group 2 on the anterior communicating artery and ipsilateral posterior communicating artery, and group 3 on the ipsilateral posterior communicating artery. Continuous middle cerebral artery FVm and electroencephalographic monitoring were performed in 45 patients during carotid endarterectomy. RESULTS: Clamped FVm was lowest in group 3 at 17+/-9 cm/s versus 36+/-16 and 33+/-11 cm/s for groups 1 and 2 (P<0.01). FVm values in groups 1 and 2 were similar. There was significant cerebral arterial vasodilation in group 3 patients on the basis of a pulsatility index of 0.38+/-0.15. The maximum FVm after clamp release was similar among the 3 groups. Normalized blood flow velocity 1 minute before release of the clamp was increased from the minimum flow velocity after clamping only in group 1 and 2 patients. CONCLUSIONS: The ipsilateral posterior communicating artery is a minor collateral pathway during acute carotid occlusion that contributes little to the collateral flow if there is a functional anterior communicating artery. Collateral flow through the middle cerebral artery is not recruited during occlusion in group 3 patients. The reperfusion FVm transient is independent of the primary collateral pathway. Documentation of functional collateral pathways on the basis of Doppler or angiographic examination may be advantageous in future studies since it can provide the basis for comparison among studies.

A comparison of alfentanil, esmolol, lidocaine, and thiopental sodium on the hemodynamic response to insertion of headrest skull pins.

STUDY OBJECTIVES: To compare the effects of four techniques for preventing or blunting the hypertensive response to the insertion of Mayfield headrest skull pins: intravenous (IV) alfentanil (ALF), esmolol (ESM), thiopental sodium (TPL), and local anesthesia using plain lidocaine (Xylocaine; XYL). DESIGN: Randomized open study. PATIENTS: 40 adult patients undergoing intracranial or spinal surgery requiring the use of Mayfield headrest skull pins for head positioning and immobilization. INTERVENTIONS: 20 minutes after anesthetic induction, and 2 to 3 minutes prior to the insertion of headrest skull pins, one of three drugs was administered IV: ALF 10 mcg/kg, ESM 1 mg/kg, or TPL 1.5 mg/kg. The fourth drug, XYL, was administered by injection into the scalp. MEASUREMENTS AND MAIN RESULTS: Blood pressure and heart rate (HR) were recorded immediately prior to and after pin insertion with balanced general anesthesia, and at 30, 60, 120, and 180-second intervals after pin insertion. The measurements were compared with the immediate preinsertion values. In the ALF and XYL groups, there was no significant increase in mean arterial pressure (MAP) or HR for any of the measurement periods. MAP was elevated immediately on pin insertion and for up to 2 minutes in the TPL group, and for up to 3 minutes in the ESM group (p < 0.05). HR changes were seen in the TPL group for up to one minute (p < 0.05). Increases in systolic blood pressure were seen in the TPL and ESM groups for up to 3 minutes, and in diastolic blood pressure for up to 2 minutes (p < 0.05). No other significant changes were observed. CONCLUSIONS: IV ALF and local injection of XYL in the scalp prevent the hemodynamic response to the insertion of skull pins in anesthetized patients. Neither ESM nor TPL prevented the hypertensive response. Local anesthetic injection into the scalp requires coordination between the anesthesiologist and surgeon, it carries the risk of needle stick injury, and it must be repeated if the surgeon repositions the headrest. The rapid onset and short half-life of ALF, coupled with the absence of hemodynamic effects at the dose used, makes this drug an alternative to the use of XYL injection.

Cerebrovascular assessment of the high-risk patient: the role of transcranial Doppler ultrasound.

With increased attention to the causes and effects of neurologic injury related to cardiopulmonary bypass anesthesia and surgery, multiple modality examination and monitoring of cerebral function and perfusion in the perioperative period may prove to be advantageous. Transcranial Doppler examination and monitoring is inexpensive, noninvasive, safe, provides unique information about the functional status of the intracranial circulation, and complements the duplex Doppler study of the extracranial carotid vessels of the neck for preoperative evaluation of the surgical patient. The transcranial Doppler examination permits quantitation of blood flow velocity of the intracranial vessels, evaluation of autoregulatory capacity and vasomotor reserve, determination of symmetry of flow velocity in the circle of Willis, assessment of collateral circulatory capacity, examination of vessels not accessible to the duplex Doppler and serves as a baseline for intraoperative monitoring and the postoperative examination. Noninvasive, unilateral or bilateral, continuous monitoring of brain blood flow velocity intraoperatively or postoperatively with trending, storage, and correlation with other physiologic variables provides evidence of cerebral perfusion, occurrence and rate of cerebral embolism, and continuous monitoring of therapeutic interventions. A review of the incidence of stroke and neuropsychologic deficit after bypass surgery is focused on parameters amenable to diagnosis using transcranial Doppler. Patient-specific risk factors for neurologic injury derived from previous studies are discussed as well as risk factors that are related to anesthetic and surgical management and equipment. A description of Doppler technology and the correlation of transcranial Doppler findings with angiography and radionucleotide scans establishes the accuracy of the Doppler examination. The preoperative examination, provocative tests of vasomotor reserve, the evaluation of cerebral collateral circulation, and examples of Doppler applications are discussed.

The effect of acute hypocapnia on middle cerebral artery transcranial Doppler velocity during orthotopic liver transplantation: changes at reperfusion.

This study examines the effects of acute hypocapnia, instituted prior to reperfusion of the graft liver, on the middle cerebral artery (MCA) Doppler blood flow velocity response to reperfusion during orthotopic liver transplantation in humans. Seventeen patients with chronic liver disease underwent continuous, noninvasive Doppler imaging of the MCA. Hyperventilation to an end-tidal Pco2 of 25 +/- 1 mm Hg was associated with a decrease in mean MCA flow velocity (FVm) from 51.6 +/- 5.7 to 37.0 +/- 3.3 cm/s (P < 0.05). After reperfusion, the Paco2 increased from 32 +/- 1 to 40 +/- 1 mm Hg (P < 0.05), mean arterial pressure (MAP) decreased from 76 +/- 3 to 60 +/- 2 mm Hg, and the FVm increased from 37.0 +/- 3.3 to 54.0 +/- 4.7 cm/s (P < 0.05). FVm increased postreperfusion despite prior hyperventilation, decreased MAP, and abrupt increases in central venous and pulmonary artery pressure, but FVm did not exceed the prereperfusion level. In 10 of the 17 patients, the baseline FVm versus Paco2 response slopes and Paco2 measured postreperfusion were used to predict the FVm response to Paco2 after reperfusion. The slopes were similar to those reported for anesthetized patients without liver disease. Predicted FVm exceeded measured FVm in 9 of the 10 patients. We conclude that mild hyperventilation prior to reperfusion of the graft liver prevents FVm increases above prereperfusion baseline level.

Intraoperative transesophageal echocardiography in orthotopic liver transplantation in a patient with hypertrophic cardiomyopathy.

With improvements in the surgical technique for orthotopic liver transplantation, patients with significant underlying systemic disease are considered candidates for transplantation, thus increasing the complexity of the medical management of these patients and necessitating additional monitoring in order to minimize the anesthetic risk. We describe the anesthetic management of orthotopic liver transplantation for a patient with severe hypertrophic cardiomyopathy and mitral insufficiency. In this case, transesophageal echocardiography proved useful in the management of the postreperfusion period of the surgical procedure.

Gastric intramural pH as indicator of early allograft viability in orthotopic liver transplantation.

The determination of the viability of OLT grafts has relied upon metabolic tests of the liver, which take several hours to evaluate and therefore are only conclusive in most patients well into the postoperative period. Earlier diagnosis of graft failure or nonfunction would allow intraoperative reassessment of surgical technique and, in the case of graft failure, earlier planning for retransplantation. Since gastrointestinal mucosal ischemia is one of the earliest manifestations of impaired core tissue in the critically ill, a tonometric nasogastric tube (Tonomitor) was used in our patients to measure intramucosal gastric pH (pHi) during the preanhepatic (stage I), anhepatic (stage II), and neohepatic (stage III) phases of OLT in 35 patients as an indicator of graft liver function and viability. Based on the results of the pHi measurement 30 min after reperfusion during stage III, patients were divided into 2 groups using a pHi of 7.30 as the dividing point. Patients with a pHi equal or higher than 7.30 were assigned to group 1 (n = 24) and patients with a pHi lower than 7.30 were assigned to group 2 (n = 11). The pHi in group 1 patients averaged 7.37 +/- 0.5 30 min after reperfusion and throughout surgery. The pHi in group 2 patients was lower than that of the group 1 patients 30 min after reperfusion, 7.23 +/- 0.04 (P < 0.001). The pHi in 10 group 2 patients returned to normal within 3 hr after reperfusion and the pHi values for these patients were not significantly different from those of group 1 at 3 hr after reperfusion. The pHi in 1 group 2 patient remained lower than 7.30 and never returned to normal; this patient underwent retransplantation the following day. Utilizing the tonometric nasogastric tube to sample intramucosal pH allowed early detection of graft function and intermittent trending of pHi in patients with questionable graft function during the operative period. It also provided a means of assessing graft function independent of enzymatic criteria, which provide little information in the early phase of transplantation.

Intraoperative monitoring of brainstem auditory evoked potentials during resection of a cavernous hemangioma in the fourth ventricle: an indirect monitor of the fifth and seventh nerves.

This case demonstrates the use of brainstem auditory evoked potentials (BAEPs) to monitor cranial nerve function. Changes in BAEPs were associated with cranial nerve dysfunction in the trigeminal nerve on the ipsilateral side and the facial nerve on the contralateral side.

Middle cerebral artery transcranial Doppler velocity monitoring during orthotopic liver transplantation: changes at reperfusion--a report of six cases.

STUDY OBJECTIVE: To determine the effect of reperfusion of the grafted liver on transcranial Doppler blood flow velocity in the middle cerebral artery in humans during orthotopic liver transplantation. DESIGN: Clinical study. SETTING: University hospital. PATIENTS: 6 patients scheduled for orthotopic liver transplantation. INTERVENTIONS: Middle cerebral artery blood flow velocity (MCAVm) was monitored continuously using a transcranial Doppler (TCD) probe. The TCD measurements were noninvasive. MEASUREMENTS AND MAIN RESULTS: The EME TC2000S TCD probe (Nicolet, Inc., Memphis, TN) was secured to the head using a strap providing continuous measurement of MCAVm. All other data were recorded by a patient monitoring system and a respiratory gas analyzer. Averaged MCAVm increased significantly in 5 of 6 patients (p < 0.001) when pre-reperfusion and post-reperfusion values were compared. Maximum post-reperfusion values for MCAVm, pulsatility index (PI), and systolic Doppler velocity (Vs) were greater than the corresponding immediate pre-reperfusion values (p < 0.05, p < 0.05, and p < 0.001, respectively). The increases in MCAVm cannot be explained on the basis of hypercarbia alone and were observed in the presence of systemic arterial hypotension and abrupt increases in central venous pressure, particularly at the time of graft reperfusion. CONCLUSIONS: MCAVm increased with reperfusion of the grafted liver. These data suggest that multiple factors--including hypercarbia, lactic acidosis, or multiple vasoactive substances released by the grafted liver--may contribute to the observed increases in MCAVm, Vs, and PI.