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[Clinical relevance of detection of microembolism signals with transcranial Doppler ultrasound diagnosis].

Detection of microembolic signals (MES) has been described in several patients groups. A potential clinical relevance of this technique has been established (1) during the first hours following carotid endarterectomy and (2) for patients with asymptomatic ICA stenosis or various autoimmune disorders. Intraoperative monitoring in patients undergoing cardiac or carotid surgery can be used to improve the surgical technique but provides no prognostic information for individual patients. Microembolic signals in patients with prosthetic heart valves cannot be used as markers for stroke risk; their potential significance as markers for neuropsychological deficits remains unclear. Recent reports suggest that MES can be used as surrogate markers for assessing the efficacy of antiplatelet agents. The fact that automated MES detection is not feasible greatly reduces the technique's applicability. On the whole, MES detection--with the exception of the patient groups listed above--provides pathophysiological rather than clinically relevant information.

Feasibility Studies↗

Evaluation of a new invasive continuous cardiac output monitoring system: the truCCOMS system.

OBJECTIVE: To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two "gold standard" methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution. DESIGN: Prospective clinical trial. SETTING: Cardiac surgery operating room and surgical ICU in a university hospital. MATERIAL AND METHODS: In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently. RESULTS: In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r2 = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement -0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r2 = 0.56, the bias was -0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were -1.39 to +1.25 l/min. CONCLUSION: The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.

Aorta↗

Cerebrovenous oxygen saturation monitoring: practical considerations and clinical relevance.

Measurement of the saturation of brain effluent blood gives a global estimate of cerebral oxygenation. It may provide clinicians with information to assist in reducing secondary insults to the brain with potential benefits to a range of patients with actual or potential acute brain injury such as trauma and cardiac bypass procedures. The technology to continuously measure this variable is simple to use but requires attention to detail; it is limited in its ability to detect discrete regions of ischaemia or hyperaemia unless these are of sufficient magnitude to influence the saturation of brain effluent blood. There are few complications that result from this invasive technique and they are usually of a minor nature. The technique also enables research opportunities from the ability to sample blood as it leaves the cranium. Poor outcomes are seen in patients with traumatic brain injury who exhibit either reduced or increased cerebrovenous oxygen saturation and it remains to be seen if detection and correction of these anomalies will produce patient benefits.

Brain Injuries↗

Separation surgery for total vertical craniopagus twins.

OBJECTIVE: A pair of conjoined twins aged 11 months underwent investigations, followed by surgical separation in Singapore General Hospital in April 2001. They were joined at the skull vertex and facing in opposite directions. METHODS: Radiological investigations including cerebral angiography, magnetic resonance imaging and computerized tomographic scans were performed, leading to the diagnosis of total vertical craniopagus. There were two separate brains, with separate arterial circulations, but with a common superior sagittal sinus. Tissue expanders were inserted in the subgaleal space for 6 months of scalp expansion prior to surgery. Pre-operative planning involved the use of virtual reality equipment and life-sized polymer models of the conjoined skulls and brains. Surgical separation of the twins was achieved after approximately 100 h of operating time, using intraoperative image guidance, microsurgical techniques and intraoperative neurophysiologic monitoring. Reconstruction of the dura, calvarium and scalp was performed with artificial dura, absorbable plates and split skin grafts. Postoperative complications included focal cortical infarction, meningitis, and hydrocephalus. CONCLUSION AND OUTCOME: Despite these complications, the twins recovered satisfactorily and were discharged to their home country within 6 months. The 3-month outcome was minor disability in one twin and severe developmental delays in the other. Separation surgery is possible for complex cranially-conjoined twins but requires detailed planning and extensive surgical management.

Anesthesia, General↗

A millennium review of skull base surgery.

Skull base surgery is a recent development in our history, in as much as most of the surgical techniques involved have been described within the last century. To provide an historical prospective the author reviews the development of this specialty, arbitrarily dating its beginning some five centuries ago with the work of Leonardo da Vinci. By picking this period we include the origin of scientific anatomy and personages interested in developing new ideas and concepts who were able to leave the stagnant period of the Middle Ages behind. In 1900 surgeons worked alone, with the concept of a skull base "team" not yet existing. Endotracheal intubation and controlled respiration was just being introduced. Intraoperative monitoring of blood pressure, pulse rate and respiration was not yet known. Harvey Cushing was to introduce this concept in the first decade of the last century. This survey traces the origins of modern skull base surgery from its antecedents in the Renaissance to the beginning of this century. A paper of this length can only provide a sampling of themes and personalities; nevertheless, it will give the reader an impressive overview of how far we have come and some ideas of what the future holds.

History, 15th Century↗

Congenital lumbosacral lipomas.

Congenital lumbosacral lipomas can be responsible for progressive defects. The general feeling is that tethering of roots, filum, or cord probably explains this evolution, and that untethering of these structures could prevent late deterioration. Like the vast majority of neurosurgeons, we too have routinely and systematically operated on lumbosacral lipomas, even in the absence of neurological deficits. This policy stemmed from our belief that spontaneous neurological deterioration was frequent, recovery from preoperative deficits rare, and surgery both efficient and benign in nature. After 22 years of experience, we felt that it was necessary to review our series of 291 lipomas (38 lipomas of the filum and 253 of the conus) operated on from 1972 to 1994. To reassess the value of prophylactic surgery, we attempted an accurate evaluation of (1) the risk of pathology, (2) the risks involved in surgery, (3) the postoperative outcome with respect to preoperative deficits, and (4) the postoperative outcome in asymptomatic patients at 1 year and at maximum follow-up. Special attention was paid to 93 patients whose postoperative follow-up was more than 5 years (average 8.7, median 8, range 5-23 years). Of these 93 patients, 39 were asymptomatic preoperatively (7 with lipoma of the filum and 32 with lipoma of the conus). Lipomas of the filum and of the conus are entirely different lesions and were studied separately. In 6 cases prenatal diagnosis had been possible. The mean age at surgery was 6.4 years. Low back skin stigmata were present in 89.4% of cases. Preoperative neurological deficits existed in 57% of the patients and were congenital in 22%. Clinical signs and symptoms recorded were pain in 13.3% of the patients and/or neurological deficits affecting sphincter (52%), motor (27.6%) and sensory (22.4%) functions. Deficits were progressive in 22.4% of cases, slowly progressive in 58.8% of these and rapidly progressive in the remaining 41.2%. In 36 patients (13.2%) the lipomas were seen to grow either subcutaneously or intraspinally. Among these patients, 21 were infants, 2 were obese adolescents, and 10 were pregnant women. The metabolism of the fat within the lipomas was studied in 11 patients and found to be similar to that at other sites. Lipomas were associated with various other malformations, either intra- or extraspinal. These associated anomalies were rare in the case of lipomatous filum (5.2%) but frequent with lipomas of the conus, except for intracranial malformations (3.6%). Therapeutic objectives were spinal cord untethering and decompression, sparing of functional neural tissue and prevention of retethering. Procedures used to achieve these goals were subtotal removal of the lipoma, intraoperative monitoring, duroplasty, and sometimes closure of the placode. Histologically, lipomas consisted of normal mature fat. However, 77% of them also included a wide variety of other tissues, originating from ectoderm, mesoderm, or entoderm. This indicates that lipomas are either simple or complex teratomas. The results of the study are as follows. (1) Surgery was easy and safe when performed for treatment of lipomas of the filum (no complications), but difficult and hazardous in the case of lipomas of the conus (20% local, 3.9% neurological complications). (2) All types of deficit could be improved by surgery, which was beneficial in all cases of lipoma of the filum and 50% of cases of lipoma of the conus. (3) In asymptomatic patients long-term surgical results depended on the anatomical type of the lipoma. They were excellent in lipomas of the filum. In lipomas of the conus they were good in the short term but eroded with time. At more than 5 years of follow-up only 53.1% of the patients were still free of symptoms. (4) Reoperations were performed in 16 patients (5.5%), 5 (31.2%) of whom improved postoperatively, while in 7 (43.7%) progression stopped, in 3 (18.7%) deterioration continued and in 1 (6.2%) the condition was wor

Adolescent↗

[Endovascular stent-graft prosthesis in aortic aneurysm].

Descending thoracic and abdominal aortic aneurysms represent a potential life-threatening situation. Resection and graft replacement of the pathologically altered aorta used to be the preferred method of treatment. Although progress has been achieved during the past decades in the management of patients with thoracic aortic aneurysms by new surgical techniques, intraoperative monitoring of somatosensory-evoked potentials, and spinal cord fluid drainage, postoperative morbidity and mortality rates still remain high. The afflicted population is usually of older age and present at the time of operation with various comorbidities such as hypertension, obstructive pulmonary disease, coronary heart disease, all of which with significant impact on surgical outcome. Postoperative complications, such as paraplegia, renal and pulmonary disease, contribute to prolonged hospital stay and higher medical cost. In this review we report on a promising alternative approach to the surgical treatment of thoracic and abdominal aortic aneurysms, namely the currently emerging utilization of the endovascular stent-graft prosthesis in both thoracic and abdominal aneurysm.

Aortic Dissection↗

A rare complication of laparoscopic adjustable gastric banding.

The most common complications of laparoscopic gastric banding (LGB) are band dislocation, port problems, and leakage in the band system. We present a case of an aneurysmal dilatation of the balloon portion of the band by filling as a rare complication of LGB. A 53-year-old male patient with morbid obesity (body mass index 40 kg/m2) was treated with LGB (adjustable Bioenterics gastric band). Six months after the operation there was no evidence of weight reduction. X-ray examination showed the band to be in the correct position. The port punction revealed no spontaneous fluid loss. The contrast filling of band demonstrated no signs of leakage but there was an abnormal dilatation of one part of the balloon. Only one filling segment of balloon was dilatated and the rest was empty. Two and a half years after the initial operation, we carried out laparoscopic band exchange. Six weeks later, the band was adjusted with 2 ml saline, and the patient reported successful reduction of food volume. He had lost 18 kg 3 months postoperatively. We conclude that band function requires careful intraoperative monitoring. In patients who do not lose weight after gastric restriction surgery, uncommon complications must also be considered.

Body Mass Index↗

Arterial complications following anterior lumbar interbody fusion: report of eight cases.

The objective of this study is to report eight cases of arterial complication following anterior lumbar interbody fusion (ALIF) and to analyze the data in order to identify possible risk factors. The authors have encountered six cases of common iliac artery occlusion and two cases of acute vasospasm as a complication of ALIF using two different approaches to spine: hypogastric-midline-transperitoneal approach at one center and minimally invasive muscle-sparing retroperitoneal approach at the other. All cases involved surgery at the L4-L5 level. All patients were smokers, and three had an existing history of vascular disease. The left iliac and common femoral arteries were involved in seven cases, while the right common iliac was involved in one case. Five patients had thromboembolism, one patient had an intimal tear and two had functional vasospasm. Circulation to the lower limb was restored by thrombectomy (five patients) and arterioplasty for the intimal tear (one patient). One of the vasospasm cases was explored (false-positive), while the other was treated conservatively. One of the patients with thrombosis developed rhabdomyolysis resulting in fatal acidosis. All but the first case at each center was diagnosed either intraoperatively or within 2 h of surgery. We believe that awareness of this potentially serious complication will lead to precautionary measures for prevention of the problem as well as early diagnosis and management of the complication if it does occur. Intraoperative monitoring of lower limb blood flow by measuring the toe oxygenation with a pulse oxymeter can prove to be helpful in early diagnosis.

Adult↗

Cerebral perfusion during off-pump coronary artery bypass grafting.

PURPOSE: It is still unclear whether cerebral perfusion is affected during off-pump coronary bypass grafting (OPCABG). We investigated the predictive value of the neurobiochemical markers of brain damage and cerebral perfusion in relation to early neuropsychological outcome after OPCABG. METHODS: We performed OPCABG in ten patients (mean age, 63.4 +/- 5.5 years). A 5.5 F oximetric catheter was placed in the jugular bulb to continuously measure jugular oxygen saturation (SjO(2)) during OPCABG. We also examined the activity of daily living (ADL) index and performed the Mini-Mental State Examination (MMSE) to assess neuropsychological state preoperatively and 7 days postoperatively. Venous serum levels of neuron-specific enolase (NSE) and brain-specific creatine kinase (CK-BB) were measured preoperatively and 24 h after skin closure. RESULTS: The mean arterial blood pressure and the SjO(2) during anastomosis of the left circumflex coronary artery (Cx) were significantly lower than that of the left anterior descending coronary artery (LAD) (P < 0.001). None of the patients died. There was no transient or permanent neurologic deficit. Cognitive decline was evident in two patients with a low SjO(2) and a high postoperative NSE level. The postoperative CK-BB value was normal in all patients. CONCLUSIONS: Monitoring intraoperative continuous cerebral oxygen desaturation and postoperative NSE levels could be useful for predicting early neuropsychological outcome after OPCABG.

Aged↗

The use of joint time frequency analysis to quantify the effect of ventilation on the pulse oximeter waveform.

OBJECTIVE: In the process of determining oxygen saturation, the pulse oximeter functions as a photoelectric plethysmograph. By analyzing how the frequency spectrum of the pulse oximeter waveform changes over time, new clinically relevant features can be extracted. METHODS: Thirty patients undergoing general anesthesia for abdominal surgery had their pulse oximeter, airway pressure and CO(2) waveforms collected (50 Hz). The pulse oximeter waveform was analyzed with a short-time Fourier transform using a moving 4096 point Hann window of 82 seconds duration. The frequency signal created by positive pressure ventilation was extracted using a peak detection algorithm in the frequency range of ventilation (0.08-0.4 Hz = 5-24 breaths/minute). The respiratory rate derived in this manner was compared to the respiratory rate as determined by CO(2) detection. RESULTS: In total, 52 hours of telemetry data were analyzed. The respiratory rate measured from the pulse oximeter waveform was found to have a 0.89 linear correlation when compared to CO(2) detection and airway pressure change. the bias was 0.03 breath/min, SD was 0.557 breath/min and the upper and lower limits of agreement were 1.145 and -1.083 breath/min respectively. The presence of motion artifact proved to be the primary cause of failure of this technique. CONCLUSION: Joint time frequency analysis of the pulse oximeter waveform can be used to determine the respiratory rate of ventilated patients and to quantify the impact of ventilation on the waveform. In addition, when applied to the pulse oximeter waveform new clinically relevant features were observed.

Algorithms↗

Another blood supply to Adamkiewicz's artery.

A 76-year-old man underwent endovascular stent-grafting therapy for chronic aortic dissection. The preoperative multi detector row helical computed tomography (CT) revealed that Adamkiewicz's artery originated from the level of thoracic 9 intercostal artery. Intraoperative monitoring of motor evoked potentials showed no reduction of amplitude in the anterior tibialis muscle after deployment retrievable stent-graft. Postoperative CT showed that stent-graft blocked the ostium of intercostal arteries including Adamkiewicz's artery. On the other hand, the distal portion of the Adamkiewicz's artery was clearly enhanced. Our result showed that there is a collateral network supplying to Adamkiewicz's artery.

Aged↗

Continuous coronary flow velocity monitoring during coronary interventions: velocity trend patterns associated with adverse events.

Continuous measurement of blood flow velocity during interventional procedures has the potential to provide an early warning of coronary flow instability, which can lead to abrupt closure or other adverse events before angiography. The magnitude and fluctuations of the average velocity over time (trend) was studied by using a 0.018-inch Doppler-tipped angioplasty guide wire in 32 patients after coronary angiography (n = 20), atherectomy (n = 2), urgent stent (n = 6), urgent vein graft thrombolysis (n = 4), or acute myocardial infarction (n = 2). The patients (mean age 60 +/- 11 years) had postprocedural in-laboratory flow monitoring for a mean of 19 +/- 11 (range 8 to 36) minutes. The coronary artery monitored was the left anterior descending in 13, circumflex in 6, right coronary artery in 9, and saphenous vein graft in 4. Seven patients had flow-related events during continuous flow velocity monitoring before serial angiographic study. These events included coronary vasospasm (abrupt flow acceleration), vasovagal flow cessation, cyclical flow variations resulting from accumulation of intraluminal thrombus, and rapid decline of flow velocity. The last two patterns were associated with abrupt vessel closure during angioplasty. Continuous flow velocity monitoring is easily incorporated into routine interventional procedures and provides an early indication of unstable flow and the potential for abrupt vessel closure and other adverse events.

Adult↗

Transesophageal echocardiographic measurements of cardiac output in cardiac surgical patients.

Transesophageal echocardiography is becoming increasingly popular as a method of intraoperative monitoring because it can be performed continuously, does not transgress the sterile operative field, and provides data with regard to valve function, ventricular volumes, and contractility. Recently it was suggested that it can be used to measure cardiac output; however, controversy remains regarding its accuracy. Cardiac output was measured simultaneously by transesophageal echocardiography (using a 5-MHz pulse-wave Doppler, single-plane viewing probe) and by the thermodilution method in 21 patients undergoing open heart operations. The cardiac outputs measured by thermodilution correlated poorly (r = 0.45) with the transesophageal values derived from the left ventricular cross-sectional area, and the mean difference was 0.47 +/- 2.17 (standard deviation) L.min-1, giving limits of agreement of from -3.87 to +4.81 L.min-1. Cardiac outputs measured by thermodilution correlated well (r = 0.95) with transesophageal Doppler values derived from pulmonary artery flow velocity, with a mean difference of 0.12 +/- 0.45 L.min-1 and narrow limits of agreement of from -0.78 to +1.02 L.min-1. Based on our findings, transesophageal Doppler echocardiographic determination of cardiac output using pulmonary artery flow measurements can provide accurate hemodynamic data in patients undergoing cardiac operations.

Aged↗

Hemifacial spasm: a review.

Hemifacial spasm can be diagnosed by observation and clinical history. It is thought to arise primarily from compression of the facial nerve at the pons, usually by an adjacent artery. Although many approaches to treatment have been tried, the most effective is microvascular decompression of the facial nerve at the pons. That operation has well-recognized risks, including ipsilateral deafness. The latter complication ordinarily can be avoided by the use of intraoperative monitoring of auditory evoked potentials.

Animals↗

Adult respiratory distress syndrome complicating percutaneous nephrolithotripsy.

In an otherwise healthy thirty-six-year-old man adult respiratory distress syndrome developed following percutaneous nephrolithotripsy. Absorption of a large volume of irrigating solution occurred during the procedure and resulted in respiratory compromise, neither of which was appreciated intraoperatively. Close intraoperative monitoring of irrigation fluid input and output is necessary, and if a significant discrepancy develops, we believe the procedure should be terminated and diuresis instituted. In a difficult procedure, consideration should be given to establishing a maximum operating time and shortened if patient risk factors so warrant.

Adult↗

Neonatal choristoma of the tongue containing glial tissue: diagnosis and surgical considerations.

There are only six case reports documenting the presence of glial tissue in the tongue. Because of the small number of cases, the presentation and biologic behavior of these lesions is poorly characterized. We present the case of a 10-day-old male infant who arrived at the University of Michigan Medical Center with a history of positional dyspnea, with resultant cyanosis and bradycardia, dysphagia, and a mass at the base of the tongue. Histopathologically, this lesion was initially labeled as a hamartoma, but was ultimately defined as a choristoma based on the exclusive presentation of glial tissue in the specimen. This paper will discuss the presentation, diagnostic evaluation, and therapeutic management of this case. In addition, the role of intraoperative electrodiagnostic monitoring to preserve neuromuscular function will be addressed.

Choristoma↗