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Serotonin syndrome (SS) is a life-threatening condition caused by serotonergic medications. We describe a unique case of SS likely caused by prolonged exposure to propofol and remifentanil alone. A young male presented for vestibular schwannoma resection. Several hours into the case, the patient demonstrated hyperthermia and hemodynamic instability, followed by clonus, rigidity, shivering, and tachycardia after emergence. SS was diagnosed using Hunter's criteria and improved with supportive measures. While the patient endorsed a history of methamphetamine use, his urine drug screen was negative. The possibility of SS should be considered when administering propofol and remifentanil, particularly with prolonged infusions., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 International Anesthesia Research Society.)

The biosynthesis of Fe-S clusters and other thio-cofactors requires the participation of redox agents. A shared feature in these pathways is the formation of transient protein persulfides, which are susceptible to reduction by artificial reducing agents commonly used in reactions in vitro. These agents modulate the reactivity and catalytic efficiency of biosynthetic reactions and, in some cases, skew the enzymes' kinetic behavior, bypassing sulfur acceptors known to be critical for the functionality of these pathways in vivo. Here, we provide kinetic evidence for the selective reactivity of the Bacillus subtilis Trx (thioredoxin) system toward protein-bound persulfide intermediates. Our results demonstrate that the redox flux of the Trx system modulates the rate of sulfide production in cysteine desulfurase assays. Likewise, the activity of the Trx system is dependent on the rate of persulfide formation, suggesting the occurrence of coupled reaction schemes between both enzymatic systems in vitro. Inactivation of TrxA (thioredoxin) or TrxR (thioredoxin reductase) impairs the activity of Fe-S enzymes in B. subtilis, indicating the involvement of the Trx system in Fe-S cluster metabolism. Surprisingly, biochemical characterization of TrxA reveals that this enzyme is able to coordinate Fe-S species, resulting in the loss of its reductase activity. The inactivation of TrxA through the coordination of a labile cluster, combined with its proposed role as a physiological reducing agent in sulfur transfer pathways, suggests a model for redox regulation. These findings provide a potential link between redox regulation and Fe-S metabolism.

Purpose: To evaluate the outcome of the management of iatrogenic arterial injuries following knee arthroplasty using a primary endovascular approach., Methods: A detailed review of the management of all iatrogenic arterial injuries to the lower limb following total knee arthroplasty (TKA) referred to the Vascular Surgical Unit of a tertiary referral hospital between July 2005 and December 2007 identified from a prospectively maintained database., Results: Of the seven cases referred over a 30-month period, six patients underwent endovascular treatment with successful limb salvage. All seven injuries were related to the popliteal artery behind the knee: pseudoaneurysm (4), intimal flap occlusion (2) and stenosis (1). One patient underwent above-knee amputation. The presentation and pattern of arterial injuries, potential risk factors for their occurrence, measures to reduce their risk and factors that aid in their early recognition are discussed., Conclusions: An endovascular approach may be considered for the management of these injuries, although it is likely to involve long-term surveillance and may not be appropriate for all cases. Surgeons performing TKA should be aware of the potential risk factors for arterial injury and maintain a high index of suspicion for these infrequent injuries during the post-operative period.

This is the first ever reported case of a radiation-induced aortic sarcoma. This patient had symptoms and signs initially interpreted as a pulmonary embolus. The extent of the disease was demonstrated with magnetic resonance imaging and magnetic resonance angiography, in particular, allowing rapid surgical intervention.

Objective: The following procedures are the 3 main methods of endovascular repair (EVR) of abdominal aortic aneurysms (AAA): aorto-aortic bypass grafting, bifurcated bypass grafting, and aorta uni-iliac grafts. The latter method has the potential disadvantage of requiring an extra anatomic graft (ie, a femorofemoral crossover bypass graft) to maintain contralateral pelvic and limb perfusion. The aim of this study was to assess the complications associated with the femorofemoral crossover bypass graft after aorta uni-iliac EVR of AAA., Method: A prospective review was conducted of the complications attributable to the femorofemoral crossover bypass graft in 136 patients who underwent EVR of AAA with an aorta uni-iliac device., Results: During a median follow-up of 7 months (range, 0 to 36 months), 4 patients had superficial wound infections that required antibiotic treatment and 2 patients had bypass graft infections. Nine hematomas developed: 7 (5%) groin hematomas (6 in patients with Dacron bypass grafts), 1 scrotal hematoma, and 1 perigraft hematoma. One bypass graft thrombus developed., Conclusion: The femorofemoral crossover bypass graft is a safe and a durable component of EVR of AAA with an aorta uni-iliac device. The results are similar to those with bifurcated devices.

Stenosis of the external iliac artery in healthy athletes, although uncommon, has been reported in competition cyclists. A case of a racing cyclist whose chronic vague leg symptoms were incorrectly attributed to L4/5 nerve root irritation is reported. This highlights the importance of clinical vascular testing when assessing ill defined leg pain. The role of trauma as a causative factor in this condition has not been previously documented.

Purpose: The aim of this study was to evaluate the feasibility of endovascular aortic aneurysm repair with use of an aortouniiliac graft secured with self-expanding (Gianturco) stents., Methods: Thirty patients with a median age of 72 years (age range, 52 to 86 years) and aneurysm diameter of 6.0 cm (range, 4.0 to 9.0 cm) were treated with an aortouniiliac endovascular graft. Of these 30 procedures, 28 were carried out electively and two as emergencies for leaking aneurysm. Of the 30 patients, 21 (70%) were considered to be at high risk for open surgery. A modified Gianturco stent, Dacron graft, and Wallstent were used for these procedures., Results: Endovascular repair was successfully carried out in 25 of 30 (83.3%) patients. All these patients were mobile and had resumed a normal diet within 48 hours of the procedure. The overall 30-day mortality rate was two in 30 (6.6%), but it was one in 28 (3.5%) for the elective cases; all deaths occurred in the group at high risk for surgery. Other complications encountered within 30 days of procedure included myocardial infarction in one patient, pneumonia in two patients, homonymous quadrantanopia in one patient, and colonic ischemia in one patient, giving an overall morbidity rate of four in 30 (13.3%). At a median follow-up of 4 months (range, 1 to 13 months), 27 of 30 (90%) patients remain alive and well., Conclusion: Endovascular aortouniiliac repair of abdominal aortic aneurysm with Gianturco stent is feasible in both elective and emergency situations. It appears to be minimally traumatic, and the majority of patients deemed to be at high risk for open surgery can safely undergo endovascular repair. However, data on more patients with longer follow-up is required to determine its role in the management of abdominal aortic aneurysm.

Hyperhomocysteinaemia is an independent risk factor for the early development of arterial disease. Homocysteine and cardiovascular risk factors were assessed in 41 young and 25 older patients with vascular disease. As homocysteine may act by the generation of free radicals, total antioxidant capacity was measured. Hyperhomocysteinaemia was found in 29 per cent of patients but there was no difference between young and older patients. Homocysteine level was unrelated to other cardiovascular risk factors. Young age, diabetes and hyperhomocysteinaemia were independent risk factors for the failure of vascular procedures (P = 0.006). Patients with hyperhomocysteinaemia had raised total antioxidant capacity. The potential of identifying and treating a subgroup of patients with a poor prognosis deserves further study.

Objectives: To assess the accuracy of Duplex ultrasound in the assessment of aortoiliac disease., Design: Prospective, semi-blind study., Setting: Vascular laboratory and radiology departments, University Hospital., Materials and Methods: Ninety-two patients underwent assessment of the aortoiliac segment by femoral pulse palpation, Duplex ultrasound and biplanar arteriography. Of these 184 aortoiliac segments, 68 were also assessed by intraarterial pressure measurements and 80 by magnetic resonance angiography (MRA)., Main Results: Femoral pulses were abnormal in all 32 occluded aortoiliac segments. Of 152 patent segments, femoral pulse palpation was misleading in 50 (33%). MRA detected all occlusions and had a sensitivity of 71% and specificity of 68% for stenoses, compared to arteriography. Colour flow Duplex misdiagnosed four occlusions as stenoses. Duplex had a sensitivity of 91% and specificity of 93% for stenoses when compared to arteriography. Two stenoses, detected by Duplex and confirmed by pressure gradients, were missed by arteriography., Conclusions: Pressure measurements remain the gold standard for aortoiliac examination, arteriography providing only morphological information. The limitations of femoral pulse palpation should be appreciated. Although MRA was faster, Duplex examination proved slightly more sensitive to stenoses. At present, colour Duplex provides the best non-invasive assessment of aortoiliac disease and could prevent unnecessary arteriograms.

Purpose: The purpose of this study was to compare the ability of ultrasonography (US), contrast-enhanced computed tomography (CT), and magnetic resonance imaging (MRI) to display the anatomy of abdominal aortic aneurysms and to detect the presence of inflammatory change., Methods: We prospectively studied 79 patients with abdominal aortic aneurysms (64 noninflammatory aneurysms [NIAAs] and 15 inflammatory aneurysms [IAAs]) with US, CT, and MRI., Results: Ultrasonography failed to diagnose the level of the aneurysm neck in three IAAs and 18 NIAAs. It failed to differentiate NIAAs from IAAs and to visualize the origins of the renal arteries in all cases. With CT the level of the aneurysm neck was incorrectly stated as lying above the level of the renal arteries in two cases of IAA and four cases of NIAA, and the renal artery origins were seen in only 10 of 77 patients. Inflammatory change was diagnosed correctly in seven of 15 patients, whereas six NIAAs were falsely diagnosed as inflammatory. MRI successfully diagnosed neck level and inflammatory change in all cases. Of two failures to visualize the renal artery origins, only one was caused by radiologic factors. In addition, characteristic radiologic features were seen in MRI images of IAAs, and these will be described both in vivo and in vitro., Conclusions: Our results suggest that MRI is superior to other methods in identifying the anatomy of aneurysms and the presence of inflammatory change.

Ten to 15% of all aortic aneurysms show inflammatory change. They are characteristically covered on their anterior and lateral sides with thick white fibrous tissue. Peri-aortic fibrosis may spread into the retroperitoneum to encase and obstruct adjacent organs making operative treatment more difficult and increasing the operative morbidity and mortality. Fifteen patients with inflammatory aneurysms and 46 patients with simple non-inflammatory aneurysms were studied prospectively. Each patient underwent magnetic resonance imaging (MRI) using a Picker Vista MR2055 scanner operating at 0.5 tesla. Each scan was reviewed by a radiologist (G.G.H.) preoperatively and a diagnosis of inflammatory or non-inflammatory aneurysm made. At operation, the diagnosis of aneurysm type was made on macroscopic features of inflammatory change, and confirmed histologically using previously published criteria. The radiological diagnosis was found to correspond to the surgical and pathological diagnosis in all cases. In cases of inflammatory aortic aneurysm the aneurysm wall appeared laminated on MRI scan, showing three or more bright, high-signal layers. These appearances of inflammatory change are characteristic, and were present in all 15 patients with such aneurysms. There were no false positives among those patients with simple aneurysms, and no false negatives. Operative specimens of aortic wall were taken from four patients with inflammatory aortic aneurysms and four patients with simple non-inflammatory aortic aneurysms, and subjected to MRI scanning. The characteristic banding appeared only in the inflammatory aneurysm wall samples. Magnetic resonance imaging is a highly sensitive investigative technique for the detection of inflammatory aneurysms, showing characteristic changes. These changes are also seen in in vitro scans of wall samples from inflammatory aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Inflammatory aneurysms of the abdominal aorta (IAA) comprise 10-15% of all aortic aneurysms (AA) but their aetiology and pathogenesis are obscure. Destruction of mural elastin is a prominent feature of IAA, and both increased elastolysis and decreased inhibition of elastolysis have been implicated. In order to study these factors, we have examined the peripheral blood of three groups of patients; 15 with inflammatory aortic aneurysms (IAA), 61 with simple aortic aneurysms (SAA) and 35 with aorto-iliac occlusive disease (OD). In all cases, alpha-1-anti-trypsin (A-1-AT), alpha-2-macroglobulin (A-2-MG), elastase inhibitory activity (E.I.A.), elastase-anti-trypsin complex, C-reactive protein (CRP), caeruloplasmin (CP) and plasma viscosity were measured. Patients with IAA had a significantly higher plasma viscosity (Mann-Whitney, p less than 0.05), E.I.A. (Mann-Whitney, p less than 0.01) and levels of A-1-AT, CRP, CP and elastase/anti-trypsin complex (Mann-Whitney, all p less than 0.05) than patients in the other two groups. There was no difference in the levels of A-2-MG between any of the groups. This study refutes the theory that reduced inhibition of elastase activity predisposes to the formation of SAA. In patients with IAA, raised marker levels indicate ongoing destruction of elastin, and suggest a difference in pathogenesis between IAA and SAA. The study also suggests that IAA are highly active metabolically, as opposed to the more degenerative SAA.

Scalds caused by domestic hot tap water constitute a significant but preventable hazard in childhood. We have reviewed some of the factors contributing to such injuries, and the experience of a regional paediatric burn unit in their treatment. There were 91 children with bath water scalds and 667 children with thermal injuries from other sources included in this study. In the former group, scalds were more common on the limbs, including the hands and feet. Scalds involving over 40% of body surface area were more common in children with bath water injuries; however, there was no difference between the groups with regard to hospital stay or requirement for skin grafting. Parents ran the bath responsible for scald production in most cases, but single parenthood did not appear to be a risk factor. First aid application made no significant difference to eventual burn area or hospital stay. It appears from this study that reduction of domestic hot water temperature is necessary. Statutory control is likely to offer the best solution to the problem of domestic hot tap water scalds in childhood.

Computer-assisted impedance analysis is a newly developed technique to identify femoropopliteal and distal vein graft stenoses before failure. Pulsatile flow is measured from the proximal and distal graft by use of an 8Mhz Doppler velocimeter. A pulse volume recorder measures pulsatile pressure within the thigh and calf. Fourier transfer analysis is performed on paired Doppler pulse volume recorder waveforms and an impedance score derived for the thigh and calf, respectively. In a retrospective review of 50 nonreversed femoropopliteal/distal grafts performed for limb salvage, postoperative biplanar intraarterial digital subtraction arteriography was compared with impedance analysis. Arteriography showed graft or runoff stenoses in 22 grafts (at risk) and 28 normal grafts (controls). Impedance scores were significantly higher in the at risk group (0.58 + [0.43 to 0.72]*), when compared with the controls (0.34 + [0.30 to 0.38], p less than 0.001*). A thigh or calf impedance score of greater than 0.45 was able to detect 20 of 22 stenoses, including 6 lesions in grafts with normal resting and postexercise ankle pressures. This score was then applied prospectively and compared with serial biplanar digital subtraction arteriography in a further 56 femoropopliteal/distal bypasses for limb salvage. Thirty-three of 34 lesions were successfully predicted and impedance scores were significantly higher in the at risk limbs (0.56 + [0.44 to 0.68]*) when compared with the controls (0.38 + [0.35 to 0.41], p less than 0.001*). In this series impedance analysis proved more sensitive than resting or stressed ankle pressures and, unlike Duplex scanning, was able to detect runoff as well as graft stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Up to 15% of abdominal aortic aneurysms are designated as inflammatory. They are characterized by marked fibrous thickening of the aneurysmal wall, with the fibrosis extending into the adjacent retroperitoneum. Thirty-five abdominal aortic aneurysms were studied, 15 inflammatory and 20 atherosclerotic. Of the inflammatory group, 10 were symptomatic and five asymptomatic. For each resection specimen, 59 microscopic features (variables) were scored semi-quantitatively. Discriminant function analysis showed that endarteritis obliterans, fibrosis around nerves or ganglia at the outer margin of mural fibrosis, and the thickness of the combined fibrotic media and adventitia gave a satisfactory high discrimination between atherosclerotic and inflammatory aneurysms. When these three variables are used together, a histological diagnosis of inflammatory aneurysm can be made with an expected accuracy in excess of 80%.

Femoro-distal vein grafts for limb salvage have a 30% failure rate at 6 months. Graft surveillance may enable the "at risk" grafts to be recognised and corrected, but there remains the need for a simple test to identify these patients. The ankle pressure response to exercise and reactive hyperaemia has been investigated prospectively in 40 "at risk" femoro-distal non-reversed grafts (median age 73 years, range 51-87 years, M/F = 33:7), defined as those with a resting ankle brachial index less than 0.9 or a drop of greater than 0.2 following a stress test. Four different stress tests have been assessed; active ankle plantar-dorsiflexion for 2 minutes (I), occlusive calf cuff 50 mmHg above systolic pressure for 2 minutes (II), treadmill exercise test for 1 minute, slope = 10%, at 3 km/hr (III) and 4 km/hr (IV). Ankle brachial indices (ABI's) were recorded before and immediately following each test and expressed as mean % drop +/- standard error of mean. Test I was only tolerated by 45% of patients whereas 55% and 50% could complete tests III and IV respectively. By contrast, 85% of patients could tolerate occlusive cuff hyperaemia (test II). Test I produced a significantly lower mean percentage drop in ABI when compared with each of the others (p less than 0.02, Mann U Whitney). There was an excellent correlation between test II and both the 3 km/hr (r = 0.77, p less than 0.001) and 4 km/hr (r = 0.84, p less than 0.001) exercise tests.(ABSTRACT TRUNCATED AT 250 WORDS)