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Biomedical subjects

P Madhavan

Publications and source records attributed to P Madhavan.

At least 19 recordsLinked to original sources
PubMed2006

Development and validation of a specific stability indicating high performance liquid chromatographic method for rizatriptan benzoate.

A gradient, reversed-phase liquid chromatographic (RP-LC) method was developed for the quantitative determination of rizatriptan benzoate, used to treat relieves migraine headache symptoms. The developed method can be also employed for the related substance determination in bulk samples. Forced degradation studies were performed on bulk sample of rizatriptan benzoate using acid (0.5 N hydrochloric acid), base (0.1 N sodium hydroxide), oxidation (3.0% hydrogen peroxide), water hydrolysis, heat (60 degrees C) and photolytic degradation. Mild degradation of the drug substance was observed in base hydrolysis and considerable degradation observed during oxidative stress. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to degradation products and the analyte was achieved on Agilent Zorbax SB-CN (250 mm x 4.6 mm, 5 microm) column. The mobile phase consists of a mixture of aqueous potassium di hydrogen ortho phosphate (pH 3.4), acetonitrile and methanol. The stress sample solutions were assayed against the qualified reference standard of rizatriptan benzoate and the mass balance in each case was close to 99.7% indicating that the developed method is stability indicating. Validation of the developed method was carried out as per ICH requirements.

Chromatography, High Pressure Liquid↗
PubMed2004

Prospective randomized controlled trial: conventional versus powered phlebectomy.

OBJECTIVES: Transilluminated powered phlebectomy (TriVex) is a new surgical technique that uses tumescent dissection, transillumination, and powered phlebectomy. The purpose of this study was to compare TriVex with conventional varicose vein surgery in terms of pain, cosmesis, recurrence, complications, and operating time. METHODS: One hundred eighty-eight limbs in 141 patients (33 men, 108 women; mean age, 42.5 years) with varicose veins were randomised to conventional (n = 100) or TriVex (n = 88). Exclusion criteria were venous ulceration or deep venous disease. Varicosities were graded with CEAP and clinical assessment (grades 1-3), and were similar in both groups. Randomization was single blinded. Long or short saphenous vein ligation or stripping was performed as indicated with duplex scanning. Operative time was from skin incision to leg bandaging. Phlebectomy was performed with conventional stab avulsions or TriVex. Patients completed assessment forms preoperatively and postoperatively (2, 6, 26, 52 weeks), and this was supplemented with physician clinical evaluation. Pain was assessed with visual analog score. RESULTS: There was a significant difference in the number of incisions for phlebectomy in the two groups (conventional, n = 29; TriVex, n = 5; P <.0001). TriVex was faster in the grade 3 (extensive) group, but this did not reach statistical significance. There was no difference in mean postoperative pain score over 8 days in the two groups (P =.4624). At 2 weeks there was no significant difference between the groups with regard to bruising (P =.77), cellulitis (P =.33), and numbness (P =.33). At 6 weeks there was no significant difference between the groups with regard to nerve injury (P =.97), residual veins (P =.79), cosmetic score (P =.837), and overall satisfaction (P =.878). At 6 and 12 months, there was no significant difference in cosmesis (P =.955, P =.088, respectively) or recurrence (P =.27, P =.11, respectively). CONCLUSIONS: TriVex is a safe and effective method for excision of varicosities and compares well, after a learning curve, with conventional surgery in regard to complications and recurrence. It has the advantage of a trend toward reduced operating time in extensive varicosities, and significantly fewer incisions, although there was no perceived difference in cosmesis during follow-up.

Adult↗
PubMed2001

Arcuate-legged nonpenetrating vascular closure staples (VCS): early experience.

Vascular closure staples (VCS) provide a novel technique for fashioning vascular anastomoses, allowing a single operator to perform suture-less anastomoses. They may be used primarily or in an adjuvant role. When VCS are compared to a running suture, advantages include the avoidance of intimal damage, platelet aggregation and intimal hyperplasia at the anastomotic suture line, and a shorter time taken to complete the anastomosis. We report our early experience using VCS in an array of vascular anastomoses and conclude that VCS are a useful addition to the vascular surgeon's armamentarium. They help to decrease the time taken to construct an anastomosis, and are particularly useful in an adjuvant setting, complementing conventionally placed sutures.

Aged↗
PubMed2001

Ultrasound guided human thrombin injection. A new modality in the management of femoral artery pseudo-aneurysms.

OBJECTIVES: We report our initial results of a prospective study of duplex ultrasound-guided injection (UGTI ) of thrombin in the management of femoral artery pseudo-aneurysms. We used human thrombin to avoid the increase in the human antibodies directed against fibrinogen, with the use of bovine thrombus, that preclude further utilisation of the bovine fibrin glue during cardio-thoracic surgery. METHODS: From 1999 to 2001, 19 patients, aged 69 (range 52-85) years presented with 21 femoral pseudo-aneurysms were treated. The mean pseudoaneurysm diameter was 30 (15-55) mm. All but two were secondary to cardiac procedures and the common femoral artery was the injured vessel in all instances. Patients were referred within 2-21 days following their iatrogenic injury. RESULTS: Immediate thrombosis of the sac occurred in 19 (90%) of the 21 pseudo-aneurysms. After a second injection, complete occlusion occurred in the remaining two patients. Two patients (CI 95%; 1-19) with three femoral pseudo-aneurysms developed leg pain. Duplex ultrasound follow-up showed two recurrences (9.5% - CI 95%; 1-19) and both were treated by repeat UGTI. There was no conversion to surgical repair. CONCLUSION: This percutaneous minimally invasive technique is safe and effective in the management of iatrogenic pseudo-aneurysms in this high-risk group of patients. Human thrombin has significant advantages over bovine thrombin.

Aged↗
PubMed2001

Instability due to unrecognised fracture-subluxations after apparently isolated injuries of the cervical spine.

Instability may present at a different level after successful stabilisation of an unstable segment in apparently isolated injuries of the cervical spine. It can give rise to progressive deformity or symptoms which require further treatment. We performed one or more operations for unstable cervical spinal injuries on 121 patients over a period of 90 months. Of these, five were identified as having instability due to an initially unrecognised fracture-subluxation at a different level. We present the details of these five patients and discuss the problems associated with their diagnosis and treatment.

Accidents, Traffic↗
PubMed2000

Suprarenal mycotic aneurysm exclusion using a stent with a partial autologous covering.

PURPOSE: To report a combined endovascular and open technique to manage a suprarenal mycotic aortic aneurysm using a stent-graft partially covered with a section of autologous artery. METHODS AND RESULTS: A 50-year-old was hospitalized for staphylococcal septicemia and severe back pain. A previously diagnosed 3-cm abdominal aortic aneurysm was found to have expanded 2 cm in 3 weeks. Aortography documented some periaortic thickening and 2 mycotic aneurysms, one posterior at the level of the superior mesenteric artery and the second at the aortic bifurcation. After intensive antibiotic therapy, an endovascular approach to exclude the suprarenal mycotic aneurysm was undertaken in tandem with surgical excision of the infrarenal aneurysm. The harvested right common iliac artery was used to partially cover a Palmaz stent, which was deployed under direct vision just above the renal artery ostia so that the covered portion of the stent excluded the aneurysm. A right axillofemoral bypass with a femorofemoral bypass completed the revascularization. Postoperatively, the patient developed renal failure, ischemic colitis necessitating a left hemicolectomy, and paraplegia. Although the patient is paralyzed, the aneurysm remains excluded with patent visceral vessels at 12 months following surgery. No organisms were grown from excised aortic tissue, and no signs of recurrent infection have been seen. CONCLUSIONS: Stent-graft repair may be able to lessen the invasiveness and reduce the morbidity associated with treatment of mycotic aortic aneurysms.

Aneurysm, Infected↗
PubMed2000

Endovascular management of rare sciatic artery aneurysm.

PURPOSE: To present a rare case of complete persistent sciatic artery aneurysm successfully treated by coil embolization and to suggest a new classification for this anomaly that encompasses both clinical and pathological factors. METHODS AND RESULTS: A 77-year-old female presented with sudden onset of sharp, throbbing left thigh and foot pain. A nontender 10.0- x 7.0-cm pulsatile mass was found over the inferolateral aspect of the left buttock on examination in the right lateral decubitus position. Angiography demonstrated a 6.9-cm sciatic artery aneurysm with the distal sciatic artery completely thrombosed. Before planned bypass grafting, the aneurysm and distal segment of the internal iliac artery were successfully embolized with coils through a left percutaneous approach. The patient's symptoms resolved with no deterioration in limb perfusion, and further revascularization was unnecessary. Postembolization imaging showed complete occlusion of the aneurysm, which has continued for 19 months. CONCLUSIONS: The application of endovascular techniques and surgical revascularization procedures provides numerous management options for the treatment of an aneurysmal persistent sciatic artery. This case demonstrates that clinical evaluation between staged procedures may obviate the need for further intervention.

Aged↗
PubMed1999

Fifteen-year experience of transperitoneal management of inflammatory abdominal aortic aneurysms.

OBJECTIVES: to assess the long-term outcome of patients with inflammatory abdominal aortic aneurysms. MATERIALS AND METHODS: over a fifteen-year period 598 cases of abdominal aortic aneurysm were treated and, of these, 32 cases (5.3%) were inflammatory in nature. The diagnosis was made on preoperative (CT) computed tomography in fifteen cases. Twenty-six patients were symptomatic on presentation and ten cases were repaired on an emergency basis. Only six were repaired electively. The transabdominal transaortic approach without dissection on the nearby adherent structures was used routinely. RESULTS: there was one postoperative death from a respiratory arrest leading to a thirty-day mortality of 3.1%. Early graft thrombosis occurred in three cases (9.3%) and all underwent successful thrombectomy. Colonic ischaemia was encountered in one patient who later developed an aortoenteric fistula. Two patients suffered a non-fatal myocardial infarction postoperatively leading to an overall morbidity of 18.7%. CONCLUSIONS: patients with inflammatory aortic aneurysms fare worse than patients with aortic aneurysms in general. Preoperative suspicion assists in planning surgery. We believe that the transperitoneal approach with an anterolateral aortotomy and minimal dissection of adherent structures offers excellent results in dealing with this difficult group of patients.

Aged↗
PubMed1999

Ipsilateral vascularised fibular transport for massive defects of the tibia.

The ipsilateral and contralateral fibulae have been used as a vascularised bone graft for loss of tibial bone usually by methods which have involved specialised microvascular techniques to preserve or re-establish the blood supply. We have developed a method of tibialisation of the fibula using the Ilizarov fixator system, ipsilateral vascularised fibular transport (IVFT), and have used it in five patients with massive loss of tibial bone after treatment of an open fracture, infected nonunion or chronic osteomyelitis. All had successful transport, proximal and distal union, and hypertrophy of the graft without fracture. One developed a squamous-cell carcinoma which ultimately required amputation of the limb. The advantage of IVFT is that the fibular segment retains its vascularity without the need for microvascular dissection or anastomoses. Superiosteal formation of new bone occurs if the tibial periosteal bed is retained. Other procedures such as corticotomy and lengthening can be carried out concurrently.

Adult↗
PubMed1999

Aorto-left renal vein fistula: is there a place for endovascular management?

PURPOSE: To describe the endovascular treatment of an aorto-left renal vein fistula. METHODS AND RESULTS: A 77-year-old man with multiple comorbidities presented with low back pain, hematuria, cyanosis, and a pulsatile abdominal mass. Imaging confirmed a 7-cm abdominal aortic aneurysm with a contained rupture into the left renal vein. Owing to the patient's high surgical risk, a Talent Endoluminal Stent-Graft was implanted to satisfactorily exclude the aneurysm. Hemodynamic stability and normal renal function were restored; however, continued perfusion of the sac prompted an attempt to percutaneously repair the renal vein defect. This effort failed, so open laparotomy was necessary. CONCLUSIONS: Although total endovascular management was not successful in this case, the initial use of a minimally invasive approach allowed the patient's clinical status to improve and lower the risk of subsequent surgery.

Aged↗
PubMed1999

Deterioration of theatre discipline during total joint replacement--have theatre protocols been abandoned?

The results of the Medical Research Council trial by Lidwell et al. in 1982 [Lidwell OM, Lowbury EJ, Whyte W et al. Effect of ultraclean air in operating rooms on deep sepsis in the joint after total hip or knee replacement: a randomised study. BMJ 1982; 285: 10-4] showed a decrease in infection rates following joint replacements carried out in ultraclean air theatres. Since then, the orthopaedic community in the UK has relied to a large extent on laminar airflow theatres to control infection following arthroplasty. At the same time, there has been a decline in the emphasis on basic principles and practices of antisepsis based on scientific evidence. We undertook this audit to establish whether published recommendations on theatre discipline were being followed in operating theatres where joint replacements are carried out, in England, Scotland and Wales. Our results show that with improvement in technology involved in clean air theatres, and availability in practice, slackness has crept into theatre protocol. In view of the fact that infection following arthroplasty has not been eliminated or indeed in some cases, maintained at the levels of the Medical Research Council study, we feel that traditional practices should be reintroduced. This study shows that there is pressing need for a set of recommendations on theatre practice for all staff in operating theatres that carry out joint replacements.

Air Microbiology↗
PubMed1997

Types of gowns used in trauma and orthopaedic theatres.

Trauma and orthopaedic surgeons are at an increased risk of acquiring viral blood-borne infections during elective and especially trauma surgery. The British Orthopaedic Association (BOA) published guidelines in 1991 for the prevention of cross-infection between patients and staff. It was recommended that only waterproof gowns be used in orthopaedic and trauma theatres. The aim of this study was to determine the compliance with the BOA recommendations. A telephone survey of 79 hospitals in England shows that only a minority (41 per cent) of hospitals use waterproof gowns exclusively.

Blood-Borne Pathogens↗