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Biomedical subjects

R J Guy

Publications and source records attributed to R J Guy.

At least 37 records · Page 2Linked to original sources
PubMed2000

Electrocardiographic changes following primary blast injury to the thorax.

Profound physiological changes occur following primary blast exposure but the contribution of cardiac arrhythmias is unknown. Thirteen rats, under intravenous anaesthesia, were exposed to a blast wave directed at the thorax (Group II); 10 other animals underwent abdominal blast (Group III) and nine animals acted as controls (Group I). Animals were monitored before, during and after blast exposure. Group II animals demonstrated apnoea, bradycardia and hypotension. No significant physiological changes were seen in Groups I or III. Group II displayed a variety of ECG disturbances, from ventricular extrasystoles to ventricular fibrillation. All abnormalities reverted to sinus rhythm within minutes except in fatally injured animals. These ECG changes probably result from stress wave injury. Significant disturbances might account for some fatalities following primary blast exposure and may exacerbate the triad of apnoea, bradycardia and hypotension. Such observations may have important consequences for the management of blast casualties.

Animals↗
PubMed1999

The pathophysiology of primary blast injury and its implications for treatment. Part II: The auditory structures and abdomen.

The authors have previously considered the mechanisms by which primary blast injury affects the respiratory and cardiovascular systems and what deductions may be made about management of the resulting injuries. This article considers the somatic effects of primary blast on abdominal and auditory structures. These injuries are usually of less immediate concern but require accurate management in order to avoid late mortality and morbidity and to return the casualty to full function. Recognition of likely injury patterns is vital to the instigation of correct management. The tympanic membrane, for instance, is easily damaged by blast and such an injury may be complicated by ossicular disruption, perilymph fistula or forceful distribution of squamous epithelium around air filled spaces with potential to form cholesteatoma. Abdominal organs can be severely disrupted by primary blast. The treatment of such injuries is not dissimilar to that of any other cause of abdominal trauma. The most challenging aspect is the identification of intestinal intramural haemorrhage and discrimination between those lesions destined for perforation or for spontaneous recovery. In this article the range and mechanism of injury are described for each system, drawing on experience from other modes of injury closely related to blast, followed by suggestions for their management established from literature reviews and experimental work undertaken by the authors during periods of full time research.

Abdominal Injuries↗
PubMed1998

Physiologic responses to primary blast.

BACKGROUND: Primary blast injuries are produced by the blast shock wave. The critical determinant of survival is pulmonary injury, but acute cardiorespiratory responses to blast exposure are not well understood. The aim of this study was to investigate these changes. METHODS: Twenty anesthetized rats were exposed to moderate blast overpressure, 10 animals receiving thoracic and 10 receiving abdominal exposure. Another 9 animals acted as controls. Respiration, heart rate, and blood pressure were recorded continuously before, during, and for 6 hours after blast exposure. RESULTS: All animals exposed to thoracic blast demonstrated apnea, bradycardia, and hypotension after blast exposure, followed by a return to preblast values. No significant cardiovascular or respiratory changes were seen in animals in the other groups. CONCLUSION: Moderate thoracic blast injury produces a reflex triad of apnea, bradycardia, and hypotension that is not present after abdominal blast. These observations may have important implications for the immediate management of patients with blast injuries.

Abdominal Injuries↗
PubMed1998

The pathophysiology of primary blast injury and its implications for treatment. Part I: The thorax.

There is insufficient evidence to support a definitive approach to the clinical management of primary pulmonary blast injury. Post-blast cardiovascular and pulmonary changes are reviewed in this paper in order to highlight important aspects in the immediate management of the blast injured casualty. Blast profiles and theoretical mechanisms of injury vary widely but all result in mechanical disruption and cause similar pathological, physiological and biochemical responses. Some patients may present acutely, while others appear unharmed and develop respiratory failure 12-24 hours later. Treatment outcome may depend on the judicious use of resuscitative fluids and respiratory support. The roles of supplementary oxygen and assisted ventilation remain controversial although administration of high inspired oxygen concentrations and respiratory support may be unavoidable. The advantage of pharmacological manipulation of reflex mechanisms is as yet unproven. Hyperbaric therapy may improve survival in pulmonary blast injury.

Blast Injuries↗
PubMed1997

Internal anal sphincter myopathy causing proctalgia fugax and constipation: further clinical and radiological characterization in a patient.

We report a case of a distinctive familial internal anal sphincter myopathy with unique histological and radiological features. A 67-year-old woman presented with a 20-year history of proctalgia fugax and outlet obstruction; other family members were similarly affected. Computed tomograpy and magnetic resonance imaging demonstrated a grossly hypertrophied internal anal sphincter. Strip myectomy of the sphincter was carried out with improvement in evacuation but little relief of proctalgia. Further relief of symptoms was obtained using oral and transdermal nitrates and a calcium antagonist. Histological examination of the excised muscle revealed hypertrophy and an abnormal arrangement of fibres in whorls; many fibres contained vacuoles with inclusion bodies positive for periodic acid-Schiff. This description of a specific anal sphincter myopathy illustrates the potential importance of histopathological studies of smooth muscle in functional disorders of the gut.

Aged↗
PubMed1995

Repeated pseudo-obstruction, mental subnormality--and serious snags.

Chronic intestinal pseudo-obstruction has certain identifiable causes but many cases remain idiopathic. The majority of patients are managed successfully by conservative means with the avoidance of surgery. A case is presented where diagnosis was made difficult by autism and which was complicated by perforation of a gastric ulcer. Management of pseudo-obstruction is discussed and emphasis placed on an awareness of alternative life-threatening pathologies at re-presentation.

Adult↗
PubMed1995

Tuberculous epididymitis presenting as acute hydrocele.

A case of tuberculous epididymitis which presented as an acute hydrocele is reported and the relevant literature reviewed. The patient had undergone contralateral orchidectomy 20 years previously for the same condition associated with pulmonary tuberculosis. The most recent episode followed unrelated illness; the diagnosis was confirmed after surgical intervention and cure was achieved with adjuvant chemotherapy. Although rare, genital tuberculosis should still be considered in cases of scrotal swelling when there is a history of previous tuberculous disease or exposure.

Acute Disease↗
PubMed1993

Pseudoaneurysm after arthroscopy of the knee. A case report.

Pseudoaneurysm of the inferior lateral genicular artery occurred in a 25-year-old man after arthroscopy. The arthroscopy was not complicated by postoperative bleeding or hemarthrosis, which has been associated with pseudoaneurysm formation. The diagnosis was confirmed on 99mTc radionuclide scanning and ultrasound, and the anatomy was demonstrated by digital subtraction angiography. Exploration and excision were performed without complication or recurrence. There are several methods for investigating these rare lesions.

Adult↗
PubMed1990

The etiologies and mechanisms of nail bed injuries.

The etiologies and mechanisms of nail bed injuries, both traumatic and disease related, are presented along with the anatomic and physiologic bases for resultant deformities. The groundwork is laid for a true understanding of the complexity of the perionychium.

Adolescent↗
PubMed1988

Diabetic neuropathy in the upper limb and the effect of twelve months sorbinil treatment.

Clinical and neurophysiological studies were undertaken, with particular reference to the arms, in 39 patients with diabetic neuropathy. The effects of an aldose reductase inhibitor, sorbinil, on neuropathy in these patients were studied in a 12 month double blind placebo controlled trial. Neurophysiological measurements, particularly of sensory amplitude, were considerably more sensitive than measurements of temperature and vibration sensation and remain of fundamental importance in measuring diabetic neuropathy at an early and potentially reversible stage. There was no significantly beneficial effect of sorbinil on clinical or neurophysiological measurements of nerve function in patients with established diabetic neuropathy. These results indicate that neurophysiological techniques are necessary, in conjunction with clinical measurements, for the assessment of 'early' diabetic neuropathy and that aldose reductase inhibitors are not effective in the treatment of established diabetic neuropathy.

Adult↗
PubMed1988

Palmar wrist pain caused by ulnar nerve entrapment in the flexor carpi ulnaris tendon.

A 38-year-old female nurse was seen initially with several years' history of recurring intermittent ulnar wrist pain and paresthesias. The pain was aggravated by specific tasks using her hands, such as typing. Splinting and two steroid injections into the area gave only temporary relief. Surgical exploration revealed a segment of the ulnar nerve composing approximately 15% of its volume to split from the main trunk of the ulnar nerve, perforate the flexor carpi ulnaris tendon, and then rejoin the ulnar nerve. The nerve branch was extracted from the flexor carpi ulnaris by dividing approximately 15% to 20% of the tendon, allowing the nerve to be removed from the perforation, and anatomically relocated. The patient resumed her normal activities and has had no further discomfort in her wrist.

Adult↗
PubMed1988

Cough threshold to citric acid in diabetic patients with and without autonomic neuropathy.

The cough reflex has been investigated in insulin dependent diabetic patients with and without autonomic neuropathy. The cough response to inhaled citric acid was determined in eight patients with diabetes who had severe autonomic neuropathy and compared with that in 10 who had no evidence of neuropathy. The patients with autonomic neuropathy had a higher median threshold for the cough response to citric acid (median 50%, range 20- greater than 100%) than non-neuropathic control patients (median 10%, range 2-20%). These results suggest that vagal innervation of the bronchial tree is damaged by diabetic autonomic neuropathy.

Adult↗
PubMed1986

A form of necrobiosis and atrophy of smooth muscle in diabetic gastric autonomic neuropathy.

Pathological changes identified in the muscular wall of the stomach from two young insulin-dependent diabetic patients suffering from severe gastric autonomic neuropathy are presented. Scattered smooth muscle cells appearing as homogeneous round eosinophilic bodies ("M" bodies) among areas of sub-total smooth muscle cell atrophy together with intercellular collagen proliferation were identified in the muscularis propria of the stomach. Ultrastructurally, the "M" bodies are transformed smooth muscle cells undergoing a form of necrobiosis with peculiar intracellular features. These changes appear characteristic of end-stage diabetic gastric autonomic neuropathy when compared with other pathological conditions involving the gastric wall. The degree and extent of involvement of the various components of the gastric wall are discussed.

Adolescent↗
PubMed1986

Successful treatment of acute head and neck dog bite wounds without antibiotics.

Dog bites continue to be the most common bite injury in the United States. We previously reported a series of 61 patients with 215 dog bite wounds. Of these, 55 patients had 188 dog bite wounds of the head and neck area which were treated with copious saline pressure irrigation, meticulous wound and wound edge debridement, repeated copious saline pressure irrigation, adequate antibiotic coverage, wound closure, and close postoperative monitoring. A wound infection rate of .53% and a patient infection rate of 1.8% were obtained using this protocol. Our present study uses the same protocol with the exclusion of antibiotic coverage. Our series of 49 patients with 145 head and neck wounds reveals a wound infection rate of 1.4% and a patient infection rate of 4%. This is not statistically significantly different from the outcome of the previous study.

Acute Disease↗
PubMed1986

Effect of temperature on blood flow and metabolism in a neurovascular island skin flap.

Using the buttock flap in 29 white Yorkshire pigs, blood flow and O2 consumption were measured at dermal temperatures between 35 degrees C and 15 degrees C. Flow was measured with an electromagnetic flowmeter and O2 consumption was calculated as the product of blood flow and the difference in flap A-VO2. Baseline flow was 6.6 +/- .9 (SE) ml/100 g/min at 35 degrees C and 3.1 +/- .02 (SE) ml/10 g/min at 15 degrees C. Blood flow through the flap stopped completely at a dermal temperature of 14 degrees C. Oxygen consumption was 0.16 +/- .02 (SE) ml/100 g/min at 35 degrees C and 0.04 +/- 0.01 (SE) ml/100 g/min at 15 degrees C. At 20 degrees C blood flow was 4.3 ml/100 g/min and metabolism was .04 ml/100 g/min. In other words, blood flow was 65% of baseline, while O2 consumption was only 25% of baseline. The therapeutic effect of local cooling at 20 degrees C deserves further investigation. The cessation of flow at 14 degrees C may be caused by increased plasma viscosity.

Animals↗
PubMed1986

Diabetes and autonomic neuropathy: an immunological association?

Lymphocytic infiltration of autonomic ganglia found at autopsy and a strong clinical association with iritis suggests that diabetic autonomic neuropathy might have an immunological basis. We measured levels of circulating immune complexes, complement (C3, C4), complement breakdown products (C3d), and insulin antibodies in diabetics with autonomic neuropathy and a history of iritis (n = 17), compared to diabetics of similar age and duration with autonomic neuropathy but no history of iritis (n = 20), and with uncomplicated insulin-dependent diabetics (n = 23), together with normal controls (n = 26). We found higher levels of circulating immune complexes in patients with autonomic neuropathy (irrespective of iritis) compared to normal controls, and differences in C3d levels suggesting complement activation. C4 levels were unexpectedly normal in the diabetics with autonomic neuropathy, in contrast to the uncomplicated insulin-dependent diabetic controls. Insulin antibody levels showed no difference between the three groups of diabetics. These findings suggest that immunological mechanisms may be implicated in the aetiology of diabetic autonomic neuropathy and that further studies are indicated.

Adult↗