Search PubMed⌕ Search

Biomedical subjects

R Lane

Publications and source records attributed to R Lane.

At least 73 records · Page 4Linked to original sources
PubMed1988

A bizarre case of vehicular suicide.

The upper torso of a man was discovered under a highway sign next to tire tread marks leading from the highway and continuing beyond the sign. The victim's lower torso and automobile were also found along the same path 31 m (101 ft) and 41 m (133 ft) beyond the sign, respectively. The decedent was initially thought to be a disposed, homicide victim who had been dismembered by his assailant(s). Accident reconstruction revealed that the victim was the driver of the automobile and was transected by the highway sign stanchion as he protruded through the passenger side window of his moving vehicle. Based on the scene findings, autopsy, and psychological autopsy, the manner of death was classified as suicidal. The criteria used by medical examiners for vehicular suicide are also discussed.

Adult↗
PubMed1988

gamma-Aminobutyric acid release from synaptosomes prepared from rats treated with isonicotinic acid hydrazide and gabaculine.

The potassium-stimulated release of gamma-aminobutyric acid (GABA) from synaptosomes was determined in preparations from control rats and from rats treated with a convulsant agent [isonicotinic acid hydrazide (INH)] and an anticonvulsant agent (gabaculine). INH treatment brought about a significant decrease in Ca2+-dependent release of GABA with no effect on Ca2+-independent release, whereas gabaculine caused an increase in Ca2+-independent release with no effect on Ca2+-dependent release of GABA. Thus, the anticonvulsant action of gabaculine was not a simple reversal of the effects of INH on GABA release. The results indicate that there are at least two pools of GABA in nerve endings and support the hypothesis that exogenous GABA is taken up first into a pool that supplies GABA for Ca2+-independent release and then is transferred to a second pool (Ca2+-dependent releasable), where it mixes with newly synthesized GABA.

Animals↗
PubMed1988

Abolition of methacholine induced bronchoconstriction by the hyperventilation of exercise or volition.

Total pulmonary resistance was measured from continuous records of flow and oesophageal pressure in five normal subjects on three separate days before and after inhalation of methacholine. The dose of methacholine produced, on average, a fivefold increase in airway resistance. Immediately after methacholine inhalation the subjects underwent a progressive exercise test on a cycle ergometer (day 1) or voluntary hyperventilation (day 2) or remained resting (day 3). On the first day during exercise pulmonary resistance fell rapidly to baseline levels within two to three minutes and remained there for the 10 minute duration of the exercise. On day 2 voluntary reproduction of the same level and pattern of ventilation as during exercise resulted in a similar fall of resistance. On the third day, when the subjects remained at rest, pulmonary resistance remained raised for 10 minutes. It is concluded that the bronchodilator effects of exercise can be explained by the increased ventilation rather than the exercise itself, but with much smaller tidal volumes than have previously been thought necessary to reduce drug induced bronchoconstriction.

Adult↗
PubMed1988

Internal maxillary artery ligation for epistaxis: an analysis of failures.

The records of 100 consecutive patients undergoing transantral ligation of the internal maxillary artery (IMA) for epistaxis, including 15 patients who developed postoperative bleeding, were reviewed. Preoperative parameters predictive of surgical failure were advanced age, anemia, and a history of hypertension. The causes of postoperative epistaxis, as determined by surgical reexploration or angiography in 12 cases, included failure to identify the IMA in the pterygomaxillary space (6 cases), blood flow through partially closed clips on the IMA (2 cases), bleeding from posterior ethmoid arteries (2 cases), and revascularization of the nasal blood supply (2 cases). The incidence of surgical failure may be reduced by proper techniques of IMA identification and ligation.

Epistaxis↗
PubMed1987

Arterial oxygen saturation and breathlessness in patients with chronic obstructive airways disease.

Nine patients with chronic obstructive airways disease performed a 6 min self-paced walk (breathing air) on a treadmill and then identical (but operator-controlled) treadmill walks breathing either air or supplemental oxygen sufficient to just prevent arterial oxygen desaturation during the exercise. During the exercises, ventilation was recorded and patients recorded their sensation of breathlessness on a visual analogue scale (VAS) every 30 s. Breathing supplemental oxygen produced a small fall in mean exercise ventilation and a large and consistent reduction in mean exercise breathlessness. In seven patients the VAS scores were higher on air than with supplemental oxygen, at similar levels of ventilation. An analysis of covariance, to control for reduction in ventilation, showed a decrease in mean breathlessness when breathing supplemental oxygen, significant at the 8% level. The reduction in breathlessness produced by preventing exercise desaturation cannot be explained by the decrease in ventilation. This suggests that hypoxia may be a stimulus for breathlessness. The mechanism is unknown.

Aged↗
PubMed1987

Breathlessness and respiratory mechanics during reflex or voluntary hyperventilation in patients with chronic airflow limitation.

1. Six patients with chronic airflow limitation rebreathed CO2. Subsequently they voluntarily copied their stimulated breathing pattern while normocapnia was maintained. On a separate occasion four of these patients performed progressively increasing exercise and later copied these breathing patterns. 2. During all experiments flow, ventilation and pleural pressures were recorded. In addition, breathlessness was measured on a visual analogue scale every 30 s. 3. In these patients voluntary copying of either form of stimulated breathing resulted in diminished breathlessness and in some cases in complete abolition of the sensation, despite similar levels and patterns of ventilation in the two situations. 4. No systematic or consistent differences in the mechanics of breathing between stimulated and voluntarily copied breathing were found. 5. There was no correlation found between breathlessness score and any mechanical variable measured. 6. These results show that despite similarity in mechanics between stimulated and voluntary hyperventilation, the sensation of breathlessness is much diminished during the latter in these patients. This suggests that the sensation of breathlessness is more dependent upon the awareness of central processing than upon input from peripheral mechanoreceptors.

Aged↗
PubMed1987

Voluntary isocapnic hyperventilation and breathlessness during exercise in normal subjects.

1. Nine normal subjects performed 6 min, constant-workload, exercise tests on a bicycle ergometer at either a 'high workload' or at a 'low workload'. During the first 'high workload' test their spontaneous breathing pattern was recorded on to magnetic tape. During one subsequent 'high workload' test and one 'low workload' test they voluntarily copied their recorded breathing pattern. During a second 'low workload' test they breathed spontaneously. Isocapnia was maintained by the operator throughout both the copying tests. During the exercise tests ventilation was recorded and subjects indicated the level of their sensation of breathlessness every 30 s. 2. Subjects felt markedly less breathless when a proportion of their ventilation was produced by voluntary effort than when the same total level of ventilation was produced entirely by the stimulus of exercise. Furthermore, voluntary isocapnic hyperventilation during exercise did not increase breathlessness above that normally associated with that level of exercise. 3. These results suggest that it is reflexly driven ventilation, and not simply the level of ventilation itself, which relates to the level of breathlessness during exercise.

Adult↗
PubMed1987

Is low-level respiratory resistive loading during exercise perceived as breathlessness?

1. The effect of adding low-level (2.7 cmH2O 1(-1) s) external respiratory resistive loads on exercise-induced breathlessness has been examined in naive normal subjects; the intensity of this loading was chosen to simulate that confronting an asthmatic subject during exercise. 2. Each of 18 subjects performed two separate tests in which workload was oscillated while the respiratory loading was changed every minute between no loading, inspiratory loading only, and inspiratory plus expiratory loading. Each loading condition was given three times, and both these changes and those in workload were unpredictable as far as the subject was concerned. 3. The purpose was to 'confuse' subjects and obtain subjective estimates of their intensity of breathlessness independent of any expectation associated solely with the readily perceptible changes in external resistances to breathing. The study design was balanced for the group as a whole, both in terms of workload and respiratory loading condition. 4. The addition of these respiratory resistive loads during exercise did not result in a significant increase in the intensity of breathlessness. 5. Estimates of the rate of work of breathing revealed that this increased more with respiratory loading than it did as ventilation rose throughout the test; on the other hand, the intensity of breathlessness increased by a greater extent with continued exercise compared with the changes accompanying the addition of respiratory loads. 6. It is concluded that the intensity of the sensation of breathlessness experienced by normal subjects during exercise is not simple a reflection of an increased rate of work of breathing being performed by the respiratory muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Abdominal aortic aneurysms and coronary artery disease: is a more aggressive approach indicated?

A retrospective study was undertaken to assess the influence of known ischaemic heart disease on the operative and the long-term survival of patients undergoing elective repair of an abdominal aortic aneurysm. One hundred and seventy-one patients underwent elective surgery between June 1977 and December 1983. The patients were divided on routine clinical grounds into cardiac and noncardiac groups. Ninety-five patients had a history of heart disease and/or an abnormal resting pre-operative ECG. Seventy-six patients had no history of heart disease and a normal pre-operative resting ECG. Two of the seven operative deaths were due to myocardial infarction with one each from the cardiac and noncardiac groups. Eight patients suffered an acute myocardial infarction with five from the cardiac and three from the noncardiac group and this was not significantly different. The overall survival of 95% at 1 year and 76% at 5 years closely follows the age/sex matched Australian population. The survival at 1 year in the cardiac group was 97% and 95% in the noncardiac group. The 5 year survival was 72% and 79% respectively. During follow-up to December 1984, 11 patients died from ischaemic heart disease with six from the cardiac and five from the noncardiac group. No significant difference was found between the two groups in the incidence of myocardial infarction or the short- and long-term survival. This study does not support a more aggressive approach to coronary artery disease in the pre-operative management of patients with abdominal aortic aneurysm.

Aged↗
PubMed1987

Gabapentin as an antiepileptic drug in man.

Gabapentin, 1-(aminomethyl) cyclohexane acetic acid, is a GABA analogue whose antiepileptic properties were tested in a double blind cross-over trial design as add-on therapy in a dose ranging study which compared 300 mg, 600 mg, and 900 mg/day (each dose given for 2 months) in 25 patients with severe partial and generalised epilepsies. A dose related antiepileptic effect was observed. All three doses were well tolerated and no psychometric impairment was noted. No significant drug interactions were seen. The drug appears worthy of further assessment.

Acetates↗
PubMed1986

The measurement of breathlessness induced in normal subjects: individual differences.

Normal subjects show wide variability in their sensory scaling of breathlessness for equivalent degrees of ventilatory stimulation and behave "characteristically' irrespective of stimulus type. Observed differences are not explained by physical characteristics, ventilatory sensitivity or pattern of breathing although there is a weak association with the degree of physical fitness. Differences are seen when scaling is performed with reference to both rigidly defined extremes of breathlessness (visual analogue scaling) and a subject's own relative changes in the intensity of this sensation (magnitude estimation). These findings may explain the common observation, in patients with respiratory disease, of dyspnoea out of proportion to the pathophysiological state.

Adult↗
PubMed1985

The measurement of breathlessness induced in normal subjects: validity of two scaling techniques.

The intensity of breathlessness induced by ventilatory stimulation resulting from hypercapnia, hypoxia or exercise has been quantified in normals by using the two different sensory scaling techniques of linear visual analogue scaling and ratio magnitude estimation. In naive individuals both techniques show good face validity. When related to ventilation, quantification of breathlessness is moderately reproducible with both methods, even when subjects are kept in ignorance of the pattern of ventilatory stimulation. There is a small within- and large between-subject variability with both scaling techniques; possible factors responsible are discussed. The reproducibility of visual analogue scaling when related to ventilation is independent of the nature of the ventilatory stimulus and is maintained over intervals as long as 1 week when memory for the score given is unlikely to be an important factor. The difficulties of interpreting subjective estimates of perceived breathlessness are discussed, together with the relative merits of the two scaling techniques.

Adult↗
PubMed1985

Breathlessness during different forms of ventilatory stimulation: a study of mechanisms in normal subjects and respiratory patients.

This study investigates the mechanisms underlying the perception of breathlessness induced by hypoxia and hypercapnia in both naive normal subjects and patients with respiratory mechanical problems. In normal subjects separately receiving both oscillating hypercapnic and hypoxic ventilatory stimulation, equivalent peak stimulus intensities in end-tidal gas were associated with a 'damped' ventilatory response when the frequency of stimulation was increased. A concomitant fall in peak breathlessness levels on a visual analogue scale was recorded in each case. In normal subjects and patients, the voluntary copying of a ventilatory pattern recorded during oscillating hypercapnic stimulation was associated with a marked diminution or complete absence of breathlessness despite equivalent levels of peak ventilations achieved. Voluntary copying of hypercapnic stimulated ventilation was not associated with any demonstrable change in the distribution of muscle movements between the chest wall and abdomen. These results suggest that the intensity of breathlessness depends on the level of effective reflex stimulation of the respiratory-related neurones in the medulla. They cannot be explained solely in terms of perception of afferent neural information arising from either chemoreceptors or respiratory mechanoreceptors.

Abdomen↗
PubMed1985

Fluid filled oculoplethysmography and carotid artery disease: imperfect but useful.

Fluid filled oculoplethysmography (OPG) is a widely used method of assessing carotid stenosis but it has limitations in the detection of bilateral internal carotid artery lesions and of external carotid artery stenoses. In this study, 157 consecutive patients having carotid angiography and fluid filled OPG were assessed to determine the accuracy of the technique and define the sources of error. Haemodynamically significant stenosis (HDS) was defined as at least 50% stenosis of the internal carotid artery (ICA). Only the most severely stenosed side of the 35 bilateral HDS lesions was detected owing to the poor reliability of ear pulse delays. Eye/eye delays alone detected the most severely stenosed side in 82 of 98 patients with an HDS stenosis of one or both ICAs for a sensitivity of 84% a specificity of 71% (41/59) and accuracy of 79% (81/157). The measurement of ear/ear pulse delays for external carotid artery (ECA) stenosis had a sensitivity of only 15% (5/34). Ear/eye pulse delays detected none of the 35 patients with bilateral HDS ICA stenosis. Bilateral equal HDS ICA stenoses were a significant source of error. Stenotic disease was present in the aortic arch and branches (five patients) or the carotid siphon (eight patients) and in seven cases it resulted in an incorrect localization on OPG. There was no diagnostic relationship between the severity of delay and the presence of total occlusion. Chronic local eye pathology was present in 13 patients and did not affect the results of the OPG. We have ceased to use ear pulse measurements for routine assessment but continue to use the eye/eye delays in conjunction with a carotid doppler imaging system.

Adult↗
PubMed1985

Intraoperative ultrasound during carotid artery surgery.

Intraoperative B-mode ultrasound (OPUS) has been used to scan 155 carotid bifurcations during endarterectomy. Intimal flaps, residual plaque and suture line stenosis were detected by this method. Most defects were found in the external carotid artery (11%) and the importance of adequately clearing this vessel is stressed. The internal carotid artery had defects in 8% of cases, most of which were of a minor nature (less than 30% encroachment on luminal diameter). The presence of minor technical defects at operation was not significantly associated with the development of postoperative bruits or restenosis. Major defects were corrected at the time of surgery. OPUS is a useful adjunct in ensuring a technically satisfactory endarterectomy.

Carotid Arteries↗
PubMed1985

Vein, Gore-tex or a composite graft for femoropopliteal bypass.

Experience with a variety of graft materials has suggested that the nature of the material significantly affects long term graft patency. In 126 femoropopliteal bypass grafts performed during a 54 month period, the over-all patency rate for RSV (68.0 per cent at three years) was significantly superior to either Gore-tex alone (34.1 per cent at three years) or a composite graft of RSV below the knee anastomosed to Gore-tex above the knee (49.3 per cent at three years). The composite graft performed significantly better than Gore-tex alone, however, in patients with poor runoff or when a distal anastomosis was performed below the knee. The reason for the superior performance of RSV or the composite over Gore-tex alone probably relates to compliance mismatch at the site of the distal anastomosis. While RSV remains the graft material of choice for femoropopliteal bypass grafting, a extensive role exists for the use of a composite graft rather than Gore-tex graft alone especially in patients with poor runoff with an anastomosis below the knee.

Aged↗