Baseline renal function and renal ultrasound findings in patients with obstetric fistulas (RENFRU): a prospective cohort study.

OBJECTIVE: To describe and compare baseline renal anatomy and renal function in patients with obstetric fistulas, and to evaluate whether preoperative renal testing and imaging may aid with operative decision making. DESIGN: A prospective cohort study. SETTING: Fistula Care Centre in Malawi. POPULATION: Women with an obstetric fistula. METHODS: Baseline creatinine testing and renal ultrasounds were performed. Surgeons completed a short questionnaire on the usefulness of creatinine and renal ultrasound on operative decision making. MAIN OUTCOME MEASURES: Baseline creatinine and renal ultrasound findings. RESULTS: Four surgeons performed operations on 85 patients. The mean creatinine in patients with vesicovaginal fistulas (VVF) was 0.60 ng/ml versus patients with uretero-vaginal fistulas (UVF) (0.79 ng/ml, P = 0.012). When a grade 3 or more hydronephrosis is absent on renal ultrasound, the negative predictive value of the presence of UVF is 93.3% (95% confidence interval [CI] 88.6-96.2) with a specificity of 97.2% (95% CI 90.3-99.6). In cases of UVF, surgeons found the renal ultrasound results useful or very useful 87.5% of the time, and the creatinine useful or very useful 75% of the time. CONCLUSION: In this pilot study, most patients with obstetric fistulas presented with a normal creatinine. In the absence of a grade 3 hydronephrosis or above on renal ultrasound, the probability of not having a UVF is 93.3%. Surgeons should consider performing preoperative renal ultrasound testing in all patients with an obstetric fistula, particularly in women with a prior laparotomy, as this population has risk factors for ureterovaginal fistula. TWEETABLE ABSTRACT: Most patients with obstetric fistulas have normal renal function. Preoperative renal ultrasounds should be performed.

Efficacy of neuromuscular exercises to promote movement quality and reduce musculoskeletal injury during initial military training in Royal Navy recruits.

INTRODUCTION: Musculoskeletal injuries (MSKIs) are a significant problem in the Royal Navy, contributing to 48% of all medical discharges from service between 2019 and 2020. The objective of the study was to assess efficacy of implementing a neuromuscular training intervention to improve movement quality and reduce MSKIs in Royal Navy recruits undertaking initial military training. METHODS: Neuromuscular training (pre-activation exercises, focusing on hip control) was integrated into the warm-up exercise regimen preceding physical training during the 10-week initial naval training (recruits) programme (January-March 2020) at HMS Raleigh (intervention group; n=162). A control group comprised (n=90) of recruits entering training from January 2019, who completed the standard warm-up programme prior to physical training. Movement control of the intervention group (intervention) was assessed before and after the 10-week programme using the Hip and Lower-Limb Movement Screen (HLLMS). Injury incidence proportion for both groups was determined retrospectively by review of medical notes. RESULTS: The control group's MSKI incidence proportion was 31%, which was higher (p<0.05) than the 8% reported in the intervention group. The majority of MSKIs were of the lower limb, and were reported in weeks 1, 2 and 5 of the 10-week training programme. Movement control, as assessed by the HLLMS score, improved (pretraining (week 1) and post-training (week 10) HLLMS score (mean (SD) pre: 11.2 (5.6); post: 8.4 (3.9); t=5.829, p<0.001) following the neuromuscular training in the intervention group but was not assessed in the control group. CONCLUSION: A neuromuscular control intervention was successfully implemented during the initial military training in the Royal Navy. The cohort undertaking the intervention demonstrated lower injury incidence compared with an equivalent cohort of recruits who undertook standard training. Movement control improved following the intervention, indicating better movement quality. Continued use of the programme may reduce military training attrition in the Royal Navy.

Coronary artery flow velocity is related to lumen area and regional left ventricular mass.

BACKGROUND: Coronary flow velocity varies widely between individuals, even at rest. Because of this variation, indices with less apparent deviation, such as the ratio of hyperemic to resting velocity (coronary flow reserve), have been more commonly studied. We tested the hypothesis that the flow continuity principle could be used to model resting coronary flow, and we examined the resulting velocity relationship. METHODS AND RESULTS: We studied coronary velocity in 59 patients using a Doppler wire to measure resting and hyperemic average peak velocities in the left anterior descending artery. Quantitative techniques were used to calculate lumen cross-sectional area and the lengths of all distal coronary branches. Branch lengths were used to estimate regional left ventricular mass. We then calculated the ratio of lumen area to regional mass (A/m). Regional perfusion was estimated from the double product of heart rate and systolic blood pressure. Resting velocity (V) varied inversely with A/m ratio [V=46.5/(A/m); r=0.68, P<0.001]. Disease in the left anterior descending artery was categorized as none or luminal irregularities only (n=22), mild (n=15), or moderate (n=22). The A/m ratio declined across these groups (8.7+/-4.0, 8.5+/-6.2, and 5. 6+/-3.0 mm(2)/100 g, respectively; P<0.04), and the resting average peak velocity increased (27+/-16, 33+/-11, and 37+/-20 cm/s, respectively; P=0.06). CONCLUSIONS: Resting coronary artery flow velocity is inversely related to the ratio of lumen area to regional left ventricular mass. Higher resting velocities are found when insufficient lumen size exists for the distal myocardial bed, as occurs with diffuse mild or moderate coronary atherosclerosis.

Muscle sounds during voluntary and stimulated contractions of the human adductor pollicis muscle.

The relationships between force, electromyography (EMG), and muscle sounds recorded by acoustic myography (AMG) were investigated for both voluntary and stimulated isometric contractions in the adductor pollicis muscle. Voluntary activity was performed at 10, 25, 50, 75, 85, and 100% of maximal voluntary contraction (MVC) force. Stimulated contractions were produced by supramaximal electrical stimulation of the ulnar nerve at the wrist at frequencies of 10, 20, 30, 50, 70, and 100 Hz. Contractions lasted for 4 s each, and were performed in random order with a 3-min rest between each. The voluntary and stimulation studies were performed in random order between subjects. Simultaneous recordings were obtained for force, force oscillation (from the differentiated force signal), and raw and integrated AMG (IAMG) and EMG (IEMG). During voluntary contractions, IAMG increased with force up to MVC (r2 = 0.99, P less than 0.001) in a curvilinear fashion and a similar relationship was seen between force and IEMG (r2 = 0.99, P less than 0.001). Conversely, during stimulated contractions as stimulation frequency increased, IAMG decreased in a fashion mirroring the frequency-force curve. The frequency of the AMG signal matched stimulation frequency and declines in total IAMG were due to reductions in amplitude of the AMG signal. The stimulation frequency-oscillation of force relationship was identical to that seen for stimulation frequency and IAMG. Integrated EMG increased linearly with stimulation frequency (r = 0.99). The stimulation results suggest that muscle sounds reflect oscillation of muscle fibers and that AMG signal characteristics are determined by motor control mechanisms rather than intrinsic contractile processes.

Acoustic myography for investigating human skeletal muscle fatigue.

Sounds produced during voluntary isometric contractions of the quadriceps muscle were studied by acoustic myography (AMG) in five healthy adults. With the subject seated, isometric force, surface electromyography (EMG), and AMG were recorded over rectus femoris, and the EMG and AMG signals were integrated (IEMG and IAMG). Contractions lasting 5 s each were performed at 10, 25, 50, 60, 75, and 100% of maximum voluntary contraction (MVC) force. Fatigue was then induced by repeated voluntary contractions (10 s on, 10 s off) at 75% MVC until only 40% MVC could be sustained. After 15 min of rest, the different force levels were again tested in relation to the fresh MVC. Both before and after fatiguing activity the relationships between force and IEMG [r = 0.99 +/- 0.01 (SD), n = 10] and force and IAMG (r = 0.98 +/- 0.02) were linear. After activity, however, the slopes of the regression lines for force and IEMG increased (P less than 0.01) but those for force and IAMG remained the same (P greater than 0.05). The present results clarify the relationship between AMG and isometric force in fatigued muscle without the problem of fatigue-induced tremor, which hampered previous studies of prolonged activity. This study contributes to the validation of AMG and shows that it is a potentially useful method for noninvasive assessment of force production and fatigue. Further studies to establish the origin of AMG activity are required before AMG can be accepted for use in neuromuscular physiology or rehabilitation.

Technical aspects of acoustic myography (AMG) of human skeletal muscle: contact pressure and force/AMG relationships.

The effect of contact pressure on acoustic myographic (AMG) recordings was examined during voluntary isometric contractions of the human quadriceps muscle in 20 normal males. A piezoelectric disk for recording muscle sounds was placed over rectus femoris at approximately mid-thigh and secured with a rubber electromyography (EMG) strap. Contact pressure was monitored by a load cell placed between the AMG device and the strap. With the subject seated, force at different percentage levels of maximum voluntary contraction (MVC) were held for 5 s each. Both AMG and EMG recordings were full-wave rectified and integrated (IAMG and IEMG) and expressed as a percentage of activity at MVC. Two contraction series were performed with 2 different contact pressures. Pressure 1 (P1), of 180 Pa was applied in all subjects. A higher pressure of either 790 Pa (P2; in 5 subjects) or 1200 Pa (P3; in 15 subjects) was also applied. No significant changes in IAMG activity (P > 0.1) occurred between P1 and P2 but P3 produced increases in IAMG at all force levels (P < 0.05 at 10, 50 and 75% MVC). Both linear and non-linear relationships between force and IAMG were observed in different subjects but the relationship also varied with the 2 contact pressures within some subjects. The force/IEMG relationship was linear in all cases. These results provide quantitative evidence that contact pressure can influence the degree of IAMG activity if the pressure is high enough. The change in the force/IAMG relationship with pressure in some subjects suggests that the different relationships observed are not determined by physiological differences between subjects but rather by technical factors.

Detection and severity of low frequency fatigue in the human adductor pollicis muscle.

The sensitivity of electrical stimulation tests for detecting low frequency fatigue (LFF) and its duration were examined in the adductor pollicis muscle of ten normal subjects. Supramaximal stimulation was applied to the ulnar nerve at the wrist and values for test stimulation force ratios of 10:100 Hz, 15:100 Hz and 20:50 Hz (2 sec at each frequency with 5 min rest between each ratio) were obtained for fresh muscle. Fatigue was then induced by voluntary isometric contractions at 50% maximal voluntary force (MVC) repeated until only 30% MVC could be achieved. Contractions lasted 10 sec with 5 sec rest between each. The three test ratios were then repeated to monitor recovery at intervals up to 72 h after activity. High frequency forces returned to fresh values by 24 h but low frequency forces were all still significantly reduced. Forces at 10 and 15 Hz were still significantly reduced at 48 and 72 h (10 Hz greater than fatigue than 15 Hz). The low/high frequency ratios, calculated once 50 and 100 Hz forces had recovered, also demonstrated differences in recovery rates. Repeatability tests indicated that 10 Hz force was more variable than other frequencies and forces at all stimulation frequencies were repeatable on different days with a coefficient of variation of less than 15%. Values for the 15:100 Hz ratio from fresh muscle in 22 normal subjects were 0.48 +/- 8. The 15:100 Hz ratio is suggested as the most appropriate test ratio for detecting LFF since 15 Hz force is more sensitive than 20 Hz and more stable than 10 Hz.

Acoustic myographic activity increases linearly up to maximal voluntary isometric force in the human quadriceps muscle.

Sounds produced during voluntary isometric contractions of the quadriceps muscle were recorded by acoustic myography (AMG) in seven healthy adults. With the subject seated, surface AMG and electromyography (EMG) were recorded over rectus femoris (RF) during isometric contractions, at different levels of maximum voluntary force. The AMG and EMG signals were amplified and integrated (IAMG and IEMG). The relationships between force and IAMG (r = 0.98 +/- 0.01, mean +/- 1 SD) and force and IEMG (r = 0.99 +/- 0) were linear in all subjects. The results for EMG confirm previous reports but those for AMG differ from the relationships reported for other muscles. Physiological and technical explanations are proposed for these differences and the necessity for further validation of the AMG technique is stressed.

Myofibrillar activation failure in McArdle's disease.

Contractile properties of the adductor pollicis muscle were examined in 9 normal volunteers and 7 patients with histochemically proven myophosphorylase deficiency (McArdle's disease). Fatiguing contractions were produced by supramaximal stimulation of the ulnar nerve, delivered over a range of frequencies, to allow further examination of the mechanisms responsible for the premature fatigue in patients. The excessive reductions in force, demonstrated in patients at all frequencies, were not associated at high frequencies (50 and 100 Hz) with excessive declines in excitation (measured as compound muscle action potential). These results demonstrate that, in patients, myofibrillar activation failure occurs over and above that due to excitation failure. Abnormal slowing of relaxation mechanisms was also confirmed. These findings appear consistent with the hypothesis of inhibition of various ATPases by metabolic products. The observed, clear differences between normal subjects and myophosphorylase-deficient patients constitute the basis of an objective screening procedure for this and other glycolytic disorders.

Acoustic myography of the human quadriceps muscle during intermittent fatiguing activity.

Integrated acoustic myography (IAMG) and electromyography (IEMG) were recorded over rectus femoris (RF) in six healthy subjects during a series of intermittent isometric contractions of quadriceps. Contractions were held for 10 sec with 10 sec rest between each, commencing at 75% maximum voluntary contraction (MVC) force and continuing to 40% MVC. The IAMG activity initially decreased (75%-60% MVC) in a linear relationship (r = 0.9) with fatigue (i.e. force loss) but then plateaued and increased once force fell below 52% MVC. The AMG/force relationship for the whole fatiguing protocol (i.e. 75%-40% MVC) was quadratic (r = 0.87). The IEMG also showed a quadratic relationship with force (r = 0.85) but activity initially increased before decreasing. The results of the present study quantify the relationship between AMG and force in quadriceps during fatigue from intermittent contractions commencing at 75% MVC. The findings confirm previous observations that AMG decreases with fatigue during strong contractions but the quadratic relationship found in the present study differs to that for other muscles during sustained contractions. The results also suggest that simultaneous recordings of AMG and EMG may help distinguish central and peripheral fatigue. Acoustic myography may therefore be a useful non-invasive monitor of force during early fatiguing activity using the present protocol but the need to study AMG during fatigue of different muscles and force levels is stressed.

Corticospinal function in severe brain injury assessed using magnetic stimulation of the motor cortex in man.

We have assessed corticospinal function in 19 post-coma patients severely brain-injured by anoxia or physical trauma. Eleven patients were unresponsive (Category 1) and eight demonstrated minimal, non-verbal responses to simple commands (Category 2). Motor evoked potentials (MEPs) could be elicited in hand and leg muscles in nine Category 1 and all eight Category 2 patients in response to transcranial magnetic stimulation (TMS). In comparison with normal subjects, threshold to TMS was significantly elevated in Category 1 but not in Category 2. Central conduction times were within the normal range except for two patients (one in each category) in whom they were prolonged. The variability in MEP amplitude to constant TMS was not significantly different from normal in either category. The size of MEPs recorded simultaneously in different hand muscles were correlated in all three groups. The presence of H-reflexes in hand muscles was associated with an absence of MEPs or a high threshold to TMS. Variability of MEPs was substantially greater than that of H-reflexes. We conclude that brain injury of a severity that may preclude consciousness and voluntary movement does not invariably predicate a non-functional motor cortex and corticospinal system.

Orbital tuberculosis in childhood.

An 11-year-old Indian girl living in England developed proptosis due to tuberculosis of the orbit. The proptosis regressed and she recovered fully after chemotherapy. While malignancy, developmental anomalies, and nontuberculous infections are commoner causes, a tuberculin test should be included among the investigations of children with proptosis.

Relationship between inspiratory mouth pressure and respiratory muscle activity in normal subjects.

The relationship between inspiratory mouth pressure and respiratory muscle activation was investigated in 20 normal non-smoking subjects (13 males). Surface electromyography (EMG) was recorded from the seventh intercostal space bilaterally during different levels of inspiratory effort monitored by a respiratory mouth pressure gauge. The mouth pressure and EMG relationship was non-linear between 20 and 100% of inspiratory effort. Quadratic regression analysis was performed between percent inspiration and percent EMG on each side of the chest. The regression equation and coefficient of determination (r2) for the right side were y = 9.73 (e0.024x-1), r2 = 0.91, and for left side were y = 10.79 (e0.023x-1), r2 = 0.88. An independent t-test did not reveal significant difference (P > 0.05) between the slopes of the regression lines from the two sides of the chest. Therefore, results of the two sides were pooled and the predictive regression equation for the combined results was y = 10.05 (e0.0236x-1). Reasons for such a non-linear relationship may include the loading mechanism of respiratory muscles, inefficiency of intercostal muscles at high levels of inspiration, their recruitment pattern and the histochemical characteristics of respiratory muscles. Since absolute EMG values cannot be used to assess changes in activation on different days, further work is required to establish the between-day repeatability of the technique described which is potentially useful for assessing respiratory muscle function pre- and post-operatively in chest surgery patients.

Maximal inspiratory and expiratory mouth pressures in sitting and half-lying positions in normal subjects.

Maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures were measured in seven normal adults in both sitting and half-lying positions on 2 days. Analysis of variance did not reveal significant differences between measurements made in the two positions for either PImax or PEmax. Measurements were repeatable and the results obtained in both positions were pooled. The coefficient of variation of PImax was 4.7% between-trials and 10.3% between-days, and those for PEmax were 3.4% and 4.4%, respectively. It is suggested that measurements of PImax and PEmax made in the half-lying position after thoracic surgery can be compared to pre-operative values which are commonly obtained in sitting without any influence from a positional effect. Details of the methodology to improve the reliability of the respiratory mouth pressures technique are discussed.

Blood irradiation with accelerator produced electron beams.

Blood and blood products are irradiated with gamma rays to reduce the risk of graft versus host disease (GVHD). A simple technique using electron beams produced by a medical linear accelerator has been studied to evaluate irradiation of blood and blood products. Variations in applied doses for a single field 20 MeV electron beam are measured in a phantom study. Doses have been verified with ionization chambers and commercial diode detectors. Results show that the blood product volume can be given a relatively homogeneous dose to within 6% using 20 MeV electrons without the need to rotate the blood bags or the beam entry point. The irradiation process takes approximately 6.5 minutes for 30 Gy applied dose to complete as opposed to 12 minutes for a dual field x-ray field irradiation at our centre. Electron beams can be used to satisfactorily irradiate blood and blood products in a minimal amount of time.

Study on examinee's dose delivered in computed tomography.

Dose profiles are presented resulting from computed tomography (CT). The profiles are positioned at the central axis, 1 cm away from the outer surface of the phantom, for single and multiple scans. A Hitachi W-1000 scanner is used with a thermoluminescent dosimeter (TLD), and standard dosimetry head and trunk phantoms. Regression equations are found linking the dose resulting from scattered radiation associated with a single scan to the distance from the scanning centre. The impact on the CT dose index value (CTDI) for varying integrating lengths is analysed. Some problems associated with CT dose measurement are noted, which may assist in the practical application of IBSS (International Basic Standard of Radiation Protection and Safety of Radiation Sources) guide levels.

Pattern of asymmetry of paraspinal muscle size in adolescent idiopathic scoliosis examined by real-time ultrasound imaging. A preliminary study.

The symmetry of lumbar multifidus size was examined in 20 patients with adolescent idiopathic scoliosis, aged 12-19 years. With the subject prone, bilateral real-time ultrasound images were obtained at the level of the 4th lumbar vertebra. Cross-sectional area and linear (horizontal and vertical) measurements were made using on-screen calipers. A pattern of asymmetry of lumbar multifidus cross-sectional area was shown to exist for the different curve types. The cross-sectional area was smaller (P < 0.0001) on the opposite side to the convexity of a primary thoracic curve, and on the convex side of a lumbar or thoracolumbar curve. The combined linear measurements (multiplied) correlated with cross-sectional area (r = 0.95) and could therefore be used for rapid clinical assessment of multifidus size. These preliminary findings provide a basis for further investigation of the role of the musculature in the pathogenesis of adolescent idiopathic scoliosis.

Evidence of lumbar multifidus muscle wasting ipsilateral to symptoms in patients with acute/subacute low back pain.

The effect of low back pain on the size of the lumbar multifidus muscle was examined using real-time ultrasound imaging. Bilateral scans were performed in 26 patients with acute unilateral low back pain (LBP) symptoms (aged 17-46 years) and 51 normal subjects (aged 19-32 years). In all patients, multifidus cross-sectional area (CSA) was measured from the 2nd to the 5th lumbar vertebrae (L2-5) and in six patients, that of S1 was also measured. In all normal subjects, CSA was measured at L4 and in 10 subjects measurements were made from L2-5. Marked asymmetry of multifidus CSA was seen in patients with the smaller muscle being on the side ipsilateral to symptoms (between-side difference 31 +/- 8%), but this was confined to one vertebral level. Above and below this level of wasting, mean CSA differences were < 6%. In normal subjects, the mean differences were < 5% at all vertebral levels. The site of wasting in patients corresponded to the clinically determined level of symptoms in 24 of the 26 patients, but there was no correlation between the degree of asymmetry and severity of symptoms. Patients had rounder muscles than normal subjects (measured by a shape ratio index), perhaps indicating muscle spasm. Linear measurements of multifidus cross-section were highly correlated with CSA in normal muscles but less so in wasted muscles, so CSA measurements are more accurate than linear dimensions. The fact that reduced CSA, i.e., wasting, was unilateral and isolated to one level suggests that the mechanism of wasting was not generalized disuse atrophy or spinal reflex inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased central drive during fatiguing contractions of the paraspinal muscles in patients with chronic low back pain.

In low back pain patients the paraspinal muscles demonstrate excess fatigability. Whether the cause is "central" as could result from impaired motor unit recruitment due to poor motivation or fear of pain, or "peripheral", and caused by defects in the contractile apparatus, is unknown. Using surface electromyography in conjunction with a standardized isometric fatigue test, this study investigates the mechanisms causing paraspinal muscle dysfunction in patients with both nonsurgical and postsurgical chronic low back pain. During the fatigue test normal subjects and both patient groups exhibited electromyographic increases. These were significantly greater in both patient groups, indicating increased central drive to their muscles. These findings may suggest that patients' excess fatigue is peripheral in origin, with increased central drive arising secondary to muscle wasting or denervation, although a central activation defect has not been excluded. Impaired physical performance in low back pain patients does not seem to be caused by lack of central drive.