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PubMed1983

The evaluation of forearm density with axial tomography.

The purpose of the present investigation was to validate axial tomography technique for estimating forearm density. Twenty forearm specimens from six male and four female embalmed human cadavers were used. Segmental mass, volume and density criteria were obtained by weight in air, hydrostatic weight and mass/volume ratio, respectively. Densities of bones and muscles were similarly measured. Segmental density as measured by axial tomography was overestimated by an average of 2.1% and the errors ranged from 0.05 to 4.81%. Results from this study indicated the presence of three density regions in the segment. Moreover, density data were found to be very similar in all zones of the central region of the segment (2/3 of its length) to actual segment density. It is thus actually possible to estimate forearm density in living humans, by taking two scans in the central zone of the segment if data pertaining to tissue densities are available.

Aged↗
PubMed1995

Variation of muscle moment arms with elbow and forearm position.

We hypothesized that the moment arms of muscles crossing the elbow vary substantially with forearm and elbow position and that these variations could be represented using a three-dimensional computer model. Flexion/extension and pronation/supination moment arms of the brachioradialis, biceps, brachialis, pronator teres, and triceps were calculated from measurements of tendon displacement and joint angle in two anatomic specimens and were estimated using a computer model of the elbow joint. The anatomical measurements revealed that the flexion/extension moment arms varied by at least 30% over a 95 degrees range of motion. The changes in flexion/extension moment arm magnitudes with elbow flexion angle were represented well by the computer model. The anatomical studies and the computer model demonstrate that the biceps flexion moment arm peaks in a more extended elbow position and has a larger peak when the forearm is supinated. Also, the peak biceps supination moment arm decreases as the elbow is extended. These results emphasize the need to account for the variation of muscle moment arms with elbow flexion and forearm position.

Biomechanical Phenomena↗
PubMed1984

Influence of nutritional status on exertion-induced forearm amino acid metabolism in normal man.

Normal volunteers were evaluated in the postabsorptive state, following 10 days of protein-calorie starvation, and during intravenous feeding ( ivf ) to determine the impact of nutritional status upon exertion-induced muscle amino acid metabolism. An isolated forearm model allowed an evaluation of recovery of metabolism following 1 min of submaximal isotonic exercise. Forearm blood flow returned to near basal levels within 15 min after exertion during postabsorptive and ivf conditions, but remained greater than or equal to 150% of basal at 1 hr after exercise during starvation. At 30 and 60 min after exercise, forearm plasma flux of total and essential amino acids were unchanged from basal in the postabsorptive state. However, the pattern of essential amino acid flux demonstrated a relative reduction in isoleucine and leucine efflux compared with basal, and this pattern persisted throughout 1 hr of recovery. During starvation, a significant (P less than 0.05) increase in total and essential amino acid efflux was observed throughout the recovery period. Starvation was also associated with significant increases in alanine and lysine efflux during recovery. Intravenous feeding was associated with a significant (P less than 0.05) uptake of essential amino acids with respect to basal levels at 30 min after exercise. At 60 min, there was a shift to total amino acid efflux but no change from basal flux for essential amino acids. During ivf , the pattern of essential amino acid uptake returned to basal within 1 hr after exertion.

Adult↗
PubMed1991

The cutaneous microcirculation of the forearm in young and old subjects.

Previous studies have shown a reduced cutaneous circulatory response to direct heat stress in the forearm circulations of older (60 to 80 year) subjects. The purpose of this study was to test the hypothesis that this aging effect is due to a reduced ability of the cutaneous microvessels in the forearm to respond to direct heat. Two groups of male subjects consented to participate; a group of 15 young individuals (Y; 20-39 year) and a group of 11 older (O; 60-79 year) individuals. The subjects rested in a supine position with the right forearm situated on the stage of a Leitz epiilumination microscope which was used to view the superficial cutaneous microvessels. The width of the red cell column (WRC), an index of vascular diameter, and the blood cell velocity (BCV) within the microvessels were measured by videomicroscopy at the presenting skin temperature (Ts) of 32 degrees, and then again after Ts had been elevated to 35 degrees then 40 degrees. At a Ts of 32 degrees, WRC and BCV for the Y group, respectively, averaged 6.6 microns and 0.22 mm/sec. Corresponding averages for the O subjects were 8.4 microns and 0.17 mm/sec. Between-group differences were not significant. At a skin temperature of 40 degrees, BCV was significantly higher compared to that at 32 degrees and 35 degrees for both groups (P less than 0.05); whereas, WRC did not significantly change. There were no significant between-group differences in BCV at the higher two temperatures. These results argue against a diminished blood flow response of superficial microvessels being responsible for the reduced cutaneous circulatory response to heat stress in older individuals.

Adult↗
PubMed1983

Effect of different prostaglandin synthesis inhibitors on post-occlusive blood flow in human forearm.

The vascular relaxation response in the human forearm that follows a short period of arterial occlusion (reactive hyperemia) was investigated with respect to its dependence on an intact PG synthesis. In 10 healthy subjects, five men and five women, forearm blood flow was measured, using venous occlusion plethysmography, in the basal state and during the recovery phase following 5 min of obstructed arterial flow. The subjects were studied at nine different occasions. At six of these they were pre-treated with the highest recommended doses of either of the PG synthesis inhibitors acetyl-salicylic acid, diclofenac, ibuprofen, indomethacin, naproxen or piroxicam; the remaining occasions were controls, performed in the absence of drugs in the beginning, middle, and end of the series. All the drugs significantly decreased the total reactive hyperemia following 5 min of arterial occlusion. Ibuprofen was the most efficient agent, inhibiting the total reactive hyperemia by more than 70%, and naproxen was least active, producing about 35% inhibition. The rest of the drugs diminished the total reactive hyperemia by 55-65%. Basal forearm blood flow was not affected by either of the agents. From these data we conclude that drugs which inhibit PG synthesis in man have in common the capacity to decrease post-occlusive reactive hyperemia. This indicates that an activation of the local release of arachidonic acid, leading to formation of vasodilator PG, is one of the main factors behind the vascular smooth muscle relaxation response to arterial occlusion.

Adolescent↗
PubMed1984

Active and passive forearm flexor tension patterns in the continuous perceptual-motor task paradigm: the significance of motivation.

The psychophysiology of skeletal muscle tension patterns during goal-directed behavior was investigated by using the continuous perceptual-motor task paradigm. Subjects were recruited to form serious-minded and playful extreme groups according to their responses to the Telic Dominance Scale (10 subjects in each group). They all performed a continuous perceptual-motor task 5 times at a 'slow' speed followed by a final 'fast' task. All performance periods lasted for 150 s. Measures of passive (tonic) and active (phasic) forearm flexor EMG activity were derived. It was concluded that serious-mindedness was significant to a tonic build-up of tension in the passive forearm flexor over the course of task performance. In contrast, the playful state was associated with high phasic response amplitudes in the active forearm flexor contingent upon changing the position of the joy-stick. Training moderated the range of state-specific EMG activation. State measures confirmed that the subjects maintained their state dominance during task performance. Error-scores and scores on felt level of arousal did not discriminate between the groups.

Adult↗
PubMedDate not supplied

Forearm arterial vascular responsiveness in insulin-dependent diabetic subjects.

The vascular reactivity of forearm arterioles was measured in 16 control subjects (C) and 30 insulin-dependent diabetic (IDDM) subjects, 16 of whom were shown to have microvascular and/or neuropathic complications (DC) including 8 with autonomic neuropathy (DCa) and 14 were shown to be free of complications (DNC). Forearm blood flow was measured by strain gauge plethysmography basally, following a cold pressor stress and following a period of arterial occlusion (reactive hyperaemia). The tests were repeated 24 h later following aspirin treatment. Both C and DNC showed a significant reduction in blood flow in the cold pressor test (C 0.64 +/- 0.12, DNC 0.89 +/- 0.22 ml/100 ml forearm tissue/min reduction in flow P < 0.005), while DC showed no significant response. Reactive hyperaemia was significantly greater in C than in DNC or DC (8.37 +/- 1.14, 5.51 +/- 1.27 and 4.95 +/- 0.75 ml/100 ml tissue/min, respectively, P < 0.02). In the DC group, DCa had significantly less response than those without autonomic neuropathy. Aspirin treatment restored the response of DNC but not DC to normal, suggesting that the abnormality in the former group may have been due to overproduction of a vasoconstrictive cyclooxygenase product (such as thromboxane A2). It is concluded that the abnormalities of vasomotor responses in diabetic subjects are complex and are apparently dependent on autonomic neuropathy, humoral and perhaps structural changes.

Adult↗
PubMed1988

The relation between forearm and vertebral mineral density and fractures in postmenopausal women.

Vertebral and forearm mineral density (VMD and FMD, respectively) were determined in 124 postmenopausal women with no crushed vertebrae or peripheral fractures, 51 who had sustained peripheral fractures only since the menopause, 62 with vertebral compression(s) only and 75 with both types of fracture. There was a very significant correlation between the two measurements in the whole set. The scatter could not be accounted for by methodological error but was partly accounted for by body weight, since VMD was related to body weight and FMD was not. Whatever criterion was used for the diagnosis of osteoporosis (whether fracture or density) the percentage of misclassified cases was very similar by the two methods. However, VMD was relatively more reduced than FMD in vertebral fracture cases and FMD was marginally more reduced than VMD in peripheral fracture cases. There is little to choose between vertebral and forearm density in the diagnosis of osteoporosis but vertebral densitometry is slightly superior to forearm densitometry in describing the severity of osteoporosis in vertebral fracture patients.

Body Weight↗
PubMed1988

Measurement of forearm rotation: an evaluation of two techniques.

In order to assess the reproducibility of two standard techniques of measuring forearm rotational movements, three trained observers used each method on twenty healthy volunteers. Analysis of the result obtained revealed no statistical difference between either method but both were subject to wide variation between observers, amounting to plus or minus 15 degrees for total forearm rotation. Comparison of individual values in forearm rotation should take account of observer error.

Adult↗
PubMed1990

Sequential forearm intravenous regional and infiltration anaesthesia: value for haemostasis.

Intravenous regional anaesthesia using 0.5% lignocaine with a forearm tourniquet is a satisfactory technique for operations on the distal forearm, wrist and hand. Since recovery of pain sensation is rapid, haemostasis after release of tourniquet becomes difficult and sometimes impossible. Local wound infiltration or metacarpal block with 1% lignocaine just before release of the tourniquet can allow subsequent haemostasis and wound closure to be carried out without causing pain. 55 patients received this sequential forearm intravenous regional and infiltrative anaesthesia. Subsequent haemostasis and wound closure could be carried out without pain in 51 patients (92.7%); three patients (5.5%) noticed mild discomfort but the operations could be finished without any additional anaesthetic agent. No complications were encountered with this modified technique.

Adolescent↗
PubMed1996

Influence of different types of recovery positions on perfusion indices of the forearm.

BACKGROUND: Basic life support guidelines of the European Resuscitation Council (ERC) suggest a modified type of recovery position compared to that recommended by the American Heart Association (AHA). However, anecdotal reports and the results of a small study by Fulstow and Smith (Resuscitation 1993; 26: 89-91) gave evidence that the new ERC position may cause an impairment of perfusion of the lower forearm. The aim of our study was to evaluate the effects of different recovery positions on arterial perfusion and venous drainage of the forearm. METHODS: We placed 20 young healthy volunteers randomly in either ERC or AHA position for 15 min first, and in the other position thereafter. Before and between volunteers were positioned supine. In a second series 10 volunteers were positioned according to the same protocol in semiprone positions as described by Morrison, Mirkhur and Craig (MMC), and Rautek's position, respectively. Forearm perfusion indices of the dependent arm were continuously assessed by photoplethysmographic pulsatility change, photoplethysmographic volume change, invasive peripheral venous pressure and non-invasive blood pressure amplitude. Subjective discomfort was assessed non-qualitatively. RESULTS: All indices of arterial perfusion demonstrated an impairment of arterial inflow in ERC, MMC and Rautek's position as well as venous congestion in these three positions. On the contrary, AHA position was associated with no significant changes of arterial flow and only moderate, insignificant signs of venous congestion. CONCLUSION: The results of this study suggest that AHA position causes less circulatory disturbances than the ERC, MMC and Rautek's positions.

Adult↗
PubMed1993

Self-generated rapid taps directed to the opposite forearm in man: anticipatory reduction in the muscle activity of the target arm.

A brief hammer tap applied passively (by the experimenter) to the forearm elicits a short-latency reflex response in the forearm flexors and extensors. When the same tap is performed actively (by the subject) using the opposite forearm, the reflex response is preceded by a short-lasting anticipatory reduction in the muscle activity appearing around the impact. This anticipatory reduction is interpreted as an alternative mode of feedforward motor control associated with damping of kinetic impulses generated within the bimanual system.

Electromyography↗
PubMed1987

Nifedipine vasodilates human forearm arteries and dorsal hand veins constricted by specific alpha-adrenoceptor stimulation.

1. The local dilative effect of the calcium entry blocker nifedipine on forearm arteries and dorsal hand veins has been studied in 27 healthy male volunteers. 2. Nifedipine induced an increase of blood flow by 1190% (P less than 0.001) in the forearm. 3. The construction of the hand veins induced by stimulation of either postsynaptic alpha 1- or alpha 2-adrenoceptors was reduced (P less than 0.001) by nifedipine. 4. The calcium entry blocker nifedipine is a potent dilator of human forearm arteries as well as of dorsal hand veins.

Adrenergic alpha-Agonists↗
PubMed1992

Changes in wrist and forearm configuration with grasp and isometric contraction of elbow flexors.

The purpose of this study was to determine the changes in wrist and forearm configuration with grasp and elbow flexor contraction by analysis of resting and grasping x-ray films of 15 normal adults and forearm scanograms of 10 other normal subjects. With grasp, a significant proximal migration of the radius (averaging 0.9 mm), a decrease in the carpal height ratio, and an increase in the lunate uncovering index were observed. With flexor contraction, there was a significant decrease in the forearm interosseous space.

Adult↗
PubMed1994

Clinical application of the forearm tourniquet.

We undertook this prospective study of 148 consecutive hand and wrist procedures to evaluate the safety and efficacy of the forearm tourniquet. Patients were assigned to three groups based on tourniquet pressure used, ranging from 50 to 125 mmHg above systolic blood pressure. The forearm tourniquet was well tolerated by all patients. No patient had neurologic complications. Minimal intraoperative bleeding occurred when the pressure was greater than 75 mmHg above systolic blood pressure. The forearm tourniquet is a safe and effective means of providing a bloodless field for wrist and hand surgery.

Forearm↗
PubMed1995

Dual energy X-ray absorptiometry of the spine--decubitus lateral versus anteroposterior projection in osteoporotic women: comparison to single energy X-ray absorptiometry of the forearm.

We investigated the discriminatory ability of dual energy X-ray absorptiometry (DXA) of the lumbar spine in the anteroposterior vs. decubitus lateral projection in 53 elderly women with at least one vertebral fracture and 63 age-matched women without fracture. Twenty-three premenopausal healthy women served as a reference group. Spine measurements were compared to forearm measurements by single energy X-ray absorptiometry (SXA). Bone mineral density (BMD) of the women with fractures was 16% lower in the AP projection and 17% lower in the decubitus lateral projection compared to age-matched women without fractures. t-Scores (deviation from normal premenopausal values in SDs) were -2.1 to -2.3 in the women without fractures, and -3.9 (AP projection), -3.1 (lateral projection) and -3.8 (forearm) in the women with vertebral fractures. t-Scores as well as z-scores for bone mineral content of the vertebral body and the vertebral posterior elements (both measured with the lateral projection) were similar. ROC analysis showed no significant difference between the AP and the lateral projection of the spine. When subjects with vertebral endplate sclerosis (about 25% in each group, with considerably elevated spinal BMD) were excluded, it did not significantly change the diagnostic abilities for fractures. We found no diagnostic advantage of the lateral projection as compared to the AP projection or forearm measurement. Future studies will reveal whether absorptiometry in the lateral projection can be improved by supine lateral scanning.

Absorptiometry, Photon↗
PubMed2006

Feasibility of forearm ultrasonography-guided nerve blocks of the radial, ulnar, and median nerves for hand procedures in the emergency department.

STUDY OBJECTIVE: We determine the feasibility of forearm ultrasonography-guided nerve blocks of the radial, ulnar, and median nerves, performed by emergency physicians, to provide procedural anesthesia of the hand in the emergency department (ED). METHODS: This was a prospective study involving a convenience sample of 11 patients presenting to an adult ED with hand pathology requiring a procedural intervention. Adults 18 years and older who presented to the ED during the 3-month study period were eligible. Physicians performing the nerve blocks were attending physicians, ultrasonography fellows, or residents who had participated in a 1-hour training session. The participants underwent ultrasonography-guided nerve blocks in the forearm to provide anesthesia. Any additional anesthesia or analgesia required to perform the procedure in the anesthetized region was recorded. Subjects rated their pain on a 100mm visual analog scale before the nerve block and 15 minutes after the nerve block. The primary outcomes for feasibility were the percentage of cases completed without rescue anesthesia or analgesia and the median reduction in pain on the visual analog scale after the nerve block. Secondary outcomes for feasibility included the median time to completion of the entire nerve block procedure for each subject (from initiation of ultrasonography to completion of the last injection) and the percentage of participants wishing to have the same procedure for similar injuries in the future. Other secondary outcomes included the percentage of participants with complications during the procedure and at 3 months. RESULTS: All procedures (100%) were completed without additional anesthesia or analgesia. The median reduction in visual analog scale score was 5.0 cm (interquartile range 3.0, 8.0; P=.003). The median time to completion of nerve blocks was 9 minutes per patient (interquartile range 6 minutes 30 seconds, 10 minutes 0 seconds), with a median of 2 blocks per patient. Ten of 11 patients (92%) stated they would wish to have the ultrasonography-guided nerve block in the future for similar injuries. There were no immediate complications and no complications reported at 3 months. CONCLUSION: Attending physicians, fellows, and residents can perform forearm ultrasonography-guided nerve blocks of the radial, ulnar, and median nerves quickly, without additional anesthesia and with high patient satisfaction, after minimal training. Although pilot data are suggestive, randomized controlled trials are needed to determine efficacy and safety. Ultrasonography-guided nerve blocks to provide anesthesia for hand procedures appear to be feasible in the ED.

Adult↗
PubMed2006

The effect of six keyboard designs on wrist and forearm postures.

There is increasing evidence that alternative geometry keyboards may prevent or reduce arm pain or disorders, and presumably the mechanism is by reducing awkward arm postures. However, the effect of alternative keyboards, especially the new designs, on wrist and arm postures are not well known. In this laboratory study, the wrist and forearm postures of 100 subjects were measured with a motion analysis system while they typed on 6 different keyboard configurations. There were significant differences in wrist extension, ulnar deviation, and forearm pronation between keyboards. When considering all 6 wrists and forearm postures together, the keyboard with an opening angle of 12 degrees , a gable angle of 14 degrees , and a slope of 0 degrees appears to provide the most neutral posture among the keyboards tested. Subjects most preferred this keyboard or a similar keyboard with a gable angle of 8 degrees and they least preferred the keyboard on a conventional laptop computer. These findings may assist in recommendations regarding the selection of keyboards for computer usage.

Adult↗