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PubMed2006

Plasma nitrite reserve and endothelial function in the human forearm circulation.

Attenuation of endothelium-derived nitric oxide (NO) synthesis is a hallmark of endothelial dysfunction. Early detection of this disorder may have therapeutic and prognostic implications. Plasma nitrite mirrors acute and chronic changes in endothelial NO-synthase activity. We hypothesized that local plasma nitrite concentration increases during reactive hyperemia of the forearm, reflecting endothelial function. In healthy subjects (n = 11) plasma nitrite and nitrate were determined at baseline and during reactive hyperemia of the forearm using reductive gas-phase chemiluminescence and flow-injection analysis, respectively. Endothelium-dependent dilation of the brachial artery was measured as flow-mediated dilation (FMD) using high-resolution ultrasound. Results were compared to patients with endothelial dysfunction as defined by reduced FMD (n = 11). Reactive hyperemia of the forearm increased local plasma nitrite concentration from 68 +/- 5 to 126 +/- 13 nmol/L (p < 0.01), whereas in endothelial dysfunction nitrite remained unaffected (116 +/- 12 to 104 +/- 10 nmol/L; n.s.), corresponding to nitrite reserves of 94 +/- 21 and -8 +/- 4%. This was accompanied by a significantly greater increase in brachial artery diameter (FMD: 8.5 +/- 0.4% vs 2.9 +/- 0.5%, for healthy subjects and endothelial dysfunction, respectively; p < 0.001). This observation suggests that nitrite changes reflect endothelial function. Assessment of local plasma nitrite during reactive hyperemia may open new avenues in the diagnosis of vascular function.

Adult↗
PubMed2004

Traumatic bowing of the forearm bones in roller machine injuries.

Slow bending forces created by rollers of rotating machines and acting on forearm bones can result in traumatic bowing even in adults. Four patients having this peculiar injury pattern in industrial accidents have been reported in this paper. Three of these had concomitant fractures of ipsilateral humerus. There were problems in appropriate reduction of the deformity due to the presence of associated overlying soft tissue injury. The literature has also been reviewed for this injury and 13 reports defining the injury profile, problems in realigning forearm bones and their subsequent maintenance have been described. The eventual outcome of such machine injuries has not been good due to persistence of some degrees of bowing and associated restriction of forearm rotation.

Accidents, Occupational↗
PubMed2004

Precision of measurements of physical workload during standardised manual handling. Part I: surface electromyography of m. trapezius, m. infraspinatus and the forearm extensors.

Though surface electromyography (EMG) has been widely used in studies of occupational exposure, its precision in terms of the variance between-days and between-subjects has seldom been evaluated. This study aimed at such an evaluation. Six women performed three different work tasks: 'materials picking', 'light assembly', and 'heavy assembly', repeated on 3 different days. EMG was recorded from m. trapezius, m. infraspinatus and the forearm extensors. Normalisation was made to a maximal (MVE), and a submaximal (RVE), reference contraction. Variance components between days (within subjects) and between subjects were derived for the 10th, 50th and 90th percentiles, as well as for muscular rest parameters. For the task 'heavy assembly', the coefficient of variation between days (CV(BD)) was 8% for m. trapezius (right side, 50th percentile, MVE normalised values). Larger variabilities were found for m. infraspinatus (CV(BD) 15%), and the forearm extensors (CV(BD) 33%). Between-subjects variability (CV(BS)) was greater, 16% for m. trapezius and 57% for m. infraspinatus, 29% for the forearm extensors. RVE normalisation resulted in larger CV(BD), while reducing CV(BS). The between-days and between-subjects variability may be used to optimise sampling strategy, and to assess the bias in epidemiological studies. The bias caused by measurement procedures per se is acceptable.

Adult↗
PubMedDate not supplied

Radial forearm free flap for coverage of postoperative lateral heel wounds after open reduction and internal fixation of the calcaneus.

For intraarticular calcaneus fractures, open reduction and internal fixation has become commonplace for the reduction of morbidity of postinjury arthritis. Despite adequate surgical results, there are often associated postoperative wound complications. The purpose of this study was to describe a unique application of the radial forearm free flap for coverage of lateral postoperative heel defects seen after calcaneal fixation. Seven lateral heel wounds after open reduction of calcaneal fractures in 6 patients were covered with radial forearm free flaps. The technique used involved passage of the pedicle of the laterally placed flap anteriorly to the Achilles tendon so that it can be anastomosed to the posterior tibial artery. Flap application was 100% successful, with good functional and cosmetic results in all patients. The radial forearm free flap provides a quick, reliable, and easily harvested source of coverage for lateral heel wounds seen after open reduction and internal fixation of the calcaneus. Tunneling of the flap pedicle anterior to the Achilles tendon is simple and provides the additional advantages of access to reliable vessels, reduced scarring, and avoidance of further wound problems often seen with incisions used to access the anterior tibial artery.

Adult↗
PubMed2004

A surgical technique for pediatric forearm pronation: brachioradialis rerouting with interosseous membrane release.

PURPOSE: In this study we used a tendon transfer technique (consisting of rerouting of the brachioradialis with interosseous membrane release) to restore active forearm pronation in patients with supination deformity secondary to brachial plexus birth palsy. METHODS: Four children (3 with flexible supination deformities, 1 with a fixed supination deformity) whose ages ranged between 5 and 9 years had brachioradialis rerouting with interosseous membrane release. RESULTS: Mean active forearm rotation was improved from 28 degrees supination before surgery to 49 degrees pronation after surgery. No patient developed elbow contracture during a minimum of 12 months of follow-up evaluation (40 months in 2 patients, 14 months in 1 patient, 12 months in 1 patient). CONCLUSIONS: These results suggest that brachioradialis rerouting combined with interosseous membrane release may be a successful means to correct supination deformity of the forearm.

Brachial Plexus↗
PubMed2004

Painful neuroma of the posterior cutaneous nerve of the forearm after surgery for lateral humeral epicondylitis.

PURPOSE: To describe a neuroma of the posterior cutaneous nerve of the forearm that can be the source of pain after surgery for lateral humeral epicondylitis. METHODS: A retrospective chart review of 9 patients having pain after surgery for lateral humeral epicondylitis was conducted to evaluate their history of pain, surgical findings during exploration of their painful lateral elbow scar, and outcome of their surgical treatment. RESULTS: In each of the 9 patients a neuroma of the posterior cutaneous nerve of the forearm was found to be within the scar of the original lateral epicondylitis surgery. For each of these patients the surgical treatment included resection of the neuroma and implantation of the proximal end of the nerve into the brachioradialis muscle proximal to the elbow joint. With this approach 8 of the patients had excellent pain relief and 1 had good pain relief at a mean follow-up time of 1.4 years (range, 1.0-2.6 years). CONCLUSIONS: Pain in the region of the scar after surgery to treat lateral humeral epicondylitis can be caused by a neuroma of the posterior cutaneous nerve of the forearm and this painful neuroma can be treated successfully by neuroma resection and implantation of the nerve proximally into the brachioradialis muscle.

Cicatrix↗
PubMed2005

Structural properties of reconstruction constructs for the interosseous ligament of the forearm.

PURPOSE: The Essex-Lopresti fracture-dislocation, also termed longitudinal radioulnar dissociation (LRUD), results in major functional impairment from pain and limitation of motion at the wrist and elbow. Interosseous ligament (IOL) reconstruction has been proposed to help treat LRUD and restore forearm stability. The objective of this study was to evaluate the biomechanical structural properties of 3 different IOL reconstruction constructs and of the intact IOL for comparison. METHODS: Structural tensile testing was performed on 24 fresh-frozen cadaveric forearms with 4 different forearm conditions: IOL intact and IOL reconstructed with Achilles tendon, flexor carpi radialis (FCR) tendon, and bone-patellar tendon-bone. Isolated radius-IOL-ulna constructs were loaded to failure in a materials testing machine with force applied along the local fiber direction. RESULTS: Stiffness in the intact IOL was 129 +/- 31 N/mm, which was significantly stiffer than any of the constructs tested. The intact IOL was 8 times stiffer than the Achilles tendon construct, 7 times stiffer than the FCR construct, and 3 times stiffer than the bone-patellar tendon-bone construct. The Achilles tendon and FCR constructs were similar to each other biomechanically but the bone-patellar tendon-bone construct was slightly stiffer than the Achilles tendon and FCR constructs. CONCLUSIONS: All graft constructs tested were inferior structurally to the intact IOL. The results of this study provide a biomechanical basis for graft selection for reconstruction of the IOL.

Aged↗
PubMedDate not supplied

Reconstruction of hand soft-tissue defects: alternatives to the radial forearm fasciocutaneous flap.

Soft-tissue defects of the hand and wrist are not an uncommon problem confronting the hand surgeon. Over the past 20 years the retrograde radial forearm fasciocutaneous flap has gained widespread acceptance in reconstruction of these defects. Appreciation of the inherent limitations of this workhorse flap and increased understanding of the blood supply of the upper extremity have prompted the development of several alternative pedicled forearm flaps. Aspects of surgical technique, specific limitations, and indications for the radial forearm fascial flap, the posterior interosseous artery flap, the retrograde radial artery perforator flap, and the dorsal ulnar artery flap are discussed and a reconstructive algorithm for flap selection is presented.

Forearm↗
PubMed2005

Flow motion pattern differences in the forehead and forearm skin: Age-dependent alterations are not specific for Alzheimer's disease.

Oscillations in laser Doppler signals derived from the forehead and forearm skin were analyzed in 77 healthy probands from 4 various age groups (ranging between 15 and 77 years) and 22 late-onset sporadic Alzheimer's disease (AD) patients. A characteristic pattern of oscillations in the microcirculatory blood flux ( approximately 8 cycles/min, 0.13 Hz) was observed in the forehead skin, the occurrence of which correlated inversely with age (r = 0.80). The occurrence of forehead vasomotion pattern was 100% in the teenagers, whereas it was significantly less in the elderly control subjects (32%) and in the AD patients (18%). Forearm reactive hyperemia was provoked by 1-min occlusion of the brachial artery, and the vascular reactivity was calculated. This phenomenon also proved to be age-dependent, but the process was not related to AD. Our results indicate that the lack of forehead vasomotion reflects aging better than does the forearm vasomotion. Both of these functions are preserved in AD.

Adolescent↗
PubMedDate not supplied

Single-injection brachial plexus anesthesia for arteriovenous fistula surgery of the forearm: a comparison of infraclavicular coracoid and axillary approach.

BACKGROUND AND OBJECTIVES: The surgical site for the creation of an arteriovenous fistula at the lateral aspect of the distal forearm may be faster and more effectively blocked with the infraclavicular coracoid approach than with the axillary approach for brachial plexus block. METHODS: Sixty uremic patients scheduled for the creation of an arteriovenous fistula at the forearm were randomized to receive a single-injection brachial plexus block with 35 to 50 mL mepivacaine 0.95% with epinephrine using the infraclavicular coracoid approach (IC group) or the perivascular axillary approach (AX group). A distal muscular contraction elicited by a nerve stimulator at current <0.5 mA was used in all patients. RESULTS: At 30 and 45 minutes, complete loss of sensation was observed more often in group IC than AX in the cutaneous distribution of musculocutaneous nerve (62% v 30% [P < .05] and 69% v 40%, respectively [P < .05]), but at 60 minutes the difference was not statistically significant. In other areas, analgesia and motor block were achieved at a similar rate. In 3 patients surgery could not be performed under the block due to changes in schedule or the use of a brachial tourniquet. Patient satisfaction was equally high in both groups. CONCLUSIONS: Blockade of the musculocutaneous nerve developed faster with the infraclavicular coracoid approach than with the axillary approach. The infraclavicular coracoid approach may be preferable in patients scheduled for the creation of an arteriovenous fistula at the forearm.

Adult↗
PubMed2005

Reproducibility of different laser Doppler fluximetry parameters of postocclusive reactive hyperemia in human forearm skin.

INTRODUCTION: Postocclusive reactive hyperemia in forearm skin is a commonly used model for studying microvascular reactivity function, particularly in the assessment of vascular effect of topically applied pharmacological substances. In this study, we investigated the reproducibility of several different laser-Doppler-derived parameters in the measurement of postocclusive reactive hyperemia at forearm skin in healthy subjects. METHODS: Eighteen young healthy male volunteers were recruited and studied in a supine position while fasted. Forearm blood flow was occluded at suprasystolic pressure for 3 min. Microvascular perfusion was measured continuously using laser Doppler fluximetry. Parameters studied were maximum increase in hyperemia perfusion (PORHmax), time-to-peak (Tp), amplitude of peak perfusion (PORHpeak), percentage of hyperemic response (PORH%) and mean velocity of the hyperemia increase (PORHmax/Tp). Measurement was performed twice within each study day for 2 study days. Coefficient of variation and intraclass correlation coefficient (ICC; with 95% confidence interval) were calculated for each parameter. An ICC value above 0.75 was interpreted as "excellent reproducibility". RESULTS: ICC analysis showed that all studied parameters, except for PORH%, demonstrated excellent reproducibility for both within- and between-day measurements. Satisfactory intraday and interday coefficients of variation (<10%) were also obtained for these parameters. CONCLUSION: Laser-Doppler-derived PORHmax, Tp, PORHpeak and PORHmax/Tp were highly reproducible parameters for measuring microvascular reactivity during reactive hyperemia, with PORHmax shown as the most reproducible index. PORH% is, however, less reproducible. These findings have implications for the use of laser Doppler fluximetry coupled with 3-min-occlusion PORHmax as a useful and reliable noninvasive clinical measurement index of microvascular function.

Adult↗
PubMed2001

Acetylcholine-mediated vasodilation in the forearm circulation of patients with heart failure: indirect evidence for the role of endothelium-derived hyperpolarizing factor.

Vasomotor responses to intraarterial administration of acetylcholine are mediated by release of nitric oxide, prostaglandins, and an unidentified hyperpolarizing factor from vascular endothelial cells. The contribution of endothelium-derived hyperpolarizing factor (EDHF) to the vasodilatory response to acetylcholine in the skeletal muscle circulation of patients with congestive heart failure (CHF) has not been previously characterized. Accordingly, to specifically assess the role of EDHF, the regional vascular effects of sequential administration of acetylcholine and nitroglycerin in the brachial artery were determined in the forearm circulation with strain-gauge venous occlusion plethysmography in patients with CHF and in normal subjects during combined systemic inhibition of cyclooxygenase activity with indomethacin and regional inhibition of nitric oxide synthase activity with l-N(G)-monomethylarginine (l-NMMA). After administration of indomethacin, infusion of l-NMMA significantly decreased the forearm blood flow response to acetylcholine in normal subjects (5.4 +/- 1.2 to 3.5 +/- 0.6 ml/min/100 ml, p < 0.05) but not in patients with CHF (5.7 +/- 1.3 to 5.7 +/- 1.4 ml/min/100 ml). Infusion of l-NMMA did not change forearm blood flow responses to nitroglycerin in either group. The presence of a noncyclooxygenase, non-nitric-oxide relaxing factor indicates that EDHF, rather than nitric oxide, may be the predominant endothelium-derived substance mediating vasodilation in response to acetylcholine in patients with CHF.

Acetylcholine↗
PubMed1988

Early reconstruction of pharynx and esophagus following corrosive injury with radial forearm flap in preparation for colon interposition.

In 24 patients, corrosive injuries involving the floor of the mouth, the pharynx, and the esophagus were repaired in two stages using a combined free forearm flap and colon for functional restoration of the alimentary tract. The results were satisfactory. Morbidity was decreased, complications were minimal, and there were no failures. In the first stage, early reconstruction with a forearm flap for the oral floor, the pharynx, and the cervical esophagus can be done safely 3 months after the original injury when the acute inflammation of the tissue has disappeared. The forearm flap is thin and pliable, and has a good blood supply for primary healing without failure or stricture. Dysphagia is eliminated because food passes down by gravity. There is no constriction or hyperperistalsis of the colon, both of which are occasionally seen with the traditional colon interposition. In the second stage, the traditional method is used to finish the reconstruction of the remainder of the esophagus.

Adult↗
PubMed1997

Prostaglandins and nitric oxide mediate insulin-induced vasodilation in the human forearm.

OBJECTIVE: To determine the involvement of prostaglandins, nitric oxide, and beta-adrenoceptor activation in insulin-induced vasodilation in the human forearm. METHODS: Fifteen normal subjects were studied. Insulin was administered into the brachial artery in the presence of saline, the cyclo-oxygenase inhibitor indomethacin (0.65 microgram/kg/min), the inhibitor of nitric oxide synthase NG-mono-methyl-L-arginine (L-NMMA, 30 micrograms/kg/min), or the non-selective beta-adrenoceptor blocker propranolol (0.2 microgram/kg/min). Forearm vascular resistance (FVR) was derived from forearm blood flow and concomitantly measured intra-arterial blood pressure. RESULTS: Insulin decreased FVR by 32 +/- 5% (P < 0.01). Both indomethacin and L-NMMA inhibited insulin-induced vasodilation, while propranolol had no effect. Single infusion of indomethacin was without effect on vascular tone, while single infusion of L-NMMA increased FVR by 81 +/- 19% (P < 0.01). CONCLUSIONS: Insulin has vasodilating properties in skeletal muscle vasculature that is mediated by increases in nitric oxide, that subsequently stimulates prostaglandin release. The latter appears to be a novel vascular action of insulin.

Adrenergic beta-Agonists↗
PubMed1999

Serum nitrite sensitively reflects endothelial NO formation in human forearm vasculature: evidence for biochemical assessment of the endothelial L-arginine-NO pathway.

OBJECTIVE: A reduced bioactivity of endothelial nitric oxide (NO) has been implicated in the pathogenesis of atherosclerosis. In humans, the endothelial L-arginine-NO pathway has been indirectly assessed via the flow response to endothelium-dependent vasodilators locally administered into the coronary, pulmonary or forearm circulation. However, biochemical quantification of endothelial NO formation in these organ circulations has been hampered so far because of the rapid metabolism of NO. Therefore, we aimed to work out a reliable biochemical index to assess endothelial NO formation in human circulation. METHODS: In 33 healthy volunteers, forearm blood flow (FBF) was measured by standard techniques of venous occlusion plethysmography at rest, after local application of the endothelium-dependent vasodilator acetylcholine (ACH), the endothelium-independent vasodilator papaverine (PAP), the stereospecific inhibitor of endothelial NO synthase (eNOS) L-NMMA, and L-arginine (ARG), the natural substrate of eNOS. In parallel, nitrite and nitrate concentrations in blood samples taken from the antecubital vein were measured by HPLC using anion-exchange chromatography in combination with electrochemical and ultraviolet detection following a specific sample preparation method. RESULTS: ACH dose-dependently increased resting FBF (from 3.0 +/- 0.3 to 10.4 +/- 0.9 ml/min per 100 ml tissue) and serum nitrite concentration (from 402 +/- 59 to 977 +/- 82 nmol/l, both p < 0.05, n = 12). A significant correlation was observed between the changes in FBF and the serum nitrite concentration (r = 0.61, p < 0.0001). L-NMMA reduced resting FBF and endothelium-dependent vasodilation by 30% and this was paralleled by a significant reduction in serum nitrite concentration at the highest dose of ACH (n = 9, p < 0.001). PAP increased FBF more than fourfold, but did not affect serum nitrite concentration (n = 11), whereas ARG significantly increased both FBF and nitrite. Basal serum nitrate amounted to 25 +/- 4 mumol/l and remained constant during the application of ACH, PAP and L-NMMA. CONCLUSIONS: The concentration of serum nitrite sensitively reflects changes in endothelial NO formation in human forearm circulation. This biochemical measure may help to characterize the L-arginine-NO pathway in disease states associated with endothelial dysfunction and to further elucidate its pathophysiological significance for the development of atherosclerosis in humans.

Acetylcholine↗
PubMed2003

Intra-arterial vasopressin in the human forearm: pharmacodynamics and the role of nitric oxide.

BACKGROUND AND OBJECTIVES: Diverse vascular effects have been ascribed to vasopressin, including the potential to cause vasodilation, vasoconstriction, and nitric oxide release. The objective of this study was to establish the pharmacodynamics, reproducibility, and nitric oxide dependence of the vasomotor actions of vasopressin in the forearm resistance vessels. METHODS: Blood flow in both forearms of 12 healthy men was measured with venous occlusion plethysmography. Continuous and discontinuous doses of 1 to 300 pmol/min vasopressin were administered by the intrabrachial route. For assessment of the contribution of nitric oxide, vasopressin was coadministered with a "nitric oxide clamp," a balanced coinfusion of 4 micromol/min L-N(G)-monomethylarginine (a nitric oxide synthase inhibitor) and 0.3 to 0.8 nmol/min sodium nitroprusside (an exogenous nitric oxide donor) to block endogenous nitric oxide production and restore normal basal blood flow, respectively. RESULTS: Vasopressin produced a dose-dependent biphasic change in blood flow with a maximum reduction in percentage change in blood flow ratio of infused and control arms of 22% +/- 5% at 3 pmol/min (P <.01) and an increase of 80% +/- 30% at 300 pmol/min (P <.01). There were no significant differences in repeated responses obtained either within or between days. Repeated discontinuous dosing did not change the magnitude of the maximum vasoconstriction or vasodilation, but prolonged continuous infusion produced maximal vasodilation at 12 minutes that subsequently resulted in substantial tachyphylaxis (P =.04). Although there was no augmentation of vasoconstriction, the nitric oxide clamp abolished vasopressin-induced vasodilation (P <.05). CONCLUSIONS: Intra-arterial vasopressin causes a reproducible dose-dependent biphasic change in forearm blood flow. Vasomotor responses are time-dependent with a modest delay to peak vasodilation and tachyphylaxis with prolonged sustained infusion. Nitric oxide release is a major contributor to vasopressin-induced vasodilation but does not directly oppose low-dose vasopressin-induced vasoconstriction.

Adult↗
PubMed1999

Impaired endothelial-dependent forearm vascular relaxation in black Americans.

BACKGROUND: Hypertension is a major cause of morbidity and mortality in the general population and has an even more significant impact on the black community in particular. Explaining the interethnic differences has been difficult. Differences in endothelial function may provide some insight into the causes of the increased incidence of hypertension in the black population versus their white cohorts. METHODS: In this study 16 black subjects and 12 white subjects received brachial artery infusions of acetylcholine (12.5, 25, and 50 microg/min) and angiotensin II (3.82, 9.55, and 19.10 ng/min). Measurement of forearm vascular resistance by venous occlusion plethysmography was conducted. RESULTS: The dose of acetylcholine at 50% maximal observed response (EC50) for black subjects was 10.6+/-2.39 microg/min and 3.3+/-0.44 microg/min in the white subjects (mean +/- SEM; P < .05). Sodium nitroprusside infusions at 1 and 2 microg/min did not cause a significant difference in response between the 2 groups. After angiotensin II was infused, forearm vascular resistance Emax was 3.42+/-0.78 mm Hg/100 mL tissue volume/min for black subjects and 3.16+/-0.99 mm Hg/100 mL tissue volume/min for white subjects. CONCLUSION: This study shows impaired endothelial-dependent forearm vascular relaxation as measured by decreased acetylcholine response in black subjects. This impairment in endothelial function may contribute to the increased incidence of hypertension in black subjects compared with white subjects. Mechanisms for this finding warrant further investigation.

Acetylcholine↗
PubMed1999

Forearm bone density in users of Depo-Provera as a contraceptive method.

OBJECTIVE: To determine the influence of depot medroxyprogesterone acetate (MPA) on bone mineral density when used as a contraceptive method. DESIGN: Cross-sectional study. SETTING: Academic tertiary-care hospital. PATIENT(S): Fifty premenopausal women who had used depot MPA as a contraceptive method for > or =1 year and 50 women who had never used hormonal contraceptive methods. INTERVENTION(S): Bone mineral density was evaluated at the midshaft and at the distal radius of the nondominant forearm using single x-ray absorptiometry. MAIN OUTCOME MEASURE(S): Bone mineral density. RESULT(S): Bone mineral density at the midshaft of the forearm was lower in depot MPA users than in women who had never used hormonal contraceptive methods, but the difference was not statistically significant. At the distal portion, bone mineral density was significantly lower in the study group. The duration of depot MPA use was not related to bone mineral density. CONCLUSION(S): Women > or =35 years of age presented with a lower bone mineral density only at the distal portion of the forearm after the use of depot MPA for > or =1 year. However, this decrease was not related to the duration of depot MPA use. It is not possible to conclude that women who use depot MPA are at risk of osteoporosis.

Adult↗