Acute effects of periarterial sympathectomy on the cutaneous microcirculation.

The clinical effects of peripheral sympathectomy on patients with vaso-occlusive disease are often dramatic and include relief of pain, improved quality of life, and healing of ulcers. Peripheral periarterial sympathectomy is known to increase skin temperature and to maximize the nutritional component of peripheral blood flow, but the pathophysiology of vaso-occlusive disease and the physiologic mechanisms of this treatment are unknown. In this study, the acute effects of periarterial sympathectomy were directly observed in a rabbit ear model of digital microcirculation (arterioles, arteriovenous anastomoses, and venules). The effects of periarterial sympathectomy on cutaneous perfusion and total flow were also examined using laser Doppler perfusion imaging and digital temperature measurements. The central auricular artery became dilated (50-100%) immediately after sympathectomy; the arterioles, arteriovenous anastomoses, and venules dilated to 165, 156, and 223%, respectively, at 30 minutes and to 187, 174, and 204%, respectively, at 60 minutes, relative to their baseline diameters prior to sympathectomy. Laser Doppler perfusion imaging values and ear temperatures were noted to increase after sympathectomy (8.9%, 3 degrees C), although the core temperature of the rabbit did not change. Thus, acute periarterial sympathectomy can (a) effectively reduce the vascular tone of the distal microvasculature and (b) increase total microcirculatory perfusion-cutaneous and thermoregulatory-by both venular and arteriolar dilation. Periarterial sympathectomy has the clinical potential to increase nutritional blood flow, thereby ameliorating the signs and symptoms of ischemia associated with thermoregulatory abnormalities. Dilation of the arteriovenous anastomoses, with a subsequent reduction in vascular resistance, may contribute to the increased cutaneous temperature noted after sympathectomy.

Decreased microvascular perfusion in the rabbit ear after six hours of ischemia.

The cellular injury produced by reperfusion of ischemic tissue with oxygen-rich blood has been studied in numerous tissues but has not been investigated extensively in thermoregulatory tissue. This study was designed (a) to compare 4 and 6 hours of ischemia to document the evidence of impaired capillary perfusion after resumption of blood flow (reperfusion injury) in a thermoregulatory end organ (the rabbit ear), and (b) to examine, with use of vital capillaroscopy (VC) and laser Doppler flowmetry (LDF), the altered microvascular blood flow in the rabbit ear after ischemia and reperfusion. One ear from each of five rabbits underwent warm ischemia for 4 hours. VC showed no deficits of capillary perfusion in these ears after reperfusion; LDF measurements in both ears also demonstrated no significant difference between control and reperfusion blood flow. One ear from each of eight additional rabbits underwent 6 hours of warm ischemia. LDF values were significantly reduced in the ischemic ear after reperfusion as compared with baseline measurements for that ear and as compared with the control ear. VC showed arrested perfusion and static plasma gaps within three to five capillaries per high-power field (an area of 300 x 500 microns) in the ischemic ear and good perfusion of all vessels in the contralateral control ear. This evidence of reperfusion injury in a thermoregulatory end organ may help to explain the poor functional result that often occurs after replantation of an amputated digit.

Quantitative analysis of cold stress performance after digital replantation.

Isolated cold stress testing (ICST) has been used to assess cold stress performance or digital thermoregulation, but statistical analysis of the results has been limited to visual comparisons of data. In this prospective study, 11 patients who underwent complete digital replantation were followed serially with ICST at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively, and the results were analyzed quantitatively. For that analysis, we devised a mathematical method that provided a cooling and a warming coefficient to fit the data. Differences in these cooling and warming coefficients were then regressed against time after replantation, patient age, number of digits replanted, hand dominance, and clinical evidence of sensory recovery. There was a significant correlation between response to isolated cold stress testing (thermoregulation) and degree of sensory recovery (p less than or equal to 0.02). This method for quantitative analysis of isolated cold stress testing data allows objective evaluation of digital blood flow patterns based on temperature, thereby providing a reliable and objective assessment of the recovery of thermoregulation in the replanted human digit.

Role of alpha-1 adrenoceptor subtypes mediating constriction of the rabbit ear thermoregulatory microvasculature.

An acute in vivo preparation of the microvasculature of the rabbit ear was used to evaluate the functional role of alpha1 (alpha1)-adrenoceptor subtypes in thermoregulatory microcirculation. The effect of alpha1-adrenoceptor subtype blockade on phenylephrine-induced vasoconstriction was assessed with the alpha1A, alpha1B, and alpha1D-adrenoceptor-selective antagonists 5-methyl-urapidil (10(-8) M), chloroethylclonidine (10(-5) M), and 8-[2-[4(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspirol[4.5]deca ne-7,9-dione dihydrochloride (BMY7378) (10(-6) M), respectively. The results demonstrated that pretreatment of the ear microvasculature with 5-methyl-urapidil or BMY7378 shifted the phenylephrine concentration-response curve rightward and significantly changed the log of the phenylephrine concentration, causing half-maximum stimulation (EC50) in arterioles (p < 0.05). BMY7378 shifted the phenylephrine concentration-response curve of the arteriovenous anastomoses about 100-fold rightward (p < 0.05). All three alpha1-adrenoceptor antagonists eliminated the vasoconstrictive effects of phenylephrine on venules. The results indicate that the ear microvasculature has a heterogenous distribution of alpha1-adrenoceptor subtypes. The alpha1A and alpha1D-adrenoceptor subtypes appear to have a greater influence on constrictive function in arterioles, whereas the alpha1D-adrenoceptor is the dominant constrictor of arteriovenous anastomoses. In general, the alpha1-adrenoceptor does not play a major vasoconstrictor role in venules. Chloroethylclonidine, an irreversible alpha1B-adrenoceptor antagonist, induced contractile responses in the ear microvasculature, probably due to its alpha2-adrenoceptor agonist effects. This study extended our understanding of the adrenergic receptor control mechanisms of a cutaneous thermoregulatory end organ characterized by two parallel perfusion circuits providing nutritional and thermoregulatory functions.

Effect of cooling on cutaneous microvascular adrenoceptors in vivo in the rabbit ear.

Previous studies have suggested that moderate cooling increases the responsiveness of vascular alpha2-adrenoceptors. However, limited information is available documenting the influence of temperature changes on adrenoceptor responses in the microvasculature of thermoregulatory organs (e.g., the human digit and the rabbit ear) subjected to a wide range of temperatures. In the present study, the effect of local cooling (24 degrees C) on cutaneous microvascular adrenoceptors in the ear was observed in vivo in male New Zealand White rabbits (total: 66 ears). The rabbit ear was studied in a temperature-controlled tissue bath; the ear preparation was pretreated with terazosin (an alpha1-adrenoceptor antagonist) (10(-5) M) or a combination of terazosin (10(-5) M) and propranolol (a beta-adrenoceptor antagonist) (10(-6) M). The microvascular diameter responses of the ear to norepinephrine (10(-11)-10(-4) M) then were determined at 24 or 34 degrees C, respectively, to determine the influences of low temperature on adrenoceptor responses to norepinephrine stimulation. The results demonstrated that low concentrations of norepinephrine induced vasodilation in arterioles and arteriovenous anastomoses. This vasodilation was followed by vasoconstriction with an increased concentration of norepinephrine in animals with alpha1-adrenergic blockade at 34 degrees C. Moderate tissue cooling increased the microvascular maximal response of the rabbit ear to norepinephrine and abolished the vasodilatation induced by a low concentration of norepinephrine. There was no significant difference in the microvascular response to norepinephrine between the two temperature conditions after simultaneous blockade of alpha1-adrenoceptors and beta-adrenoceptors. Data from the present study indicate that moderate cooling does not enhance the responsiveness of alpha2-adrenoceptors to norepinephrine. In contrast, cooling reduced the beta-adrenergic activity of arterioles and arteriovenous anastomoses after norepinephrine stimulation.

The results of replantation after amputation of a single finger.

We reviewed fifty-nine consecutive cases of patients who had replantation of a single finger (excluding the thumb) after traumatic amputation, with an average follow-up of fifty-three months. Fifty-one (86 per cent) of the replanted fingers survived. Survival was found to be affected by the age of the patient, the number of vessels that were anastomosed, and the replantation experience of the surgeons. The survival rate was not affected by the gender of the patient, the mechanism of injury, or which finger was amputated. As compared with survival only, the functional results were most dependent on the level of amputation. The proximal interphalangeal joint in amputated fingers that were replanted distal to the insertion of the flexor superficialis tendon had an average range of motion of 82 degrees after replantation, while those amputated proximal to the insertion had an average range of motion of only 35 degrees after replantation. The average operating time was six hours and ten minutes, and the average time until the patient returned to work was 2.3 months. Based on this experience, it is our opinion that replantation of a single finger that was amputated distal to the insertion of the flexor superficialis tendon is justified, but that replantation of a single finger that was amputated proximal to this insertion is seldom indicated.

The results of radial and ulnar arterial repair in the forearm. Experience in three medical centers.

Sixty-two patients with ninety injuries to the radial or the ulnar artery, or to both of these arteries, had arterial repairs using microvascular techniques in three medical centers. Twenty-six of the twenty-eight patients who had an ischemic hand secondary to injuries to both arteries and a successful operative repair had at least on patent vessel at follow-up. Of the other two patients, one had an amputation through the forearm for ischemia of the hand and the other had a viable hand supplied by collateral vessels, although both the radial and the ulnar arteries were thrombosed. The over-all success rate for all repairs was 54 per cent. After 47 per cent of the one-artery and 57 per cent of the two-artery lacerations, the vessels were patent at follow-up. Repairs of acute sharp transections of the radial artery within thirty-six hours of injury were most successful. Of the factors other than operative technique that strongly influence vessel patency after repair, back pressure in the distal arterial stump and the extent of the ischemia of the hand relative to its normal blood supply (a function of the completeness of the palmar arch) appear to be the most important.

Neuromuscular blockade in the management of cerebral palsy.

Neuromuscular blocking agents-45% alcohol, 4% to 6% aqueous phenol, local anesthetics, and botulinum A toxin-have been used for many years in the evaluation and management of spasticity and movement disorders in children with cerebral palsy. Recent reports suggest that longer-acting neuromuscular blocking agents may impact positively on the natural history of dynamic deformity and improve health-related quality of life. This review includes the mechanism of action, techniques, indications, complications, and clinical outcomes associated with these agents.

Salvage of lower extremities following combined orthopedic and vascular trauma. A predictive salvage index.

A retrospective review of 676 tibial-fibular fractures and 985 femoral fractures treated over a 71-month period yielded associated major vascular trauma in 12 (1.7%) tibial-fibular fractures and in five (0.5%) femoral fractures. Vascular trauma combined with orthopedic trauma was also identified in four other cases--two disruptions of the pubic symphysis and two dislocations of the knee without fracture. Nine (43%) of the 21 involved limbs were eventually amputated. Limb survival was not related to the temporal relationship of vessel repair to skeletal stabilization; the presence or absence of shock on admission; the presence of associated but repaired venous injury; or the presence of unrelated injuries. Limb survival was related to the interval from injury to arrival in the operating room; the level of arterial injury; and the quantitative degree of muscle, bone, and skin injury. By combining these variables a limb salvage index was established that identified lower extremities likely to require amputation after combined orthopedic and vascular trauma (sensitivity 78%, specificity 100%). Use of this predictive salvage index may prevent the trauma surgeon from attempting to salvage a doomed or useless lower extremity and may thus permit early prosthetic rehabilitation to follow definitive primary amputation.

The fibula-flexor hallucis longus osteomuscular flap.

Limb salvage after loss of bone and soft tissue may require many operations to obtain soft-tissue cover and bony continuity. We describe a fibula-flexor hallucis longus osteomuscular flap which can provide both soft tissue and bone in a single stage. The flap is based on the peroneal vessels and is covered by a split-thickness skin graft. We report the results in five patients with an average bone defect of 8.3 cm and soft-tissue and skin loss. All regained a normal gait on the donor side; four had clinical and radiological union with excellent soft-tissue cover, but one required later amputation due to diffuse coagulopathy. The flap provides free vascularised bone with muscle cover. It has a dependable, long pedicle with minimal morbidity at the donor site, and allows monitoring of the vascularity of the fibular graft.

Management of vasospastic disorders of the hand.

Vasospastic disorders of the upper extremity are common and often difficult to treat. Using the proposed classification system (Table 2) allows management based upon pathologic condition, physiologic staging, and response to treatment. Identifying patients in this way also helps in determining which treatments are most appropriate. The basic approach to management includes environmental and behavioral modifications including cessation of tobacco use, protection of hands, and avoidance of situations that trigger the vasospastic response. Pharmacologic therapy may provide good results in a majority of patients. Surgical intervention is reserved for patients with vaso-occlusion, ischemia, and refractory symptoms in spite of attempts at medical management. Surgical options include vascular reconstruction, peripheral sympathectomy, or a combination of techniques. The goal of medical and surgical management is to increase total or nutritional blood flow in the digits.

Thermoregulatory abnormalities of the foot.

Thermoregulatory abnormalities are well known but poorly understood phenomena. Pathologic alterations of microvascular blood flow occur in a variety of diseases of the foot, and often cause severe functional impairment. The structure, function, and methods for testing thermoregulatory abnormalities are reviewed. Pathologic manifestations of abnormal thermoregulation are also discussed.

The vascularized cutaneous scapular flap.

Five cases of cutaneous free tissue transfer using the cutaneous and circumflex scapular vessels are presented. The free scapular flap is an excellent choice when intermediate-sized (6 to 10 by 10 to 16 cm) uninnervated flap coverage is necessary and cannot be achieved by conventional methods. The flap is exposed easily and has a constant artery and venous system, 2- to 3-mm-diameter vessels, and a 4- to 6-cm vascular pedicle. The shoulder donor site can be closed primarily. Like all shoulder wounds, it has a tendency to spread, but not functional deficit exists at the shoulder or on the posterior chest wall.

Current status of noninvasive techniques in the diagnosis of upper extremity disorders. Part I. Evaluation of vascular competency.

To determine vascular competency in the upper extremity, one must completely evaluate both structural anatomy and the functional performance capabilities of the vascular system. Unfortunately, no single noninvasive test currently available is capable of providing all that information (Table 4-1). Definitive structural anatomy can only be ascertained by surgery or arteriography, although gross anatomic detail can be provided by Doppler techniques and radionuclide scans. Radionuclide scans give good dynamic and static perfusion data and can be coupled with stress testing, but their repeatability is limited by radiation. Isotope clearance techniques are difficult to combine with stress testing, but they do provide excellent information on vascular perfusion. Measurement of segmental arterial pressures, plethysmography, thermography, thermometry, and Allen testing all provide excellent perfusion data and can all be combined with stress testing. The future is bright. Current advances in high-resolution ultrasound real-time imaging combined with quantitative flow by Doppler assessment will provide noninvasive information about structural anatomy and blood-flow characteristics.

Ligamentous injuries of the wrist in athletes.

The athlete's wrist is particularly prone to injury. Although many wrist injuries are dismissed as sprains or strains, a number of these injuries involve significant ligamentous damage that can lead to chronic carpal instability. A complete knowledge of the carpal ligamentous anatomy and classification of wrist instability patterns is necessary for the adequate diagnosis and treatment of these injuries.

Diagnostic study of vascular lesions.

Detailed diagnostic evaluation of upper extremity vascular lesions is not possible with any single existing test or study. Arteriography and improved arteriographic techniques, including digital subtraction imaging, have increased dramatically the resolution of this procedure. Unfortunately, reactive vasospasm and limited run-off still preclude the provision of complete information about vascular anatomy. Surgical exploration, of course, provides direct access to arterial and venous structures in a limited area, but it has obvious limitations. Indirect information about the structural anatomy can be obtained by Doppler techniques, ultrasound scans, and radionuclide imaging. These techniques also provide limited information about changes in perfusion during stress. Plethysmography, thermography, thermometry, and measurements of segmental arterial pressure, when combined with stress testing, provide excellent indirect evidence of both static and dynamic states. A combination of pressure measurements and intraoperative ultrasound associated with direct surgical measurement will provide quantitative and qualitative analysis of antegrade and retrograde flow and allow the surgeon to look at the intima of vessels without surgically traumatizing the vessel wall. Within the next decade, real-time information with three-dimensional reconstruction of arterial and venous structures as well as quantitative analysis of segmental areas of blood flow will be provided by the use of combinations of these techniques or techniques that have not yet been reported.

Ulnar artery thrombosis.

Management of ulnar artery thrombosis is a complex problem. Diagnosis is confirmed by Allen testing; other special studies are needed for adequate evaluation of circulation, and arteriography is necessary before definitive therapy can be planned. Treatment must be patient oriented and directed at the underlying abnormality. Options for treatment include arterial reconstruction using reversed interposition vein grafting, mechanical sympathectomy performed by surgical resection of the thrombosed segment and ligation of the artery, and nonsurgical treatment.

Stress testing in the evaluation of upper-extremity perfusion.

Stress testing is an important element in the evaluation of upper extremity vascular perfusion. Advances in noninvasive testing provide mechanisms to evaluate the static structural characteristics of the arterial system, to define patient and nonpatient vessels to identify areas of thrombosis or occlusion, to evaluate arterial wall motility and elasticity, and to observe the nutritional capillary bed. To understand upper-extremity vascular function, however, some form of stress testing is crucial. The techniques discussed previously continue to evolve and serve only as examples of the potential of noninvasive tests evaluated before, during, and after stress. Stress testing provides techniques that allow us to understand the functional components of vascular perfusion and to monitor our attempts at interventions.

Fractures and ligamentous injuries of the wrist.

Rapid diagnosis, appropriate management, and sport-specific rehabilitation are important in the management of any wrist injury in the athlete. The addition of technetium scans, CT, arthroscopy, and MRI in the evaluation of the athlete's wrist has provided valuable and powerful diagnostic tools. The versatility and relatively low invasiveness of arthroscopic intervention and the subsequent early return to activity make this technique especially attractive in the high-performance athlete. Suspicion of potential injuries, complete knowledge of wrist mechanics and anatomy, and a careful physical examination are still the most important tools in the evaluation of wrist injury. It is important to approach each athlete in a patient-oriented manner, taking into account the fact that many of these injuries have the potential to be career ending. Treatment that will provide the best possible long-term wrist function must be the physician's ultimate goal. In addition, the importance of appropriate and activity-specific rehabilitation cannot be overemphasized.

The pharmacologic approach to the painful hand.

The management of reflex sympathetic dystrophy with oral, topical, and parenteral medications is complex. This article outlines the pharmacologic options available to treat dystrophic pain, provides an overview of mechanisms-of-action, and defines relative indications for administration.