The effects of limb elevation and increased intramuscular pressure on nerve and muscle function in the human leg.

In this study we investigated the effects of increased intramuscular pressure (IMP) on nerve and muscle function in the leg and foot. In study A, muscle pressure was increased by inducing venous stasis in both legs, placed in plaster casts, of eight healthy subjects having a mean age of 29 years. The results from elevated and non-elevated limbs were compared. In study B, two different models for increasing IMP were studied in nine healthy subjects having a mean age of 32 years. The results of increased IMP and decreased blood perfusion pressure on local (= leg) and distal (= foot) function of muscle and nerve induced by venous stasis of a leg in a plaster cast and by external compression of the contralateral leg were compared. Contraction pressure of the tibialis anterior muscle in the leg was recorded. A biphasic compound muscle action potential was measured from the extensor hallucis brevis and the extensor digitorum muscles as an indication of foot muscle function. Muscle contraction pressure was 87 (SD 38) mm Hg in the vein-obstructed leg and 133 (SD 42) mm Hg in the externally compressed leg (P<0.05). In both studies the skin sensibility of the feet was significantly lower in the vein-obstructed elevated leg after 30 min (P<0.05). Vein stasis in an elevated human leg in a plaster cast defines a model for simulating imminent acute compartment syndrome with reversible neuromuscular dysfunction.

Wound closure by dermatotraction after fasciotomy for acute compartment syndrome.

Intramuscular pressure (IMP) was measured in 16 patients during secondary wound closure by dermatotraction with external tissue extension (ETE). Secondary wound closure was done 4-16 days after fasciotomy for acute compartment syndrome. The traction between wound edges was 2.5 N in the first six patients and 3.5 N in the following 10 patients. Mean (SD) IMP was 6.9 (3.5) mmHg before wound closure. It increased to 12.3 (1.4) mmHg in the 2.5 N group and to 24.7 (7.0) mmHg in the 3.5 N group when dermatotraction was applied. Mean (SD) leg perfusion pressure in the 2.5 N group decreased by 7% to 69.3 (10.9) mmHg and in the 3.5 N group by 23% to 62.2 (7.4) mmHg. None of the patients needed a skin graft. We conclude that dermatotraction by ETE raises IMP intraoperatively sufficiently to preserve adequate limb perfusion pressures.

A comparison of results after arthroscopic anterior cruciate ligament reconstruction in female and male competitive athletes. A two- to five-year follow-up of 429 patients.

The aim of this study was to compare the results after arthroscopic anterior cruciate ligament reconstruction in female and male competitive athletes who had a pre-injury Tegner activity level of > or =7 and a non-injured contralateral anterior cruciate ligament. One hundred and thirty-three female and 296 male patients were followed at 38 (21-68) months after the index operation. All the patients were operated on by experienced knee surgeons using patellar tendon autografts and interference screw fixation. At the index operation the median age of the female patients was 23 (1645) years and the median age of the male patients was 26 (16-47) years. The reconstruction was performed a median of 10 (0-141) and 10 (0-203) months after the injury in women and men respectively. The patients were re-examined by independent observers. At the follow-up, the median Lysholm score was 89 (38-100) points in the female group and 90 (22-100) points in the male group (P=0.015). The IKDC evaluation system, subjective anterior knee pain, subjective evaluation of the results, the knee-walking test and the KT-1000 tests revealed no differences between the groups. The mean (+/-2 SD) pre-injury Tegner activity level was 8.1 (+/-1.9) (median 8 (7-10)) in the female group and 8.4 (+/-1.8) (median 9 (7-10)) in the male group (P=0.003). At the follow-up, the Tegner activity level was 6.2 (+/-3.8) in the female group and 6.8 (+/-3.6) in the male group (P=0.012). At the follow-up, the Tegner activity level had decreased by 1.9 (+/-3.8) for the women and 1.6 (+/-3.3) for the men, as compared with the pre-injury level (n.s.). The difference between the performed and the desired activity level at the follow-up was 1.1 (+/-3.2) in the female group and 0.9 (+/-3.0) in the male group (n.s.). In the female group 53/133 (40%) and in the male group 115/296 (39%) returned to the pre-injury activity level (n.s.). The median one-leg-hop quotient was 93 (0-116)% in the female group and 96 (0-130)% in the male group (P=0.006). Concomitant meniscal injuries prior to the index operation, at the index operation or during the follow-up period were found in 64/133 (48%) women and in 185/ 296 (62%) men (P<0.01). The main conclusion was that the overall results in female and male athletes were comparable two to five years after the anterior cruciate ligament reconstruction. However, concomitant meniscal injuries were more common in male than females athletes after anterior cruciate ligament injuries.

Abnormally increased intramuscular pressure in human legs: comparison of two experimental models.

BACKGROUND: Abnormally increased pressure in the anterior compartment of 20 legs in 10 subjects was induced by applying venous stasis of a casted leg and external compression by a cylindrical air splint of the contralateral leg. The effects of increased intramuscular pressure (IMP) on blood perfusion pressure and clinical symptoms in the foot were compared during 30 minutes by the two methods. RESULTS: Intramuscular pressure increased to 38.9 (SD = 2.9) mm Hg when venous stasis was applied and to 39.8 (SD = 1.6) by external compression (not significant). Blood perfusion pressure in the anterior compartment decreased significantly to 25 mm Hg in both legs when they were elevated. Subjects experienced loss of sensation and muscular weakness only in the foot of the casted obstructed leg. CONCLUSIONS: Venous stasis of a casted elevated leg is an alternative experimental model to induce abnormally increased intramuscular pressure and neuromuscular dysfunction in the human leg. The venous stasis model may be better than external compression in the study of pathogenesis and pathophysiology of simulated imminent acute compartment syndrome in man.

Effects of limb elevation on abnormally increased intramuscular pressure, blood perfusion pressure, and foot sensation: an experimental study in humans.

OBJECTIVES: To study the effects of limb elevation on abnormally increased intramuscular pressure (IMP) and blood perfusion pressure in the anterior compartment of the leg. DESIGN: An experimental cross-over design. The test leg was elevated and the control leg was kept at heart level. PARTICIPANTS: Eight healthy subjects with a mean age of twenty-nine years. INTERVENTION: IMP was measured in the anterior compartment of the leg, and blood pressures were taken in the left arm and both legs. Four variables were recorded (with or without venous stasis, with or without plaster cast). All measurements were made simultaneously in both legs. RESULTS: When the leg was obstructed by venous stasis and elevated to between thirty-three and thirty-five centimeters, IMP decreased from 16.5 to 9.8 millimeters of mercury. When venous stasis was simulated in a level casted leg, the IMP was thirty-eight (SD = 6.4) millimeters of mercury but showed only a slight decline to thirty-five (SD = 7.8) millimeters of mercury after the leg was elevated. Blood perfusion pressure fell significantly once the leg was elevated, decreasing 53 percent from forty-seven (SD = 7.8) to twenty-five (SD = 8.0) millimeters of mercury (p < 0.001). All subjects experienced loss of foot sensation in the elevated limb. CONCLUSION: In those cases in which venous stasis increased IMP levels in the anterior compartment of the leg, elevating the limb produced a 40 percent reduction in IMP. However, limb elevation did not significantly reduce increased IMP levels when the venous stasis occurred in a casted leg. Therefore, we believe casted legs in which abnormally increased IMP is attributable to venous stasis should not be elevated above heart level because elevation induces low perfusion pressure and sensory dysfunction.

Secondary wound closure following fasciotomy for acute compartment syndrome increases intramuscular pressure.

OBJECTIVES: To study the effects of secondary wound closure on intramuscular pressure (IMP) in patients treated by fasciotomy for acute compartment syndrome. STUDY DESIGN: Prospective experimental study with an unbiased observer. METHODS: Twelve patients (mean age, thirty years) were treated for acute compartment syndrome by fasciotomy, early postoperative edema reduction, and secondary wound closure on the third or fourth day. The syndrome was confirmed by measurements of IMP in seven legs, three thighs, and two arms. The IMP was recorded in appropriate compartments with a noninfusion technique before, during, and after secondary wound closure by wire sutures. The IMP was not allowed to exceed thirty millimeters of mercury (four kilopascals) in the underlying compartment during wound closure. Patients were followed up at thirty-six months after surgery. RESULTS: By using an IMP limit of thirty millimeters of mercury, local perfusion pressure remained above fifty millimeters of mercury in all patients. With this protocol, the wound was closed on the third or fourth day in five patients. Seven patients needed repeated secondary wound closure. The distance between skin edges did not exceed 0.5 centimeter in any of the patients by the eleventh day. No patient needed skin transplantation. None had signs of ischemic contracture at follow-up. CONCLUSION: Secondary wound closure or wound adaptation starting on the third day after fasciotomy seems to be a safe method of treatment in normotensive patients if IMP during wound closure is not allowed to exceed thirty millimeters of mercury.

Evaluation of techniques for measuring negative intramuscular pressures in humans.

Negative external pressure has been used previously in experiments on the blood circulation in humans and is currently being considered as a counter-measure to the musculoskeletal deconditioning which occurs during the exposure to microgravity. Intramuscular pressure (IMP) measurement is an important tool for determining the effectiveness of the transmission of negative pressure. Therefore two IMP techniques, a fibre optic transducer-tipped catheter and a fluid-filled teflon catheter with side holes, were evaluated using laboratory and human tests for measuring negative pressures. For the laboratory tests, both catheters were placed inside a lower leg negative pressure (LLNP) chamber and pressures of 0, -20, -50, -80, -100 and back to 0 mmHg were applied. Both catheters measured pressures equally and remained stable over 1 min at all pressure levels. When the teflon catheter was infused at rates commonly used for IMP recordings at normal atmospheric pressures, the drip rate at the catheter tip increased inversely with the magnitude of negative pressure. The cables and pressure tubings of the catheters within the LLNP chamber were not affected by the negative pressures. For tests in humans, the catheters were inserted side by side in the tibialis anterior muscle in eight legs of four human volunteers. The leg was placed in the LLNP chamber and pressures of 0, -20, -50, -80 and back to 0 mmHg were applied. The teflon catheter was used without infusion. Both catheters measured IMP similarly at rest and both remained stable over 1 min at all pressure levels; also the IMP during muscle contractions and immediately following contractions was similarly recorded by both catheters. We concluded that both catheter systems are suitable for recording negative pressures over a wide range. As is the case with recordings at normal atmospheric pressures, the fibre optic transducer-tipped catheter system may be preferred when recording IMP in a negative pressure environment when complex limb movements are involved.

Complex health problems. Clinically assessing self-management abilities.

Assessment of self-care abilities by staff nurses is critical to planning post-hospitalization care. Assessment instruments must be comprehensive and yet usable by busy nurses. Orem's three categories of self-care deficits (universal, developmental, and therapeutic) provided a basis for the development of a Self-Management Inventory.

A plan for staff development in gerontologic nursing.

Although aging of the population is evident and increased use of health services by the elderly is well-documented, the knowledge base of acute-care nurses in gerontologic nursing may be insufficient. Nursing staff development educators are in a strategic position to respond to this deficit. The approach used by an 800-bed Veterans Administration Hospital to determine the gerontologic learning needs of its nursing staff and a plan to meet these needs is reported. Recommendations for other organizations that plan to provide staff development in gerontologic nursing are offered.

Promotion of interdisciplinary practice through an automated information system.

Communication among and between health team members is in a state of confusion. This confusion could be eliminated by an interdisciplinary approach to care that includes communication via an automated nursing information system. The nursing data base model of Romano et al was analyzed to determine if it could serve as the basis for an effective information system for interdisciplinary practice/communication. This data base model has some empirical support, but it reflects a multidisciplinary approach to care, rather than the preferred interdisciplinary approach.