Abstract
Objective
To compare the effects of active and passive calf muscle contraction on the hemodynamics of the lower extremity vein.
Methods
30 females were selected by convenient sampling. The hemodynamic indexes of the common femoral vein were measured by Duplex ultrasound during the active ankle pump exercise, active circular exercise, passive ankle pump exercise, passive circular exercise, and massage the calf muscles.
Results
There was no significant difference in the velocity of common femoral vein when the subjects do active ankle pump exercise, active circular exercise, and massage the calf muscles (p > .05), but the velocity of common femoral vein was faster than that of passive ankle pump exercise and passive circular exercise (p < .01).
Conclusion
The effects of active ankle exercise and massage on promoting venous blood return of lower extremity are better than that of passive ankle exercise.
Introduction
Deep Vein Thrombosis (DVT) is a common complication of hospitalized patients. Because of its high mortality and morbidity, the prevention and treatment of DVT are gradually attracting the attention of all subjects. 1 The bedridden patients have a high incidence of DVT due to restricted mobility capability and slow venous blood velocity. 2 It has been reported that the incidence of DVT is 6.4% in Asian elderly patients with hip fracture without drug prevention. The incidence of DVT after drug prevention is still as high as 3.6%. 3 For the risk factor of “slow blood flow,” 4 the main preventive measure for bedridden patients is to promote the blood flow return of the lower extremity veins through the contraction of the calf muscles and the compression of the intermuscular and intramuscular veins. The main methods of calf muscle exercise are active and passive ankle exercise (including ankle pump exercise and circular exercise) and massage the muscles behind the calf. It has been proved that5–7 active ankle exercise can improve the hemodynamics of lower extremity vein. However, there are few related studies on which active ankle exercise mode is more effective and easier to be accepted by patients. In addition, there was no relevant study to analyze the effect of passive exercise and massage on the improvement of lower extremity venous hemodynamics. The purpose of this study is to further compare which active exercise mode can more effectively promote the venous blood return of the lower extremity on the basis of the existing research. The effect of passive exercise and massage on the improvement of venous hemodynamics of lower extremity was also analyzed. So as to clarify the effect of different exercise methods on improving the hemodynamics of the lower extremity vein, and optimize the clinical measures to prevent DVT.
Materials and methods
Subjects
This study was approved by the ethics committee of our hospital and acquired the informed consent of the subjects. 30 females were selected by convenient sampling. The age of the subjects was 21.5 ± 1.0 years (mean±SD) (range 20–24 years). The body mass index was 20.3 ± 3.9 kg/m2 (mean ± SD) (range 17.3–32.2 kg/m2). Exclusion criteria are as follows: (ⅰ) subjects with cardiopulmonary disease; (ⅱ) subjects with lower extremity venous disease; (ⅲ) subjects with blood system disease; and (ⅳ) subjects with lower extremity disability.
Experimental design
30 subjects were assigned to perform active ankle pump exercise, active circular exercise, passive ankle pump exercise, passive circular exercise, and massage the muscles behind the calves separately. Duplex ultrasound was used to detect the hemodynamic indexes (PSV Peak systolic velocity; TAMV Time-averaged mean velocity; TRTB Time from the end of the ankle pump exercise to the time-averaged mean velocity of common femoral venous blood flow returns to the baseline) of the common femoral vein in the above five exercise modes. Ratings of perceived exertion (REP) were used to evaluate the fatigue degree of the subjects at the end of the active ankle exercise (active ankle pump exercise and active circular exercise) and the fatigue degree of the helpers at the end of the passive ankle exercise (passive ankle pump exercise and passive circular exercise) and the massage. The comfort scale was used to evaluate the comfort of the subjects at the end of exercise.
In order to ensure the independence of the test results and eliminate the interference of previous interventions on the test results, this study stipulates that the subjects should rest in bed for 30 min before each round of test. When carrying out ankle exercise, it is stipulated that activities are prohibited in other parts except the ankle. In order to eliminate the interference of the changes of the pressure in the chest and abdominal cavity on the test results, it is required to empty the bladder before the measurement and keep breathing at a constant speed during the measurement. The same helper assisted the subjects in passive ankle exercise and massage to reduce the heterogeneity of test results.
Exercise method of ankle
Ankle exercise includes ankle pump exercise and ankle circular exercise(Figure 1). Exercise method of ankle.
Ankle pump exercise: The subjects were lying on the bed, with their legs slightly outstretched, thighs relaxed, ankles padded with cotton pads, feet back extended (toes toward themselves), and plantar flexed (toes away from themselves) for one time. The frequency of ankle pump exercise is 30 times/min, exercise for 3 min. The angle of plantar flexion and back extension is the maximum angle that can be achieved at the specified frequency. The active ankle pump exercise was completed by the subjects themselves, while the passive ankle pump exercise was performed by the helper to assist the subjects to complete the above actions. The exercise frequency is controlled by a timer.
Circular exercise: The subjects were lying on the bed with their legs slightly outstretched, their thighs relaxed, and their ankles padded with cotton pads. With the ankle joint as the center, make 360 degrees of pronation, dorsiflexion, valgus, and plantar flexion around the foot, try to maintain the maximum range of action. The frequency is 30 times/min, exercise for 3 min. The active circular exercise was completed by the subjects themselves, while the passive circular exercise was performed by the helper to assist the subjects to complete the above actions. The exercise frequency is controlled by a timer.
Massage
The subjects were lying on the bed with their legs slightly outstretched, their thighs relaxed, and their ankles padded with cotton pads. The helper separated the thumb from the other four and placed the palm behind the calves in an encircling manner, from ankle to popliteal squeeze the muscle behind the calf intermittently for 3 min.
Self-evaluation method of RPE scale
The RPE scale includes 15 values ranging from 6 to 20, each of which corresponds to a different fatigue sensation characteristic. After the exercise, the subjects and helper give the corresponding value based on the subjective fatigue sensation, that is, the RPE score. 8
Comfort evaluation scale
A comfort scale was used to evaluate the subjects' comfort, with a scale of 0–10. At the end of exercise, the subjects chose the corresponding score according to their subjective feelings. 0–4 points represent that the feeling is uncomfortable; 5–7 points represent that the feeling is good; and 8–10 point represents that the feeling is comfortable. The higher the score is, the higher the comfort.
Measuring methods
Bilateral common femoral venous hemodynamics were measured using the Duplex ultrasound (Philips portable color Duplex ultrasound CX50). The detection was completed by one operator who has been trained for the use of ultrasound before.
Body position: During the detection, the subjects took supine position, the leg being examined relaxed.
Parameter setting: The probe frequency is 3.5 MHz; the sampling volume was set to 1/2–2/3 of the diameter of the venous lumen, Placed in the center of the blood vessel; and angle between sound beam and blood vessel <60°.
Examination step: During the examination, the subject breathed calmly and relaxed his limbs. First, place the probe transversely in the groin, and use two-dimensional ultrasound to clearly show the cross-sectional view of the blood vessel. Then, follow the blood vessel down to determine the position of the deep femoral vein and the superficial femoral vein. 1 cm above the upper intersection is the position to be measured for this study. Then, fix the probe, instruct the patient to perform ankle movement as required, and at the same time start to detect changes in blood flow velocity. The values were automatically calculated by the computer of the Doppler system and displayed on the screen.
Statistical methods
Data was inserted into an SPSS database and analyzed using SPSS 21.0. The data presented were regarded as being normal in distribution and the results were presented as mean ± standard deviation (x ± s). T-test was used for comparison between two independent samples. For comparison between multiple independent samples, LSD analysis of variance was used for comparison if the homogeneity test of variance was satisfied, and Tanhane analysis of variance was used for comparison if the homogeneity test of variance was not satisfied. p-value was 0.05, values smaller than this were regarded as significant and values larger than this as nonsignificant.
The measurement data can be directly displayed on the ultrasonic display screen. To ensure the accuracy of the data, a special person is responsible for reading and recording the data during the measurement process, and two persons will enter the data into the Excel table later.
Results
Changes of hemodynamics of the common femoral vein when the calf muscles are moved in different ways
Changes of hemodynamics of the common femoral vein when the calf muscles are moved in different ways (n = 60).
PSV Peak systolic velocity; TAMV Time-averaged mean velocity; TRTB Time from the end of the ankle pump exercise to the time-averaged mean velocity of common femoral venous blood flow returns to the baseline; PSV and TAMV:Active ankle pump exercise VS Active circular motion VS Massage p > .05; Passive ankle pump exercise VS Passive circular motion p > .05; Comparison between other groups p < .01. TRTB:Passive ankle pump exercise VS Passive circular motion VS Massage p > .05; Passive ankle pump exercise VS Passive circular motion p > .05; Comparison between other groups p < .01.
There was no significant difference between the groups in the TRTB during the active ankle pump exercise, active circular exercise, and massage (p > .05). The TRTB of the above three exercise modes was longer than that of passive ankle pump exercise and passive circular exercise, and the difference between the groups was statistically significant (p < .01). There was no statistically significant difference in TRTB between the passive ankle pump exercise and passive circular exercise, (p > .05)(Table 1).
Changes in fatigue degree and comfort of subjects when calf muscles are moved in different ways
Changes in fatigue degree and comfort of subjects when calf muscles are moved in different ways (n = 60).
RPE score of subjects :Active ankle pump exercise VS Resting state、 Passive ankle pump exercise、 Passive circular motion p < .01; Active circular motion VS Resting state、 Passive ankle pump exercise、 Passive circular motion p < .01; Active ankle pump exercise VS Active circular motion p < .01; Resting state VS Passive ankle pump exercise VS Passive circular motion p>0.05. Comfortable score of subjects: Passive ankle pump exercise VS Passive circular motion p > .05; Comparison between other groups p < .01.
When massaging, the comfort of the subjects was better than that of passive ankle pump exercise and passive circular exercise, better than that of active circular exercise and better than that of active ankle pump exercise, and the difference between the groups was statistically significant (p < .01). There was no significant difference in comfort between passive ankle pump exercise and passive circular exercise (p > .05)(Table 2).
Changes of fatigue degree of helpers when assisting the subjects to exercise in different ways
Changes of fatigue degree of helpers when assisting the subjects to exercise in different ways (n = 60).
RPE score of auxiliary athletes: Passive ankle pump exercise VS Passive circular motion P > .05; Comparison between other groups p < .01.
Discussion
At rest, the main power of venous blood return of the lower extremities comes from the negative pressure produced by the chest during inhalation and the siphon negative pressure produced by the heart during diastole. In addition, the muscle pump is also an important motive force to promote the return of venous blood in the lower extremities,9–10 single contraction of calf muscle can discharge 60–90 ml of venous blood. When the calf muscles contract, they can effectively promote the venous blood return by squeezing the intramuscular and intermuscular veins. The ankle exercise and the massage of the calf muscles are to use this mechanism to achieve the purpose of DVT prevention.
Analysis of the effect of different activities of calf muscles on promoting venous blood return of lower extremity.
In this study, we analyzed and predicted the effect of various exercise modes on DVT prevention by comparing the blood flow velocity of the common femoral vein. The results showed that the velocity of venous blood flow was the fastest when the muscles contract actively, that is to say, when the subjects do the active ankle pump exercise and the active circular exercise. At the academic exchange forum in China, some scholars pointed out that the effect of active circular exercise on promoting venous blood return of lower limbs is better than that of active ankle pump exercise. In clinical practice, the author also realized that the effect of circular exercise is better than that of ankle pump exercise. Theoretically, ankle pump exercise only involves the contraction and relaxation of triceps and anterior tibialis muscles to drive the plantar flexion and dorsiflexion of ankle joint. While, the circular exercise includes four exercise modes of the ankle joint: varus, dorsiflexion, valgus, and plantar flexion, which will involve more muscle contraction and relaxation. Under the same intensity of contraction, circular exercise can squeeze more lower extremity veins, accelerate the blood return of lower extremity veins, and reduce the probability of blood sediment deposition. However, the results of this study showed that although the blood flow velocity of the common femoral vein during the active circular exercise was numerically higher than that of the ankle pump exercise, there was no statistical difference between the two groups, it may be related to the small sample size of this study. It remains to be further verified whether the effect of circular exercise on preventing DVT is better than ankle pump exercise.
The effect of massaging the calf muscles to promote the venous blood flow return of the lower extremity was similar to that of active ankle exercise. Partsch H, et al. 11 once pointed out that the compression of calf muscles can also release anti-inflammatory and anticoagulant mediators by increasing the shear stress in the microcirculation of vein wall. However, the effect of passive ankle exercise on promoting venous blood return of lower limbs was relatively poor, but compared with the resting state, the effect was still obvious. The reason may be that it is difficult for the helpers to grasp the pull strength of all angles and pull the calf muscles of each part effectively when they are doing passive ankle pump exercise and passive circular exercise. The contractility of the calf muscles is not as strong as that of the active exercise, so compared with the active ankle exercise, the compression strength of the calf muscles to the intermuscular and intramuscular veins will be weaker. However, many patients, especially the elderly, with lower limb fractures or limited mobility of the lower limb, in most cases, cannot carry out effective activities. Therefore, passive exercise assisted by others would be a good way to improve venous hemodynamics and prevent DVT.
In addition, it can be seen from the results of this study that the TRTB is longest when the subjects perform active circular exercise, but it was only 52 s at this time. It can be concluded that the effect of this kind of exercise to improve hemodynamics is relatively short-lived. Increasing the number of exercises per unit time is the guarantee to prevent DVT effectively. However, how many times an hour or at least a day of such exercise can play a role in preventing DVT remains to be further studied.
The analysis of fatigue degree and comfort when the calf muscles are moved in different ways
From the perspective of fatigue, although the fatigue degree of the lower limb is acceptable to the subjects during the active ankle pump exercise and active circular exercise, as shown in this study, the fatigue degree of the subjects will be lower when the circular exercise is performed in the same time, and the implementation of the patients may be better in clinical. Among the three ways to assist the passive exercises of calf muscles, the fatigue degree of the helpers is the most obvious when massaging the calf muscles. At this time, the RPE score was 14.1 and the corresponding fatigue degree was “slightly tired,” showing that the above three kinds of passive exercises will not cause the obvious fatigue of the helpers, which has a high clinical feasibility.
From the perspective of the subject’s comfort, active contraction of the calf muscles for a long time will produce a significant sense of fatigue. 12 In addition, the patients are affected by disease and the fatigue threshold will decrease. 13 Therefore, patients' compliance is poor, which often needs the supervision of nurses. Relatively speaking, the comfort of passive exercise will be higher, besides massage not only can promote the venous blood return of lower limbs but also can massage muscle tissue and relieve muscle tension, so compared with active and passive ankle exercise, its comfort will be higher.
Conclusion
No matter how the calf muscles move, they can promote the venous blood return of lower extremity. In all forms of exercise, active ankle exercise is the most effective way to improve the venous hemodynamics of the lower extremity, without the assistance of others, and it can also increase the calf muscle strength. So patients who can actively exercise should encourage active ankle exercise. In order to reduce the fatigue of active activities, the patient can be instructed to alternate the ankle pump exercise and the circular exercise, and the circular exercise will be the best. For patients with consciousness disorder, weak lower limb activity, and poor compliance with active activity, passive ankle exercise can be carried out. For those with limited ankle exercise, the calf muscles should be massaged to prevent DVT.
In this study, we analyzed the effects of different exercise modes on the hemodynamics of the lower extremity vein, but also had some limitations: the subjects of this study are all healthy young women, the results may have some biases. However, Dix FP et al. 14 have proved that the muscle contraction strength and form are the key factors to improve the hemodynamic effect of lower extremity vein for both healthy people and clinical patients. Therefore, although this study only included healthy women due to the limitations of experimental conditions, the results are still applicable to clinical patients to a certain extent. In addition, due to the small sample size of this study, more scientific test results need to be verified by large samples.
Footnotes
Acknowledgment
Thanks to QinmaoFang, director of the ultrasound department of our hospital, for providing technical support for this study.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Author’s Note
Shuhong Yang contributed equally to this article.
Guarantor
Tianhua Li
Contributorship
Junqin Ding, Tianhua Li, and Chenhao Dou were responsible for designing the study. Tianhua Li, Chenhao Dou, Shuhong Yang, Qian Geng, and Qing Lu were responsible for preparing the manuscript content. Yahui Zhang, Jingjing Yu, and Fang Hu contributed on data collecting. Junqin Ding contributed on revising the manuscript content.
Abbreviations
DVT Deep Vein Thrombosis; PSV Peak systolic velocity; TAMV Time-averaged mean velocity; TRTB Time from the end of the ankle pump exercise to the time-averaged mean velocity of common femoral venous blood flow returns to the baseline; REP Ratings of perceived exertion
