Efficacy of intermittent pneumatic compression (IPC) in lower limbs on the blood flow of common femoral veins

ORIGINAL ARTICLE

Efficacy of intermittent pneumatic compression (IPC) in lower limbs on the blood flow of common femoral veins

Marcondes Figueiredo^I; Patrícia Polizel Simão^II; Beethoven Marques Alves Pereira^III; Nilson Penha-Silva^IV

^IPhD, Angiology and Vascular Surgery, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil.

^IIPhysician, vascular ultrasonographer.

^IIIGraduate student, Faculdade de Medicina, Universidade Federal de Uberlândia (UFU), Uberlândia, MG, Brazil.

^IVPostdoctoral fellow in Biochemistry, Southern Illinois University, Carbondale, IL, USA. University of Texas Medical Branch (UTMB), Galveston, Texas, USA. Professor, Instituto de Genética e Bioquímica, UFU, Uberlândia, MG, Brazil.

ABSTRACT

BACKGROUND: Prophylaxis of venous thromboembolism, a very common post-surgical complication, can be made pharmacologically or via mechanical methods, such as the use of anti-thrombosis socks and intermittent pneumatic compression (IPC). IPC is a mechanical method of prophylaxis that deserves the attention of the medical community.

OBJECTIVE: To evaluate the effect of IPC on the blood flow of common femoral veins in feet, legs and thighs of healthy adults.

METHODS: The sample was comprised of 10 volunteers (seven females and three males), adults (20-40 years), without history of venous thromboembolism. After a rest period (10 min), with the patient in the supine position, blood flow was measured (three times) via vascular ultrasonography at the femoral vein, 1 cm above of the saphenofemoral junction, in both limbs, without (control) and with IPC in the patient’s foot, leg and thigh. Compression (130 mmHg on foot and 45 mmHg on leg and thigh) was applied at compression cycles of 11 seconds and emptying cycles of 20-60 seconds. Blood flow evaluations were performed at compression cycle peaks. Values were compared by analysis of variance (Tukey test), p < 0.05 indicating statistically significant difference.

RESULTS: Use of IPC on the left and right lower limbs caused a percentage increase in the femoral blood flow of 37.6 and 70.8% (feet), 143.9 and 164.7% (legs), and 132.6 and 128.9% (thighs), respectively. Variations were statistically significant for application in legs and thighs.

CONCLUSION: Use of IPC improves blood flow when applied in legs or thighs.

Keywords: Intermittent pneumatic compression, venous thrombosis, ultrasonography, femoral vein.

RESUMO

CONTEXTO: A profilaxia do tromboembolismo venoso pode ser feita por métodos farmacológicos ou de forma mecânica, com o uso de meias antitrombo e compressão pneumática (CPI). A CPI é um método mecânico de profilaxia que merece melhor atenção da comunidade médica.

OBJETIVO: Avaliar o efeito do uso de compressão pneumática intermitente (CPI) nos pés, pernas e coxas de adultos saudáveis sobre o fluxo sanguíneo nas veias femorais comuns.

MÉTODOS: A amostra foi constituída de 10 voluntários (sete mulheres e três homens) adultos (20-40 anos), sem antecedente de tromboembolismo venoso. Após repouso (10 min) em decúbito dorsal, o fluxo sanguíneo era medido (três vezes) por ultra-sonografia vascular na veia femoral, a 1 cm acima da junção safeno-femoral, em ambos os membros, sem controle e com CPI no pé, perna e na coxa. A compressão (130 mmHg no pé e 45 mmHg na perna e na coxa) foi aplicada em ciclos de 11 segundos de compressão e 20-60 segundos de esvaziamento. As aferições de fluxo foram realizadas no pico de fluxo do ciclo de compressão. Os valores foram comparados por análise de variância (teste de Tukey), com p < 0,05 indicando diferença estatisticamente significante.

RESULTADO: A utilização de CPI nos membros inferiores, esquerdo e direito, promoveu elevações percentuais relativas no fluxo venoso femoral de 37,6 e 70,8% (pés), 143,9 e 164,7% (pernas) e 132,6 e 128,9% (coxas), respectivamente. As variações foram estatisticamente significantes para as aplicações nas pernas e coxas.

CONCLUSÃO: A CPI melhora o fluxo sanguíneo quando aplicada na perna ou na coxa.

Palavras-chave: Dispositivo de compressão pneumática intermitente, trombose venosa, ultra-sonografia, veia femoral.

Introduction

Pulmonary embolism (PE) is the main cause of death in hospitalized patients. Most fatal embolisms are secondary to deep venous thrombosis (DVT) of the lower limbs.¹

Prophylaxis of venous thromboembolism can be performed by pharmacological methods, especially low-molecular-weight heparin,^2-4 or by mechanical methods, such as using compression stockings³ and intermittent pneumatic compression (IPC).^3,5-8

IPA was initially used in patients to prevent venous thrombosis after surgical treatment,^8,9 but it also started being used during surgical treatment and in periods of patient's immobility.¹⁰ Its action is based on increase in venous flow in lower limb veins and on induced fibrinolytic activity in blood flow.¹⁰

This study aimed at evaluating the effect of using IPC on feet, legs and thighs on venous flow in the femoral vein of healthy young adults using vascular ultrasound.

Population

This study is in agreement with resolution 196/96 of the Brazilian Health Council and Helsinki Declaration, and was previously approved by the Ethics Committee of Hospital Santa Catarina, in Uberlândia, Minas Gerais, Brazil.

The sample was comprised of 10 adult volunteers (seven women and three men; 20-40 years) with no history of venous thromboembolism. Femoral blood flow was measured by vascular ultrasound (ATL^® HDI 5000 and 4-7 MHz linear transducer) in the common femoral vein, approximately 1 cm above the saphenofemoral junction, always by the same examiner. Twenty limbs were analyzed. Measurements were performed after a 10-min rest in the supine position, initially without compression (control), and later with compression of 130 mmHg in the foot and 45 mmHg in the leg and thigh (aided by the SCD EXPRESS^®), with compression cycles of 11 s and emptying cycles of 20-60 s. These devices are sequential, that is, chambers are inflated sending blood flow toward the heart.

Femoral blood flow values were initially submitted to a normality evaluation test (Kolmogorov-Smirnov). Values between different groups were later compared using analysis of variance (Tukey's test), with p < 0.05 indicating significant statistical difference.

RESULTS

In all situations femoral flow values followed Gaussian distributions (α = 0.05), according to Kolmogorov-Smirnov test. Table 1 shows the values obtained for femoral flow. In all situations the values obtained for leg and thigh were significantly higher than that obtained for control.

Table 1 - Click to enlarge

Since there were no statistically significant differences between the right and left limbs, the data were grouped and another analysis was performed. Such analysis showed that flow values were higher when the IPC was applied in the leg and thigh in relation to foot and control, although there was no significant difference between values obtained for leg and thigh (Table 1).

Discussion

The method used in this study was case-control, i.e., the patient was his own control even before receiving IPC. Application of IPC in the leg and thigh of young and healthy patients (18 women and eight men) was evaluated by Flam et al.¹⁰ They showed a higher increase in flow when IPC was applied in the leg in relation to the thigh.

Pneumatic compression can be sequential or non-sequential.^11,12

This study compared maximal flow point in the compression cycle between three different regions (foot, leg and thigh) of the right and left lower limbs using sequential compressors, one for the foot and another for the leg and thigh, changing the stocking between different sites.

The main mechanism of action of IPC is elimination of venous stasis, which is reduction in blood flow velocity and volume inside the vein. Venous stasis is considered as the main triggering factor of deep venous thrombosis.¹³ Size, duration and profile of blood flow increase will depend on the compression system.¹⁴ When compression is applied in the limb, the compressed area accelerates blood flow, facilitating emptying and preventing stasis.¹⁵

In fact, use of IPC in the postoperative period reduces venous thromboembolism in 60%. It increases venous flow in the femoral vein when applied in the foot, leg and thigh,¹⁶ but it is more efficacious when applied in the leg and thigh in relation to the foot.^16,17

In this study use of sequential IPC was also evaluated in the foot, leg and thigh. Applications of IPC in the leg and thigh, but not in the foot, significantly increased femoral vein flow (Table 1). Although increased flow resulting from application in the foot had not been significant, applications of IPC in the leg and thigh caused significant increase in femoral flow in relation to application in the foot, which is in agreement with previous reports in the literature.^16,17 Although IPC is established as a mechanical method of venous thromboembolism prophylaxis,^18,19 adherence of the medical community to this procedure is low.^20-22

Therefore, it is necessary to increase physicians' awareness of the importance of IPC. A change in attitude in the medical community could reduce mortality caused by pulmonary embolism, which reaches up to 50,000 cases/year in the USA, where there are 160 new cases of deep venous thrombosis for each 100,000 inhabitants.¹⁸

Conclusion

Application of IPC in the leg and thigh increases blood flow, reducing stasis.

References

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Correspondence

Publication Dates

• Publication in this collection
  20 Feb 2009
• Date of issue
  Dec 2008

History

• Accepted
  03 Sept 2008
• Received
  15 Feb 2008