Venous hemodynamic study by air plethysmography in the pre- and postoperative period of lower limb varicose veins

Abstracts

Contexto: O tratamento cirúrgico das varizes primárias dos membros inferiores deve proporcionar alívio da estase venosa, a fim de evitar a evolução da doença venosa para estágios de maior gravidade clínica. Objetivo: Estudar as alterações da hemodinâmica venosa em pacientes portadores de varizes primárias dos membros inferiores no pré e pós-operatório, utilizando a pletismografia a ar. Método: Foram estudados 63 membros inferiores em 39 pacientes (35 mulheres e quatro homens), com média de idade igual a 46,3 anos, operados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo, no período de janeiro de 2001 a dezembro de 2004. Os membros inferiores foram classificados de acordo com a classificação CEAP, em critério clínico = C2 a C6 (C2 = 6, C3 = 32, C4 = 15, C5 = 7 e C6 = 3), critério etiológico = Ep, critério anatômico = As e critério fisiopatológico = Pr. Os pacientes foram avaliados por exame clínico pré e pós-operatório, mapeamento dúplex pré-operatório e pletismografia a ar pré e pós-operatória. Resultados: Houve melhora da hemodinâmica venosa no pós-operatório, demonstrada pela diminuição do índice de enchimento venoso e da fração de volume residual e aumento da fração de ejeção nos membros inferiores submetidos à operação de varizes. Conclusão: A operação venosa superficial aliviou a estase venosa e proporcionou adequado tratamento, com o objetivo de interromper a evolução fisiopatológica da doença venosa crônica, em qualquer nível de gravidade clínica.

Varizes; membros inferiores; pletismografia

ORIGINAL ARTICLE

Venous hemodynamic study by air plethysmography in the pre- and postoperative period of lower limb varicose veins

Nei Rodrigues Alves Dezotti^I; Edwaldo Edner Joviliano^I; Mariana Key Toma^II; Takachi Moriya^III; Carlos Eli Piccinato^IV

^I

^IIFormer monitor, Division of Vascular and Endovascular Surgery, Department of Surgery and Anatomy, FMRP-USP, Ribeirão Preto, SP, Brazil

^IIIPhD. Professor, Division of Vascular and Endovascular Surgery, Department of Surgery and Anatomy, FMRP-USP, Ribeirão Preto, SP, Brazil

^IVProfessor, Division of Vascular and Endovascular Surgery, Department of Surgery and Anatomy, FMRP-USP, Ribeirão Preto, SP, Brazil

Correspondence

ABSTRACT

Background: Surgical treatment of primary varicose veins of the lower limbs might contribute to venous stasis relief by preventing evolution of the venous disease to worse severity stages.

Objective: To study venous hemodynamic changes in patients with primary varicose veins of the lower limbs during the pre- and postoperative period using air plethysmography.

Method: Sixty-three lower limbs of 39 patients (35 females and four males, mean age of 46.3 years) were evaluated. They were all operated at Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, between January 2001 and December 2004. Lower limbs were classified according to the CEAP classification: clinical criteria = C2 to C6 (C2 = 6, C3 = 32, C4 = 15, C5 = 7 and C6 = 3), etiologic criteria = Ep, anatomic criteria = As, and pathophysiological criteria = Pr. The patients were submitted to pre- and postoperative clinical examination, preoperative duplex scan and pre- and postoperative air plethysmography.

Results: Improvement in venous hemodynamics was observed after surgery, confirmed by reduction in the venous filling index and residual volume fraction and increase in the ejection fraction in the lower limbs submitted to varicose vein surgery.

Conclusion: Superficial varicose vein stripping contributed to venous stasis relief and provided appropriate treatment, preventing pathophysiological evolution of chronic venous disease independently of clinical severity.

Keywords: Varicose veins, lower extremity, plethysmography.

Introduction

Primary varicose veins of the lower limbs are one of the most frequent diseases in patients seeking treatment in vascular surgery outpatient clinics, generating a demand for treatment that often exceeds the capacity of the public health system, with consequent formation of waiting lines in many Brazilian cities.¹

Varicose veins of the lower limbs, categorized as C₂ in the CEAP international classification,² are defined as dilated, tortuous and elongated veins, with changes in their function.³ They are more common in females and are associated with other factors, such as age, ethnicity, number of pregnancies, orthostatism over long periods of time, obesity and intestinal function.^3-9

Varicose veins can be primary or essential, when the deep venous system is normal, and secondary, as a consequence of disease in the deep venous system, such as reflux and/or obstruction.^3.7

Complaints motivating medical visit are varied and include esthetic problems, pain, edema, feeling of weight on the lower limbs, cramp and pruritus.^5,6,10-12

Air plethysmography (APG) is a noninvasive method that, in the early 1960's, started being used to study changes relative to lower limb volume as a response to postural changes and to muscle exercises.¹³

APG was introduced by Christopoulos et al. in 1988 as a noninvasive test for quantitative assessment of chronic venous disease (CVD). Such authors described that the venous filling index (VFI) measures the varied degrees of venous reflux, therefore it is an important instrument for CVD diagnosis in situations where clinical signs are not evident.¹⁴

In addition to venous reflux analysis, reported as the main consequence of valve reflux, APG also assesses calf muscle pump function by measuring ejection fraction (EF) and residual volume fraction (RVF).¹⁵

Such assessments can be used to analyze the effects of clinical or surgical treatment of primary varicose veins of the lower limbs, which aim at improving venous reflux and calf muscle pump function.

Intention was to quantitatively assess changes in venous hemodynamic in patients with varicose veins of the lower limbs in the preoperative period and compare with the results observed in the postoperative period. The aim is to investigate the possible relief of venous stasis after resection of the great saphenous vein, varicose veins and ligation of incompetent perforating veins using APG.

This study aims at quantitatively studying venous hemodynamic changes using APG in the pre- and postoperative period of varicose vein surgery of the lower limbs.

Population and methods

Thirty-nine patients (63 lower limbs) were prospectively assessed, 35 (88.6%) women and four (11.4%) men, mean age 46.3 years, receiving care at the Vascular Surgery Outpatient Clinic of Hospital das Clínicas (HC), Faculdade de Medicina de Ribeirão Preto (FMRP), Universidade de São Paulo (USP) and submitted to surgery by a single professor of Vascular Surgery from January 2001 to December 2004. Patients were selected according to the following criteria:

- Exclusion criteria: patients with past history of varicose vein surgery, patients with congenital malformations, diabetes mellitus, heart disease, arterial and lymphatic vasculopathies, collagenosis and myopathy, trauma with or without associated fractures, post-phlebitic syndromes, patients with osteopathy and isolated or associated arthropathy and those that refused to sign the consent form.- Inclusion criteria: patients with symptomatic primary varicose veins of the lower limbs, categorized according to CEAP international classification: clinical criterion = C

₂

to C

₆

; etiologic criterion = E

_p

; anatomic criterion = A

_s

; and physiopathologic criterion = P

_r

²

.Sixty-three lower limbs were evaluated: C

₂

= 6 (9.5%), C

₃

= 32 (50.8%), C

₄

= 15 (23.8%), C

₅

= 7 (11.1%) and C

₆

= 3 (4.8%).

Lower limbs were assessed by clinical examination before and after surgery, duplex scan (DS) before surgery and APG in the pre- and postoperative period (30-40 days after surgery).

Clinical examination

The patient was placed at an illuminated environment and examined when standing upright, thus allowing filling and visualization of superficial varicose veins. Medial, anterior and posterior lateral aspects of the lower limbs were assessed.

The examination was performed according to semiological classical standards through inspection, palpation, percussion and auscultation, in addition to performing the tourniquet test (Brodie-Trendelenburg test).

Duplex scan

DS was performed with the aim of excluding patients with diseases in the deep venous system.

Linear high-frequency probes (7.0 to 10 MHz) were used, able to produce B-mode images, color Doppler ultrasound and spectral curves based on pulsed Doppler. An Aspen-Siemens^® (Erlangen, Germany) device was used.

Vessels with reflux longer than 0.5 second were considered as insufficient.

Examinations were performed by a single independent examiner, and the result was informed to the main researcher.

Air plethysmography

Examinations were performed at the Laboratory of Noninvasive Vascular Investigation of the Division of Vascular and Endovascular Surgery of HC-FMRP-USP, in the evening, by two examiners concomitantly. Maneuvers were started only after demonstrating the examination to the patient and assuring their comprehension.

Examinations were performed in the preoperative period and between the 30th and 45th postoperative day.

Calf muscle pump function was studied by APG. The SDV 3000 (Angiotec^®, Belo Horizonte, Brazil) device was used, with computer-automated calibration. The technique described and standardized by Christopoulos et al. in 1988 was used for the study and evaluated parameters were VFI, EF and RVF.¹⁴

VFI is the variation of volume produced in the limb divided by the corresponding time in seconds, when passing from the supine to the orthostatic position, calculated using the formula VFI = 90% x venous volume (VV) / 90% of venous filling time (VFT90) and expressed in mL/s.

Calf pump function was studied using the data obtained from the variables EF and RVF.

EF provides an estimate of venous reflux during physical activity and the changes that result in less ejected blood. EF is the percentage of ejected total VV in a single contraction of the calf muscle, calculated using the formula EF = ejected volume (EV) / VV x 100.

RVF is linearly related to outpatient venous pressure (OVP), measuring it noninvasively, i.e., measured by the formula RVF = residual volume (RV) / VV x 100.¹⁶

Normal values reported in the literature are VFI < 2, EF > 40% and RVF < 35%.^14,17,18

Surgical treatment

Surgical treatment was performed with the aim of repairing reflux points in assessed limbs.

Of 63 lower limbs under study, radical great saphenous vein stripping (SVS) and varicose vein excision (VVE) were performed in 55 and SVS with ligation of perforating veins (LPV) and VVE were performed in eight lower limbs.

Statistical analysis

The variables studied by APG for hemodynamic evaluation in the pre- and postoperative period were VFI, EF and RVF. Such variables did not have distribution of normality according to Kolmogorov-Smirnov test (p < 0.01). Therefore, the non-parametric approach was used in the analysis, and significance level was set in p ≤ 0.05.

Pre- and postoperative values of VFI, RVF and EF, obtained by APG in 63 lower limbs, were compared using Wilcoxon non-parametric test for paired samples represented in tables. Charts formed by boxes with three horizontal lines and one vertical line were also used. The intermediate horizontal line represents median, below which are 50% of the observations. The lower line is the first quartile, and the upper line is the third quartile, with values that leave 25 and 75% of data below them, respectively.¹⁹ There are "asterisks" in the vertical line, which represent discrepant values.

All patients received clear and objective information to clarify the aim, purposes, risks and benefits of the study. A consent term was developed and later approved by the Research Ethics Committee of HC-FMRP-USP, in accordance with the guidelines and regulating rules of research involving human beings, contained in resolution no. 196 and resolution no. 251 of the Brazilian Health Council and in the Declaration of Helsinki and Nuremberg Code.

Results

Pre- and postoperative values of VFI, RVF and EF obtained by APG in 63 lower limbs were compared.

Median, quartile and mean values of VFI variables were compared before and after surgery, as shown in Table 1.

There was significant loss in postoperative VFI values when compared with preoperative values (Figure 1).

Median, quartile and mean values of EF in the pre- and postoperative periods are represented in Table 2. Comparison of EF values in the pre- and postoperative periods showed significant increase in EF in the postoperative period (Figure 2).

Median, quartile and mean values of RVF in the pre- and postoperative periods are represented in Table 3. There was significant loss in postoperative RVF values when compared with preoperative values (Figure 3).

Noninvasive examinations have significantly contributed to comprehension of venous changes that occur in CVD.

DS has been used as a substitute for phlebography in the identification of venous reflux produced by valve incompetence of deep, superficial or perforating lower limb veins.²⁰ Such technique enables examiners to determine the anatomic changes that contribute to CVD and to obtain information about their impact on venous hemodynamic. It is able to identify sites that have pathological changes, but the quantitative analysis of hemodynamic changes in such sites is much dependent on the examiner's technical skill and experience, in addition to requiring more time to perform the examination.

Photoplethysmography (PPG) has been used as a selection examination in many laboratories because refilling time detected by PPG, which corresponds to the VFI measured by APG, has proved to be sensitive, although not specific, as a reflux indicator. Some authors demonstrated that VFI provided by PPG can detect whether incompetence is on the superficial or deep venous system;^21,22 however, a study conducted in Brazil by Sardinha in 1987 did not obtain a similar result.^23,24 One disadvantage of PPG is the fact of not identifying degrees of clinical severity in relation to venous insufficiency.²⁵

APG measures many parameters of lower limb venous function, including VFI, EF and RVF.

The VFI corresponds to the venous filling of the limb under study as a result of changing it from the supine to a standing position and represents the measurement of venous reflux.¹⁴ It was considered the best parameter, obtained by APG and indicating clinical severity of the limb under study.^14,26,27.

Variation indexes of EF, as it is the ratio between EV and VV, are independent from limb size. Thus, it can be used to compare different groups of patients without the need of measuring VV in each limb. It provides an idea of venous reflux during physical activity and the changes that result in less ejected blood. EF is reduced in venous disease, especially in situations of deep venous system occlusion and when there are factors determining a reduction in calf muscle pump.¹⁷

A 30-70% EF is observed in lower limbs with primary varicose veins and may fall to values close to 10% in deep venous disease.²⁸

Measurement of RV and RVF shows that, in the presence of venous insufficiency of the lower limbs, there is reduction in venous emptying, and consequently in EV. After a movement of foot flexion as a result of calf muscle contraction, the blood volume expelled by leg veins corresponds to the blood coming from the capillaries associated with venous reflux in each relaxation period. If there is insufficiency of the venous system in the limb under study there will be, in this stage, a significant increase in RVF, in contrast to the EV and EF measurement, which are not dependent on venous reflux.

Existence of a linear correlation between OVP and RVF, indicating that an estimate of OVP can be obtained noninvasively by RVF using APG.^22,29

Although not all authors are in agreement, the higher the OVP (in a proportional and linear manner), the higher the RVF. For example, a 35% RVF corresponds to approximately 35 mmHg of OVP. Values below 35% are considered adequate. There is a direct relationship between venous pressure and severity of venous disease.³⁰

Many studies quantified venous reflux obtained by APG and showed that obtained parameters can be correlated to clinical stages and also be used to monitor the results of venous operation after different types of intervention.^31-37

The importance of superficial venous reflux in advanced stages of CVD was studied by many authors, who concluded that more than 50% of their patients with phlebopathic ulcer only had superficial venous insufficiency.³⁸

This study was planned with the aim of evaluating hemodynamic changes after venous surgery in patients with superficial venous insufficiency with competent deep venous system.

The hemodynamic changes of lower limbs surgically treated due to varicose veins were quantitatively assessed using APG, evaluating VFI, EF and RVF values in the pre- and postoperative periods. There was significant improvement in studied parameters after the treatment, shown by reduction in VFI and RVF and increase in EF.

Reduction in VFI can be explained by reduction in venous reflux after VE. Possible explanations for non-reduction in postoperative VFI in some limbs can be the existence of dilated capillaries in the most distal portion of the leg, forming only small arteriovenous fistulas in patients with CVD³¹ or failure in surgical treatment. Reduced RVF and increased EF in the postoperative period result from reduction in venous reflux, evaluated by VFI, and consequent reduction in VV of the lower limb under study. It should be remembered that the limb VV refers to the blood volume present in the veins and varies according to limb position, muscle pump activities and integrity of venous valves.¹⁷

It is known that CVD progressively worsens, and may have major consequences in the future. It is possible to contribute to a more rational management and treatment of patients with venous diseases of the lower limbs using noninvasive examinations, with the aim of reducing the socioeconomic impact caused by such diseases.

This investigation suggests use of APG associated with clinical examination and DS as a protocol to evaluate venous disease in the pre- and postoperative periods, since APG is a noninvasive examination, has low cost, can be easily performed and its results provide a hemodynamic quantification of venous disease.

It can be concluded that superficial venous surgery is an adequate form of treatment as an attempt to interrupt the physiopathologic evolution at any degree of clinical severity (CEAP) of CVD.

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Publication Dates

• Publication in this collection
  26 May 2009
• Date of issue
  Mar 2009

History

• Received
  09 July 2008
• Accepted
  26 Dec 2008