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Indian Journal of Physiotherapy and Occupational Therapy

Effect of Graded Incremental Mobilization on Exercise Tolerance Following Lung Resection Surgery

Author(s): T Sivakumar, G Arun Maiya

Vol. 2, No. 3 (2008-07 - 2008-09)

T Sivakumar1, G Arun Maiya2

1Assistant Professor, 2Head and Associate Professor, Dept of Physiotherapy, Manipal College of Allied Health Sciences, Manipal University, Manipal

Abtract

Objective: To evaluate the effect of graded early mobilization on exercise tolerance during post operative period following lung resection surgeries
Design: Controlled experimental trial; Descriptive study.
Subjects: Patient who underwent elective lung resection surgery were selected and randomly assigned in to two groups control group and experimental group using block randomization.
Procedure: All patients were evaluated preoperatively for pulmonary function measures and six minute walk distance (6MWD) with spirometry and six minute walk test respectively. Patients in both groups underwent conventional postoperative physiotherapy protocol. Experimental group patients received graded incremental mobilization exercises in addition. The mobilization exercises were incremented by 150% for every session. Pulmonary function measures and 6MWD were measured on tenth postoperative day and at the end of fourth postoperative week.
Results: Within group comparison of the variables was done with paired ‘t’ test and between group comparisons with independent ‘t’ test. FEV1, MVV and 6MWD were reduced on tenth postoperative day and showed a recovery by fourth week in both groups. However in experimental group the decrease on tenth day was less, and significantly (p = 0.00) improved during fourth week postoperatively when compared to control group.
Conclusion: Graded incremental mobilization enhances the recovery of lung function and exercise tolerance in the post operative period following lung resection surgeries.
Keywords: Graded incremental mobilization, exercise tolerance, six minute walk test, six minute walk distance, lung resection.

Introduction

Lung resection is the common surgical procedure in various advanced pulmonary pathologies like, pulmonary tuberculosis, lung abscesses, and bronchiectasis. Lung resection may lead to various levels of circulatory and ventilatory dysfunctions. Ventilatory dysfunction is greatest in the first three weeks post operatively and shows subsequent improvement.1,2 The resection of the pulmonary parenchyma, thoracic incision and diaphragmatic inhibition were quoted as the factors causing the reduced ventilatory dysfunction.1-3 The exercise tolerance following pulmonary resection also follows the same pattern of ventilatory dysfunction i.e., greater reduction in the early postoperative period and subsequent improvement during fourth week following the surgery.4-6 As reported in many studies, exercise tolerance following lung resection, is reduced and the major contributing factor for this ventilatory dysfunction following the surgery. As the ventilatory dysfunction improves the exercise tolerance shows improvement.4-6

In patients with low aerobic reserve, the surgery and its accompanying multiple co-morbidities impose a major load on the remaining lung. There is a need for effective management to optimize the oxygenation according to the increased demand and to prevent complications following surgery in these patients. Incremental exercises above the threshold intensities can be a stimulus and lead to better optimization of oxygenation, and thereby improve exercise tolerance during the postoperative period. The objective of this study was (i) to evaluate the changes in exercise tolerance following lung resection with six minute walk test and (ii) to evaluate the influence of graded incremental mobilization exercises on exercise tolerance during postoperative period following lung resection.

Methodology

Eighteen patients who were electively posted for pulmonary resection were selected for the study. Informed consent was taken from the patients. All patients were randomly assigned into two groups control group and experimental group. All patients were evaluated preoperatively and preoperative physiotherapy was given to both the groups.

The experimental group patients were given instructions regarding the graded incremental mobilization. Following surgery physiotherapy treatment started in the day of surgery. Patients in both groups were treated according to routine postoperative physiotherapy protocol. Patients in experimental group received graded incremental mobilization exercises from postoperative day two onwards.

In this, every session the patient’s mobilization was incremented by 150% of the prior session. For example, every session the patient was asked cover 150% of the distance covered in the previous session. Following the discharge, experimental group patients were given maintenance program.

All patients performed pulmonary function test(PFT) and six minute walk test( 6MWT) preoperatively(preop), tenth postoperative day (Post op I) and at the end of fourth postoperative week (Post op II). PFT was performed according to American thoracic society guidelines. 6MWT test was performed according to American thoracic society guidelines statement.7 The parameters considered for the statistical analysis were FEV1, Maximum Voluntary Ventilation (MVV) and Six minute walk test distance (6MWD).

Statistical analysis

Within group comparison of preoperative and post operative measures of control and experimental group was done using Wilcoxon signed rank test. And to evaluate the effect of graded incremental mobilization exercises, comparison changes between the control and experimental group was done using Mann Whitney U test. The level of significance was set at p d” 0.05.

Results

Out of eighteen patients underwent elective lung resection surgery; fifteen patients were taken up for the study. Among the three excluded, one expired during acute post operative period as perioperative complication and the other two had co morbid diseases which would affect their exercise performance in 6MWT. The characteristic features of the patients who participated in this study are summarized in the table 1.

Though pneumonectomy and lobectomy lead to various levels of pulmonary dysfunction, they were considered together. This might have lead to variability in the outcome measures, however having equal no of pneumonectomy and lobectomy patients in either group would have reduced the confounding due wide range of dysfunction (table 1).

The preoperative and postoperative PFT and 6MWD measures of control group and experimental group are summarized in the table 2 and table 3 respectively. From the data collected from control group, it is evident that there is a decrease in the early postoperative period (post op I) from preoperative period (pre op) and recovery subsequently by one month postoperative period (post op II) of FEV1, MVV and 6MWD. The decrease during post op I from preop values is statistically significant (table 2); but the subsequent improvement during post op II was not significant (table 2).

The analysis of data from the study group, it was found that changes in the FEV1, MVV and 6MWD following surgery were similar to that of control group. The decrease during the post op I from preop (table 3), and the improvement during post op II was found to be statistically significant (table 3). The change in 6MWD in the experimental group during fourth postoperative week is 57m which is more than threshold for clinical significance7 which is not evident in control group. On comparison between the experimental group and control group, there was statistically significant difference in the recovery during fourth postoperative week.

The differences in the pulmonary function measures and six minute walk distance between the control and experimental groups are illustrated in the figure 1 3. The results indicate that there was better improvement in pulmonary function and 6MWD in experimental group than control group but which is also clinically significant according to ATS statement guidelines.7

Table 1: Characteristics of patients in control group and experimental group

Demographics Control Group n = 8 Experimental Group n = 7
Age (yrs) 39.8±7.8 39.8±7.0
Gender 5 males &
3 females
4 males &
3 females
Operative
procedure
Pneumonectomy = 2
Lobectomy = 6
Pneumonectomy = 2
Lobectomy = 5

Table 2: Pulmonary function and 6MWD (mean SD) of control group

Parameters Pre op Post op I_. p# Post op II
FEV1 1.76±0.49 0.04 1.32±0.38٭ 0.75 1.36±0.38
MVV (l/min) 69.2±17.2 0.01 52.5±15.9٭ 0.77 53.5±12.7
6MWD (m) 352±144.9 0.04 281±103.0٭ 0.34 292±95.5

٭ p value of difference of Post op I against Pre op
# p value of difference of Post op II against Post op I

Table 3: Pulmonary function and 6MWD (mean SD) of control group

Parameters Pre op Post op I p# Post op II
FEV1 1.75±0.54 0.01 1.26±0.41٭ 0.00 1.55±0.35٭
MVV (l/min) 62.3±21.0 0.01 49.4±17.1٭ 0.00 61.5±12.9٭
6MWD (m) 495±104.9 0.00 406±102.6٭ 0.00 463±107.5

٭ p value of difference of Post op I against Pre op
# p value of difference of Post op II against Post op I

Discussion

The posterolateral thoracotomy and lung resection impose severe injury to chest wall and lung in the early post operative period. These leads to decrease pulmonary function and thereby exercise capacity.1-5 Recovery in pulmonary function is evidenced from third post operative week. Exercise capacity follows the pulmonary function in the trend of recovery.4,5 The routine physiotherapy protocol lacks exercises of training threshold to enhance the recovery of exercise capacity during the early postoperative period. Therefore in our study we included graded incremental exercise to enhance recovery of exercise tolerance in the early post operative. The graded increment is based on the patient’s performance and on every successive session the patient effort was increased by 150%.

6MWT is one of the popular and common used exercise tolerance test used worldwide health care set up. The reliability and validity of 6MWT were established, and found to be good, making it a reliable research tool in assessing exercise tolerance. We have considered 6MWT to measure exercise tolerance in lung resection patients in the postoperative period for its feasibility and reproducibility.

In this study, the pulmonary function test variable i.e., FEV1, and MVV which predicts exercise tolerance, were found to be reduced in the early postoperative period(post op I). This also confirms the findings in the earlier studies by Miyoshi et al4 and Nezu et al6. The exercise tolerance in terms of 6MWD of control group was reduced in the early postoperative period during 10th postoperative day. Following this initial drop the exercise tolerance has increased when measured at fourth week post operatively.

This is in keeping with the results of the previous study by Miyoshi et al.4 Miyoshi et al in their study have concluded that ventilation was the major restricting factor for the exercise tolerance in the acute post operative period. But it may be primitive to conclude that ventilation is restricting factor for exercise tolerance, as this needs a direct measurement of ventilatory reserve by analysis of expired gases. Moreover hemodynamic variables indicates that circulation along with ventilation were also responsible for reduced exercise tolerance in the postoperative period.

The improvement in experimental group in the late post operative period nearly reached the preoperative status. The FEV1 and MVV which had a fall of 70% in the early postoperative period were improved to 90% by one month against 80% in the control group population. Similar changes were accounted in MVV also. These results suggest that the recovery pattern in experimental can be attributed to vigorous early mobilization protocol.

The exercise tolerance, 6MWD that had fallen to 60% in the early postoperative period had almost reached the preoperative status in the late postoperative period. The improvement in 6MWD from the acute postoperative period till the one month was 57m in experimental group against 12m in control group. This mean increase in 6MWD exceeds the 54m threshold for clinical significance as reported in ATS guidelines statement for 6MWT.7,8

These inter group difference, which was clinically and statistically significant, could be due to absence or desensitization of symptoms and enhanced recovery of pulmonary function. These changes in the experimental group can be attributed to graded incremental mobilization exercises. From the observation of patients in both the groups, it was found that two patients in control group had postoperative pulmonary complications, and none of the patients in the experimental group had any postoperative complications.

Conclusion

From this study we conclude that following lung resection surgery,

1. Exercise tolerance is reduced in the early postoperative period and recovers subsequently improves by fourth week postoperatively as evidenced by 6MWT

Graph 1: Changes in Forced expiratory volume in 1s (FEV1) between groups

Changes in Forced expiratory volume

Graph 2: Changes in Maximum Voluntary Ventilation (MVV) between groups

Changes in Maximum Voluntary Ventilation (MVV)

Graph 3: Changes in distance (6MWD) covered in 6MWT between groups

Changes in distance (6MWD)

2. Graded incremental mobilization exercises lead to enhanced recovery of exercise tolerance in the post operative period.

Recommendations for further research are to consider more objective measures to evaluate the limiting factors for exercise tolerance and their recovery pattern following lung resection surgeries.

References

  1. Gorlin R, Knowles JH, Storey CF. Effects of thoracotomy on the pulmonary function. J Thorac Surg 1957; 34: 242-49
  2. Hazerligg SR et al. The effect of muscle sparing versus standard posterolateral thoracotomy on pulmonary function. J Thorac Cardiovasc Surg 1991; 101: 394- 401
  3. Maeda et al. Diaphragm function after pulmonary resection. Am Rev Respir Dis 198; 137: 678-81
  4. Miyoshi et al. Exercise capacity of thoracotomy patients in the early postoperative period. Chest 2000; 118: 384-90
  5. Nugent et al. Effect of thoracotomy patients and lung resection on exercise capacity in patients with lung cancer. Thorax 1999; 54(4): 334-38
  6. Nezu et al. Recovery and limitation of exercise capacity after lung resection. Chest 1998; 113(6): 1511-16
  7. ATS statement: Guidelines for the six minute walk test(6MWT). Am J Respir Crit Care Med 2002; 166: 111-7
  8. Redelmeier, D. A., A. M. Bayoumi, R S Goldstein and G H Guyatt. Interpretation small differences in functional status: the six minute walk test (6MWT) in chronic lung disease patients. Am J Respir Crit Care Med 1996; 155: 1278-82

Corresponding Author:
T Sivakumar

Assistant Professor, Dept of Physiotherapy, MCOAHS, Manipal University
Manipal, Karnataka 576104, India

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