Introduction

Median sternotomy has become the standard approach to the heart and great vessels in most cardiac procedures. Cardio pulmonary dysfunction refers to the impairment of one or more steps in the oxygen transport pathways which can impair the oxygen transport. Overall factors that can impair transport of oxygen pathway from atmosphere to the tissue include cardiopulmonary pathology, bed rest and recumbency, extrinsic factors related to patients medical case, intrinsic factors related to patient or sonic combination of these factors ₁,₂ . Positioning and mobilization are two interventions that have potent and direct effect on several steps in the oxygen transport pathway. These have a primary role in improving oxygen in acute and chronic cardiopulmonary dysfunction and in averting the negative effect of the immobility and recumbency particularly those related to cardiopulmonary and cardiovascular dysfunction. Open heart surgery is associated with number of pulmonary ₃,₄,₅ or cardiac complications ₆,₇,₈ .In 1941, Dripps & Water ₉ ‘ described the therapeutic benefits of position changes & “stirring hospitalized patients , few years later Dock reported on” the evil sequelae of bed rest” in a special issue of the journal of American Medical Association ₁₀ . However, by this time, mobilization to effect the oxygen transport was not integrated into physical therapy practice as a primary intervention ₁₁ .Body positioning is defined as the application of positioning to optimize oxygen transport primarily by manipulating the effect of gravity on cardio pulmonary and cardio vascular system .The effect of body positioning are ₁₂ :

• To optimize oxygen transport in acute cardiopulmonary dysfunction.

• To optimize oxygen transport in post acute and chronic stage of cardiopulmonary dysfunction.

• To prevent the negative effect of immobility, particularly those that adversely effect oxygen transport.

• Improved ventilation/perfusion matching, lung volumes and muco cilliary

• Clearance, to reduce the work of breathing (WOB) and work of heart 12,13 .

Among various positions used in the ICU sitting to improve V/Q matching, redistribution oedema and increase functional residual capacity for patients with ARDS, side lying with affected lung uppermost to improve V/Q matching for patients with unilateral lung disease ₁₃ .Several studies have shown that when shifting the subject from sitting to supine position, dynamic lung compliance decrease while pulmonary flow resistance increase ₁₃ , ₁₄,₁₅,₁₆,₁₇,₁₈ . This has been attributed mainly to the reduction in functional residual capacity (FRC) in the supine posture. Mobilization is defined as the therapeutic and prescriptive application of low intensity exercises in the management of cardiopulmonary dysfunction usually in acutely ill patients. The primary goal of mobilization is to exploit the acute effects of exercise to optimize oxygen; even a relatively low intensity mobilization stimulus can impose considerable metabolic demands on patients with cardiopulmonary compromise. In addition mobilization is performed in upright position that is the physiological position, to optimize the effect of being upright on central and peripheral hemodynamics and fluid shifts. Thus mobilization is prescribed to elicit both the gravitational stimulus and exercise stimulus and the considerable evidence had accumulated in the physiologic and clinical medicine literature supporting that the mobilization is primary intervention to directly enhanced oxygen transport in patients with acute cardio vascular dysfunction.

Method

30 subjects were studied following an open-heart surgery from intensive care unit of cardio vascular thoracic surgery department Govind Ballab Pant Hospital, New Delhi from 15 January 2005 to 30 January 2006. The study sample was the convenience sample of those who were admitted to the department for cardiovascular surgery.

The age of the subject is between 20 to 50 years with mean age of 35.3±9.8. Out of 30 subjects selected 12 patients underwent Mitral valve replacement,7 patients underwent coronary artery bypass graft,3 patients underwent Aortic valve replacement,2 patients have underegone left atrial myxoma excision,3 patients have undergone ventral septal defect closure ,one each have undergone atrial septal closure, left atrial clot excision & repair of Tetralogy of fallots. Subjects included in the study are uncomplicated cardiac surgery ,were males and females between the age of 20 to 50 years. Any uncooperative patient, patient with pre operative chronic pulmonary disease and those with any previous thoracic operation, smokers, older age , over weight persons, patients having any musculoskeletal problem or any neurological disorder that restricts ability to do lower limb exercises were excluded from the study. The design of the study was the same subject cross over design.

Protocols for data collection

Instrumentation for data collection

Data analysis

Results

Heart rate

Non significant results were obtained between group I and II when a pair wise comparison was done of half lying position (HL) with supine lying position with mobilization.

Figure 1

Diagram A showing comparison of means of heart rate in different body positions

Respiratory rate

Pair wise comparison carried out between group I and II showed that significant changes were observed in respiratory rate when the comparison was done between half lying position (HL) with supine lying position with mobilization (Se).

Figure 2

Diagram B showing comparison of means of respiratory rate in different body positions

Systolic blood pressure

Figure 3

Diagram C showing comparison of means of systolic blood pressure in different body positions

Non significant results were obtained between group I and II when a pair wise comparison was done of half lying position (HL) with supine lying position with mobilization (Se).

Diastolic blood pressure

Figure 4

Diagram D showing comparison of means of Diastolic blood pressure in different body positions

Non significant results were obtained between group I and II when a pair wise comparison was done of half lying position (HL) with supine lying position with mobilization (Se).

Partial Pressure of oxygen in the arterial blood

Non significant results were obtained between group I and II when a pair wise comparison was done of half lying position (I-IL) with supine lying position with mobilization (Se).

Figure 5

Diagram E showing comparison of means of partial pressure of oxygen in different body positions

Saturation of oxygen in the arterial blood

Partial pressure of carbon dioxide in the arterial blood

Non significant results were obtained between groups 1 and 2 when a pair wise comparison was done of half lying position with supine lying position with mobilization (Se)

Figure 6

Diagram F showing comparsion of means of partial pressure of carbon dioxide in different body positions

Discussion

This study is an attempt to correlate the impact of positional variation and mobilization on the parameters of heart rate , respiratory rate , systolic blood pressure ,diastolic pressure , partial pressure of oxygen and carbon dioxide in the arterial blood .Positional variation and mobilization are two basic physiotherapy tools and the results obtained have a direct clinical impact in physiotherapy management of patients .The basic aim is to answer the question whether there is significant change in parameters and if there is a positive correlation immediate steps should be taken to expand the present knowledge and results should be utilized in clinical settings .The results indicate as follows.

When comparison was done of half lying position (HL) with supine lying with mobilization (Se) no significant changes were observed in the heart rate. Thomas W. Rowland in his study showed that as the intensity of work increase there is a linear increase in both the heart rate and venous return, while the stroke volume remains essentially normal ₁₈ . Thandani and Parkes 1978 showed that shifting the individual from supine position to half lying position is associated with increase in the heart rate to compensate the decrease in the end diastolic and the stroke volume ₁₉. Exercise causes an increase in the ventilation & the increase can be about 20 folds during strenuous exercise. Similar results were seen in this study but the increase was not statistically significant when compared with that of half lying position The reason for the increase in ventilation with exercise is not fully answered but at least two effects seem to be predominantly concerned.

The brain on transmitting impulses to the contracting muscles is believed to transmit collateral impulses into the brain stem to excite the respiratory centre. This causes an increase in the ventilation.

During exercises, the body movements especially of the arms & legs are believed to increase pulmonary ventilation by exciting joint & muscle propioceptors that then transmit excitatory impulses to the respiratory centre.

When the subjects are placed in the half lying position (HL) the blood pressure increases due to both increase in heart late and also because of the increase in the peripheral vascular resistance. Exercise on the other hand also results in an increase in the blood pressure due to sympathetic activation, that of half lying, where although it was greater but was statistically insignificant. There are various factors that would result in an increase in the blood pressure caused primarily due to increased sympathetic activity. They are as follows:

• Vasoconstriction of arterioles & small arteries in most of the tissues the body besides the active muscles.

• Increased pumping activity by heart.

• A greater increase in mean systolic filling pressure caused mainly by venous contraction.

Thus when the comparison were made between half lying position and supine lying position with mobilization (Se) no significant changes were observed in blood pressure parameters in between them. When Pa0₂ values were compared between half lying position(HL) and supine lying position with rnobilization(Se) no significant difference was found between them.Jon A.Hardie et al ₂₀ in his study found a significant difference in PaO2 in the sitting and the supine position .In half lying position (HL) the diaphragm is displaced downwards thus increases the vertical dimensions of the thoracic cavity thus altering the arterial blood composition having a positive effect on it .Exercise in supine position is disadvantageous for the patient as it may significantly limit optimal cardio pulmonary response to exercise & hence the overall therapeutic benefit. Julio Sandova et al ₂₁ in 1999 carried out a study to check the effect of body position changes on pulmonary gas exchange in Eisenmenger's Syndrome & concluded that, as a whole the PaO2,SaO2 were significantly affected by changing from sitting to supine position while other variables PaCO2 & PH remained particularly un affected. Jon A Hardie et al ₂₀ found the similar result that mean sitting PaCO2 & PH and mean supine PaCO2 & PH were not statically different . However in this study no significant difference was found in PaCO2, and Sa02values when comparison was done between half lying position (HL) and supine lying position with mobilization(Se).