Coronary Artery Bypass Graft surgery (CABG) is a medical procedure used in the treatment of coronary artery disease (CAD). CAD is a disease that causes narrowing of the coronary arteries (the blood vessels that supply oxygen and nutrients to the heart muscle) due to the accumulation of fatty deposits called plaques within the walls of the arteries. Investigations such as electrocardiogram, stress tests, cardiac catheterization, imaging tests such as chest x- rays, echocardiography, or computed tomography (CT), and blood tests to measure blood cholesterol, triglycerides, and other substances are used to diagnose CAD. The accretion of plaques over the years causes symptoms such as chest pain, fatigue, palpitations, and shortness of breath. Some patients with CAD may be symptom free in the early stages; the disease will progress until sufficient artery blockage exists to cause symptoms and discomfort. Blockage of the coronary arteries will cause the heart muscle to weaken due to inadequate blood supply, leading to a condition called ischemia. If the blood flow is not restored to the particular area of the heart muscle, the tissue dies, leading to myocardial infarction or heart attack. In order to restore blood supply and treat the narrowing of the arteries, the blocked portion of the artery is bypassed or rerouted with another piece of vessel, this is called CABG surgery1.
Despite the many advances and development in anesthesia, surgical techniques, and postoperative care for CABG surgery, postoperative pulmonary complications (PPCs) retain a high postoperative morbidity and mortality rate
1. The risk of PPC has increased in CABG procedure due to two factors: intra-operative and external. The intra-operative factors are factors that are associated with the surgical procedure such as general anesthesia, surgical incision, type of graft, topical cooling for myocardial protection, and cardiopulmonary bypass
2. General anesthesia increases the risk of PPC when the anesthetic component is administered to the patient while lying in supine position; it results in respiratory depression leading to a Ventilation-Perfusion (VQ) mismatch. In the surgical approach, the incision site in the upper thoracic area, which is a standard 20cm incision, decreases the preservation of pulmonary function. The type of graft used such as “IMA” increases the risk of attaining PPC. Topical cooling also used in CABG increases the incidence of phrenic nerve injury. Cardiopulmonary bypass which is unique to this surgery causes additional lung injury and longer pulmonary recovery, which occurs due to the acute systemic and pulmonary inflammatory response which is known as “pump lung” or “post pump syndrome
2. External factors that could increase the risk of acquiring PPC are aging, the prevalence of surgical delay, increased sickness and complex health problems. The diagnosis of PPC, requires symptomatic pulmonary dysfunction symptoms such as increased work of breathing, shallow respiration, ineffective cough, and hypoxemia 2; in addition to clinical findings such as atelectasis, pleural effusion, pneumonia etc. The most frequent types of PPC associated with CABG are atelectasis which ranges from16.6% to 88%, phrenic nerve paralysis (30 % to 75%), and pleural effusion (27%-95%) 2.
Acquiring PPC leads to the increased use of medical supplies and other health care expenses. Numerous interventions have been used to treat PPC but, due to variance in opinions, no resolution has been reached to which is the most effective and efficient intervention in treating PPC. To prevent postoperative complications such as PPC, less invasive techniques are applied by physical therapists. Physical therapists are responsible for the management and rehabilitation of the patient, which includes treating and educating the patient and helping them to attain the maximum function, and satisfying level of independence; this is achieved by decreasing the level of limitation and impairment. Physical therapy treatments include mobilization and airway clearance techniques, positioning, breathing exercises, coughing maneuvers, mobility and functional exercises. Physical therapy has been known to intervene in surgical procedures such as CABG, but most of the intervention used in patient’s rehabilitation is performed postoperatively. Recent studies have confirmed that post-operative patients, “especially in CABG” can improve as much as 50% 3 by introducing pre-operative physical therapy management. The preoperative management targets patients pre-surgically and directs its rehabilitating techniques towards the reduction of a possible PPC pre-operatively. Preoperative physical therapy management includes appropriate patient selection, preoperative PT assessment, patient education, and pre-operative physical therapy treatment (PPTT). These management protocols further enhance post-operative results by training patients on post-operative techniques. Thus pre- and post- operative physical therapy management is performed to reduce post-operative CABG pulmonary complications.
Literature review
Pre-operative Physical Therapy Treatment
Preoperative management is an early involvement of physical therapy prior to surgery. It is a method used in prevention of patient deterioration by directing its efforts towards the patient’s respiratory and physical condition. Preoperative physical therapy management ensures that the patient is in the best respiratory and physical condition prior to surgery, to be able to have a rapid recovery. Preoperative management mainly focuses on appropriate patient selection, patient education, pre-operative assessment, and preoperative treatment.
Appropriate patient selection
Patients undergoing surgery have certain characteristics which can increase or alter the risk of any surgical complications especially in CABG. These characteristics affect the outcome of surgery, therefore leading to post operative complications. Suitable patient selection in preoperative rehab is important. This allows the physical therapists to categorize patients. Patients can either be classified as low risk or high risk patients. Classifying patients in such order ensures that each patient will obtain a tailored preoperative management program according to their condition and will receive maximum benefits from the program 4.
The characteristics that alter the patients risks are pre-existing respiratory problems, obesity, age, smoking, patient motivation, and nutritional status 4.
Pre-existing respiratory problems is of three factors infection, restrictive defects, and obstructive defects. Infection may affect both upper and lower respiratory tracts. If the upper respiratory tract is infected, it will cause increased mucus production. And if it infects the lower respiratory tract it may initiate impaired gas exchange leading to hypoxia secondary to pneumonia, resulting in exacerbation of infection. Restrictive defects include lung fibrosis, pulmonary oedema, and pleural effusion. The restrictive may reduce lung volume, resulting in an increase of airway resistance and closing of airways following anesthesia. Obstructive defects are also known as Chronic Obstructive Pulmonary Diseases (COPD). The occurrence of COPD in patients undergoing surgery will lead to an increase in the anesthesia dose due to bronchial hyperactivity.
Obesity is another characteristic that can upgrade a patient into the higher risk group. Obesity is usually detected by using the Body Mass Index (BMI). According to Selsby and Jones 1993, increase in body mass may lead to reduced lung compliance by approximately one third; this is due to the additional weight on the chest wall.
As a person ages the lung loses its elasticity in recoiling and the lung volume is reduced. During aging, respiration is reduced by weakening of the respiratory muscles and stiffening of the rib cage.
Smoking is the major cause of greater ventilation/perfusion (V/Q) shunt, and impaired oxygenation during anesthesia. This is because smoking results in narrowing of the airways, excessive mucus secretion and decreased mucus clearance, and irritable airways.
Patient motivation is the current mental or cognitive, and emotional state of the patient. Any disturbance in such states may result in decrease patient compliance and increases the duration of the patient’s recovery.
Preoperative PT assessment
Pre-operative assessment is a technique used to establish an outline of the patient’s current status, and form a baseline to assess the patient’s progress. The pre-operative assessment includes subjective and objective assessments.
Subjective assessment is an interrogation procedure used by the physical therapist to obtain information to help with the preoperative treatment program. During the subjective assessment, open-ended questions 4 are used, which allows the patient to discuss their current problems. There are five main points that need to be clarified during this type of assessment; dyspnea, cough, secretion (sputum and haemoptysis), wheeze, and chest pain.
During the objective assessment, the physical therapists use their own skill in examining the patient. The physical therapists examines by observation, palpation, percussion, and auscultation. Further details may be obtained by the use of tests such as spirometry arterial blood gases (ABG’s), and chest radiographs 4.
When assessment is completed, the physical therapist analyzes the information obtained and integrates it with their knowledge, resulting in a problem list.
According to the problem list the physical therapists addresses these problems by setting specific, measurable, achievable, realistic, and time specific goals according to the problems obtained from examination. A well designed treatment plan is set to help resolve these problems.
Patient Education
Patient education plays an important role in rehabilitation. The patient is educated by the staff, which includes the surgeon, physical therapists and nurses. The patient is educated on preoperative and postoperative programs or protocols. During patient education, verbal and written information is given to patients. The role of the physiotherapist in patient education is to highlight and clarify the main points of the CABG procedure, allowing the patient to become familiar with the surgery. The physical therapist also explains the main effects of surgery on the respiratory function, location of the wound, and wires and monitors attached. The instructions given before the surgery puts the patient at ease and postoperatively accelerates the functional recovery of the patient. To reinforce the verbal information, leaflets and brochures are given to help the patient.
Pre-operative Physical Therapy Treatment (PPTT)
PPTT is directed towards maximizing pulmonary function 4 by the reduction of PPC and the use of non-invasive PT interventions. Since PPTT is a newly emerged, few studies are found that discuss the preoperative treatment of patients undergoing CABG procedures. Therefore no precise treatment techniques or protocols are followed during PPTT. Studies have suggested that the most common types of PPC that occur following CABG surgery are atelectasis, and pneumonia.
Atelectasis “which is an abnormal respiratory condition “causes lung collapse, therefore leading to deprivation of gas exchange. It is caused by an obstruction of major airways and bronchioles. It is a complication that is frequently seen in post-operative period and is found in the basilar region in post CABG. To treat and prevent such condition deep breathing techniques and incentive Spirometry is used 5.
Pneumonia is an infection or inflammation of the lungs. It can be caused by microorganisms such as bacteria, viruses, or fungi or by a potential complication such as pleural effusion. Pneumonia is treated by pharmaceutical agents, coughing techniques, and breathing exercises 5.
It was found that both PPC’s are caused by the patients inability to expectorate sputum and due to insufficient diaphragmatic breathing. Therefore the most appropriate way to treat such conditions is to rehabilitate patients preoperatively.
PPTT treatments are of a large variety and no precise treatment has been advised solely for treatment. During my investigation I have came upon many techniques used. The most common treatment used within the PPTT is breathing exercises (BE), respiratory muscle devices, and sputum expectoration techniques.
BE are several techniques used to help increase the muscle strength and increase air entry. It is performed by inflating and deflating the lungs. There are many types of BE some are pursed lip breathing (PLB), paced breathing, diaphragmatic breathing, segmental breathing, sustained maximal inspiration (SMI), and global lung expansion.
Respiratory muscle devices are instruments used to help strengthen the surrounding breathing muscle by the use of resistance as shown with the inspiratory muscle trainers (IMT) and aids the patient in air entry by visual aid, as shown with the incentive spirometer (IS).
The sputum expectoration techniques are tactics used to expel secretions from the lung. One of the most common techniques used nowadays is the secretion removal technique, this is a method used to remove mucus from the lung and helps in expectorating the sputum, it is known as postural drainage. This method can be applied according to area of secretion and can be modified according to the patient’s condition. Other supporting or assisting techniques is coughing and the Forced Expiratory technique. Coughing is used to help the patient to expectorate sputum. The PT can teach the patient the correct method and may support the patient incision or wound when coughing if needed, or assists the patient by applying force on the abdomen, increasing the abdominal pressure therefore giving extra force. FET is less forceful technique, it is similar to coughing, and the patient huffs instead of coughing. This method brings the mucus to the upper airways and is usually followed by coughing to expel sputum.
An observational follow up study was performed by Isabel Yanez-Barage. The purpose of the study was to examine the use of preoperative respiratory physiotherapy, on the incidence of pulmonary complications in CABG surgery. Two groups of patients were involved in the study. The first group was the intervention group, whom received PPTT and the second group was the control group, who had no PPTT. The apparatuses used within the study included Incentive IS and, BE. Prior to their use, uses and importance of the apparatus was explained to the patients. The techniques that was used during the study, were ten deep BE, diaphragmatic breathing, thirty long expansion maneuvers, tactile stimulation, three stages of Sustained Maximum Inspiration (SMI), ten global lung expansion, secretion removal techniques, supported or assisted coughing. The above techniques were put in a program, and all exercises were performed in two sessions per day, while the SMI was performed six times per day, five sets with 30-60 seconds rest between each set. The results of the study showed that the presence of atelectasis occurred 48hours after surgery. The PPTT group had a 17.3% of atelectasis, while the non PPT group had 36.3%. The study also showed that a relationship existed between atelectasis and patient gender, and that 21.8% was found in females while 37.5% in males 3.
Another study performed by Erik H. J. Hulzebos, focused on two primary outcomes. One was post operative complications, which is pneumonia. The second outcome measure is the post-operative pulmonary complications (PPC), which include the influences of morbidity and mortality rate, the length or duration of stay at hospital, and the overall resource utilization. The interventions used in this study included such as IMT and IS, while the techniques included are patient education in active cycle of breathing techniques and Forced Expiratory Techniques (FET). The program followed within the study was the use of FET and performing it on daily basis seven times per week for duration of two weeks before surgery, and the IMT was done for twenty minutes, six times per week without supervision and once per week with PT supervision. The result of the primary outcome measure is that18% (25 of 139) of the patients from the IMT group developed PPC, while patient 35% (48 of 137) of usual care group developed PPC. The incidence of pneumonia was less in the IMT group whom had 6.5% (9 of 139). While on the other hand the usual care group had a higher incidence which was 16.1% (22 of 137).The usual care group had also another complication, where 3 of the 22 patients developed respiratory failure and died after surgery as a result of cardiac failure, while none of the IMT patients died. The study concluded that preoperative physical therapy reduced PPC by 50%. The study suggests that no a single PT techniques or intervention is better than the other in preventing PPC. Pre-operative PT has increased inspiratory force, decreased the incidence of PPC and hospitalization, and reduced morbidity 1.
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Post-operative Physical Therapy Management
Post operative complications are common in patients undergoing cardiothoracic surgeries. According to Agnieszka Piwoda et al, the fundamentals to a properly designed and conducted cardiac surgery, is physical therapy management 6. To minimize postoperative complications, physical therapy management is introduced. Postoperative physical therapy (POPPT) starts the instant the patient is transferred from the operating room to the intensive care unit (ICU), which lasts 1 to 2 days and is continued in the ward from 2nd day till the date of discharge which is the 7th day 6.
During the patients stay at the ICU postoperative, physical therapy rehab is aimed towards the reduction of airway obstruction, increasing and enhancing ventilation-perfusion matching, which is also known as gas exchange (VQ matching), restoring normal gasometrical values which when by doing so, the patient is prevented from re-intubation 6, decreasing ventilatory failure where the patient becomes dependent to the mechanical ventilator 3, and preventing thrombo-embolitic changes altogether leading to a decrease in ICU stay. The ward rehab starts when the patient gains early extubation; this allows the patient to regain contact with reality. During this period the physical therapist is able to eradicate secretion accumulation, and rapidly mobilize or ambulate the patient 6. Maintenance of permanent and intensive mobilization will improve cardiopulmonary tolerance, leading to an increase in physical endurance and patient independence, therefore reducing hospital stay 7.
Most of the studies involving a majority of patients undergoing CABG are focused on reducing basilar atelectasis and pneumonia and hypoxemia 7 by applying specific post operative physical therapy objectives such as recruiting lung tissue from shunt to zone of low ventilation in relation to perfusion 8, increasing lung capacities especially FVC and FEV8, decreasing respiratory muscle dysfunction 3, increasing respiratory muscle function “diaphragm” 6, restoring thoracic breathing manoeuvres by strengthening postural and respiratory muscles, and endorsing effective breathing patterns by reducing the work of breathing 7.
To achieve optimum results and regain the inclusive functional independency, POPPT management should include airway clearance techniques, early mobilization, bed mobility and positioning, breathing exercises (BE), and patient education. Specific post operative physical therapy techniques such as the use of intensive deep breathing exercises and devices such as IS, and IMT should be emphasized when rehabilitating post CABG patients. Prior to POPPT, an extensive patient evaluation similar to the preoperative assessment should be performed. When assessing the patient problems, goals should be set and are treated accordingly.
Airway clearance techniques
A manual or mechanical procedure that assists in clearance of secretion from the airways is known as Airway Clearance Techniques (ACT) 9. ACT is indicated for impaired mucociliary transport or an ineffective and unproductive cough. When choosing an ACT the patient’s pathophysiology, symptoms and medical status should be taken in consideration. The techniques included in ACT are Postural Drainage (PD), manual chest clearance, and coughing.
PD is a technique that drains secretion by gravity assistance, and the use of more than one body position. There are 12 positions used during PD 9, in each position the segmental bronchus is drained perpendicular to the floor. These positions can be modified according to the patient’s medical status. The most affected segment should be prioritized. The patient is positioned using an adjustable bed, pillows or blanket rolls, and enough personnel to assist in moving the patient safely. PD is used for approximately 5-10 minutes solely and longer if tolerated 9.
Manual chest clearance technique is the application of manual supplementary techniques such as vibration, percussion, and shaking to postural drainage positions 10.
Coughing technique is a forceful airstream method used to remove secretions out through the trachea and to the mouth. Coughing technique is performed in four stages, and may be applied before, during and after PD and manual chest clearance techniques. In CABG patients, the coughing technique is supported using splinting. This is done is applying pressure to the incision site either by using a pillow or a belt. This techniques helps with decreasing the pain associated with the surgery.
Early mobilization
Early mobilization or ambulation is the method used to set patients in motion postoperatively by using the assistance of PT. The patient mobilization process is performed gradually and according to the patient’s tolerance. Mobilization starts by sitting the patient from supine to a long sitting position. Then when further stability is regained the patient is positioned on the edge of the bed. The patient is then progressed to standing, and later when the patient regains more stability, walking is initiated.
Positioning
Positioning is a therapeutic and ventilatory movement that is used to assist the patient in regular changing of position while in bed. It is essential in the patient early stages of recovery. Positioning allows the patient to progress from dependence to independence. The technique involves the selection of certain positions to assist the patient with efficient and diaphragmatic breathing patterns. The technique is indicated for patients with diaphragmatic weakness, patients unable to correctly use the diaphragm for efficient inspiration, or who have inhibition of diaphragm muscle due to pain 9. The training usually commences in the ICU. An example used by Sadowsky et al on positioning is the performance of ROM exercise with breathing. The exercise is performed by the patient inspiring air and accompanying it with shoulder flexion, abduction, external rotation, and eyes in an upward gaze. Then the patient exhales with shoulder extension, adduction, internal rotation and downward gaze. In addition to the exercise the patient is asked to tilt the pelvis posteriorly. This allows diaphragmatic breathing pattern and optimizes the length-tension relationship of the diaphragm 9. This technique progression should be applied to transfer, ambulation, and stair climbing. This technique is highly recommended for patient patients that underwent CABG since they are likely to have 90.7% of diaphragmatic elevation 11.
Breathing exercises
Breathing exercises are maneuvers used for patients with signs and symptoms of decreased strength or endurance of the diaphragm and intercostal muscles 9. There are many breathing exercises one of them is known as the Active Cycle of Breathing Technique (ACBT) 10. ACBT includes a group of breathing techniques such as breathing control, thoracic expansion exercises, and forced expiration technique. Other methods that assist BE are respiratory devices such as Inspiratory Muscle Trainers (IMT) and Incentive Spirometry (IS). Respiratory devices are mechanical equipments used in attempt to reduce postoperative pulmonary complications particularly atelectasis and pneumonia. BE and respiratory devices are suggested for patients at high risk of having atelectasis such as CABG patients, whom are for 24.7% of postoperative atelectasis 9, 11.
A study performed by Elizabeth Westerdahl investigated the effect if deep breathing exercise on pulmonary function, atelectasis, and Arterial Blood Gases (ABG’s) after CABG. The study was performed on two groups, the first group was the deep breathing group and the second was the control group. Both groups were approached similarly in assessment, positioning, and mobility once or twice daily during the first 4 postoperative days. Chest PT was done twice in the first 4 post-op days, the therapy includes early mobilization, instructions in coughing techniques, and daily active exercises of the shoulder girdle, upper back, and assistance to turn form side to side and get out of bed. The deep BE group received an extra program, performing breathing exercises every hour during the day for four postoperative days. The exercise used is, 30 slow deep breaths with PEP blow bottle device, a 50cm plastic tube in a bottle containing 10 cm of water. The exercise was performed sitting; it is 3 sets of 10 deep breathing exercises with 30-60 seconds pause between each set. If needed, patient coughs during the pause to mobilize secretion. The result of the study illustrate that atelectasis was found in large areas at basal level close to the diaphragm and minor at the upper level near the apex. There was a significant decrease in atelectasis in deep breathing group by one half compared to the control group, and the correlation between PaO2 and atelectasis was weak. Recruited lung tissue is most likely converted from shunt regions to zones with low ventilation in relation to perfusion. In conclusion, Patients who performed deep-breathing exercises had a significant smaller atelectasis, and less reduction in FVC and FEV on the 4th post-op day. 8
Patient education
Patient education which is an integral part of the post-operative physical therapy management is applied similarly to the preoperative patient education program. When educating a patient in the post-operative period, the instructions given should highlight the thought of improving quality of life by emphasizing on points such as having healthy eating habits, ceasing smoking, achieving independence, and accentuating the benefits of rehab, and returning back to ADL. Patients should also improve their physical education by participating in other therapies that have been introduced such as tai chi, PNF, NDT Bobath and music therapy 6.
Conclusion
As PPC has been of great concern to health professionals, the reduction of complications that accompany major surgeries such as CABG is of an important development. The main objective in physical therapy with regard to CABG is to reduce PPC by intervening with less invasive protocols. The combination of both pre-operative and post-operative physical therapy management has had effective results in managing CABG patients.
The reduction of PPC by the use of preoperative physical therapy management has led to many advantages. Some of them are significant reduction in mechanical ventilators duration therefore reducing the duration of ICU stay, reduced hospitalization, decreased morbidity and mortality rate, enhanced early functional recovery, improved lung function and gas exchange. Such accomplishments are significant, but more studies have to be performed to develop PPTT programs and provide a certain protocol
The reduction of PPC by the use of postoperative physical therapy has lead to the best outcome of treatment. It has decreased complications associated with surgery and reduces PPC, allowing the patient to regain maximum physical condition, reducing ICU and hospital stay by achieving physical and functional independence therefore assisting the patient in regaining better-quality of life 5. The patient can further continue physical therapy at the cardiac facility to promote additional cardiopulmonary conditioning.
In Kuwait, post-operative PT management is more widely-used than preoperative. During my investigation I found out that the chest hospital is aware of the preoperative management and is applying it, but in an informal way. I would like to call attention to the use of post-operative PT management in association with pre-operative physical therapy management to help the patient have a better surgical outcome, regain maximal independence and improve the quality of their life.
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