WHY ITS NEEDED ?
By. dr. Deddy Tedjasukmana , SpKFR-K,MARS
INTRODUCTION
Postoperative pulmonary complications contribute significantly to overall perioperative morbidity and mortality rates. Pulmonary complications occur much more often than cardiac complications in patients undergoing elective surgery to the thorax and upper abdomen. The frequency rate of these complications varies from 5-70%. Postoperative pulmonary complications prolong the hospital stay by an average of 1-2 weeks. Postoperative pulmonary complication is defined as an abnormality that produces identifiable disease or dysfunction, is clinically significant, and adversely affects the clinical course. Complications may arise from atelectasis, infection (eg, bronchitis, pneumonia), prolonged mechanical ventilation and respiratory failure, exacerbation of an underlying chronic lung disease, and bronchospasm.
Several published studies include complications that have no clinical significance. However, recent studies define postoperative pulmonary complications as the events influencing outcome following surgery. These include complications either known to prolong the hospital stay or known to be responsible for morbidity and mortality.
Specialised skills of Rehabilitation Medicine is concern in respiratory assesment and treatment especially in pre and post operative, assesment of functional capacity and identification of factors limiting eg fatique, shortness of breath, weakness, anxiety, ischemic pain, orthopedic limitation etc. Education of patients and cariers in exercise, prescription of individualised exercise program and early mobilisation in ward is important for patients after thoracic and upper abdominal surgery.
SURGERY AND THE RESPIRATORY MUSCLES
Respiratory muscles are the only skeletal muscles vital to life. Surgical procedures can affect the respiratory muscles by a number of pathophysiological mechanisms including thoracoabdominal mechanics, reflexes, neuromechanical coupling, and loss of muscular integrity. Impairment of respiratory muscle function after surgery may lead to postoperative complications such as hypoventilation, hypoxia, atelectasis, and infections, some of which may be life threatening.
The most important function of the respiratory muscles is breathing since they are the motor arm of the respiratory system. Breathing, a lifelong task, is borne mainly by the inspiratory muscles, especially the diaphragm. A second function of the respiratory muscles is to perform explosive manuvers such as coughing and vomiting. The respiratory muscles also have a role as stabilizers of the thorax and abdomen since they take part in the formation of the thoracic and abdominal walls.
A surgical incision of the chest or abdominal wall affects the integrity of the respiratory muscles and thus directly affects their function. It is well known that dysfunction of the respiratory muscles due to surgery may lead to a reduction in the vital capacity and tidal volume, total lung capacity and, thus, insufficient cough. This may cause atelectasis in the basal lung segments and a decrease in functional residual capacity which, in turn, affects the gas exchange properties of the lung by increasing the ventilation/perfusion mismatch.
The situation maybe further aggravated by hypoventilation due to several factors including sedation, pain, and increased mechanical load. As a result, hypoxia may ensue with a detrimental effect on the condition of the patient. In addition, atelectasis maybe a risk factor for pulmonary infections which have significant morbidity and mortality in this patient population. In severe cases these consequences of respiratory muscle impairment may lead to respiratory failure and death.
RISK FACTORS
· Age
Despite early suggestions of an increased risk of pulmonary complications with advanced age, this is not an independent risk factor for pulmonary complications. In a study of patients older than 80 years, the overall 30-day mortality rate was 6.2% . Several other studies have shown that age is not a predictor for postoperative pulmonary complications; therefore, surgery should not be declined because of advanced age alone.
· Obesity
Obesity decreases the expiratory reserve volume and functional residual capacity of lungs; morbid obesity causes restrictive lung disease, decreases thoracic compliance, and leads to alveolar hypoventilation. In severe cases, obesity is associated with pulmonary hypertension, cor pulmonale, and hypercapnic respiratory failure. Obesity causes a reduction in lung volume, ventilation-perfusion mismatch, and relative hypoxemia, which are accentuated after surgery. Obesity increases the risk of postoperative pulmonary complications and respiratory failure in patients undergoing abdominal surgery, but it may not be a risk factor in thoracic surgery.
· General health status
Patients who have poor exercise capacity are at increased risk of developing postoperative pulmonary complications. In a study by Gerson et al in 1990, an inability to raise the heart rate with simple exercise predicted a pulmonary complication rate of 79%.
· Smoking
Patients who currently smoke have a 2-fold increased risk of postoperative complications, even in the absence of COPD. The risk is highest in patients who smoked within the last 2 months. Patients who quit smoking for more than 6 months have a risk similar to those who do not smoke. Warner et al prospectively investigated the role of preoperative smoking cessation on postoperative pulmonary complications in patients undergoing coronary artery bypass surgery. Those who currently smoked developed postoperative complications at a rate of 33%, compared with 57% for individuals who quit for less than 8 weeks. The complication rates were 11.9% in persons who never smoked and 14.5% in patients who had quit for more than 8 week
· Chronic obstructive pulmonary disease
This is one of the most important risk factors. Patients with severe COPD (forced expiratory volume in 1 s [FEV1] <40% predicted) are 6 times more likely to have a major postoperative complication. Despite the increased risk, a prohibitive level of pulmonary function for an absolute contraindication is not apparent. The benefits of surgery must be weighed against these complications. A careful preoperative evaluation of patients with COPD should include identification of high-risk patients and aggressive treatment. Elective surgery should be deferred in patients who are symptomatic, have poor exercise capacity, or have acute exacerbation.
· Asthma
Inadequate control of asthma preoperatively may increase the risk of postoperative complications. Optimal asthma control is defined as the absence of symptoms and an FEV 1 of more than 80% of predicted or personal best.
PROCEDURE-RELATED RISK FACTORS
Ø Surgical site
The incidence of complications is inversely related to the distance of the surgical incision from the diaphragm. The complication rates for upper abdominal surgery range from 17-76%. For lower abdominal surgery, the rate is 0-5%. For thoracic surgery, the rate is 19-59%.
Ø Duration of surgery
Patients undergoing procedures lasting longer than 3-4 hours have a higher incidence rate of pulmonary complications compared to those undergoing surgeries lasting shorter than 2 hours (40 vs 8%).
Ø Type of anesthesia
Data are inconsistent about whether the complication rate is lower with spinal or epidural anesthesia compared to general anesthesia. A study published in 1984 (Celli, 1984) reported no difference in patients anesthetized with spinal or general anesthesia for abdominal surgery. A study of high-risk patients shows that the rate of respiratory failure is significantly higher with general anesthesia (Tarhan, 1973). Several other studies (Yeager, 1987; Pedersen, 1990) found high rates of respiratory failure and other postoperative complications in patients undergoing general anesthesia compared to spinal or epidural anesthesia. The spinal or epidural anesthesia is safe and should be considered in high-risk patients.
Ø Keyhole surgery
These techniques use small incisions, and the reduced manipulation of visceral organs minimizes the adverse effects on respiratory muscles. Smaller incisions, performed without separation of the ribs and resulting in less postoperative pain, lead to early ambulation and reduced pulmonary complications.
PREOPERATIVE EVALUATION
à History
Obtain a complete history and perform a complete physical examination to help identify risk factors. Seek any history of smoking, exercise intolerance, unexplained dyspnea, or cough. Note evidence of COPD, such as decreased breath sounds, wheezes, crackles, or a prolonged expiratory phase.
à Pulmonary Function Tests
Several retrospective studies of routine preoperative pulmonary function test (PFT) results found only a marginal benefit in predicting postoperative complications in patients, other than those undergoing lung resection. Therefore, the results from PFTs should not be the sole reason to alter plans for necessary surgery. These could be used to identify high-risk patients for whom aggressive perioperative management is warranted. The American College of Physicians consensus statement suggests the following indications for preoperative PFTs: patients undergoing cardiac or upper abdominal surgery with a history of smoking or dyspnea, patients undergoing lower abdominal surgery if dyspnea or history of smoking indicates prolonged surgery, all patients undergoing lung resection, additionally, indications for preoperative PFTs have been suggested as follows: age older than 60 years, positive smoking history and presence of pulmonary diseases
à Spirometry
Bedside spirometry is an often underused but extremely useful tool for objectively evaluating the respiratory status of patients preoperatively. Spirometry can be used to predict postoperative complications and to guide optimization of airflow obstruction in preparation for surgery. Gass and Olsen (1986) suggested high postoperative risk in patients who had an FEV1 of less than 70% predicted, an FVC of less than 70% predicted, and FEV1-to-FVC ratio of less than 65%.
à Chest Radiograph
Chest x-ray studies add little to the clinical evaluation in healthy patients. All patients older than 60 years or those with clinical findings of cardiac or pulmonary disease should have a preoperative chest x-ray film taken unless they had one in the last 6 months.
à Exercise Testing
A comprehensive physiologic evaluation is dependent on the interaction among pulmonary function, cardiovascular function, and oxygen use. This may take the form of stair climbing or complete cardiopulmonary exercise testing.
Complete cardiopulmonary exercise testing may help identify patients who achieve a maximal oxygen consumption (VO2 max). Expressing VO2 max as mL/kg may be more useful. A VO2 max of more than 20 mL/kg/min is associated with the fewest postoperative complications
Complete cardiopulmonary exercise testing may help identify patients who achieve a maximal oxygen consumption (VO2 max). Expressing VO2 max as mL/kg may be more useful. A VO2 max of more than 20 mL/kg/min is associated with the fewest postoperative complications
Thoracic and upper abdominal surgery is associated with a reduction in vital capacity by 50% and functional residual capacity by 30%. Diaphragmatic dysfunction, postoperative pain, and splinting cause these changes. Following upper abdominal surgery, patients shift to a breathing pattern with which ribcage excursions and abdominal expiratory muscle activities increase. This shift is attributed to decreased central nervous system out put to the phrenic nerves, thus inhibiting diaphragmatic stimulation. A reflex mechanism arising from the sympathetic, vagal, or splanchnic receptors is thought to be responsible. In humans, this reflex inhibition is partially reversed by epidural anesthesia.
Following upper abdominal and thoracic surgery, patients maintain adequate minute volume, but the tidal volume is smaller and the respiratory rate increases (ie, rapid shallow breathing). These breathing patterns, along with the residual effects of anesthesia and postoperative narcotics, inhibit cough, impair mucociliary clearance, and contribute to the risk of postoperative pneumonia.
Patients who are unable to be frequently mobile in the ward and are at risk of developing atelectasis, should be encouraged to carry out regular thoracic expansion exercise preferably with an end inspiratory hold of afew second, regulary breathing exercise can be used .
The postoperative manouever of a 3 second hold at full inspiration has been said to decrease collaps of lung tissue. Thoracic expansion exercise can be encoaraged with proprioceptive stimulation by placing a hand, either the patients or therapist, over the part of the chest wall where movement of the chest is to be encouraged.
Beside deep breathing exercises, incentive spirometry appear to be equally effective, there are components of chest physical therapy and have been shown to reduce postoperative pulmonary complications following thoracic and upper abdominal surgery
2. Pain control
Adequate postoperative pain control helps minimize pulmonary complications by encouraging earlier ambulation and performance of lung expansion maneuvers. Acut pain is a complex proces affected by the physiologicsl reaction of desease , as well as physiological and social factor. An individuals perception of pain, may depen on his previous experience of pain as well as his current degree of control over his particular situation.
It is essential that pain relief is manage well , especially over the immediate post operative period when the patientmay be spending more time in bed or chair than walking around the ward . If postoperative pain is not managed appropriately the following effects may occur increased anxiety, increased heart rate and blood pressure, decreased movement therefore increased risk of deep pain thrombosis, and increased respiratory complication .
Rehabilitation medicine is concern with advise on positioning, moving and wound support, is also beneficial. Techniques which promote relaxation such as self hypnosis. Modality Trans electrical nerve stimulation (TENS) can be use for alternatively to medication.
3. Mucus clearance
Mucus hypersecretion is one of determinants of post operative pulmonary com-plikcations. The proposed mechanisms for pathogenesis of post operative pulmonary abnormalities have altered litle since early 20 th century. There are still two basic theories to explain their occurrence : regional hypoventilation and stasis of mucus. Regional hypoventilation there are several physiological factors that may contribute to alveolar closure, these relate to reductions in functional residual capacity. The consequences of the reduction in functional residual capacity are reduced lung complience, altered surfactant proverty, impaired gas exchange, retension of lung secretion and atelectasis.
Stasis of mucus may be aresult of changes in the cardiorespiratory phisiology during the post operative periode. Leith and Bouros in research that effective cough is important for transfort and expectoration of lung mucus and essenstiale elements in the prevention and treatment of problem of mucus clearence is breathing exercice and manual control expiratory maneuvers.
Cough efficiency is thought to improve as mucus viscosity decrease and periciliary fluid increase . Nebulized have been shown to accelerate mucociliary clearence, this effect is usually attributed to rheological alteration in the sputum allowing improved transfortation by the cilia.
4. Prevention of thromboembolism
Prevention of deep venous thrombosis is important for all major surgeries .Risk is also high in elderly persons . Exercise training has been shown to increase blood flow to the lower extremity, other possible mechanisms for improvement include redistribution of blood flow to prevent thromboembolism .
5. Early mobilitation
With the development of surgery many patients are often able to mobilize indefendently from a very early stage postoperatively. Some patients will requare assistence because of the presence of the various drips and drains and it is sometimes safer to have assisting for the first stand or walk if the patients general fatique and the risk of postural hypotension.
Advice on optimum and regular change of position while the patient in bed is essensial for patients in the early stages of recovery. Suitable seating at a height appropriate to the individual can also improve patient independence, particulrly for those patients after thoracic and upper abdomonal surgery who find it difficult to move from sitting in alow chair to standing but are fully indefendence once up on their feet. Walking short distance can begining around bed and than walk slowly in hall.
SUMMARY
Surgery may affect the function of respiratory muccle in a number of ways. Some types of surgical procedure adversely influence respiratory muscle function while others have a favourable effect.
Preoperative respiratory mucle training may prevent post operative pulmonary complications by increasing both inspiratory and expiratory muscle strength in patients undergoing thoracic and upper abdominal surgery.
The following post operative measures help minimize pulmonary complication in at-risk patients eg measure to improve vital capacity, deep breathing and couging, adequate pain control, bronchodilators etc.
During the postoperative period and depending on the type of surgery performed, deep breathing exercise, lung expansion maneuver, mucus clearence with effective cough may be used to prevent complications. Finally early mobilisation is main factors contributing normaly funtion every patients post operative prosedure.
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