A 69-year-old woman with a history of chronic obstructive pulmonary disease (COPD), current smoker with a 20-pack/year history of smoking, hypertension, and abdominal aortic aneurysm (AAA), was admitted to the ICU after requiring emergency surgery for a leaking AAA. The patient arrived in the ICU endotracheally intubated and sedated. She was weaned from the ventilator within the first 24 hours after surgery. An aggressive respiratory care bundle was instituted and the patient was transferred out of the ICU within 48 hours.

Figure. No caption available.

All patients are at risk for postoperative pulmonary complications (PPCs) following anesthesia and surgery. The degree to which PPCs pose a problem is dependent on the patient's health-related risks and the type of surgery and anesthesia. The most clinically significant PPCs are infection (including bronchitis and pneumonia), prolonged mechanical ventilation, respiratory failure, atelectasis, bronchospasm, and COPD exacerbation.1

Defining the problem

PPCs are as common as cardiovascular events, with an incidence of approximately 2% to 5%. Among the PPCs is pneumonia, a frequently occurring healthcare-associated infection, second only to urinary tract infections.1-4,5

Several anesthetic agents alter the balance between the elastic recoil pressures of the chest wall and the lung wall, leading to reduced lung volumes and compliance. This results in a greater tendency for atelectasis, especially in the dependent parts of the lungs. These alterations can lead to a ventilation-perfusion mismatch, impaired gas exchange, and hypoxemia.6 Anesthetics alter the consistency of secretions, as well as the ability to eliminate the secretions, which increases the patient's risk for pneumonia. Viscous secretions that are present after surgery are, in most cases, directly related to the type of anesthetic agent that was used during the surgery.7

The type of surgical incision and the invasiveness of the surgical procedure can also pose a risk for PPCs.6 Atelectasis and pneumonia are common causes of PPCs particularly after abdominal and thoracic surgery.

Patients who smoke have an increased risk for postoperative infection and mortality. Smoking cessation at least a year before major surgery substantially reduces the mortality and the pulmonary events associated with cigarette smoking.8 Prolonged exposure of the airways to cigarette toxins leads to bronchoconstriction, reduced mucociliary clearance, thickening of the mucus-secreting membrane, dilated distal airways, and destruction of alveolar walls and macrophages.7,9 These structural and functional changes that occur secondary to smoking result in the alveolar spaces filling with exudate and an additional insult to pulmonary function.

With knowledge of the epidemiology and risk factors, patient-care plans can be designed to decrease the incidence of PPCs.10

Understanding the pathophysiology of postoperative pneumonia

Postoperative mucus plugs and decreased surfactant production are directly related to anesthetic agents, hypoventilation, immobility, ineffective coughing, and extensive smoking history, which lead to atelectasis.7,9

Due to the effect of anesthetic agents, concentrated oxygen, and position during surgery, the patient can develop absorption atelectasis and impaired surfactant, which leads to a reduction in alveolar surface tension. Consequently, lung expansion is compromised, and collapse of the dependent alveoli ensues.9,11

Most patient positions during the intraoperative period contribute to shifting of abdominal viscera upward toward the diaphragm. This results in upward displacement of the diaphragm. These alterations reduce ventilatory force and tidal volume.12

Patient risk factors, including anesthetics and smoking, favor colonization of microorganisms that triggers an acute inflammatory and immune response and subsequent increased mucus production, respiratory membrane thickening, increased work of breathing, and impaired gas exchange.9 (See Risk factors for postoperative pneumonia.)

Clinical manifestations

The clinical presentation of HAP and VAP can be variable but should be suspected in patients with a new or progressive pulmonary infiltrate on radiographic imaging plus fever, purulent sputum, leukocytosis, or hypoxemia. Physical assessment findings may include a dull percussion note, bronchial breath sounds, late inspiratory crackles or rhonchi, and increased tactile fremitus and transmitted voice sounds over the involved lung area(s). Alteration in breathing patterns, such as dyspnea and tachypnea, may occur. Blood and sputum cultures are often positive and are a standard part of the diagnostic evaluation.13 (See Types of pneumonia.)

Preventive strategies for postoperative pneumonia

The critical care nurse should institute evidence-based practices to prevent postoperative pneumonia. Patients with risk factors for HAP should be assessed and monitored closely as part of prevention. Preventive strategies for postoperative pneumonia should be approached as care bundles. A bundle is a structured way of improving care by collectively and reliably performing a set of evidence-based practices to improve patient outcomes.26

It's important to educate the patient about the following five major interventions that have proven to decrease HAP. These interventions are performed as a care bundle for their synergistic effectiveness and include:

* deep-breathing exercises and use of the incentive spirometry (IS)

* coughing

* positioning

* early mobilization and ambulation

* optimal pain management.22

Deep breathing and IS

One of the major factors contributing to postoperative pneumonia and related complications is reduced lung volumes resulting from a shallow, sighless breathing pattern caused by the effects of general anesthesia, analgesia, and pain. Teach the patient to take three or four deep breaths every 5 to 10 minutes. Full lung expansion is important, and every effort must be made to enhance the patient's ability to accomplish it.14 These deep breaths stimulate the release of surfactant from type II alveolar cells, which favors alveoli expansion.9

Deep breathing and IS assist with secretion clearance. They also promote the release and distribution of surfactant that reduces alveolar surface tension and favors alveolar reexpansion after surgery. Deep breathing also opens the pores of Kohn leading to ventilation of the collapsed alveoli from well-ventilated alveoli.9 IS also promotes deep breathing, lung expansion, and improved gas exchange. It should be performed 10 times each hour while awake in combination with deep-breathing exercises. Whenever possible, the patient should be taught how to use the incentive spirometer, as well as coughing and deep-breathing exercises, preoperatively. However, an updated Cochrane review failed to support an advantage of independent use of IS over other techniques.15 Based on this evidence, it's recommended that IS be combined with deep-breathing exercises.

Coughing

An effective cough clears the airway of secretions. During the early and intermediate postanesthesia recovery period, the use of the cascade cough technique is a very effective maneuver to promote airway clearance of thick secretions.14 Teach patients to take a slow, deep breath, hold their breath for 2 seconds, then perform a series of coughs from the beginning to the end of expiration, followed by breathing slowly and resting. This technique is most effective when performed in a sitting position. Adequate pain management and splinting of incisions facilitate coughing. In the case where the patient is unable to sit in a chair or upright in bed, place the patient in a side-lying position with hips and knees flexed, or in a semi-Fowler position with the head and arms supported with pillows and the knees flexed. These alternative positions lessen abdominal tension and still permit complete movement of the diaphragm, improving the effectiveness of the cough.14

High-risk postoperative patients may benefit from the use of devices that assist in clearing secretions. The devices are used in concert with respiratory care bundles. Collaboration with respiratory therapy can assist the ICU nurse in selecting a device that is appropriate for their patient. Incorporating its use in to the patient's plan of care can greatly reduce the incidence of pneumonia in at-risk populations.

Positioning

Upright patient positioning promotes and facilitates lung expansion, maintains an unobstructed airway, prevents aspiration, and favors airway clearance. Regular repositioning also contributes to mobilization of secretions that stimulates coughing and deep breathing as well as decreases atelectasis.14

Mobilization and early ambulation

Despite few studies conducted to support early ambulation, fast-track recovery after surgery, reported by the Cochrane database, included early ambulation as part of the program.16

Patient mobilization promotes movement of secretions in the lung, which stimulates coughing and deep breathing and leads to clearance of thick secretions and production of surfactant, decreasing alveolar surface tension and atelectasis. It also contributes to lung expansion and decreases hypoventilation in the postoperative patient. In the postoperative fast-track recovery program there isn't a consensus of how to define early ambulation.16,17

However, depending on surgery and patient condition, early ambulation can be safely initiated as early as 4 to 8 hours after recovery from general anesthesia.18

Pain management

A major consideration in the postoperative patient is optimal pain management. Because certain opioids depress the cough reflex, mucociliary escalator, and the respiratory center, they shouldn't be used indiscriminately.14

In addition to making sure the patient is being properly treated for pain, the identification of sedation and respiratory depression secondary to opioids such as I.V. fentanyl and morphine is key. Pain related to high-risk surgical procedures has been associated with a decrease or elimination of the normal sigh mechanism, which further negatively affects lung expansion, lung volume, and, ultimately, leads to atelectasis and pneumonia.14,19

The ICU nurse should be aware of the synergistic effects of the medications used during surgery with those prescribed for postoperative pain management. In some cases it may be necessary to decrease the dose or change the type of analgesia administered during the first 24 hours following general anesthesia, but this decision must always be based on the patient's report of pain and clinical status.14

Preventive strategies for postoperative VAP

Both the CDC and the Institute for Healthcare Improvement have established evidence-based care bundles to prevent VAP. The general elements of the bundle include hand hygiene compliance, elevation of the head of the bed to 30[masculine ordinal indicator] to 45[masculine ordinal indicator] unless medically contraindicated, daily sedation vacations and assessment of readiness to extubate, continuous suctioning of subglottic secretions, daily oral care with chlorhexidine, peptic ulcer disease prophylaxis, deep venous thrombosis prophylaxis, and not routinely changing, on the basis of duration of use, the patient's ventilator circuit.20-22,26,27

Conclusion

As evidence-based practice continues to evolve, nursing care to prevent pneumonia in the postoperative patient will lead to improved patient outcomes and decreased ICU length of stays and healthcare costs. The critical care nurse's knowledge of the patient's risks and evidence-based interventions such as respiratory care bundles is essential.

Risk factors for postoperative pneumonia

Preoperative considerations involve identifying the patient's risk factors for postoperative pneumonia. Risk factors include general anesthesia; age greater than 65; an extensive smoking history; obstructive sleep apnea (OSA), COPD, and immunocompromise. Thoracic (open) surgery, aortic surgery, and upper abdominal surgery are the major surgical procedures that increase the risk of PPCs. These procedures are considered greater risk factors than the patient's health-related conditions.2,7,25

Special attention needs to be given to the aging adult during the perioperative phase and especially during the postoperative period. Aging is accompanied by a decrease in pulmonary and renal function. Age-associated changes in the pulmonary system include decreased respiratory muscle strength, reduced thoracic compliance, and decreased cough reflex. Age-associated changes in the renal system include decreased kidney mass and reduced glomerular filtration rate. These alterations lead to an increased work of breathing and a decreased ability to eliminate drugs used during surgery. As a result of these changes, the older adult is at increased risk for postoperative pneumonia.7

Central to the critical care nurse's plan of care is the recognition of the risk of aspiration pneumonia. Anesthetic agents, pulmonary secretions, and postoperative nausea and vomiting work synergistically to increase the patient's risk of developing aspiration pneumonia. Aspiration pneumonia creates the additional risk of pneumonitis, which poses an additional risk for an already compromised patient.14,28 The risk of developing postoperative pneumonia further increases if pain isn't well managed. Suboptimal pain management can result in shallow breathing and hesitancy for patients to change position. These factors increase the tendency for pooled secretions in dependent portions of the lungs, which further increases the risk of developing pneumonia.2

Types of pneumonia

Pneumonia involves an acute inflammatory process of the lung parenchyma caused by infectious agents that can lead to alveolar consolidation and pulmonary infiltrates. Pneumonia is classified as community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), or healthcare-associated pneumonia (HCAP). CAP is defined as pneumonia acquired in the community. If pneumonia occurs 48 hours or more after hospital admission and didn't appear to be incubating at the time of admission, it's referred to as HAP. HAP is a frequently occurring healthcare-associated infection that increases the length of stay for ICU patients.

VAP is a type of HAP that develops more than 48-72 hours after endotracheal intubation.14 VAP accounts for 25% of the infections occurring in critically ill patients and is the reason for half of the antibiotics used in mechanically ventilated patients.23 Length of stay is often increased 7-9 days as compared with patients without VAP. Healthcare costs may increase up to $40,000 for this subset of patients.24

The literature has identified pneumonia's contribution to increased costs in the ICU setting. Pneumonia also greatly impacts patient morbidity and mortality. It's estimated that pneumonia is associated with a mortality of 8% to 15%.23

HCAP is defined as pneumonia that occurs in a nonhospitalized patient with extensive healthcare contact, including I.V. therapy, wound care, or I.V. chemotherapy within the preceding 30 days; residence in a long-term-care facility; hospitalization in an acute care hospital for 2 or more days within the previous 90 days; or attendance at a hospital or hemodialysis clinic within the previous 30 days. This article focuses on HAP and VAP in the postoperative setting.

REFERENCES