Pulmonary Medicine

Preoperative Pulmonary Assessment of Patients Undergoing Non-Thoracic Surgery

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What every physician needs to know:

Postoperative respiratory complications are a significant cause of morbidity and mortality after surgery. Effective management of patients at risk for respiratory difficulty after surgery requires knowledge of the predictable changes in pulmonary physiology that are associated with surgery and anesthesia, as well as an awareness of the factors that may increase a patient’s risk for development of postoperative respiratory compromise.

Although several screening tests are available, a careful history and physical examination remain the essential elements of preoperative pulmonary evaluation. A number of interventions, both before and after surgery, may help to minimize the risk of postoperative pulmonary complications. However, the focus of care in all patients after surgery is close monitoring and early detection of emerging respiratory complications.


Not applicable.

Are you sure your patient has a postoperative pulmonary complication? What should you expect to find?

Postoperative pulmonary complications include at least one of the following conditions: (1) atelectasis; (2) infection, including acute tracheobronchitis and pneumonia; (3) exacerbation of underlying chronic lung disease; (4) respiratory failure and or need for prolonged mechanical ventilation; (5) thromboembolic disease (although this problem is sometimes categorized as a cardiovascular complication).

Beware: there are other diseases that can mimic a postoperative pulmonary complication:

Not applicable.

How and/or why did the patient develop a postoperative pulmonary complication?

Many postoperative respiratory complications are an exaggerated manifestation of expected postoperative changes in pulmonary function that are the result of the surgery itself, anesthesia, or various pharmacologic interventions. These include the following:

A Restrictive Pattern of Pulmonary Function

The restriction is manifested by moderate to severe reductions in the vital capacity (VC) and smaller but more important reductions in the functional residual capacity (FRC) after thoracic and abdominal surgery. These findings may persist for up to a week or more after surgery. The restrictive physiology appears to be due in large part to diaphragm dysfunction. The derangement increases the risk of atelectasis, which may worsen oxygenation and increase the work of breathing.

Diaphragm Dysfunction

Diaphragm dysfunction may be the major contributor to reductions in lung volumes noted after abdominal and thoracic procedures. The precise mechanisms that underlie diaphragm dysfunction are not fully understood. Some evidence implicates a decrease in central nervous system output to the phrenic nerves that may be due to inhibitory reflexes triggered by sympathetic, vagal, or splanchnic receptors in the chest or abdominal cavities.

Impaired Gas Exchange Manifested by Hypoxemia

In the first twenty-four hours after surgery, hypoxemia is largely related to the residual effects of the anesthesia (alveolar hypoventilation, ventilation-perfusion mismatch, anesthetic-induced inhibition of hypoxic pulmonary vasoconstriction, right-to-left shunting, and depressed cardiac output).

Following thoracic and abdominal surgeries, hypoxemia is also due to processes that include decreased lung volumes (particularly FRC); alveolar hypoventilation induced by narcotic analgesics; increased dead space ventilation caused by rapid, shallow breathing; and decreased mixed venous oxygen tension that is due to increased oxygen consumption and decreased oxygen delivery from anemia and impaired cardiac output.

Respiratory Depression

In the early postoperative period, the residual effects of pre-anesthetic or anesthetic agents inhibit respiratory drive and ventilatory responses to hypoxia, hypercapnia, and acidemia. Subsequently, narcotics administered for postoperative pain depress both hypoxic and hypercapnic ventilatory responses, thereby decreasing minute ventilation and increasing PaCO2. In addition, narcotics reduce or even completely suppress sighs, and they precipitate sleep apnea in susceptible patients.

Impairment of Lung Defense Mechanisms (Cough and Mucociliary Transport)

Pain, muscle weakness, and excessive use of narcotics may suppress cough. An ineffective cough, atelectasis, presence of an endotracheal tube, and inhalation of anesthetic or dry, hyperoxic gas mixtures (which damage the cilia) act in concert to impair mucocillary clearance.

Which individuals are at greatest risk of developing a postoperative pulmonary complication?

Pulmonary risk factors related to surgery may be divided into preoperative, intraoperative, and postoperative factors:

Preoperative Risk Factors

The presence of respiratory symptoms, whether chronic, new, or changing.

Chronic lung disease, particularly chronic obstructive pulmonary disease (COPD) with an FEV1 less than 65 percent of predicted, or the presence of hypercapnia. Risk is also enhanced in patients with restrictive lung disease who are undergoing thymectomy for myasthenia gravis, lung resection for an aspergilloma, or corrective surgery for kyphoscoliosis.

Smoking, independent of its association with COPD, is an important risk factor. Smoking cessation for eight weeks or more is associated with a statistically significant reduction in postoperative respiratory complications. Concerns (based on retrospective studies) that stopping smoking for a shorter period of time before surgery paradoxically increases the risk of complications have not been confirmed by prospective studies.

Compromised state of health, with an American Society of Anesthesiologists (ASA) classification of II or greater is a predictor for postoperative respiratory problems.

Other risk factors

Respiratory tract infections, whether active or recent (within the last month).

Obesity, with the risk likely to be modest in the absence of coexisting cardio-pulmonary disease.

Malnutrition, which is likely to be a factor when severe, but aggressive preoperative nutritional support has not been shown to decrease the incidence of postoperative pulmonary problems.

Advanced age, with recent data suggesting that the risk increases significantly above age eighty.

Intraoperative Risk Factors

General anesthesia - General anesthesia is presumed to be a risk factor, although evidence is lacking that epidural or regional anesthesia decreases postoperative pulmonary complications.

Duration of anesthesia - Respiratory complications are more common in procedures that last more than four hours compared to those that last less than two hours.

Surgical site - The risk for postoperative pulmonary complications (excluding thromboembolism) increases in the following order: non-thoracoabdominal procedures (<1 %), lower abdominal surgery (<5 %), upper abdominal surgery (> 5 %).

Type of surgical incision. Respiratory complications are more common in patients who receive vertical, rather than horizontal, abdominal incisions, and open, rather than laparoscopic or thoracoscopic, procedures.

Postoperative Risk Factors

  • Immobilization

  • Inadequate pain control

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

A preoperative arterial blood gas analysis is indicated only in the setting of advanced lung disease.

What imaging studies will be helpful in making or excluding the diagnosis of a postoperative pulmonary complication?

Indications for a preoperative chest x-ray include new or unexplained respiratory symptoms or signs and chronic lung disease (and no recent chest x-rays).

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of a postoperative pulmonary complication?

Preoperative pulmonary function testing in the form of spirometry is indicated in the settings of:

  • Chronic obstructive pulmonary disease

  • Restrictive lung disease (for which lung volume measurements should also be performed)

  • Unexplained cough or dyspnea

  • Cigarette smoking (more than twenty pack-years)

What diagnostic procedures will be helpful in making or excluding the diagnosis of a postoperative pulmonary complication?

This section is not applicable to the discussion.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of a postoperative pulmonary complication?

This section is not applicable to the discussion.

If you decide the patient has a postoperative pulmonary complication, how should the patient be managed?

Management of postoperative pulmonary complications focuses on prevention and early detection.

Preoperative Interventions

  • Postponement of procedures for patients with recent or active respiratory infections.

  • Optimization of lung function in patients with decompensated COPD using bronchodilator and anti-inflammatory therapy.

  • Smoking cessation (ideally for at least eight weeks).

Postoperative Interventions

  • Postoperative monitoring and vigilance based on the presence of preoperative and intraoperative risks for the development of postoperative respiratory compromise.

  • Early patient mobilization and ambulation to promote clearance of secretions, minimization of development of atelectasis, and reduction in the risk for thromboembolism.

  • Prophylactic lung expansion maneuvers, including incentive spirometry or deep breathing exercises.

  • Adequate analgesia. In many postoperative situations, patient-controlled analgesia, epidural analgesia, and intercostal nerve blocks provide more effective pain control than parenteral narcotics do.

  • Prophylaxis for thromboembolism

Specific management of patients who experience atelectasis, respiratory infection, exacerbation of an underlying lung disease, respiratory failure, need for prolonged mechanical ventilation, or pulmonary embolism after surgery should be managed as described elsewhere.

What is the prognosis for patients managed in the recommended ways?

Individual elements of the approach outlined above have been demonstrated effective in reducing the risk of post-operative pulmonary complications. The approach, including all its elements, is likely to prevent or limit the development of respiratory complications after surgery. However, confirmatory data are lacking.

What other considerations exist for patients with a postoperative pulmonary complication?

This section is not applicable to the discussion.

What’s the evidence?

Canet, J, Gallart, L, Gomar, C, Paluzie, G, Vallès, J, Castillo, J. "ARISCAT Group. Prediction of postoperative pulmonary complications in a population-based surgical cohort.". Anesthesiology. vol. 113. 2010. pp. 1338-50.

DeLisser, HM, Grippi, MA, Fishman, AP. "Perioperative respiratory considerations in the surgical patient". Pulmonary diseases and disorders. McGraw Hill. 2008. pp. 663-675.

Dureuil, B, Viirès, N, Cantineau, JP, Aubier, M, Desmonts, JM. "Diaphragmatic contractility after upper abdominal surgery". J Appl Physiol. vol. 61. 1986. pp. 1775-80.

Fairshter, RD, Williams, JH. "Pulmonary physiology in the postoperative period". Crit Care Clin. vol. 3. 1997. pp. 287-306.

Excellent review of the changes in respiratory physiology that occur after surgery.

Hall, JC, Tarala, RA, Hall, JL, Mander, J. "A multivariate analysis of the risk of pulmonary complications after laparotomy". Chest. vol. 99. 1991. pp. 923-7.

Hall, JC, Tarala, RA, Hall, JL. "A case-control study of postoperative pulmonary complications after laparoscopic and open cholecystectomy". J Laparoendosc Surg. vol. 6. 1996. pp. 87-92.

Hall, JC, Tarala, RA, Tapper, J, Hall, JL. "Prevention of respiratory complications after abdominal surgery: a randomised clinical trial". BMJ. vol. 312. 1996. pp. 148-52.

The authors conclude that, when the use of resources is taken into account, the most efficient regimens of prophylaxis against respiratory complications after abdominal surgery are deep-breathing exercises for low-risk patients and incentive spirometry for high-risk patients.

Johnson, DC, Kaplan, LJ. "Perioperative pulmonary complications". Curr Opin Crit Care. vol. 17. 2011. pp. 362-369.

An excellent review that summarizes the various conditions that have been identified as postoperative pulmonary complications.

Myers, K, Hajek, P, Hinds, C, McRobbie, H. "Stopping smoking shortly before surgery and postoperative complications: a systematic review and meta-analysis". Arch Intern Med. vol. 171. 2011. pp. 983-989.

There is concern that smoking cessation within a few days or weeks before surgery may increase risk of developing postoperative pulmonary complications. The authors perform a systematic meta-analytic review of the literature and conclude that this fear is unfounded.

Pasquina, P, Tramèr, MR, Walder, B. "Prophylactic respiratory physiotherapy after cardiac surgery: systematic review". BMJ. vol. 327. 2003. pp. 1379.

The authors conclude from a systematic review of the literature that prophylactic respiratory therapy following cardiac surgery does not decrease the incidence of postoperative pulmonary complications (atelectasis, pneumonia, or hypoxemia).

Ramaswamy, A, Gonzalez, R, Smith, CD. "Extensive preoperative testing is not necessary in morbidly obese patients undergoing gastric bypass". J Gastrointest Surg. 2004. pp. 8159-64.

This article supports the recommendation that routine preoperative screening with chest x-ray, pulmonary function testing, and arterial blood gas analysis is not warranted in the absence of undefined respiratory disease or symptoms.

Simonneau, G, Vivien, A, Sartene, R, Kunstlinger, F, Samii, K, Noviant, Y. "Diaphragm dysfunction induced by upper abdominal surgery: role of postoperative pain". Am Rev Respir Dis. vol. 128. 1983. pp. 899-903.

This classic physiological study demonstrates that abdominal surgery induces marked diaphragmatic dysfunction that lasts about one week and that is not suppressed by postoperative pain relief.

von Ungern-Sternberg, BS, Boda, K, Chambers, NA, Rebmann, C, Johnson, C, Sly, PD. "Risk assessment for respiratory complications in paediatric anaesthesia: a prospective cohort study". Lancet. vol. 376. 2010. pp. 773-83.

This study supports the concept that a recent respiratory tract infection may be a risk factor for development of postoperative pulmonary complications. The incidence of postoperative pulmonary complications (atelectasis or pneumonia) was 2.7 percent after laparoscopic cholecystectomy and 17.2 percent after open cholecystectomy (p < 0.05). The combination of ASA classification greater than 1 and age greater than 59 years identified 88 percent of the patients who developed a postoperative pulmonary complication (either pneumonia or atelectasis).

The authors conduct a prospective multicenter, observational study of a large population of patients who underwent a broad range of non-bariatric surgical procedures and found a 5 percent incidence of respiratory complications (respiratory infections, respiratory failure, pleural effusions, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis). Seven independent risk factors were identified: low preoperative arterial oxygen saturation, acute respiratory infection during the previous month, age, preoperative anemia, upper abdominal or intrathoracic surgery, surgical duration of at least 2 h, and emergency surgery.
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