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(Chest. 2001;120:1152-1156.)
© 2001 American College of Chest Physicians

Spirometry in Surgery for Anterior Mediastinal Masses*

Oleh W. Hnatiuk, LTC, MC, USA, MD, FCCP; Phillip C. Corcoran, LTC, MC, USA, MD and Angel Sierra, CRTT

* From the Pulmonary and Critical Care Medicine Service (Dr. Hnatiuk and Mr. Sierra), Department of Medicine, and Cardiovascular Thoracic Service (Dr. Corcoran), Department of Surgery, Walter Reed Army Medical Center, Washington, DC.

Correspondence to: LTC Oleh W. Hnatiuk, MD, FCCP, Chief, Pulmonary and Critical Care Medicine Service, Ward 77, Walter Reed Army Medical Center, Washington, DC 20307-5001; e-mail: oleh.hnatiuk{at}na.amedd.army.mil


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 References
 
Study objectives: To identify the impact of upright and supine spirometry (USS) on the choice of anesthesia and outcomes in patients undergoing surgery for anterior mediastinal masses (AMMs).

Design: Retrospective cohort study.

Setting: A referral, tertiary-care, military medical center.

Patients: We reviewed the records of all patients who underwent surgery for AMMs between June 1994 and December 2000 at Walter Reed Army Medical Center. Patients aged >= 18 years who had "anterior mediastinal mass" listed as the preoperative diagnosis, which had been confirmed by a preoperative CT scan, and who had available preoperative spirometry data were included in our analysis. In cases in which surgery was performed more than once on the same individual, only data from the first operation were evaluated.

Measurements: Patient demographics, the results of pulmonary function testing, perioperative complications, type of anesthesia, type of surgery, and pathology were used in the evaluation.

Results: Thirty-seven patients (median age, 31 years; age range, 19 to 86 years) were included in the final analysis. There were 24 men and 13 women in this group. The mean (± SD) seated FVC and FEV1 values for the group were 4.02 ± 0.75 L (90.7 ± 13.3% predicted) and 3.22 ± 0.56 L 89.6 ± 14.2% predicted. Twelve patients (32.4%) had USS ordered, and 10 patients (27.0%) had USS performed. USS was ordered significantly more frequently in younger and symptomatic patients (p = 0.022 and p = 0.005, respectively). Spirometry suggestive of possible upper airway obstruction was found in four patients. However, general anesthesia was used in all four patients without complications. Only two patients suffered perioperative complications. One of these patients had normal USS values but underwent surgery under local anesthesia nonetheless.

Conclusions: The recommendation to perform USS prior to surgery on AMMs is based on anecdotal data. Our study found that the incidence of perioperative complications in surgery for AMMs is low. We also found that USS is not ordered in all patients preoperatively and that the results do not always alter the anesthetic technique when abnormal. One patient who experienced a perioperative complication had normal USS values. Larger studies are necessary to further evaluate the utility of USS in surgery for AMMs.

Key Words: anterior mediastinal mass • preoperative spirometry


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Conclusion
 References
 
Currently published guidelines for preoperative pulmonary function testing cover a wide variety of surgical procedures. However, these guidelines do not include specific recommendations for spirometry in asymptomatic adults undergoing surgery for anterior mediastinal masses (AMMs).1 Despite this, upright and supine spirometry (USS) continues to be recommended by anesthesiologists2 3 as part of the preoperative evaluation in these patients, following an algorithmic approach first recommended by Neuman et al4 in 1984.

The physiologic basis for these recommendations dates back to the late 1960s when abnormal shapes of upright flow-volume (FV) curves were observed in some individuals with large airway obstruction.5 These abnormal shapes and accompanying FV ratios were subsequently considered as potential screening tools for the presence of upper airway obstruction (UAO).6 7 8 Recently, normal indices for spirometric changes from seated to supine have been reported.9 However, to date, no study has shown that preoperative spirometry, including postural spirometry, predicts perioperative complications in individuals undergoing surgery for AMMs. We hypothesized that USS would infrequently prove helpful in the evaluation and management of these patients. Specifically, we believed that we would find that USS is inconsistently ordered and does not alter the anesthetic approach or correlate with perioperative complications.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Conclusion
 References
 
Procedure and Data Collection
This retrospective cohort study was performed using a coded data collection sheet to preserve patient confidentiality. Patient identifiers also were removed from all spirometry results and were coded. All patients who were beneficiaries of the military medical system who were >= 18 years of age, were listed in the WRAMC Cardiothoracic Surgery Service operative ledger from June 17, 1994, to December 31, 2000, with a preoperative diagnosis of "anterior mediastinal mass," "mediastinal mass," "substernal goiter," or "thymic mass," and had undergone a CT scan confirming the diagnosis were included in the final analysis.

Patient-related variables included age, sex, race, presence of airway symptoms (ie, cough and dyspnea), and size of mediastinal mass as determined by CT scan. The test-related variables collected included the following: whether preoperative USS was ordered/performed; the presence of written acknowledgment of the fact that USS was performed by any member of the operating team (ie, the surgeon or the anesthesiologist) prior to the time of surgery; an annotation in the chart of the interpretation of the test results prior to surgery by any member of the operating team; an annotation in the chart of alterations in the anesthetic (from general anesthesia [GETA] to local anesthesia) or surgical approach specifically related to the results of spirometry by any member of the operating team. The procedure-related variables that were collected included annotation of any complications during intubation, the intraoperative period, or extubation. We also noted subsequent complications during the immediate (6-h) postextubation period by any health-care provider. These included pulmonary complications (ie, aspiration, airway obstruction, bronchospasm, difficulty during intubation/extubation, hypercapnea, hypoxemia, lobar atelectasis, pneumonia, pneumothorax, pulmonary edema, pulmonary embolism, and reintubation), cardiac complications (ie, arrhythmia, congestive heart failure, hypotension, and myocardial infarction), and other complications (ie, anaphylaxis, adverse drug reaction, bleeding, cerebrovascular accident, seizure, renal failure, malignant hyperthermia, oliguria, and death).

Symptoms were considered present if there was any mention of dyspnea or orthopnea in the history taken at hospital admission, in the notes on physical examination, in the resident admission note, and in the attending or anesthesia preoperative notes. The CT scan was considered abnormal if the final preoperative radiographic report mentioned tracheal compression. USS results were considered abnormal if any of the following criteria were met: flattening of the expiratory FV loop (ie, variable intrathoracic UAO) or of both FV loops (ie, fixed UAO).6 In patients who had undergone only seated spirometry testing, USS was considered to be abnormal if the FV loop showed evidence of intrathoracic obstruction by having either an FEV1/peak expiratory flow rate (PEFR) ratio of >= 10 mL/L/min or an FEV1/forced expiratory volume in 0.5 s ratio of >= 1.5.7 8 In patients with seated and supine spirometry data available, the USS results were considered to be abnormal if the changes in FVC, FEV1/PEFR ratio, and FEV1/forced expiratory volume in 0.5 s ratio from seated to supine were > 8.0%,9 10.1%,10 and 12.2%,10 or in patients with standing and supine spirometry data available, the USS results were considered to be abnormal if there was a change in FVC of > 18.9%.11 All testing followed published guidelines for the performance of pulmonary function tests12 13 14 15 using standard pulmonary function equipment (SensorMedics Corp; Yorba Linda, CA). The interpretation of USS results was performed by a board-certified pulmonologist using published guidelines.16 The interpreter was blinded to outcomes. Normal values were derived from Crapo et al.17

Statistical Analysis
The data are presented as the mean ± SD or as proportions with 95% confidence intervals. Groups were compared using the two-sample t test for continuous variables or the Fisher’s Exact Test (two-tailed) for categoric data. Data were analyzed using computer software (SPSS for Windows, version 10.0; SPSS, Inc; Chicago, IL). A p value of < 0.05 was considered to be statistically significant.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Conclusion
 References
 
Between June 17, 1994, and December 31, 2000, 37 patients met the entry criteria and underwent their first surgery for CT scan-documented AMMs. Seven studies were excluded because of unavailable data. The median age of the final group was 31 years (age range, 19 to 86 years). There were 24 men and 13 women in the study group. The mean seated FVC for the group was 90.7 ± 13.3% predicted (or 4.02 ± 0.75 L). The mean seated FEV1 for the group was 89.6 ± 14.2% predicted (or 3.22 ± 0.56 L). Only two patients in our study group underwent surgery using local anesthesia. The rest of the cases were performed under GETA.

Fifteen of the study group patients (40.5%) complained of dyspnea or orthopnea. Local anesthesia was used in 2 of these 15 patients. In the first case, the CT scan showed evidence of airway compression, the FV loop was normal, and spirometry revealed no significant changes from the upright to supine positions. In the second case, the patient presented with superior vena cava syndrome, but the CT scan showed no airway compression, the FV loop was normal, and spirometry revealed no significant changes from the upright to supine positions. This patient experience a postoperative pneumothorax.

Evidence of tracheal compression on the CT scan was found in two other symptomatic patients. One of these two patients experienced an intraoperative complication that was unrelated to the airway. This 21-year-old man with dyspnea on exertion, chest pain, and normal results of a physical examination had surgery using GETA. He unexpectedly required cardiopulmonary bypass to control bleeding from the erosion of an epidermoid cyst into his superior vena cava. USS was not ordered in this case. The second symptomatic patient with an abnormal CT scan had normal USS results and underwent surgery using GETA without complications.

Of the 22 patients who did not complain of dyspnea or orthopnea, two had a CT scan showing tracheal compression. In one of these cases the FV loop was abnormal, but there were no significant changes in spirometry from upright to supine position. In the other asymptomatic case, USS was not ordered. Surgery was performed using GETA in both of these cases without complications. Although symptomatic patients were more likely to experience complications than asymptomatic patients (14.3% vs 0%; p = 0.158), this difference was not statistically significant, likely because of the small study group size. A summary of selected patient characteristics can be found in Table 1 .


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  		Table 1. Selected Patient Characteristics*

 
All patients in the study group had standard spirometry performed preoperatively. Of the twelve patients who had USS ordered, 10 patients had standing and supine spirometry performed, and 2 other patients had seated and supine spirometry performed. USS was significantly more likely to be ordered in younger and symptomatic patients (Table 2 ). More importantly, complications did not significantly occur more frequently in those patients who had USS ordered than in those who did not have USS ordered. In all cases in which USS was ordered, the chart contained an acknowledgment of the performance of spirometry by a member of the operating team. In 9 of the 25 cases in which seated spirometry was ordered, there was no physician acknowledgment of PFT results on the chart.


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  		Table 2. USS Grouped Characteristics*

 
Spirometry results that were suggestive of possible UAO was found in four subjects, two of whom were symptomatic. GETA was used in all of four of these cases without complications. In the first asymptomatic patient, the percentage change in FEV1/PEFR ratio from sitting to supine was 13.5%. In the second asymptomatic case, the standing FV loop was consistent with a diagnosis of fixed UAO. In the symptomatic patients, the FVC changed 28.2% from standing to supine, and 10.2% from seated to supine. There was no correlation between abnormal spirometry results and symptoms, abnormal CT, anesthetic technique, or complications in our study group.

In the study group, surgical procedures included anterior mediastinal exploration (14 patients), median sternotomy (13 patients), cervical mediastinal exploration (7 patients), and video-assisted thoracoscopy (3 patients). Postoperative diagnoses included hyperplastic thymus (10 patients), benign thymoma (8 patients), lymphoma (8 patients), teratoma (2 patients), germ cell tumor (2 patients), malignant thymoma (2 patients), cysts (2 patients), adenocarcinoma (1 patient), lipoma (1 patient), and sequestration (1 patient).


   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Conclusion
 References
 
In this study, the perioperative complication rate was low (5.4%) and USS was ordered for only 32.4% of the patients undergoing surgery for AMMs. When the results were abnormal, USS did not result in an alteration of the anesthetic technique. The four patients with abnormal USS results all underwent GETA without difficulty. The decision to use local anesthesia in two of the study patients was based on factors other than USS results.

None of the patients with abnormal USS experienced a perioperative complication. In both patients who had complications, there were strong clinical reasons to suspect abnormal USS results. Both patients were symptomatic, one with a CT scan showing tracheal compression and the other with superior vena cava syndrome. However, only the first patients had had USS ordered, the results of which were normal. In this patient, a decision was made to perform surgery using local anesthesia anyway, and he suffered an intraoperative complication nonetheless. The second patient had normal seated spirometry results.

Because we found very few complications in our study group despite the fact that the majority of patients did not have USS performed, or that when it was performed abnormal results did not affect the management of the patient, we believe that USS is not necessary for the typical patient undergoing surgery for AMMs. However, the current recommendations on this topic differ from our viewpoint.

Recommendations for USS prior to surgery for AMMs can be traced to the anecdotal case reports4 of three patients, all < 18 years of age, who underwent surgical evaluation of AMMs. Two of these cases involved perioperative difficulties with the airway without describing the results of spirometry at all. In the third case, the results of USS were reportedly abnormal. A biopsy of the mass was performed under local anesthesia with a good outcome. Interestingly, even in this last case, a review of the provided FV loop diagram fails to reveal a significant difference between upright and supine peak expiratory flows or a classic expiratory plateau. Nonetheless, the authors concluded that "an upright and supine flow volume loop... is the most sensitive noninvasive study for the diagnosis of airway obstruction. General anesthesia should be avoided if... positive." The figure from this case report, describing an algorithmic approach to the patient with an AMM, is the same one that still appears in two anesthesiology textbooks.2 3

To our knowledge, there is only one case report with documented USS results in an adult undergoing surgery on an AMM.18 In this case, a 24-year-old man with a cough exacerbated by assuming the supine position underwent a diagnostic mediastinoscopy and was unable to be adequately oxygenated because of extrinsic tracheal obstruction by the AMM. His condition did not improve until his endotracheal tube was advanced past the site of airway obstruction. The authors provided figures of the USS that was performed several days after surgery and chemotherapy. The FV loops reportedly showed reductions in both inspiratory and expiratory flows, although neither the quantitation of the extent of the abnormalities nor the classic expiratory changes of variable UAO was present. On the basis of this single case report, these authors concluded that "a disproportionate reduction in maximal flow should alert the clinician to the presence of tracheomalacia and its inherent risk of precipitating airway collapse after endotracheal intubation." A review on this topic in the anesthesia literature 1 year later repeats this claim.19 The review cites numerous references of respiratory distress in children undergoing anesthesia for mediastinal masses.


   Conclusion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
References
 
The recommendations to perform USS prior to surgery for AMMs are based on anecdotal data. USS is not ordered in all patients, abnormal results do not alter the choice of anesthetic technique, and USS may not be any better at predicting perioperative complications than symptoms and CT scanning. More prospective studies evaluating USS in surgery for AMMs are needed.


   Footnotes
 
Abbreviations: AMM = anterior mediastinal mass; FV = flow volume; GETA = general anesthesia; PEFR = peak expiratory flow rate; UAO = upper airway obstruction; USS = upright and supine spirometry

Presented in part at CHEST 1998, the International Scientific Assembly of the American College of Chest Physicians, Toronto, Ontario, Canada, November 8–12, 1998.

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

Received for publication January 21, 2001. Accepted for publication May 10, 2001.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 References
 

  1. Zibrak, JD, O’Donnell, CR, Marton, K (1993) Indications for pulmonary function testing. Clin Chest Med 14,227-236[ISI][Medline]
  2. Benumof, JL, Alfery, DD (1994) Anesthesia for thoracic surgery. Miller, RD eds. Anesthesia 4th ed. ,970 Churchill Livingstone New York, NY.
  3. Eisenkraft, JB, Cohen, E, Neustein, SM (1997) Anesthesia for thoracic surgery. Barash, PG Cullen, BF Stoelting, RK eds. Clinical anesthesia 3rd ed. ,790 Lippincott-Raven Publishers Philadelphia, PA.
  4. Neuman, GG, Weingarten, AE, Abramowitz, RM, et al (1984) The anesthetic management of the patient with an anterior mediastinal mass. Anesthesiology 60,144-147[ISI][Medline]
  5. Miller, RD, Hyatt, RE (1969) Obstructing lesions of the larynx and trachea: clinical and physiologic characteristics. Mayo Clin Proc 44,145-161[ISI][Medline]
  6. Miller, RD, Hyatt, RE (1973) Evaluation of obstructing lesions of the trachea and larynx by flow-volume loops. Am Rev Respir Dis 108,475-481[ISI][Medline]
  7. Rotman, HH, Liss, HP, Weg, JG (1975) Diagnosis of upper airway obstruction by pulmonary function testing. Chest 68,796-799[Abstract/Free Full Text]
  8. Owens, GR, Murphy, DM (1983) Spirometric diagnosis of upper airway obstruction. Arch Intern Med 143,1331-1334[Abstract]
  9. Vilke, G, Chan, T, Clausen, J (2000) Spirometry in normal subjects in sitting, prone, and supine positions. Respir Care 45,407-410[Medline]
  10. Meysman, M, Vincken, W (1998) Effect of body posture on spirometric values and upper airway obstruction indices derived from the flow-volume loop in young nonobese subjects. Chest 114,1042-1047[Abstract/Free Full Text]
  11. Allen, SM, Hunt, B, Green, M (1985) Fall in vital capacity with posture. Br J Dis Chest 79,267-271[ISI][Medline]
  12. . American Thoracic Society. (1979) ATS statement: Snowbird Workshop on Standardization of Spirometry. Am Rev Respir Dis 119,831-838[ISI][Medline]
  13. . American Thoracic Society. (1987) Standardization of spirometry: 1987 update; statement of the American Thoracic Society. Am Rev Respir Dis 136,1285-1298[ISI][Medline]
  14. Gardner, RM (1988) Standardization of spirometry: a summary of recommendations from the American Thoracic Society; the 1987 update. Ann Intern Med 108,217-220
  15. . American Thoracic Society. (1995) Standardization of spirometry: 1994 update. Am J Respir Crit Care Med 152,107-136
  16. . American Thoracic Society. (1991) Lung function testing: selection of reference values and interpretative strategies. Am Rev Respir Dis 144,1202-1218[ISI][Medline]
  17. Crapo, RO, Morris, AH, Gardner, RM (1981) Reference spirometric values using techniques and equipment that meets ATS recommendations. Am Rev Respir Dis 123,659-664[ISI][Medline]
  18. Prakash, UBS, Abel, MD, Hubmayr, RD (1988) Mediastinal mass and tracheal obstruction during general anesthesia. Mayo Clin Proc 63,1004-1011[ISI][Medline]
  19. Pullerits, J, Holzman, R (1989) Anesthesia for patients with mediastinal masses. Can J Anaesth 36,681-688[Abstract/Free Full Text]




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