percent of the 30 patients who required diagnostic bronchoscopy required it because of failure to consider the diagnosis preoperativelyP That is probably par for most hospitals and is a more important problem than any deficiency of the sputum examination.
John F. Cary, ·M.D., Manaa8tl8, Virginia REFERENCES
1 Baughman RP, Dohn MN, Loudon RG, Frame Pr. Bronchoscopy with bronchoalveolar lavage in tuberculosis and fungal infections. Chest 1991; 99:92-7 2 Counsell SR, Tun JS, Dittus RS. Unsuspected pulmonary tuberculosis in a community teaching hospital. Arch Intern Med 1989; 149:1274-78 3 Heffner JE, Strange C, Sahn SA. The impact of respiratory failure on the diagnosis of tuberculosis. Arch Intern Med 1988; 148:
1103-08
7b the Editor: We appreciate Dr Cary's comments regarding our article. We had hoped to avoid any confusion regarding the sensitivity and specificity of bronchoscopy in patients with tuberculosis. We had specifically included all those patients who were diagnosed at the University of Cincinnati over the period of time of the study to point out that sputum examination alone allowed diagnosis of half of the cases of tuberculosis. However, there were some patients in whom the diagnosis of tuberculosis was not made by sputum examination alone. In some cases, sputum could not be obtained because the patient did not have a productive cough (three of the 50 patients who underwent bronchoscopy). We have reported our results to show that bronchoscopy with lavage added to the potential diagnosis of patients with tuberculosis. In patients with obscure pulmonary infiltrates and symptoms, bronchoscopy with lavage is often performed. Testing the specimens for tuberculosis is high yield: more than 90 percent of the time tuberculosis is diagnosed from the bronchoscopy specimen. The purpose of our subgroup analysis of the 30 patients with negative prebronchoscopy sputum samples was to point out that bronchoscopy did add to the diagnostic yield in those cases. Following previous recommendations to wait until sputum cultures were available would have delayed diagnosis in 21 of the 30 cases subsequently found to be tuberculosis. In conclusion, I agree with Dr Cary that sputum examination is an important diagnostic study in patients with tuberculosis. I also agree that, in many instances, not considering the diagnosis of tuberculosis is one of the reasons for missing it. However, I would like to point out that as our patient population changes (including those with human immunodeficiency virus infection) and patients undergo more extensive evaluation, bronchoscopy with lavage for cultures of fungus and acid-fast bacilli will continue to be useful.
Robert P. Baughman, M .D., F. C. C .P. Pulmonary/Critical Care Medicine, Univemty
of Cincinnati Medical Center;
Cincinnati
Role of Physician Care Units
Assistants
In Critical
7b the Editor: We read with interest the article by Dubayho et al, 1 which appeared in the January 1991 issue of Cheat, in which they discussed the role of physician assistants (PAs) in critical care units. At Emory University Hospital, the Department ofAnesthesiology has employed PAs in the postoperative cardiac and thoracic/vascular
surgical intensive care units (ICU s) for 12 years. Each PA is assigned to an attending anesthesiologist, and his or her duties are very similar to those described in the article. In addition, the PAs participate in research projects, educational activities, and quality assurance data gathering. One of the greatest contributions of our PAs is the continuity of care that they provide fur patients. The complexity of care for the critically ill patient increases yearly, and the monthly rotation of residents through the ICU presents the potential of a break in the continuity of care. Our PAs serve as a "tie line" and not only preserve continuity but also ensure that patient therapeutics and ICU procedures are carried out within the guidelines established by our department. This aspect is appreciated not only by our attending std but by the nursing std as well. All of our PAs received their training here at Emory University School of Medicine, Division of Allied Health. All had sciencemajor bachelor's degrees prior to entering the 24-month training program and were granted a master's degree upon graduation. The program curriculum was directed by the Department of Anesthesiology. The majority of PAs are also registered respiratory therapists. Our experience and that of Dubaybo et al show that PAs can have an important role in the critical care setting. We hope that these insights may open new doors to PAs interested in critical care. W Robert Grabenkort, M.M.Sc., and James G. Ramsay, M.D.,
Department of Anesthesiology, School of Medicine,
Emory University
Atlanta REFERENCE
1 Dubaybo BA, Samson MIC, Carlson Rw. The role of physicianassistants in critical care units. Chest 1991; 99:89-91
The Concertina
Effect In Preexcltatlon
7b the Editor: In their report of a case of pseudo-preexcitation with concertina effect, which appeared in the February 1991 issue of Cheat, Oreto and colleagues• failed to completely grasp and communicate the elegant metaphor embodied in the concertina effect. Their statement that "the concertina effect is a phenomenon where the QRS complexes reflect alternating phases of gradual widening and narrowing" is incomplete and inaccurate. The case they report with ECG traces is not an example of the concertina effect. First introduced by OhneJll in 1944, the concertina effect is a metaphor wherein the QRS complexes are likened to the pleats in the bellows of the concertina, a type of accordion. As the ends of the bellows are drawn apart, the distance between adjacent pleats increases and the individual pleats become wider. This is analogous to slowing of the heart rate in WolfF-Parkinson-White (WPW) syndrome, wherein the ECG displays increasing distance (cycle length) between QRS complexes and associated widening of the QRS complex. Conversely, as the concertina or accordion bellows is compressed, the adjacent pleats move closer to one another and the individual pleats become narrower, analogous to cardiac acceleration with QRS complexes progressively moving closer to one another and becoming progressively narrower. The analogy teaches that as the heart rate increases, the degree of preexcitation diminishes in a progressive manner. In contrast, changes in the degree of preexcitation occurring in the absence of the aforementioned changes in heart rate and cycle length are not examples of the concertina effect. Thus, the case described by Oreto et al, wherein the degree of pseudo-preexcitation changed while the heart rate remained relatively constant, does not illustrate the concertina
effect.
CHEST I 101 I 1 I JANUARY, 1992
293
John F. Cary, ·M.D., Manaa8tl8, Virginia REFERENCES
1 Baughman RP, Dohn MN, Loudon RG, Frame Pr. Bronchoscopy with bronchoalveolar lavage in tuberculosis and fungal infections. Chest 1991; 99:92-7 2 Counsell SR, Tun JS, Dittus RS. Unsuspected pulmonary tuberculosis in a community teaching hospital. Arch Intern Med 1989; 149:1274-78 3 Heffner JE, Strange C, Sahn SA. The impact of respiratory failure on the diagnosis of tuberculosis. Arch Intern Med 1988; 148:
1103-08
7b the Editor: We appreciate Dr Cary's comments regarding our article. We had hoped to avoid any confusion regarding the sensitivity and specificity of bronchoscopy in patients with tuberculosis. We had specifically included all those patients who were diagnosed at the University of Cincinnati over the period of time of the study to point out that sputum examination alone allowed diagnosis of half of the cases of tuberculosis. However, there were some patients in whom the diagnosis of tuberculosis was not made by sputum examination alone. In some cases, sputum could not be obtained because the patient did not have a productive cough (three of the 50 patients who underwent bronchoscopy). We have reported our results to show that bronchoscopy with lavage added to the potential diagnosis of patients with tuberculosis. In patients with obscure pulmonary infiltrates and symptoms, bronchoscopy with lavage is often performed. Testing the specimens for tuberculosis is high yield: more than 90 percent of the time tuberculosis is diagnosed from the bronchoscopy specimen. The purpose of our subgroup analysis of the 30 patients with negative prebronchoscopy sputum samples was to point out that bronchoscopy did add to the diagnostic yield in those cases. Following previous recommendations to wait until sputum cultures were available would have delayed diagnosis in 21 of the 30 cases subsequently found to be tuberculosis. In conclusion, I agree with Dr Cary that sputum examination is an important diagnostic study in patients with tuberculosis. I also agree that, in many instances, not considering the diagnosis of tuberculosis is one of the reasons for missing it. However, I would like to point out that as our patient population changes (including those with human immunodeficiency virus infection) and patients undergo more extensive evaluation, bronchoscopy with lavage for cultures of fungus and acid-fast bacilli will continue to be useful.
Robert P. Baughman, M .D., F. C. C .P. Pulmonary/Critical Care Medicine, Univemty
of Cincinnati Medical Center;
Cincinnati
Role of Physician Care Units
Assistants
In Critical
7b the Editor: We read with interest the article by Dubayho et al, 1 which appeared in the January 1991 issue of Cheat, in which they discussed the role of physician assistants (PAs) in critical care units. At Emory University Hospital, the Department ofAnesthesiology has employed PAs in the postoperative cardiac and thoracic/vascular
surgical intensive care units (ICU s) for 12 years. Each PA is assigned to an attending anesthesiologist, and his or her duties are very similar to those described in the article. In addition, the PAs participate in research projects, educational activities, and quality assurance data gathering. One of the greatest contributions of our PAs is the continuity of care that they provide fur patients. The complexity of care for the critically ill patient increases yearly, and the monthly rotation of residents through the ICU presents the potential of a break in the continuity of care. Our PAs serve as a "tie line" and not only preserve continuity but also ensure that patient therapeutics and ICU procedures are carried out within the guidelines established by our department. This aspect is appreciated not only by our attending std but by the nursing std as well. All of our PAs received their training here at Emory University School of Medicine, Division of Allied Health. All had sciencemajor bachelor's degrees prior to entering the 24-month training program and were granted a master's degree upon graduation. The program curriculum was directed by the Department of Anesthesiology. The majority of PAs are also registered respiratory therapists. Our experience and that of Dubaybo et al show that PAs can have an important role in the critical care setting. We hope that these insights may open new doors to PAs interested in critical care. W Robert Grabenkort, M.M.Sc., and James G. Ramsay, M.D.,
Department of Anesthesiology, School of Medicine,
Emory University
Atlanta REFERENCE
1 Dubaybo BA, Samson MIC, Carlson Rw. The role of physicianassistants in critical care units. Chest 1991; 99:89-91
The Concertina
Effect In Preexcltatlon
7b the Editor: In their report of a case of pseudo-preexcitation with concertina effect, which appeared in the February 1991 issue of Cheat, Oreto and colleagues• failed to completely grasp and communicate the elegant metaphor embodied in the concertina effect. Their statement that "the concertina effect is a phenomenon where the QRS complexes reflect alternating phases of gradual widening and narrowing" is incomplete and inaccurate. The case they report with ECG traces is not an example of the concertina effect. First introduced by OhneJll in 1944, the concertina effect is a metaphor wherein the QRS complexes are likened to the pleats in the bellows of the concertina, a type of accordion. As the ends of the bellows are drawn apart, the distance between adjacent pleats increases and the individual pleats become wider. This is analogous to slowing of the heart rate in WolfF-Parkinson-White (WPW) syndrome, wherein the ECG displays increasing distance (cycle length) between QRS complexes and associated widening of the QRS complex. Conversely, as the concertina or accordion bellows is compressed, the adjacent pleats move closer to one another and the individual pleats become narrower, analogous to cardiac acceleration with QRS complexes progressively moving closer to one another and becoming progressively narrower. The analogy teaches that as the heart rate increases, the degree of preexcitation diminishes in a progressive manner. In contrast, changes in the degree of preexcitation occurring in the absence of the aforementioned changes in heart rate and cycle length are not examples of the concertina effect. Thus, the case described by Oreto et al, wherein the degree of pseudo-preexcitation changed while the heart rate remained relatively constant, does not illustrate the concertina
effect.
CHEST I 101 I 1 I JANUARY, 1992
293
