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A Matter of Terminology
Our results are in accordance with the article of Fletcher et aJ3 who systematically tested the accuracy of this catheter system in humans. He also found a consistent underestimation of the fiberoptic pulmonary artery catheter Sv02 values below 50% compared with direct spectophotometry and proposed two equations to adjust the catheter measurements: (1) Catheter=-11 .68+ 1.1892XCOOX (2) Catheter=COOX-210.997 exp (-0.099XCOOX) Catheter=Sv02-0pticath Spectrophotometry=Sv02-Spectroph otometer. Figure 1 shows the difference between catheter and spectrophotometry on the basis of equation 1. Concerning our measurements, this equation gave the best conformity in the range from 20 to 50%. 50
a0 q: 0
Reprint requests: Dr. Nakanishi, Cardiac Division, Department of Internal Medicine , National Cardiovascular Center, 5-7-1 Fujishirodai, Suita-Shi, Osaka 565, Japan
// ///
30
//-;·
20
en
10
0
Norifumi Nakanishi, MD, National Cardiovascular Center, Osaka, Japan
/;/
40 ~
.£Cll
Sv02 values readout from the fiberoptic pulmonary artery catheter from ranges 100 to 20%. Our method to evaluate the fiberoptic catheter and the results were already published in Japan in 1992. The illustration of experimental system and the figures of the result in this article are shown below.
0
10
20
30
40
50
8,02 spectrophotometer, % FIGURE 1. Comparison of Sv02, measured spectrophotometrically and by fiberoptic pulmonary artery catheter. In consideration of this adjustment, we agree that the continuous measurement of Fick cardiac output is applicable for continuous determination of cardiac output during exercise and a useful tool to investigate hemodynamics especially in patients with severely impaired left ventricular function.
Eberhard Stengele, MD, PhD, Heart Center, Bad Krozingen , Federal Republic of Germany
FIGURE 1. The circuit of blood gas equilibrium and blood gas analysis for in vitro calibration. Blood is perfused through a tube from the gas equilibrium system to the fiberoptic catheter tip and CO-oximeter by a roller pump. Gas exchange occurs in the water bath on the mixer. S0280%CAL
(%) 100
,.~~
80
M
><
0
60
~-
•
40 20
,.
,
,/
S0230%CAL
(%) 100
y:x
, Y=X
80
(')
>< 0
60 40
y =1.003x-Q.603
r=-0.998
n=SO
/ 0 o"-~20--4~0--6~0-~80-~100(%)
20
'
1 Nakamishi N, Joshioka T, Okano Y, et al. Continuous fick cardiac output measurement during exercise by monitoring of mixed venous oxygen saturation and oxygen uptake Chest 1993; 104:419-26 2 Stengele E, Meyer K, Trenk D, et al. Kontinuierliche Messung der gemischtveniisen Sauerstoffsiittigung (Sv02) zur Beurteilung der myocardialen Funktionsreserve bei Patienten mit schwerer linksventrikuliirer Dysfunktion. Z Kardiol 1994; 83(suppll):199 3 Fletcher EC, Miller T, Thornby Jl. Accuracy of fiberoptic central venous saturation catheter below 50%. J Appl Physiol 1988; 64:2220-23
To the Editor: We cannot agree with the comments of Dr. Stengele about our article published in Chest (Chest 1993; 104:419-26), because experiments by our colleague to evaluate the accuracy of the fiberoptic pulmonary artery catheter (Opticath) shows good correlations between spectrophptometrically measured Sv0 2 and 1774
-"""'
.,I'
y =0.986X+0.746 r=0.997
,/
n=SO
/ 0 o"--~20~~40--60~-80~~100(%)
IL-282
REFERENCES
_,.
IL-282
FIGURE 2. Correlations between the Sa02 measured by fiberoptic oximeter (OX-3) and by CO-oximeter (IL-282) in high (80%) and low (30%) saturation blood.
A Matter of Terminology Alveolar-Arterial Oxygen Gradient To the Editor: I would like to commend Stein and colleagues (Chest 1995; 107:139-43) on showing that normal arterial hemoglobin oxygenation does not exclude the diagnosis of acute pulmonary embolism. The use of the term "alveolar-arterial oxygen gradient," however, needs some discussion. The authors predict the normal alveolar partial pressure of oxygen from the standard alveolar gas equation, which assumes an idealized lung where all alveoli are perfused and ventilated uniformly. Even a normal lung contains alveoli with different partial pressures of oxygen in both the alveolar space and end-capCommunications to the Editor
illary blood depending on the distribution of ventilation and blood flow. The systemic arterial blood oxygen tension is a result of a mixture of all end-capillary blood derived from the lung combined with blood from anatomic shunts. Therefore, there are many true alveolar-arterial oxygen "gradients" that cannot be represented accurately by one number. The authors are not describing a true physical gradient but rather, an abstract mathematical difference. I would use the term alveolar-arterial oxygen "difference" for the mathematical subtraction of the measured arterial oxygen tension from the idealized alveolar oxygen tension.
Adults and the Elderly," an article published in Chest in July 1994. They summarized that the young "were more likely to have hemoptysis, fever, and cough ... . " Although the reference probably did not appear in their literature search, there has been a previous description of this phenomenon. The consumption of young men that are in the flower of their age, when the heat of blood is yet brisk, and therefore more disposed to a feverish fermentation, is for the most part acute. But, in old men, where the natural heat is decayed, it is more chronicaJ.l
It is reassuring that some clinical aphorisms have enduring value.
Carl M. Kirsch, MD, FCCP, Division of Respiratory/ Critical Care Medicine , Santa Clara Valley Medical Center, San jose, California
Fistulas Do Not Always Cause Pericardial Effusion
Michael D. Iseman, MD, FCCP, National jewish Center for Immunology and Respiratory Medicine, Denver, Colorado REFERENCE
1 Morton R. Phthisiologia. 1689
To the Editor: Mahaisa variya and colleagues report (Chest 1994; 106:1285-88) on an atrial-esophageal fistula, which adds another interesting case to the roughly 65 comparable cases reported, usually due to benign esophageal disease and sometimes involving the pericardium. The authors note: "The adherence of the esophagus and the myocardium, therefore, provides a potential for fistula development." This needs correcting: the esophagus does not adhere to the myocardium ; the pericardium is interposed between the esophagus and the adjacent cardiovascular structures from the level of T-3 to T-11 1 The probable reason that a fistula does not always cause pericardia! effusion, because it must perforate the interposed pericardium , is the unusual structure of the pericardium over the left atrium-a basketwork of fibers in the parietal pericardium, which tightly clasp the left atrium 2 This is also the reason why none but very large pericardia! effusions under pressure penetrate behind that structure, and why patients stabbed in the back through the left atrium tend to bleed into the pleural cavity rather than the pericardium. These remarks are not made to criticize but rather to amplify a nice report.
David H. Spodick, MD, DSc, Cardiology Division , Saint Vincent Hospital, Worcester, Massachusetts REFERENCES
Spodick DH. Macro- and Micro-physiology and anatomy of the pericardium. Am Heart J 1992; 124:1046-51 2 Spodick DH. The normal and diseased pericardium: current concepts of pericardia! physiology, diagnosis and treatment. J Am Coli Cardiol1983; 1:240-51
Tuberculosis in Young Adults and the Elderly To the Editor: Korzeniewska-Kosela and colleagues (Chest 1994; 106:28-32) reported their observations contrasting "Tuberculosis in Young
Pleural Tuberculosis in HIV-Infected Patients To the Editor: We have read with great interest the article by Relkin et al (Chest 1994; 105:1338-41), which appeared in Chest in May 1994, about the characteristics of pleural tuberculosis in patients infected by HIV. In this report the authors found that patients with pleural tuberculosis and HIV infection, had compared with a group of HIV -negative patients, significantly fewer positive tuberculin skin tests, more acid-fast bacteria identifiable in pleural tissue, higher proportion of positive Mycobacterium tuberculosis (MT) cultures of sputum and pleural biopsy (PB), and similar pleural biopsy histologic conditions. It has been suggested that delayed hypersensitivity plays a major role in the pathogenesis of tuberculous pleural effusion, 1 and T-lymphocytes play a central role in cell-mediated defences against MT. 2 Because HIV infection results in specific depletion of CD4 cells, we might therefore expect to find more acid-fast bacteria identifiable in pleural tissue, sputum, and pleural fluid (PF), and fewer granulomas on PB specimens. To evaluate this hypothesis, we retrospectively studied all cases with a definitive diagnosis of pleural tuberculosis from 1986 through December 1991 at our hospital. Inclusion criteria in the study were (1) positive culture of PF, PB specimen(s), or both for MT, (2) presence of granuloma on PB with PF, PB, and negative sputum cultures for fungi, parasite, and atypical mycobacteria and with a clear clinical response to antituberculous treatment, and (3) positive sputum culture for MT associated with exudative pleural effusion, if all other causes of effusion have been ruled out. One hundred and three patients with a definite diagnosis of pleural tuberculosis were finally included. Ten subjects (10%), eight men and two women whose mean age was 29 years (SD=7) were infected with HIV. The remaining 93 patients (90% ), 60 men and 33 women whose mean age was 28 years (SD= 15) had no HIV infection. We found that the HIV -positive group had significantly higher rate of positive sputum cultures for MT (4/ 10 [40%] against 10/ 78 [13%] in noninfected patients, p<0.05), and fewer positive tuberculin skin tests (2/10 [20%], against 57/88 [65%] in HIVnegative patients, p<0.05). In our series, granuloma on pleural CHEST /107161 JUNE, 1995
1775
a0 q: 0
Reprint requests: Dr. Nakanishi, Cardiac Division, Department of Internal Medicine , National Cardiovascular Center, 5-7-1 Fujishirodai, Suita-Shi, Osaka 565, Japan
// ///
30
//-;·
20
en
10
0
Norifumi Nakanishi, MD, National Cardiovascular Center, Osaka, Japan
/;/
40 ~
.£Cll
Sv02 values readout from the fiberoptic pulmonary artery catheter from ranges 100 to 20%. Our method to evaluate the fiberoptic catheter and the results were already published in Japan in 1992. The illustration of experimental system and the figures of the result in this article are shown below.
0
10
20
30
40
50
8,02 spectrophotometer, % FIGURE 1. Comparison of Sv02, measured spectrophotometrically and by fiberoptic pulmonary artery catheter. In consideration of this adjustment, we agree that the continuous measurement of Fick cardiac output is applicable for continuous determination of cardiac output during exercise and a useful tool to investigate hemodynamics especially in patients with severely impaired left ventricular function.
Eberhard Stengele, MD, PhD, Heart Center, Bad Krozingen , Federal Republic of Germany
FIGURE 1. The circuit of blood gas equilibrium and blood gas analysis for in vitro calibration. Blood is perfused through a tube from the gas equilibrium system to the fiberoptic catheter tip and CO-oximeter by a roller pump. Gas exchange occurs in the water bath on the mixer. S0280%CAL
(%) 100
,.~~
80
M
><
0
60
~-
•
40 20
,.
,
,/
S0230%CAL
(%) 100
y:x
, Y=X
80
(')
>< 0
60 40
y =1.003x-Q.603
r=-0.998
n=SO
/ 0 o"-~20--4~0--6~0-~80-~100(%)
20
'
1 Nakamishi N, Joshioka T, Okano Y, et al. Continuous fick cardiac output measurement during exercise by monitoring of mixed venous oxygen saturation and oxygen uptake Chest 1993; 104:419-26 2 Stengele E, Meyer K, Trenk D, et al. Kontinuierliche Messung der gemischtveniisen Sauerstoffsiittigung (Sv02) zur Beurteilung der myocardialen Funktionsreserve bei Patienten mit schwerer linksventrikuliirer Dysfunktion. Z Kardiol 1994; 83(suppll):199 3 Fletcher EC, Miller T, Thornby Jl. Accuracy of fiberoptic central venous saturation catheter below 50%. J Appl Physiol 1988; 64:2220-23
To the Editor: We cannot agree with the comments of Dr. Stengele about our article published in Chest (Chest 1993; 104:419-26), because experiments by our colleague to evaluate the accuracy of the fiberoptic pulmonary artery catheter (Opticath) shows good correlations between spectrophptometrically measured Sv0 2 and 1774
-"""'
.,I'
y =0.986X+0.746 r=0.997
,/
n=SO
/ 0 o"--~20~~40--60~-80~~100(%)
IL-282
REFERENCES
_,.
IL-282
FIGURE 2. Correlations between the Sa02 measured by fiberoptic oximeter (OX-3) and by CO-oximeter (IL-282) in high (80%) and low (30%) saturation blood.
A Matter of Terminology Alveolar-Arterial Oxygen Gradient To the Editor: I would like to commend Stein and colleagues (Chest 1995; 107:139-43) on showing that normal arterial hemoglobin oxygenation does not exclude the diagnosis of acute pulmonary embolism. The use of the term "alveolar-arterial oxygen gradient," however, needs some discussion. The authors predict the normal alveolar partial pressure of oxygen from the standard alveolar gas equation, which assumes an idealized lung where all alveoli are perfused and ventilated uniformly. Even a normal lung contains alveoli with different partial pressures of oxygen in both the alveolar space and end-capCommunications to the Editor
illary blood depending on the distribution of ventilation and blood flow. The systemic arterial blood oxygen tension is a result of a mixture of all end-capillary blood derived from the lung combined with blood from anatomic shunts. Therefore, there are many true alveolar-arterial oxygen "gradients" that cannot be represented accurately by one number. The authors are not describing a true physical gradient but rather, an abstract mathematical difference. I would use the term alveolar-arterial oxygen "difference" for the mathematical subtraction of the measured arterial oxygen tension from the idealized alveolar oxygen tension.
Adults and the Elderly," an article published in Chest in July 1994. They summarized that the young "were more likely to have hemoptysis, fever, and cough ... . " Although the reference probably did not appear in their literature search, there has been a previous description of this phenomenon. The consumption of young men that are in the flower of their age, when the heat of blood is yet brisk, and therefore more disposed to a feverish fermentation, is for the most part acute. But, in old men, where the natural heat is decayed, it is more chronicaJ.l
It is reassuring that some clinical aphorisms have enduring value.
Carl M. Kirsch, MD, FCCP, Division of Respiratory/ Critical Care Medicine , Santa Clara Valley Medical Center, San jose, California
Fistulas Do Not Always Cause Pericardial Effusion
Michael D. Iseman, MD, FCCP, National jewish Center for Immunology and Respiratory Medicine, Denver, Colorado REFERENCE
1 Morton R. Phthisiologia. 1689
To the Editor: Mahaisa variya and colleagues report (Chest 1994; 106:1285-88) on an atrial-esophageal fistula, which adds another interesting case to the roughly 65 comparable cases reported, usually due to benign esophageal disease and sometimes involving the pericardium. The authors note: "The adherence of the esophagus and the myocardium, therefore, provides a potential for fistula development." This needs correcting: the esophagus does not adhere to the myocardium ; the pericardium is interposed between the esophagus and the adjacent cardiovascular structures from the level of T-3 to T-11 1 The probable reason that a fistula does not always cause pericardia! effusion, because it must perforate the interposed pericardium , is the unusual structure of the pericardium over the left atrium-a basketwork of fibers in the parietal pericardium, which tightly clasp the left atrium 2 This is also the reason why none but very large pericardia! effusions under pressure penetrate behind that structure, and why patients stabbed in the back through the left atrium tend to bleed into the pleural cavity rather than the pericardium. These remarks are not made to criticize but rather to amplify a nice report.
David H. Spodick, MD, DSc, Cardiology Division , Saint Vincent Hospital, Worcester, Massachusetts REFERENCES
Spodick DH. Macro- and Micro-physiology and anatomy of the pericardium. Am Heart J 1992; 124:1046-51 2 Spodick DH. The normal and diseased pericardium: current concepts of pericardia! physiology, diagnosis and treatment. J Am Coli Cardiol1983; 1:240-51
Tuberculosis in Young Adults and the Elderly To the Editor: Korzeniewska-Kosela and colleagues (Chest 1994; 106:28-32) reported their observations contrasting "Tuberculosis in Young
Pleural Tuberculosis in HIV-Infected Patients To the Editor: We have read with great interest the article by Relkin et al (Chest 1994; 105:1338-41), which appeared in Chest in May 1994, about the characteristics of pleural tuberculosis in patients infected by HIV. In this report the authors found that patients with pleural tuberculosis and HIV infection, had compared with a group of HIV -negative patients, significantly fewer positive tuberculin skin tests, more acid-fast bacteria identifiable in pleural tissue, higher proportion of positive Mycobacterium tuberculosis (MT) cultures of sputum and pleural biopsy (PB), and similar pleural biopsy histologic conditions. It has been suggested that delayed hypersensitivity plays a major role in the pathogenesis of tuberculous pleural effusion, 1 and T-lymphocytes play a central role in cell-mediated defences against MT. 2 Because HIV infection results in specific depletion of CD4 cells, we might therefore expect to find more acid-fast bacteria identifiable in pleural tissue, sputum, and pleural fluid (PF), and fewer granulomas on PB specimens. To evaluate this hypothesis, we retrospectively studied all cases with a definitive diagnosis of pleural tuberculosis from 1986 through December 1991 at our hospital. Inclusion criteria in the study were (1) positive culture of PF, PB specimen(s), or both for MT, (2) presence of granuloma on PB with PF, PB, and negative sputum cultures for fungi, parasite, and atypical mycobacteria and with a clear clinical response to antituberculous treatment, and (3) positive sputum culture for MT associated with exudative pleural effusion, if all other causes of effusion have been ruled out. One hundred and three patients with a definite diagnosis of pleural tuberculosis were finally included. Ten subjects (10%), eight men and two women whose mean age was 29 years (SD=7) were infected with HIV. The remaining 93 patients (90% ), 60 men and 33 women whose mean age was 28 years (SD= 15) had no HIV infection. We found that the HIV -positive group had significantly higher rate of positive sputum cultures for MT (4/ 10 [40%] against 10/ 78 [13%] in noninfected patients, p<0.05), and fewer positive tuberculin skin tests (2/10 [20%], against 57/88 [65%] in HIVnegative patients, p<0.05). In our series, granuloma on pleural CHEST /107161 JUNE, 1995
1775