Liver Involvement in Acute Q Fever

•

'~

.#

.~..

60 55

=

Ideal Flow Resistor / (Slope Aesi,lane. / for an ideal linear / /

50

sYstem)~//

45 e,

0

a:

40

o~

35

(l)E

~1:

30

w'"

25

wO a:C\I (1)0

a: e,

20 15 10 5

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

/

Siemens (Fully open position - No CPAP) (Higher ~1.t8nt)*

Ideal Threshold Resistor

90

120

150

180

210

FLOW RATE (L/min)

* (Provided by S.G. Olsson Siemens-Elema)

note that the Siemens valve was set in the "fully open" position when the measurements were performed; had the system been set to generate continuous positive airway pressure (CPAP~ the 0bserved pressure drop data may have been higher (Ie, greater resistance across the valve). The Hamilton Veolar ventilator (Hamilton Medical Inc, Reno, NV) also has a servo-controlled expiratory pressure valve that operates and responds as a low Bow-resistant threshold resistor. 1 Concerning the test methods used, intubated subjects can generate peak exhaled Bow rates up to approximately 270 Umin during coughing. 3 Peak exhaled Bowrates during simulated coughing with endotracheal intubation ranged from 50 to 200 Umin in our stud)t ~ evaluated the resistance characteristics of a variety of expiratory positive pressure valves using a sinusoidal Bow wave fOrm, since intubated patients do not cough with a constant Bow wave form. 3 Expiratory time and volume were not evaluated since the key independent and dependent variables were exhaled Bow rate and the pressure drop across the valve, respectively Evaluating resistance (pressure drop and Bow J1\le) of expiratory positive pressure valves was the objective of the' stud)t All ventilators were studied intact; no components were isolated during testing. The methods used are clearly described in the paper. Mr. Olsson was unable to reproduce our findings because his evaluations were performed differently from ours. First, he used constant Bow rates (a nonphysiologic application~ while we used sinusoidal Bow rates. Seeondlg he tested the Siemens expiratory positive pressure valve in the fully open position with no CP~ while we examined the valve with CPAP at various levels. A fully open valve ofters less resistance to Bow than one that is set to provide CPAP. Increased resistance with increasing levels of CPAP have been reported with the Siemens expiratory positive pressure valve.4.5 As described earlier, since PaRV, as R increases and V is not changed P must increase. For these reasons, his data (pressure drop) are lower than ours. Our study was designed appropriately to determine the Bow resistive characteristics of a variety of expiratory positive pressure valve systems during simulated coughing. \\brk of breathing was

not reported in our study and, therefore, is not germane to this discussion.

MlchtJelj. Banner, R.R.T., M.Ed.; Sa"...,n Lampotang. AI .E.; Philip G. BOfINn, M.D., F.C.C.E, and DtWUlA. DeMlUtez" R.R.T., M.P.A.,

Univenity ofFlorida College ofMedldne

Departments ofAneatheafology, and Medicine, and College ofEngineering. Dept ofMechamcalEngineering. GtJlnemUe, Florida

REFERENCES 1 Banner MJ, Lampotang S, Boysen PC, Hurd TE, Desautels DA. Flow resistance of expiratory positive pressure valve systems. Chest 1986;90:212-17 2 Banner MJ. Expiratory positive-pressure valves: Flow resistance and work of breathing. Respir Care 1987; 32:431-36 3 Gal TJ. Effects of endotracheal tube intubation on normal cough performance. AnestheSiology 1980;52:324-29 4 Cox D, Niblett DJ. Studies on continuous positive airway pressure breathing systems. Dr J Anaesth 1984;56:905-11 5 Link J. Increases in expiratory resistance of the PEEP valve of the servoventilator. Intens Care Med 1983; 9: 137-38

Liver Involvement In Acute Q Fever 7b the Editor:

We have read with interest the recent report by Marrie et al (Cheat 1988;93:98-103) concerning the epidemiologic investigation

of an outbreak of Q fever, and we would like to add some comments on the apparent lack of liver involvement in the patients reported in the article. Although Q fever is considered primarily a respiratory disease, hepatic dysfunction is common in C bumetti infections, either in epidemic or sporadic cases.1-t Symptoms related to liver involvement CHEST I 94 I 4 I OCTOBER, 1988

815

have been estimated to occur in 11 to 65 percent of the patients with acute Q fever.- When liver-function tests are considered, 70 to 85 percent of patients have abnormal values. V\e reviewed 38 patients with acute Q fever cared for at our hospital in the lastseven years. V\e found that 18 patients (47.3 percent) presented with pneumonia, 16 (42.1 percent) presented with hepatitis without evidence of pulmonary involvement, and four (10.6 percent) presented with a febrile, self-limited illness without evidence of pulmonary or liver involvement FUrthermore, among patients with pneumonia seven (38.8 percent) had liver and/or spleen enlargement, seven (38.8 percent) had elevated levels of AS1; six (33.3 percent) elevated levels of ALl; five (27.7 percent) elevated levels of albline phosphatase, nine (50 percent) elevated levels of GGYI: and six (33.3 percent) elevated levels of LDH. However; the level of hepatic transaminMeS was significantly higher in those patients without pneumonia when compared with those with pneumonia, (p =.0001) as was the level of direct bilirubin (p = . 004~ On the other hand, mean interval between the beginning of the symptoms and hospitalization was significantively higher in patients without pneumonia (4.5±2.3 vs 11.2±8.8 days, p= .004~ Lackof data referring to liver dysfunction in the article by Marrie et al is surprising, especially ifwe consider that 14 patients were at some time admitted to a hospital. Although Marries article focuses mainly on epidemiologic aspects of Q fever, it could be interesting to know how many of their patients presented clinical and/or laboratory evidence of liver involvement and also if there were patients with only hepatitis. This could be important to further define the spectrum of organ involvement in acute Q fever and may document differences between epidemic and sporadic cases of acute Q fever. ~

Domingo, M.D.;

Josep Orobitg, M.D.;

Je8U8 Colomina, M.D.; Elvira Alvarn, M.D., and Josep Cadsjidch, M.D., DepartrnlJnt ofInternal Medicine, Hospital dela Santa Crn i Sant Ibu, Barcelona, Spain REFERENCES

1 Marrie 1), MacDonald A, Durant H, Yates L, McCormick L. An outbreak of Q fever probably due to contact with a parturient cal Chest 1988; 93:98-103 2 Leedom JM. Q fever: an update. In: Remington J, Swartz MN, eels. Current clinical topics in infectious diseases. New York: McGraw Hill, 1980; 304-31 3 Sawyer LA, Fishbein DB, McDade JE. Qfever: current concepts. Rev Infect Dis 1987; 9:935-46 4 Spelman OW. Q fever. A study of 111 consecutive cases. Med J Aust 1982; 1:547-53 5 Clark WH, Leonette EH, Railsback OC, Romer MS. Q fever in California. VII. Clinical features in one hundred eighty cases. Arch Intern Med 1951; 52:54-66

7b the Editor: Our study (Chest 1988;93:98-103) was an epidemiologic one. Patients were admitted to a community hospital and did not have liver function tests performed. However, since we have begun the study of Q fever in 1979, we have identified 170 patients with Q fever in Nova Scotia. None of these patients have presented with hepatitis. We have also studied 20 patients with severe pneumonia due to Q fever who were hospitalized at the Victoria General Hospital in Halifax. All of these patients had serial liver function tests carried out Alkaline phosphatase was above the upper limit of normal in 57 percent, AST was elevated in 52.6 percent and ALT in 42.8 percent These figures

are similar to the data quoted by Domingo et all We have also studied 40 patients with Mycoplasma pneumonitJe and 14 with Legionella pneumophiltJ pneumonia. We found that 47.5 percent of the Mycoplasma patients and 64 percent of the Legionella patients had an elevated albline phosphatase level. AST was elevated in 37.5 and 57 percent of these two groups respectivelg and AI.:r in 27.5 and 30.7 percent In most instances, patients with Q fever pneumonia had very mild elevation of the various liver function tests. Mean AST was 54 (upper limit of normal is 29) and ALT 48.1 (upper limit of normal 41~

None of the 21 patients had bepatosplenomegaly Indeed, only two of 50 patients with Q fever pneumonia that I personally examined had splenomegaly These data would suggest that indeed there may be something different about Q fever in Nova Scotia compared with Q fever in Spain-this could reflect strain or host differences. It is important to realize, howeveI; that abnormal liver function tests do not necessarily mean involvement of the liver by Q fever since mild abnormalities of liver function tests are common in various atypical pneumonias. Thomas]. MatTie, M.D., Dalhousie University, Victoria GeneralHospital,

Halifax, Nova Scotia

Diagnostic Value of Bronchography 7b the Editor: I read with great interest Dr. Cervantes-Perezs recent letter illustrating the use of bronchography in the diagnosis of lobar torsion.! It is both nostalgic and refreshing for those of us who performed countless bronchographies in the past to see that it still has a place in diagnostic radiolog and I hope that the young generation of radiologists will continue to take advantage of this excellent diagnostic modality in carefully selected cases. It must be noted, however, that Dr. Cervantes-Perezs claim to be the first to diagnose lobar torsion by bronchography is upset by nine years by Huang and Cho. 1 Also, a similar case was illustrated by Felson 3 not too long ago.

Yahya M. Ber1cmen, M.D.

Department ofRadiology,

New YorkHospital, Cornea Medical Center; New York

REFERENCES

1 Cervantes-Perez E Letter to the editor. Chest 1988; 93:445-46 2 Huang Cho SR. Torsion of the lung without trauma. Radiology 1979; 132:25-26 3 Felson B. Lung torsion: radiographic findings in nine cases. Radiology 1987; 162:631-38

n

7b the Editor: I wish to answer some of Dr. Berkmens questions. My basic objective in informing your readers about our case of lobar torsion was to demonstrate the usefulness of bronchography as a diagnostic procedure prior to surgery in some cases of pulmonary torsion, and to relate this to the report of Shorr and Rodriguez (Chest 1987; 91:297-28~ From this point of vi~ the matter of whether our case was or wasn't the first to be preoperatively diagnosed by means of bronchography is irrelevant However; the additional information Dr. Berkmen provided confirms our impression that our case was the Communications to the Editor