T7horax (1963), 18, 77

Cardio-respiratory studies in a patientwith an absent left pulmonary arteryP. L. LANDRIGAN 1, I. E. PURKIS, D. E. ROY,

AND L. CUDKOWICZ

From the Department of Medicine and Anaesthesia, Dalhousie University,and the Victoria General Hospital, Halifax, Nova Scotia

Congenital absence of a main pulmonary arteryto one lung is a well-documented anomaly(Fraentzel, 1868; Miller, 1937; Blalock, 1948;Findlay and Maier, 1951; Madoff, Gaensler, andStrieder, 1952) and its association with unilateralcystic lung disease was emphasized in particularby Mannix and Haight (1955) and by Steinberg(1958). According to Madoff and others, a

preponderance of congenital cardiac defects isapparent in patients with an absence of the leftpulmonary artery. In their own report of a patientwith a right-sided anomaly, other congenital heartdefects were absent. When a lung is deprived ofits main pulmonary arterial circulation, there isconsiderable expansion of a systemic collateralcirculation (Bloomer, Harrison, Lindskog, andLiebow, 1949).Haemoptyses, usually stemming from the

expanded arterial collateral circulation (Cudkowicz,1952), are a frequent, early, and most distressingsymptom (Findlay and Maier, 1951) and pneumon-ectomy may be necessary. Such a decision mayalso be reinforced by the failure of broncho-spirometry to demonstrate a significant oxygenconsumption by the affected lung. Oxygen uptakesvarying from 0 to 7% of the total consumptionhave been found under such circumstances(Madoff et al., 1952; Smart and Pattinson, 1956;Fishman, Turino, Brandfonbrener, and Himmel-stein, 1958; Tabakin, Hanson, Adhikari, andMiller, 1960), suggesting little, if any, participationin gas exchange by the abnormal lung.Fishman and his colleagues (1958) and

Tabakin and others (1960), however, added tothe study of the function of these lungs duringbronchospirometry by the inclusion of suchadditional measurements as CO2 excretion and'effective' bronchial blood flows. Here we reporta patient with congenital absence of the leftmain pulmonary artery, whose clinical findings

'In receipt of Grant No. 9310-73 from the Defence ResearchBoard.

suggested, and routine investigations confirmed,the diagnosis. Additional information supportingthis diagnosis and concerning particularly thequantity of 'effective' bronchial collateral bloodflow, as well as the participation of the affectedlung in overall gas exchange, was obtained duringbronchospirometry.

CASE REPORT

A 44-year-old white housewife was admitted to theVictoria General Hospital, Halifax, N.S., in March1960 because of a persistent cough and mucoidsputum. These symptoms began in 1954 and followedan upper respiratory infection, an incident whichpreviously had left no sequelae. In 1957 she con-tracted a left-sided pneumonia and for some timeafterwards expectorated purulent green sputum whichon only one occasion became blood-stained. Whenthe purulent sputum subsided, the cough remained.She denied other symptoms and seemed unaware ofbreathlessness.The clinical findings were confined to the chest,

which disclosed a decrease in expansion, impairmentin percussion note, and absence of tactile fremitus andvocal resonance in the area of the left lower lobe.Medium and low-pitched expiratory wheezes wereaudible in the same territory. Clubbing of the fingerswas absent, the colour of the mucous membraneswas normal, and the neck veins showed no engorge-ment. The apex beat was not displaced, and theheart sounds were normal. A medium-pitched mid-systolic murmur of 1/6 intensity was present along theleft sternal border, loudest in the second left inter-costal space, as well as a high-pitched early diastolicmurmur of similar intensity and distribution. Theperipheral pulses were equal, the rhythm regular, andthe blood pressure was 120/75 mm. Hg.

SPECIAL INVESTIGATIONS The haemoglobin was 14.5g./100 ml.; P.C.V., 48%; W.B.C., 9,900/c.mm. witha normal differential count. Erythrocyte sedimenta-tion rate was 26 mm. in one hour. Serology wasnegative. Plasma proteins: total, 6.5 g./100 ml.;albumin, 4.2 g./100 ml.; globulin, 2.3 g./100 ml.Repeated sputum cultures demonstrated a normalflora and cultures for tubercle bacilli were negative.

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FIG. 1. Radiograph shows trans-lucency of left lung field.

FIG. 2. Left bronchogram showsectasia of left lower lobe bronchiand small cysts in communicationwith abnormal bronchi.

FIG. 1

Electrocardiograms revealed a variable atrial pace-maker.Radiographs of the chest showed an increase in

translucency of the left lung fields, plethora of theright lung, and a normal cardiac silhouette (Fig. 1).Tomography of the left lung failed to depict a leftpulmonary artery shadow. Bronchography revealedextensive bronchiectasis and some cystic changes inthe left lung which communicated with the bronchi(Fig. 2).CARDIAC CATHETERIZATION The catheter could not bepassed into the left main pulmonary artery. A dyedilution curve recorded from a femoral artery, afterdelivery of the bolus into the main pulmonaryartery, revealed a normal contour. An angiocardio-gram from the right ventricle showed the absence ofthe left main pulmonary artery, as well as anomalousprimary branching of the right main pulmonary artery(Fig. 3).

RESPIRATORY FUNCTION STUDIES Table I summarizesthe respiratory function tests, which show moderatelysevere restrictive lung disease, as well as enlargementof physiological dead space and an abnormally highalveolar-arterial PCO2 gradient. The alveolar ventila-tion was normal, and the carbon monoxide diffusingcapacity was reduced by more than 50 per cent. FIG 2

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Cardio-respiratory studies in a patient with an absent left pulmonary artery

FIG. 3. Pulmonary angiogram shows an absence of the left pulmonary arteryand two large abnormal divisions reaching the right upper lobe.

TABLE IPULMONARY FUNCTION STUDIES

Actual IValues

Resting minute ventilation (1.1/min.)Vital capacity (1.)3-sec. timed vital capacity (1.)Maximum expiratory flow rate (. /min.)Maximum breathing capacity (1./min.)Index of intrapulmonary mixing (% N2)Air velocity indexResting 02 consumption (ml./min.)Residual volume (1.)Total lung capacity (1.)Functional residual capacity (1.)Resting arterial 02 saturation on air (°)Resting arterial 02 saturation on 02 (°/°)Alveolar Pco2 (mm. Hg)Arterial Pco2 (mm. Hg)A-a Pco2 gradient (mm. Hg)Arterial pHDead space (ml.)Alveolar ventilation (1. min.)Carbon monoxide diffusing capacity(ml./min./mm. Hg)

7 162-272-0

29097.50-81*1

195-01-293.541*5

951003040107-36

2804-76

9 0 (rest

BRONCHOSPIROMETRY

Bronchospirometry was used to mezfollowing: (1) minute ventilation Eelimination from each lung while b4respired ambient air; (2) oxygen consumminute ventilation of each lung while brespired oxygen; (3) oxygen consumpti4left lung on oxygen, while the normal i

respired air; and (4) oxygen consumpti4

left lung on oxygen, while the normal right lungrespired a 10% oxygen in nitrogen mixture.

VormalStandards METHOD After topical anaesthesia and without% of Normal) premedication a 37 Carlens' catheter was placed82-4 so that its distal lumen entered the left main88-4 bronchus. Its position was checked by fluoro-91-4 scopy. The absence of gross leaks was established20 once air could no longer be displaced from one0-8-1-1

spirometer to the other. After the cuffs had been4-21. inflated the reduction in the left respiratory

movements, already noted clinically, becameimmediately apparent in the left spirogram.For measurements of minute ventilation,

5 mm. Hg alveolar and dead space ventilations, and CO2output during ambient air breathing, expired airwas collected for three minutes in two anaesthetic

ing) bags interposed between the expiratory circuits andthe spirometers by two three-way valves.

Arterial blood was collected through a Cournandneedle placed in a brachial artery during the third

asure the minute of the first three procedures and in the firstand CO2 minute of the fourth study.oth lungs The oxygen content and capacity of whole bloodiption and were determined by the Van-Slyke-Neill mano-oth lungs metric apparatus. The gas volumes of the bagson by the were measured in a Tissot gasometer and the CO2right lung content analysed in duplicate in a modifiedon by the Haldane gas analyser (Campbell, 1960). Whole

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arterial blood pH was determined in the Astrupapparatus, and the arterial Pco, was calculatedby the Astrup technique.For the second, third, and fourth study the

respective gas mixtures were introduced into the9-litre spirometers. Before the bilateral oxygenconsumption was measured both lungs respiredoxygen for three minutes before being switchedinto the spirometers.

Effective bronchial arterial blood flow to the leftlung was calculated according to the Bloomertechnique (Bloomer et al., 1949), and adaptationof this technique in man gives estimates which varyfrom 0 86 to 1 9 1./min. (Madoff et al., 1952;Fishman et al., 1958; Tabakin et al., 1960).Bronchial arterial collateral blood flows in excessof this have to be expected in main pulmonaryartery atresia associated with Fallot's tetralogyand were demonstrated by a different method byBing, Vandam, and Gray (1947). The Bloomertechnique assumes that, in patients whose lungsare deprived of their main pulmonary arterycirculation, all left pulmonary capillary blood flowis systemic in source and has a precapillary 02content equivalent to that of brachial arterialblood while both lungs respire air. This oxygencontent is expressed as CaO2. On switching the leftlung to oxygen the left alveolar Po, rises rapidly

and a new left alveolar-capillary Po, gradient isestablished, permitting 02 diffusion to occur at thatnew gradient. The uptake of oxygen by the leftlung is measured and is expressed as Vo,LBA.It is assumed that the left pulmonary venous bloodis now fully saturated and that its content is equalto that of the arterial 02 capacity. By applyingFick's principle, the collateral bronchial bloodflow QBA to the left lung can be calculated asfollows:

QBA VO2LBA x 100arterial 02 capacity -CaO,

RESULTS Table II shows that the left lungparticipated in 101 % of a total minute ventilationof 825 1./min. Similarly, 845% of a total CO2output of 284 ml./min. was derived from the leftlung. The overall alveolar ventilation of 5 661./min. was normal and maintained the arterialPco, at 40 mm. Hg. During bilateral oxygenbreathing (Table III), the left lung took up 11.9%of the total oxygen consumption of 305 ml./min.and participated in 8 5% of the total minuteventilation of 7-23 1./min. The arterial oxygensaturation, which was 93%, rose to 100% duringbilateral oxygen breathing. With the left lung onoxygen alone, the arterial oxygen saturationdropped to 97%, but an increase in oxygen

TABLE IIBRONCHOSPIROMETRIC MEASUP EMENTS ON AMBIENT AIR

Right % of Left % ofLung Total Lung Total

Minute ventilation (I. min.)

Rate of respirationCO2 output (ml. 'min.)

Alveolar ventilation (1. 'min.)

Dead space ventilation (I. min.)Physiological dead space (ml.)

7-42 89-9

11260

1191-55 24

Total Arterial BloodAttalvses

0 83 10 1 8 25 Hb 15 5 g. 100 ml.0, content 19-5 vol.%

8-45 284 O., capacity 20-49 vol.°°2 saturation 93%

5-66 Pco, 40 mm. HgpH 7-38

,%.Cf2-59234

TABLE IIIBRONCHOSPIROMETRIC MEASUREMENTS WITH BOTH LUNGS ON OXYGEN

Right ° of LeftLung Total Lung

% ofTotal

Total Arterial BloodAnalvses

02 consumption (ml. min.)Minute ventilation (. 'min.)Ventilatory equivalent for 0., (1.'min.)

2696-582 45

88-1 36-091 5 0-65

179

11.9 3058-5 723

02 content 20 39 vol.',0. capacity 20-30 vol.°02 saturation 100%Pco. 34 5 mm. Hg

TABLE IVBRONCHOSPIROMETRIC MEASUREMENTS WITH RIGHT LUNG ON AMBIENT AIR AND LEFT LUNG ON OXYGEN

02 consumption (ml. 'min. )Minute ventilation (I. min.)

Right % of LeftLung Total Lung

45 06 64 89 0 0-822

, ofTotal

Total Arterial BloodAnalyses

O., content 19 9 vol.',11 0 746 02 saturation 970'/

Pco2 355 mm. Hg

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Cardio-respiratory studies in a patient with an absent left pulmonary artery

TABLE VBRONCHOSPIROMETRIC MEASUREMENTS WiTH RIGHr LUNG ON 10% OXYGEN IN NITROGEN AND LEFT LUNG ON OXYGEN

Right % of LeftLung Total Lung

02 consumption (ml./min.)Minute ventilation (I./min.)

85 012-04 90-8 1-23

% ofTotal

Total Arterial BloodAnalyses

9-2 13-27 O2content 10-24vol.%02 capacity 20-59 vol.%02 saturation 49-2%Pco2 34-5 mm. Hg

consumption from 36 to 45 ml. /min. occurred(Table IV) with a slight rise in minute ventilation.When the right lung was placed on a 10% oxygenin nitrogen mixture the arterial oxygen saturationdropped to 49-2% in spite of an almost 100%increase in the oxygen consumption of the leftlung, which continued to respire pure oxygen. Thesystemic arterial hypoxaemia raised the totalminute ventilation to 13-27 1./min., but therestrictive disease of the left lung provided thatlung with only 9-2% of the total minute ventilation(Table V). The effective left bronchial arterialblood flow calculated from procedures 2 and 3was:

QLBA= Vo2LBAarterial 02 capacity -CaO2

4520-39 - 5 X 100=506 ml./min.203 19-5

DISCUSSION

The associated bronchiectatic and cystic lesionsof the left lung of this patient appear to haverestricted its movements so that its participationin total minute ventilation was only 10 to 11 percent. The overall alveolar ventilation in thepresence of the enlarged physiological dead spaceremained adequate, as shown by the normalarterial Pco2 levels. Because there were grosslyrestricted movements of the left lung, participationin gas exchange was equally impaired and only8-5% of the total CO2 elimination during ambientair breathing stemmed from the left lung and itssystemic blood supply. Nevertheless, the oxygenconsumption increased by raising the left alveolar-capillary Po2 gradient or during deliberatereduction of that of the right lung. The limit inparticipation of gas exchange was imposed on theleft lung of this patient by the reduced diffusingcapacity and the relatively low effective bronchialarterial blood flow of 05 1./minute. In the twostudies reported by Tabakin and others (1960),the bronchial arterial blood flows were 183 and1-81 1./min. respectively. It is also of interest that,in the two patients studied by these authors, theleft lungs contributed 52 and 35% respectively to

the total ventilation, whereas the oxygenconsumptions of the anomalous sides were 7 and5%, respectively. The corresponding CO2 excre-tions were 37 and 26% of the total, respectively,with a normal diffusing capacity, measured in theirsecond patient only, of 24 ml./min./mm. Hg.These observations would thus be in keeping withan almost normal participation in alveolar ventila-tion and a slightly lowered systemic arterial-leftalveolar Pco2 gradient.A lung deprived of a main pulmonary artery

and endowed with a large bronchial collateralcirculation continues to possess useful respiratoryfunction. Elimination of CO2 from such a lungrenders it active in effective alveolar ventilation.The CO2 component derived from this lung hasthe effect of diminishing physiological dead spaceand thereby reduces the obligatory minute ventila-tion. A low oxygen consumption alone by theanomalous lung, while oxygen is respired bilaterallyduring bronchospirometry, is unlikely to providefull information concerning total respiratoryfunction of that lung, particularly as the oxygenconsumption of that lung clearly can be increasedduring any deliberate reduction in systemic bloodPo2 tension. This manoeuvre in conjunction withseparate CO2 measurements seems necessary inany assessment concerning its participation in gasexchange, particularly if a pneumonectomy iscontemplated as a respite from haemoptyses.

SUMMARY

In a patient with an absent left pulmonary arteryand associated left-sided bronchiectasis and cysticlung disease, the clinical diagnosis was establishedby radiography and a right ventricular angiogram.Bronchospirometry revealed that the left lungparticipated in 10-1% of the total minute ventila-tion, eliminated 8-45% of the total CO2 excretion,and shared in 11-9% of the total oxygen consump-tion. The left lung oxygen consumption of 36ml./min. increased to 45 ml./min. while respiringthe right lung on air alone and reached 85 ml./min.if a 10% oxygen mixture in N2 was respired tothe normal lung. The effective collateral arterialblood supply to the left lung was calculated at

- - ---, ---

- I . I

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0-506 millilitre/minute. The significance of thesefindings is discussed.

We wish to thank Mr. L. Diamond, Department ofMedical Photography, Dalhousie University, for thereproduction of the radiographs.

REFERENCES

Bing, R. J., Vandam, L. D., and Gray, F. D., Jr. (1947). Bull. JohnsHopk. Hosp., 80, 107, 121.

Blalock, A. (1948). Surg. Gynec. Obstet., 87, 385.Bloomer, W. E., Harrison, W., Lindskog, G. E., and Liebow, A. A.

(1949). Amer. J. Physiol., 157, 317.

Campbell, E. J. M. (1960). Brit. med. J., 1, 457.Cudkowicz, L. (1952). Thorax, 7, 270.Findlay, C. W., Jr., and Maier, H. C. (1951). Surgery, 29, 604.Fishman, A. P., Turino, G. M., Brandfonbrener, M., and Himmel-

stein, A. (1958). J'. cli . Invest., 37, 1071.Fraentzel, 0. (1868). Virchows Arch. path. Anat., 43, 420.Madoff, I. M., Gaensler, E. A., and Strieder, J. W. (1952). New Engl.

J. Med., 247, 149.Mannix, E. P., Jr., and Haight, C. (1955). Medicine (Baltimore),

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Miller, J. F. (1937). Amer. J. Dis. Child., 53, 1268.Smart, J., and Pattinson, J. N. (1956). Brit. med. J., 1, 491.Steinberg, I. (1958). Amer. J. Med., 24, 559.Tabakin, B. S., Hanson, H. S., Adhikari, P. K.. and Miller, D. B.

(1960). Circulation, 22, 1107.

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