Intensive Care Medicine

Intens. Care Med. 5,189-191 (1979)

9 by Springer-Verlag 1979

Differential Ventilation in Unilateral Lung Disease: Effects on Respiratory Mechanics and Gas Exchange D. Rivara 1 *, J.L. Bourgain 1, p. Rieuf2, A. Harf 3 and F. Lemaire 1 1Servicede R6animation M6dicale(ProfesseurRapin), 2Service de R66dueation Fonctionnelle (Pr. Ag. Hamonnet), 3Service d'Exploration Fonctionnelle (Pr. D. Laurent), H6pital Henri Mondor, F-94010 Cr~teil, France

Abstract. Conventional PEEP ventilation has been recently reported to be deleterious in some cases of ARF with unilateral pneumonia. In such respect, two cases of unilateral bacterial pneumonia were intubated with a Carlens tracheal tube. Measurement of tidal volume, static compliance, and functional residual capacity of each lung showed marked inequality. Subsequently, both patients were ventilated with a selective distribution circuit, allowing the introduction of a PEEP valve in the expiratory line of the diseased lung. Evident improvement in blood gases was obtained within 24 hours, as tidal volume, static compliance, and FRC of the diseased lung were markedly improved. In one case equalisation of V/Q ratio was documented using the 81m Kr method. Final recovery was obtained in one case.

Key words: Adult respiratory distress syndrome (ARDS), Positive end-expiratory pressure ventilation (PEEP), Selective distribution ventilation, Double lumen tracheal tube, Static compliance, Intra-pulmonary shunting, Unilateral pneumonia.

Introduction Failure of conventional ventilation with positive endexpiratory pressure (PEEP) in cases of ARF with unilateral pneumonia [12] has led some authors [2,3,6,15] to propose selective differential ventilation via a double lumen tracheal tube. The purpose of this technique is to control partition of both tidal volumes and to apply different levels of PEEP in each expiratory circuit (10). Whilst G.C. Carlon et al. [2] use two completely separate circuits and ventilators, Cavanilles et al. propose *D. Rivara was research fellow from October 1978 to July 1979 and his present address is: U.C.I. IMPASA L.A. Herrera 2275, Montevideo, URUGUAY

one selective distribution circuit, with an inspiratory retardation device for the unaffected more compliant lung, and PEEl/ valves in one or both expiratory circuits [3]. We have recently treated two cases of ARF with unilateral pneumonia with unilateral PEEP, using the Cavanilles' selective distribution circuit and its efficiency was assessed by changes in blood gases, chest x-ray appearance, tidal volume (VT), airway pressure (Paw), static compliance (C stat.) and functional residual capacity (FRC).

Case Reports Case 1 : a 26 year old man presented with severe septic shock and pulmonary edema, complicating a urinary infection. After surgical cure of the focus of infection, hypoxemia was controlled by mechanical ventilation with PEEP, and PaO 2 (FiO2 = 1)increased from 152mmHg to 325 mmHg within two days. By the 10th postoperative day, chest x-rays showed a right-sided pneumonia and blood and tracheal cultures grew staphylococcus aureus. Fiberoptic bronchoscopy did not show any bronchial obstruction: PaO2 decreased to 181 mmHg (FiO2 = 1), with zero end expiratory pressure (ZEEP). Even low level PEEP (+ 5) provoked an overdistension of the opposite lung and was ineffective in improving blood gases. Selective ventilation was then applied via a Carlens tube [2]. Initial measurement of separate tidal volumes showed a marked discrepancy between both lungs. Right lung VT was 250 ml and left lung 800 ml (Table 1). Total static compliance, measured with a two litre syringe [1,7] was 13 ml/ cmH20 for the right lung and 58 ml/ cm H20 for the left lung. The static pulmonary pressure volume (P-V) curve of the right lung exhibited two inflexions, the first at low pulmonary volume, the other at higher lung volume (Fig.l). F.R.C. measured by closed circuit N2 washout method was : 0.370 litre for the right lung and 1.250 for the left lung. Ventilation-perfusion (VQ) ratios were measured by the krypton 81m inhalation perfusion method [7] and showed marked in0342-4642/79/0005/0189/$1.00

D. Rivara eta].: Differential Ventilation in Unilateral Lung Disease

190

C stat

Pa02

mm.Hg _500

V ml.

1 and 2

LL

1.5.

3oo'1~

7 t

P

.4oo

/I

l /

1

I

,'

a s

i

RL 2

d

Cst !

l

/

95

""

,"

"

t

..... ?--i""

R&-I. . . . . . *

60

Paw

100

./

O..o'" .-O v 9' ~

q

l,

/

0" d

.o

d

r

.*

o/"

.

/ - 200

"~

o~COO o ~

0

40

20

(r,,b)

Fig.l.C. Stat : static compliance; Paw: airway pressure; V: lung volume above F.R.C., KL 1, RL 2: right lung on day 1, right lung on day 2; LL1 and 2: left lung day 1 and 2. Marked improvement of C static of the right lung after 24 h of unilateral PEEP is obvious (from 13 to 24 ml/mb)

o

s

lo

po..15 ,., mb

.Fig.2. The arrow (~) indicates the inflexion point on P-V curve. C. Star: static compliance; Paw: Airway pressure during super syringe compliance measurement; same scale is used for PEEP values; V: lung volume above F.R.C. Schema shows the drastic and immediate improvement in PaO~ after application of unilateral PEEP beyond the i~ftex]on Point of P-V curve

Table 1. Case 1 ZEEP (both lung) V T (ml) C. Stat

PEEP + 9 right lung Day 1

(ml/mb) Day 2 F.R.C. (L) Day 1 V/Q 81

mKr

Case 2

R.L. L.L. 250 800

500

500

13

58

ZEEP (both lung)

R.L. L.L. 700 500

PEEP (+10) 700 (both lung)

500

PEEP + 10 left lung

650

600

55

29

24 50 0.370 1.250

Ventilation 4% Perfusion 22%

96% 78%

~A/O %

1.23

0.18

equalities in both ventilation and perfusion distributions (Table 1): Application of PEEP to the expiratory line of the diseased lung and inspiratory retardation flow device in

the inspiratory line of the normal lung gave equalization o f both tidal volumes (500 ml each) (Table 1, Figl). Optimal PEEP was chosen as follows: static pressurevolume hfitial inflexion (at a P(aw) of 7 cmH2 O) was interpreted as corresponding to the recruitment o f previously closed air spaces [5]. Expiratory pressure was thereby raised beyond the inflexion point (8 cmH2 O) and a marked increase in PaO2 was immediately obtained (432 mmHg) (Fig. 2) [I1]. However, the Carlens tube was removed 24 h later because fiberoptic bronchoscopy showed mild alteration of carinal and low tracheal mucosa. Final recovery was obtained within a few weeks. Case 2 : a 59 year old man, four days after a cholecystectomy, developed acute necrotizing pancreatitis with shock and acute renal failure. Initially pulmonary edema was treated by mechanical ventilation with PEEP. After an improvement, lasting ten days, pulmonary edema, predominantly leftsided was again evident on the chest x-rays. The inequality o f edema, failure to improve with mechanical ventilation with PEEP, were clear indications for selective pulmonary ventilation. Initial spirometry showed marked inequality, the right lung tidal volume

D. Rivara et al.: Differential Ventilation in Unilateral Lung Disease Table 2. Blood gases (FiO 2 = 1.0) Case 1

Case 2 PaO2

ZEEP (both lungs)

PaO2

324

PEEP (both lungs)

(+5)

282

PEEP (One lung)

(+9) 493 (Right lung)

94 (+10)

127

(+10) 181 (Left lung)

was 700 ml and the left was 500 ml. Static compliance was 55 ml/cmH20 for the right lung and 29 ml/cmH20 for the left lung. After 24 h of selective ventilation (10 cmH20 PEEP for the left lung), X-rays showed reexpansion of the left lung and a marked resorption of edema. The improvement in PaO: is shown in Table 2. The patient unfortunately died from haemorrhage during a surgical procedure.

Discussion Abnormalities in the mechanical pattern of ventilation and V/Q ratio abnormalities have recently been documented in unilateral lung injury [3]. Our data confirm, in two similar cases, the very tow static compliance, the reduced FRC and V/Q ratio of the diseased lung (Table 1). In such a pathophysiological situation, it is not surprising that conventional ventilation with bilateral PEEP is usually ineffective or even deleterious, producing an overdistension of the normal lung. This was seen in both cases on the chest x-rays. Diversion of blood flow into the diseased lung, in association with the increase of the dead space of the normal lung [4], amplifies markedely the V/Q inhomogeneity [9]. This situation, according to G. C. Carlon [2], is a clear indication for the replacement of the tracheal tube by a double lumen Carlens tube for selective mechanical ventilation. The setting we used allowed continuous control of the partition of both tidal volume equalization being obtained by simultaneous adjustements of PEEP in one circuit and inspiratory retardation into the other. Defmite and stable improvement in lung condition was suggested by clearing and distension of the diseased lung on x-rays, in case 1 by the upward shift of the P-V curve after 24 hours of unilateral PEEP (Fig. 1), and in both cases by the increase in PaO2. Powner et al. [12] have raised the question of determining the "optimal" PEEP of each lung. If the goal of PEEP is to increase FRC until every collapsed air space is opened up and recruited, and if the inflexion point on static P/V curve corresponds to that level [5-11], then tidal ventilation has, logically, to be moved along the P/V curve above this inflexion point (which actually correlates to the "optimal" quasi-static compliance of P. Suter [14] ). Figure 2 shows that, when expiratory

191

pressure exceeded the inflexion point (7 cmH20), PaO2 increased drastically, suggesting an opening up of collapsed air spaces (Table 2). However, homogeneisation of V/Q ratios has been reported in anesthetized man more simply by lateral decubitus ventilation (the affected lung being placed up) [13]. Since this latter way is much easier to carry out, a comparison between these two alternative methods of ventilation needs to be assessed.

References 1. Bendixen, H.H., Egbert, LD., Hedley-Whyte, L., Laver, M.B., Pontoppidan, H.: In: Respiratory Care. St. Louis: Mosby Co t 965 2. Carlton, G.C., Ray, C., Klein, R., Goldinger, P.L., Miodownik, S.: Criteria for selective positive end expiratory pressure and independent synchronized ventilation of each lung. Chest 74, 501-508 (1978) 3. Cavanilles, J.M., Garrigosa, F., Prieto, C., Oncins, J.R.: Selective ventilation distribution circuit. Intens. Care Med. 5, 95-98 (1979) 4. Dueck, R., Wagner, P.D., West, J.B.: Effect of positive end expiratory pressure on gas exchange in dogs with normal and edematous lungs. Anesthesiology 47,354-366 (1977) 5. Falke, K., Pontoppidan, H., Kumar, A., Leith, E.D., Geffin, B., Laver, M.B.: Ventilation with end expiratory pressure in acute lung disease. J. Clin. Invest. 51, 2315-2323 (1972) 6. Glass, D.D., Tonessen, A.S., Gabel, J.C., Arens, J.F.: Therapy of unilateral pulmonary insufficiency with a double lumen endotracheal tube. Crit. Care Med. 4, 323-326 (1976) 7. Harf, A., Lemaire, F., Lorino, H., Atlan, G.: Etude de la m6canique ventilatoire, application ~ la ventilation artificielle. Bull. Physio-Path. Resp. 1 I, 709-722 (1975) 8. Harf, A., Pratt, T., Hughes, J.M.B.: Regional distribution of VA/Q in man at rest and with exercise measured with krypton81m. J. Appl. Physiol. Respir. Environ. Exercise Physiol. 44, 115-123 (1978) 9. Kanarek, D.J., Shannon, D.C.: Adverse effect of positive end expiratory pressure on pulmonary perfusion and arterial oxygenation. Am. Rev. Resp. Dis. 112, 457-459 (1975) 10. Kusajima, K., Webb, W.R., Parker, F.B.: Pulmonary responses of unilateral (PEEP) on experimental fat embolism. Ann. Surg. 181,676-680 (1975) 11. Lemaire, F., Simoneau, G., Harf, A., Rivara, D., Teisseire, B., Atlan, G., Rapin, M.: Static pulmonary pressure-volume curve, positive end expiratory pressure ventilation and gas exchange in acute respiratory failure (abstract). Am. Rev. Resp. Dis. 119, (suppl.), 328 (1979) 12. Powner, D.J., Eross, B., Grenvik, A.: Differential lung ventilation with PEEP in the treatment of unilateral pneumonia. Crit. Care Med. 5, 170-172 (1977) 13. Rehder, K., Wenthe, F.M., Sessler, A.D.: Function of each lung during mechanical ventilation with PEEP in man anesthetized with thiopental-meperidium. Anesthesiology, 39, 597-606 (1973) 14. Suter, P.M., Fairley, H., Isenberg, M.D.: Optimum end expiratory airway pressure in patients with acute pulmonary failure. N. Engl. J. Med. 292, 284-289 (1975) 15. Trew, F., Rogers, W.B., Poher, W.A.: Differential ventilation of the lungs in mna. Crit. Care Med. 4, 112-116 (1976) Professeur F. Lemalre Service de r~animation m6dicale H6pital Henri Mondor F-94010 Cr~teil France