Dopamine, dobutamine, digitalis, and diuretics during intraaortic balloon support

Transcription

1 Dopamine, dobuamine, digialis, and diureics during inraaoric balloon suppor Sephen Slogoff, M.D. n his presenaion, should like o discuss some conceps of drug herapy for inraaoric balloon paiens. Figure 1 shows our Texas Hear nsiue (TH) paien classificaion diagram. These daa, compiled over a 1-year period, characerize paiens' condiions 24 hours posoperaively or pos-inraaoric balloon inserion. Paiens in Class A have essenially a 100% chance of survival; hose in Class B have abou an 80% chance; and hose in Class C have no chance of survival. Therefore, i is imperaive o manipulae paiens pharmacologically in such a way as o remove hem from Class C. To move paiens ino Class B or Class A, we mus increase heir cardiac oupu. Because mos of hese paiens are suffering from coronary arery disease, however, i is imporan o minimize or a leas no increase myocardial oxygen consumpion. Achieving an accepable balance beween hese wo hemodynamic funcions makes managing such paiens difficul. Cardiac oupu is proporionae o hear rae imes conraciliy, imes preload or wedge pressure (which is wha we measure), divided by aferload. n oher words, cardiac oupu rises wih an increase in hear rae, conraciliy, or filling pressure, and i falls wih a decrease in peripheral vascular resisance (Fig. 2). Myocardial oxygen consumpion, which mus be kep as low as possible, also increases proporionaely wih hear rae, conraciliy, filling pressure, and aferload (Fig. 2). There- Presened a he Seminar and Workshop: Advances in nraaoric Balloon Pumping, Texas Hear nsiue, Houson, March 8, Address for reprins: Sephen Slogoff, M.D., Deparmen of Aneshesiology, Texas Hear nsiue, P.O. Box 20269, Houson, Texas Cardiovascular Diseases, Bullein of he Texas Hear nsiue Volume 7 Number 3 Sepember

2 fore, cardiac oupu frequenly mus be augmened a he expense of myocardial oxygen consumpion, and, conversely, myocardial oxygen consumpion ofen mus be lowered a he expense of cardiac oupu. Figure 3 illusraes he hemodynamic effecs of inraaoric balloon pumping. The hear rae is diminished, and conraciliy is essenially unaffeced. Reducions in sysemic vascular resisance, preload, and lef venricular end-diasolic pressure lead o a decrease in oxygen consumpion. All indices of myocardial oxygen consumpion are eiher reduced or unchanged. Moreover, because of diasolic augmenaion, coronary perfusion is increased; he cardiac oupu is also measurably increased. Even wih balloon assisance, however, many paiens are sill inadequaely perfused. Figure 4 shows drugs ha a paien in Class C or Class B can receive during he posoperaive period when pharmacologic suppor is needed in addiion o he balloon. High-dose dopamine (2 1O,g/kg/min) significanly increases he hear rae and conraciliy as a resul of is bea effec; i also significanly augmens sysemic vascular resisance as a resul of alpha simulaion, bu of iself probably has no direc effec on end-diasolic or wedge pressure. s ne effec is an increase in myocardial oxygen consumpion. Therefore, alhough highdose dopamine augmens he cardiac oupu, i also causes he already compromised myocardium o increase is oxygen deb. Dobuamine, which has recenly been made available o he general medical communiy, produces effecs similar o hose of high-dose dopamine. Alhough dobuamine does no cause a marked increase in hear rae, i does significanly increase conraciliy by means of bea simulaion. also enhances sysemic vascular resisance wihou significanly changing end-diasolic pressure. augmens oxygen consumpion and cardiac oupu. Epinephrine, like dobuamine, produces an increase in oxygen consumpion and cardiac oupu. Digialis, a long-acing inoropic agen, causes a reduced hear rae and increased conraciliy. Alhough i does no have a marked longerm effec on sysemic vascular resisance, digialis does produce a reducion in end-diasolic pressure. Because of enhanced conraciliy. however, is ne effec is o increase boh oxygen consumpion and cardiac oupu. Because of he risk of digialis-induced arrhyhmias, his drug is rarely indicaed for balloon paiens, who frequenly are oliguric and are herefore more suscepible o digialis oxiciy. Besides augmening he cardiac oupu, all of he aforemenioned drugs also increase myocardial oxygen consumpion. And for he mos par, hey increase sysemic vascular resisance, which is undesirable in balloon paiens. Figure 5 liss a second group of drugs ha are classified as vasodilaors raher han inoropic agens. The vasodilaors include niroprusside, niroglycerine, low-dose dopamine ('5,ug/kg/min), and isoproerenol. The vasodilaors ac somewha differenly from he inoropic agens. Niroprusside causes sysemic vasodilaaion, wih a decrease in filling 326

3 TH ABP/ALVAD CLASSFCATON s in _ u - CAROAC TNOEX ( L/MNM* S - CLASS A CLASS B Survival = 100% (78/78) Survival = 80% (45/56) Survival =5 1% ( /100) CLASS C SYSTEMC VASCULAR RESSTANCE ( OYNES*SEC/CMeo5 ) Fig. 1 Paien classificaion diagram. ABP = inraaoric balloon pump; ALVAD = abdominal lef venricular assis device. Co C< HR X CONTRACTLTY X PRELOAD AFTERLOAD MV02 C HR X CONTRACTLTY X PRELOAD X AFTERLOAD TH Fig. 2 Cardiac oupu rises wih an increase in hear rae, conraciliy, or filling pressure, and i falls wih a decrease in peripheral vascular resisance. ABP EFFECTS HR CONTRACTLTY SVR LVEDP MV02 CO ABP TH Fg. 3 The hemodynamic effecs of inraaoric balloon pumping. 327

4 pressure. Of iself, niroprusside does no direcly affec conraciliy, bu i does produce an increase in hear rae secondary o hypoension. Filling pressure is reduced, vascular resisance or aferload is reduced, conraciliy remains unchanged, and he hear rae is slighly increased, yielding a ne reducion in oxygen consumpion. Bu because he aferload is reduced (and cardiac oupu is inversely relaed o aferload), he adminisraion of niroprusside o paiens wih hear failure frequenly is associaed wih an increase in cardiac oupu. Alhough similar o niroprusside, niroglycerin primarily dilaes he venous circulaion; i affecs he arerial circulaion only slighly a high dosages. A reducion in oxygen consumpion may be accompanied by a drop in cardiac oupu because of he primary reducion in filling pressure. DOPAMNE (10 MCG/KG/MN) DOBUTAMNE (10 MCG/KG/MN) EPNEPHRNE (0.0' MCG/KG/MN) DGTALS NOTROPC AGENTS HR CONTRACTLTY SVR f f - ~f f f LVEDP MVO2 CO -f - - _+ T TH Fig 4 Drugs ha a paien in Class C or Class B can receive during he posoperaive period, when pharmacologic suppor is needed in addiion o he balloon. f VASODLATOR AGENTS NTROPRU-SSDE (2 MCG/K6/MN) NTROGLYCERN (1 MCG/KG/MN) DOPAMNE (5 MCG/KG/MN) SOPROTERENOL (0-02 MCG/KG/MN) HR CONTRACTLTY SVR LVEDP MVO2 CO f f T TH Fig. 5 A group of drugs classified as vasodilaors raher han inoropic agens. 328

5 TH ABP/ALVAD CLASSFCATON Niroprusside CLASS A CARDACDgli NDEX L/MNM**2 ) CLASS B.SDigilis 1. 0 Epinephrine-,-. S - Dobuomine e(hd)_dopamine(ld)-isoproerenol CLASS C SYSTEMC VASCULAR ( OYNESeSEC/NMeS ) RESSTANCE Fg. 6 Balloon classificaion diagram ploing herapeuic ranges for pharmacologic agens. Low-dose dopamine rarely produces an increase in sysemic vascular resisance, bu enhances boh conraciliy and hear rae, while leaving end-diasolic pressure unchanged. also augmens myocardial oxygen consumpion and cardiac oupu. When an inoropic agen is needed, a persuasive argumen in favor of low-dose dopamine is ha i has a dopaminergic effec-i ends o increase he urine oupu. For some reason, a hese doses, he drug is associaed wih arerial vasodilaion. soproerenol is conraindicaed excep in rare cases, because i causes a remendous increase in hear rae ha may produce a paradoxical fall in cardiac oupu and venricular irriabiliy. Our balloon classificaion diagram (Fig. 6) plos cardiac oupu agains sysemic vascular resisance wih wha is considered a saisfacory wedge pressure-approximaely 14 orr. f a paien is in Class C because of a low cardiac oupu and low sysemic vascular resisance, he needs a drug such as epinephrine, which will increase conraciliy and sysemic vascular resisance. As sysemic vascular resisance increases wihin Class C, a drug ha increases conraciliy and cardiac oupu bu has a lesser effec on sysemic vascular resisance is indicaed. Such a drug would be high-dose dopamine or dobuamine. Wih higher sysemic vascular resisances, low-dose dopamine is desirable. Besides producing vasodilaaion, low-dose dopamine will also augmen he cardiac oupu and cause a significan increase in urine oupu. 329

6 There is a group of paiens wih cardiac oupus ranging from normal o significanly reduced who are in Class C because of heir remendous peripheral vascular resisance. The adminisraion of niroprusside frequenly will benefi hese paiens and permi movemen ino an accepable hemodynamic saus. Digialis may be indicaed for he few paiens who need assisance in progressing from Class B ino Class A, bu i has no place as he primary herapeuic agen for anyone in Class C. n pracice, mos of our paiens are reaed wh niroprusside and dobuamine. We rarely appreciae how inensely vasoconsriced hese paiens are unil we acually calculae sysemic vascular resisance and find how easily cardiac oupu can be augmened by a niroprusside infusion. 330