The effect of oxygenator mechanical characteristics on energy transfer during clinical cardiopulmonary bypass

Abstract

The hollow-fibre oxygenator is a key component of any extracorporeal circuit used to provide cardiopulmonary bypass (CPB) during open-heart surgery. Since the oxygenator is placed downstream of the pump, the energy losses over it have a direct impact on the quality of pulsatile pressure and flow waveforms. The objective of this study was to describe the effects of hydrodynamic characteristics of the oxygenator on energy transfer during pulsatile, normothermic CPB. Twenty-three adult patients scheduled for coronary bypass surgery were divided randomly into two groups, using either an oxygenator (Group 1) with a relatively high-resistance and low-compliance (2079 ± 148 dyn.s.cm^-5 and 0.00348 ± 0.00071 ml^.mmHg^-1, respectively) or an oxygenator (Group 2) with a relatively low-resistance and high-compliance (884 ± 464 dyn^.s^.cm^-5 and 0.01325 ± 0.00161 ml^.mmHg^-1, respectively). During perfusion, pre- and post-oxygenator pressures, radial artery pressure, and blood flow were recorded simultaneously.

A 32% decline of mean pressure was observed in Group 1 and a 16% decline in Group 2 (p<0.0001). Another decrease by approximately 73% in mean pressure in the rest of the perfusion system was noted in both groups. The mean radial artery pressure did not differ between the groups (74 ± 6 mmHg in Group 1 and 73 ± 6 mmHg in Group 2, p=0.608). Although lower total energy transfer indices were noticed through the low-resistance oxygenator (Group 2), both oxygenators showed a decrease of the generated pump oscillatory energy of approximately 50%. Despite the differences in resistance and compliance of the hollow-fibre oxygenators used, both oxygenators cause a comparable loss of generated oscillatory energy. Exclusion of the oxygenator downstream of the pulsatile pump would improve energy transfer during CPB.

Get full access to this article

View all access options for this article.

References

Likosky DS An epidemiologist’s review of the case for pulsatile flow during cardiopulmonary bypass. J Extra Corpor Technol 2009; 41: P30- 32.

Grossi EA , Connolly MW , Krieger KH , et al. Quantification of pulsatile flow during cardiopulmonary bypass to permit direct comparison of the effectiveness of various types of "pulsatile" and "nonpulsatile" flow. Surgery 1985; 98(3): 547-554.

Wright G. Hemodynamic analysis could resolve the pulsatile blood flow controversy. Ann Thorac Surg 1994; 58(4):1199- 1204.

Undar A. Myths and truths of pulsatile and nonpulsatile perfusion during acute and chronic cardiac support. Artif Organs 2004 ; 28(5): 439-443.

Undar A. , Rosenberg G. , Myers JL Major factors in the controversy of pulsatile versus nonpulsatile flow during acute and chronic cardiac support. Asaio J 2005; 51(3): 173-175.

Undar A. , Masai T. , Frazier OH , Fraser CD, Jr. Pulsatile and nonpulsatile flows can be quantified in terms of energy equivalent pressure during cardiopulmonary bypass for direct comparisons. Asaio J 1999; 45( 6): 610-614.

Undar A. , Eichstaedt HC , Masai T. , et al. Precise quantification of pulsatility is a necessity for direct comparisons of six different pediatric heart-lung machines in a neonatal CPB model. Asaio J 2005; 51(5): 600-603.

Haines N. , Wang S. , Undar A. , Alkan Y. , Akcevin A. Clinical outcomes of pulsatile and non-pulsatile mode of perfusion. J Extra Corpor Technol 2009; 41 (1): P26-29.

Wright G. The hydraulic power outputs of pulsatile and non-pulsatile cardiopulmonary bypass pumps. Perfusion 1988; 3(2): 251-262.

10.

Wright G. Factors affecting the pulsatile hydraulic power output of the Stockert roller pump. Perfusion 1989; 4(1): 187-195.

11.

Gourlay T. , Taylor KM Pulsatile flow and membrane oxygenators. Perfusion 1994; 9(3): 189-196.

12.

Rees W. , Schiessler A. , Schulz F. , et al. Pulsatile extracorporeal circulation: fluidmechanic considerations . Perfusion 1993; 8(6): 459-469.

13.

Inzoli F. , Pennati G. , Mastrantonio F. , Fini M. Influence of membrane oxygenators on the pulsatile flow in extracorporeal circuits: an experimental analysis. Int J Artif Organs 1997; 20(8): 455-462.

14.

Undar A. , Lodge AJ , Daggett CW , et al. The type of aortic cannula and membrane oxygenator affect the pulsatile waveform morphology produced by a neonate-infant cardiopulmonary bypass system in vivo. Artif Organs 1998; 22(8): 681-686.

15.

Undar A. , Koenig KM , Frazier OH , Fraser CD, Jr. Impact of membrane oxygenators on pulsatile versus nonpulsatile perfusion in a neonatal model. Perfusion 2000; 15(2): 111-120.

16.

Wang S. , Haines N. , Undar A. Quantification of pressure-flow waveforms and selection of components for the pulsatile extracorporeal circuit. J Extra Corpor Technol 2009; 41( 1): P20-25.

17.

Undar A. , Lodge AJ , Runge TM , et al. Design and performance of a physiologic pulsatile flow neonate-infant cardiopulmonary bypass system. Asaio J 1996 ; 42(5): M580-583.

18.

Nichols WW , O’Rourke MF McDonald’s blood flow in arteries: theoretic, experimental and clinical principles. 3rd ed. London: Edward Arnold. A division of Hodder&Stoughton, 1990 .

19.

Shepard RB , Simpson DC , Sharp JF Energy equivalent pressure. Arch Surg 1966 ; 93(5): 730-740.

20.

Undar A. Energy equivalent pressure formula is for precise quantification of different perfusion modes. Ann Thorac Surg 2003; 76(5): 1777-1778.

21.

Undar A. , Ji B. , Lukic B. , et al. Quantification of perfusion modes in terms of surplus hemodynamic energy levels in a simulated pediatric CPB model. Asaio J 2006; 52( 6): 712-717. 22. Undar A. , Ji B. , Lukic B. , et al. Comparison of hollow-fiber membrane oxygenators with different perfusion modes during normothermic and hypothermic CPB in a simulated neonatal model. Perfusion 2006; 21(6): 381- 390. 23. Lee JJ , Lim CH , Son HS , et al. In vitro evaluation of the performance of Korean pulsatile ECLS (T-PLS) using precise quantification of pressure-flow waveforms. Asaio J 2005; 51(5): 604-608.

22.

Ji B. , Ündar A. Comparison of perfusion modes on micro-circulation during acute and chronic cardiac support: is there a difference? Perfusion 2007; 22( 1): 115-119.

23.

Nakayama Y. , Nakanishi N. , Sugimachi M. , et al. Characteristics of pulmonary artery pressure waveform for differential diagnosis of chronic pulmonary thromboembolism and primary pulmonary hypertension. J Am Coll Cardiol 1997; 29(6): 1311-1316.

24.

Cay S. , Cagirci G. , Balbay Y. , et al. Effect of aortic pulse and fractional pulse pressures on early patency of sapheneous vein grafts. Coron Artery Dis 2008; 19(7): 435-439.

25.

Milnor WR , Bergel DH , Bargainer JD Hydraulic power associated with pulmonary blood flow and its relation to heart rate. Circ Res 1966; 19(3): 467-480.

26.

Fiore GB , Redaelli A. , Guadagni G. , et al. Development of a new disposable pulsatile pump for cardiopulmonary bypass: computational fluid-dynamic design and in vitro tests. Asaio J 2002; 48( 3): 260-267.

27.

Lim CH , Son HS , Lee JJ , et al. Optimization of the circuit configuration of a pulsatile ECLS: an in vivo experimental study. Asaio J 2005 ; 51(5): 609-613.