Effects of Hypertonic Saline and Lactated Ringer's on Right Ventricular Function After Cardiac Surgery

Abstract

Postoperative right ventricular (RV) dysfunction is frequent after cardiac surgery and is associated with a worse outcome.1Kaul TK Fields B. Postoperative acute refractory right ventricular failure: Incidence, pathogenesis, management and prognosis.Cardiovasc Surg. 2000; 8: 1-9Google Scholar RV dysfunction can be treated by optimization of preload.2Haddad F Couture P Tousignant C Denault AY. The right ventricle in cardiac surgery, a perioperative perspective: II. Pathophysiology, clinical importance, and management.Anesth Analg. 2009; 108: 422-433Google Scholar Hypertonic saline (HS) allows the use of a smaller volume, reduces tissue edema, improves left ventricular function, and induces a selective arteriolar vasodilation.3Sirieix D Hongnat JM Delayance S et al.Comparison of the acute hemodynamic effects of hypertonic or colloid infusions immediately after mitral valve repair.Crit Care Med. 1999; 27: 2159-2165Google Scholar We compared the effect of an infusion of HS or lactated Ringer's (LR) on RV function in 30 patients after cardiac surgery. The need for volume resuscitation within 2 hours after arrival in the intensive care unit was used to determine eligibility. The patients were randomized to receive 3 mL/kg of 7.5% HS or 10 mL/kg of LR. Hemodynamic data were recorded before volume expansion (baseline) and 30 and 60 minutes after volume expansion. Baseline hemodynamics values were similar in both groups (Table 1). Hypertonic saline (p < 0.001) but not LR (p = 0.08) increased RV ejection fraction 30 minutes after administration. There were no other significant differences between the 2 groups.Table 1Evolution of Hemodynamic Parameters Over TimeGroupBaseline30 min60 minpHeart ratebeat/minHSLR75 ± 1579 ± 1277 ± 1480 ± 1281 ± 1480 ± 120.67Mean arterial pressure (mmHg)HSLR60 ± 763 ± 1367 ± 1172 ± 1067 ± 871 ± 160.19Cardiac index(L/min/m2)HSLR1.76 ± 0.481.75 ± 0.312.67 ± 0.612.12 ± 0.562.46 ± 0.462.06 ± 0.540.06Mean pulmonary arterial pressure (mmHg)HSLR16 ± 320 ± 4.619 ± 422 ± 718 ± 520 ± 60.04Pulmonary artery occlusion pressure (mmHg)HSLR6 ± 38 ± 39 ± 310 ± 48 ± 310 ± 30.61Central venous pressure (mmHg)HSLR5 ± 48 ± 58 ± 49 ± 48 ± 49 ± 40.46Right ventricular ejection fraction (%)HSLR24 ± 825 ± 533 ± 828 ± 529 ± 728 ± 70.41Right ventricular end-diastolic volume index (mL/m2)HSLR103 ± 24101 ± 5196 ± 2391 ± 18102 ± 2294 ± 190.99Mixed venous oxygen saturation (%)HSLR68 ± 1062 ± 870 ± 565 ± 666 ± 965 ± 50.63NOTE. Mean ± standard deviation.Abbreviations: HS, hypertonic saline; LR, lactated Ringer's. Open table in a new tab NOTE. Mean ± standard deviation. Abbreviations: HS, hypertonic saline; LR, lactated Ringer's. We found that volume expansion with HS after cardiac surgery significantly improved postoperative RV function. However, the duration of this effect was limited, as we found no significant difference beyond 1 hour after infusion (data not shown). The increase in plasma osmotic pressure associated with administration of hypertonic saline produces a rapid transfer of interstitial and intracellular fluid into the intravascular compartment,4Mazzoni MC Borgström P Arfors KE et al.Dynamic fluid redistribution in hyperosmotic resuscitation of hypovolemic hemorrhage.Am J Physiol. 1988; 255: H629-H637Google Scholar allowing a volume expansion of between 3- and 7-fold the perfused volume.5Järvelä K Koskinen M Kaukinen S et al.Effects of hypertonic saline (7.5%) on extracellular fluid volumes compared with normal saline (0.9%) and 6% hydroxyethyl starch after aortocoronary bypass graft surgery.J Cardiothorac Vasc Anesth. 2001; 15: 210-215Google Scholar The effect of HS on the RV has not been extensively reported. Under experimental conditions, RV contractility and RV pulmonary arterial coupling are improved by HS hydroxyethyl starch, but not by isotonic saline.6Kerbaul F Rondelet B Bénas V et al.Hypertonic saline hydroxyethylstarch restores right ventricular-arterial coupling after normovolemic hemodilution in piglets.Anesthesiology. 2011; 115: 136-143Google Scholar Our findings confirmed and extended these previous results. Several studies have found that HS increases cardiac output and decreases vascular resistances.7Bauer M Kortgen A Hartog K et al.Isotonic and hypertonic crystalloid solutions in the critically ill.Best Pract Res Clin Anaesth. 2009; 23: 173-181Google Scholar,8Kreimeier U Messmer K. Small-volume resuscitation: From experimental evidence to clinical routine: Advantages and disadvantages of hypertonic solutions.Acta Anaesthesiol Scand. 2002; 46: 625-638Google Scholar The hemodynamic effect of HS lasted approximately 1 hour, as seen in our study. These results were similar to those observed when comparing HS with isotonic saline and hydroxyethyl starch in a similar patient population.5Järvelä K Koskinen M Kaukinen S et al.Effects of hypertonic saline (7.5%) on extracellular fluid volumes compared with normal saline (0.9%) and 6% hydroxyethyl starch after aortocoronary bypass graft surgery.J Cardiothorac Vasc Anesth. 2001; 15: 210-215Google Scholar According to our study, postoperative HS infusion from cardiac surgery appeared to be more effective than LR in improving RV ejection fraction and hemodynamics without side effects, although this beneficial effect was transient. None.