Plasma arginine vasopressin levels and arterial pressure during open heart surgery

Efficacy of tolvaptan for fluid management after cardiovascular surgery: A systematic review and meta-analysis of randomized control trials

The purpose of this study was to systematically search the literature and analyze evidence from randomized controlled trials (RCTs) comparing tolvaptan with conventional diuretics for postoperative fluid management in cardiac surgery patients. An electronic search of PubMed, Scopus, BioMed Central, CENTRAL (Cochrane Central Register of Controlled Trials) and Google scholar databases was carried out up to 1st December 2019. Four RCTs were included. Tolvaptan was co-administered with conventional diuretics in all the studies. The mean postoperative urine output was significantly greater in patients receiving tolvaptan as compared to controls (MD=0.39; 95% CI: 0.17 to 0.61; P=0.006, I²=48%). Body weight of patients on tolvaptan returned to pre-operative levels significantly earlier (MD=-1.57; 95% CI: -2.48 to -0.66; P=0.007, I²=50%). There was statistical significant difference in the highest postoperative serum sodium levels (MD=2.34; 95% CI: -1.65 to 3.03; p<0.00001, I²=0%), lowest serum sodium levels (MD=2.05; 95% CI: 1.41 to 2.68; p<0.00001, I²=0%) and mean serum sodium levels (MD=1.69; 95% CI: 0.98 to 2.40; p<0.00001, I²=0%) between the tolvaptan and control groups. Lowest serum potassium was significantly higher with tolvaptan as compared to the control group (MD=0.10; 95% CI: 0.01 to 0.18; P=0.03, I²=19%). There was no significant difference in the length of ICU stay or incidence of arrhythmias between the two groups. The quality of the included studies was not high. Within the limitations of our study, our results indicate that co-administration of tolvaptan with low dose of conventional diuretics significantly increases urine output while maintaining electrolyte balance in postoperative cardiac surgery patients. Faster return of body weight to pre-operative levels is evident with tolvaptan. Further high-quality RCTs are required to confirm this evidence.

Opioid-induced endocrinopathies

The use of opioids is becoming a global epidemic, leading to a rise in the occurrence and recognition of the effects of opioid drugs on the endocrine system. Nonetheless, opioid-induced endocrinopathies still remain underdiagnosed, mainly because of symptom under-reporting by patients and poor clinician awareness. Hypogonadism is the most well recognised consequence of opioid use, but the inhibitory effects of opioid drugs on the hypothalamo-pituitary-adrenal axis and their negative effects on bone health also require attention. Hyperprolactinaemia might be detected in opioid users, but clinically relevant thyroid dysfunction has not been identified. The effects of opioids on other hormones have not been clearly defined. Assessment of gonadal and adrenal function (particularly if high index of clinical suspicion of hypogonadism or hypoadrenalism) and evaluation of bone health are advised in people that use opiods. Discontinuation or reduction of opioid dose and appropriate hormone replacement are the management approaches that should be considered for hypogonadism and hypoadrenalism. Further research is needed to facilitate the development of evidence-based guidelines on the diagnosis and optimal management of opioid-induced endocrinopathies.

The effect of tolvaptan on renal excretion of electrolytes and urea nitrogen in patients undergoing coronary artery bypass surgery

Background

Adequate fluid management is an important component of patient care following cardiac surgery. Our aim in this study was to determine the benefits of tolvaptan, an oral selective vasopressin-2 receptor antagonist that causes electrolyte-free water diuresis, in postoperative fluid management. We prospectively examined the effect of tolvaptan on renal excretion of electrolytes and urea nitrogen in cardiac surgery patients.

Methods

Patients undergoing coronary artery bypass surgery were randomized to receive conventional loop diuretics (Group C, n = 30) or conventional loop diuretic therapy plus tolvaptan (Group T, n = 27). Fractional excretions of sodium (FENA), potassium (FEK) and urea nitrogen (FEUN) were measured in both groups during post-surgical hospitalization.

Results

Urine output was greater with tolvaptan (Group T) than without it (Group C), and some patients in Group C required intravenous as well as oral loop diuretics. Serum sodium concentrations decreased after surgery in Group C, but were unchanged in Group T (postoperative day [POD] 3, 139.8 ± 3.5 vs. 142.3 ± 2.6 mEq/L, p = 0.006). However, postoperative FENA values in Group C did not decrease, and the values were similar in both groups. Serum potassium levels remained lower and FEK values remained higher than the preoperative values, but only in Group C (all p < 0.05). BUN increased postoperatively in both groups, but it remained higher than its preoperative value only in Group C (all p < 0.01). Group T showed an initial increase in BUN, which peaked and then returned to its preoperative value within a week. The FEUN increased postoperatively in both groups, but the change was more pronounced in Group T (POD7, 52.7 ± 9.3 vs. 58.2 ± 6.5 %, p = 0.025).

Conclusions

Renal excretion of sodium and potassium reflects the changes in serum concentration in patients treated with tolvaptan. Patients treated only with loop diuretics showed a continuous excretion of sodium and potassium that led to electrolyte imbalance, whereas the combination of loop diuretics and tolvaptan increased renal urea nitrogen elimination. Tolvaptan therefore appears to be an effective diuretic that minimally affects serum electrolytes while adequately promoting the elimination of urea nitrogen from the kidneys in patients undergoing coronary artery bypass surgery.

Trial registration

The present study is registered with the UMIN Clinical Trials Registry (ID: UMIN000011039)

Post cardiac surgery vasoplegia is associated with high preoperative copeptin plasma concentration

Introduction

Post cardiac surgery vasodilatation (PCSV) is possibly related to a vasopressin deficiency that could relate to chronic stimulation of adeno-hypophysis. To assess vasopressin system activation, a perioperative course of copeptin and vasopressin plasma concentrations were studied in consecutive patients operated on for cardiac surgery.

Methods

Sixty-four consecutive patients scheduled for elective cardiac surgery with cardiopulmonary bypass were studied. Hemodynamic, laboratory and clinical data were recorded before and during cardiopulmonary bypass, and at the eighth postoperative hour (H8). At the same time, blood was withdrawn to determine plasma concentrations of arginine vasopressin (AVP, radioimmunoassay) and copeptin (immunoluminometric assay). PCSV was defined as mean arterial blood pressure < 60 mmHg with cardiac index ≥ 2.2 l/min/m², and was treated with norepinephrine to restore mean blood pressure > 60 mmHg. Patients with PCSV were compared with the other patients (controls). Student's t test, Fisher's exact test, or nonparametric tests (Mann-Whitney, Wilcoxon) were used when appropriate. Correlation between AVP and copeptin was evaluated and receiver-operator characteristic analysis assessed the utility of preoperative copeptin to distinguish between controls and PCSV patients.

Results

Patients who experienced PCSV had significantly higher copeptin plasma concentration before cardiopulmonary bypass (P < 0.001) but lower AVP concentrations at H8 (P < 0.01) than controls. PCSV patients had preoperative hyponatremia and decreased left ventricle ejection fraction, and experienced more complex surgery (redo). The area under the receiver-operator characteristic curve of preoperative copeptin concentration was 0.86 ± 0.04 (95% confidence interval = 0.78 to 0.94; P < 0.001). The best predictive value for preoperative copeptin plasma concentration was 9.43 pmol/l with a sensitivity of 90% and a specificity of 77%.

Conclusions

High preoperative copeptin plasma concentration is predictive of PSCV and suggests an activation of the AVP system before surgery that may facilitate depletion of endogenous AVP stores and a relative AVP deficit after surgery.

The vasopressin and copeptin response in patients with vasodilatory shock after cardiac surgery: a prospective, controlled study

OBJECTIVE

To evaluate arginine vasopressin (AVP) and copeptin plasma concentrations in patients with vasodilatory shock after cardiac surgery.

DESIGN

Prospective, controlled, clinical study.

SETTING

Surgical intensive care unit and cardiac surgery ward in a tertiary university teaching hospital.

PATIENTS AND PARTICIPANTS

Thirty-three critically ill patients with vasodilatory shock after cardiac surgery and ten control patients undergoing uncomplicated aorto-coronary bypass surgery.

MEASUREMENTS AND RESULTS

Hemodynamic, laboratory and clinical data were recorded daily in all patients during the first 7 days after cardiac surgery. At the same time, points blood was withdrawn to determine plasma concentrations of AVP (radioimmunoassay) and copeptin (immunoluminometric assy). Standard tests, a mixed effects model and regression analyses were used for statistical analysis. The course of AVP was significantly different between groups (P < 0.001). While AVP concentrations were lower in the study group on the first postoperative day, they were higher than that in the control group from postoperative day 3 on. There was no difference in the postoperative AVP response between study patients with or without chronic angiotensin-converting enzyme inhibitor therapy. Except during continuous veno-venous hemofiltration, AVP and copeptin correlated significantly with each other (P < 0.001; r = 0.749).

CONCLUSIONS

The AVP response to cardiac surgery is significantly different between patients with vasodilatory shock and patients undergoing uncomplicated aorto-coronary bypass surgery. Although no causative relationship between AVP concentrations and cardiovascular instability can be drawn from these results, our data support the hypothesis that inadequately low AVP plasma levels contribute to the failure to restore vascular tone in vasodilatory shock after cardiac surgery.

Vasopressin therapy for vasoplegic syndrome following cardiopulmonary bypass

BACKGROUND

Hypotension refractory to maximal doses of alpha-adrenergic drugs after cardiac operations employing cardiopulmonary bypass (CPB) has been referred as "vasoplegic syndrome." Vasopressin has been used for its therapy with encouraging results.

MATERIAL AND METHODS

16 patients (mean age 71, range 47 to 84 years) were treated with intravenous vasopressin (0.1-1 IU/min) for hypotension refractory to maximal doses (>30 microg/kg/min) of norepinephrine after undergoing complex cardiac operations employing CPB. Preoperative ejection fraction was 40.5% (mean, range 20% to 60%), preoperative NYHA class was 3.5 (mean). Hemodynamic measurements were obtained one hour before and one hour after beginning vasopressin infusion; urine output was measured for the 4 hours before and the 4 hours after beginning the infusion. Duration of vasopressin treatment was 58.8 +/- 37.3 hours (mean +/- SD).

RESULTS

Systolic blood pressure increased from 89.6 +/- 7.9 to 119.6 +/- 10.5 mmHg (mean +/- SD) (p < 0.001); systemic vascular resistance increased from 688.0 +/- 261.7 to 1043.3 +/- 337.1 dyne/s/cm2 (mean +/- SD) (p < 0.001); cardiac index decreased from 2.69 +/- 0.8 to 2.2 +/- 0.5 L/min/m2 (mean +/- SD) (p < 0.008); urine output increased from 36.8 +/- 30.4 to 72.8 +/- 38.2 mL/h (mean +/- SD) (p < 0.001). Seven patients (44%) survived the hospital stay.

CONCLUSIONS

High-dose vasopressin is effective in the treatment of the vasoplegic syndrome after cardiac operations employing cardiopulmonary bypass.

Vasopressin in cardiovascular patients: therapeutic implications

Vasopressin is a vital homeostatic protein which regulates fluid balance via its antidiuretic effects and vascular tone via its vasoconstrictive effects. Endogenous vasopressin deficiency has been implicated in several disease states resulting in vasodilatory shock. In particular, vasopressin levels are low in patients following cardiac surgery and in those with ventricular dysrhythmias. Several recent studies have demonstrated the effectiveness of exogenous vasopressin in providing haemodynamic support in patients with postcardiopulmonary bypass vasodilatory shock and refractory ventricular fibrillation. This manuscript reviews the pathophysiological and clinical basis for vasopressin replacement in patients with cardiovascular collapse.

Endothelin receptors in cultured and native human radial artery smooth muscle

In human vascular smooth muscle cells endothelin-1, acting at both endothelin A and endothelin B receptors, has been demonstrated to be both a potent vasoconstrictor and mitogen. Our aim was to study the functional expression of endothelin receptors in human radial artery smooth muscle using both native tissue and cultured cells (RASMCs). Radial artery smooth muscle cells were cultured from arterial explants and loaded with the calcium fluorescent dye fura-2. Cells responded to endothelin-1 and a variety of other vasoconstrictors with rises in cytoplasmic calcium ([Ca2+]c). Arterial rings responded to endothelin-1 with an increase in tension. The response of both cells and arterial rings to endothelin-1 was characterized using the selective endothelin A receptor antagonist BQ123 and the endothelin B receptor antagonist BQ788. The RASMCs were found to express [Ca2+]c responses consistent with the expression of only the endothelin A receptor. Endothelin-1-mediated vasoconstriction in radial artery rings was unaffected by BQ788 but was completely blocked by BQ123. Using the selective radioligands [125I]-PD151242 and [125I]-BQ3020 and a combination of in vitro receptor autoradiography and isolated cell preparations, endothelin A receptors were confirmed to be present on RASMCs and on arterial sections, whereas endothelin B binding was barely detectable on native smooth muscle and on RASMCs.

Management of vasodilatory shock after cardiac surgery: identification of predisposing factors and use of a novel pressor agent

BACKGROUND

Cardiopulmonary bypass can be associated with vasodilatory hypotension requiring pressor support. We have previously found arginine vasopressin to be a remarkably effective pressor in a variety of vasodilatory shock states. We investigated the incidence and clinical predictors of vasodilatory shock in a general population of cardiac surgical patients and the effects of low-dose arginine vasopressin as treatment of this syndrome in patients with heart failure.

METHODS

Patients undergoing cardiopulmonary bypass (n = 145) were studied prospectively. Preoperative ejection fraction, medications, and perioperative hemodynamics were recorded, and postbypass serum arginine vasopressin levels were measured. Vasodilatory shock was defined as a mean arterial pressure lower than 70 mm Hg, a cardiac index greater than 2.5 L/min/m2, and norepinephrine dependence. Predictors of vasodilatory shock were investigated by logistic regression analysis. The hemodynamic responses of patients who received arginine vasopressin infusions for vasodilatory shock after cardiopulmonary bypass for left ventricular assist device placement or heart transplantation were analyzed retrospectively.

RESULTS

Eleven of 145 general cardiac surgery patients (8%) met criteria for postbypass vasodilatory shock. By multivariate analysis, an ejection fraction lower than 0.35 and angiotensin-converting enzyme inhibitor use were independent predictors of postbypass vasodilatory shock (relative risks of 9.1 and 11.9, respectively). Vasodilatory shock was associated with inappropriately low serum arginine vasopressin concentrations (12.0 +/- 6.6 pg/mL). Retrospective analysis found 40 patients with postbypass vasodilatory shock who received low-dose arginine vasopressin infusions, resulting in increased mean arterial pressure and decreased norepinephrine requirements.

CONCLUSIONS

Low ejection fraction and angiotensin-converting enzyme inhibitor use are risk factors for postbypass vasodilatory shock, and this syndrome is associated with vasopressin deficiency. In patients exhibiting this syndrome after high-risk cardiac operations, replacement of arginine vasopressin increases blood pressure and reduces catecholamine pressor requirements.

Release of vasoactive substances during cardiopulmonary bypass

Cardiopulmonary bypass is associated with bleeding and thrombotic complications, massive fluid shifts, and cellular and hormonal defense reactions that are collectively termed "the whole body inflammatory response." A host of vasoactive substances are produced, released or altered during cardiopulmonary bypass. These hormones, autacoids, and cytokines react with specific receptor proteins distributed throughout the body, and mediate the vascular smooth muscle and endothelial cell contractions that are responsible for much of the morbidity associated with open heart operations. This essay briefly reviews the actions, sources, and perturbations of the approximately 25 vasoactive substances known or believed to be altered by cardiopulmonary bypass, and provides an introductory reference list.