Abstract P209: Loss Of Rgs2 Specifically In CD4+ T Cells Decreases The Hypertensive Response To Vasopressin

Regulator of G protein Signaling (RGS) family members can modulate multiple cardiovascular hormones and are associated with hypertension and preeclampsia, a hypertensive disorder in pregnancy. We previously observed a 9-fold increase in RGS2 in CD4+ T cells isolated from women with preeclampsia compared to normotensive women. Further, in non-pregnant mice, we showed that loss of RGS2 in CD4+ T cells prevented angiotensin II-induced hypertension (measured via radiotelemetry) and resulted in increased levels of the anti-inflammatory cytokines interleukin 4 and transforming growth factor beta. We hypothesize that modulating RGS2 in CD4+ T cells may be a therapeutic strategy for hypertension. The objective of this study was to determine if loss of RGS2 specifically in CD4+ T cells protects against the development of arginine vasopressin-induced hypertension in mixed background CD4+ RGS2 knockout mice (CD4 RGS2 KO ). To generate mice wherein RGS2 is specifically knocked out in CD4+ T cells, CD4-Cre+ mice (C57BL/6J) were crossed with RGS2 flox/flox mice (B6SJLF1/J). Female 8-12 week old CD4 RGS2 KO or littermate control mice (n=5 per group) from this mixed strain were administered 24 ng/hr vasopressin for 21 days via mini-osmotic pump. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MP), and heart rate (HR) were assessed using a high throughput non-invasive blood pressure system. Prior to vasopressin infusion, KO and CTL mice showed no differences in SBP, DBP, MP, or HR. At 9-13 days of vasopressin-infusion, KO mice had a significantly lower 24-hr SBP [KO 138.7 ±4.7 vs CTL 155.9 ±3.4 mmHg, p<0.05], DBP [KO 106.9 ±4.1 vs CTL 122.8 ±2.9 mmHg, p<0.05], MP [KO 117.2 ±4.3 vs CTL 133.5 ±3.0 mmHg, p<0.05], and HR [KO 378 ±18.7 vs CTL 445 x±12.8 BPM, p<0.05] compared to CTL mice. Here, we demonstrate that in a mixed strain CD4+ RGS2 KO mouse, loss of RGS2 specifically in CD4+ T cells prevented vasopressin-induced hypertension. Therefore, RGS2 expression in CD4+ T cells may play an expanded role in the modulation of hypertension.

Diabetes Insipidus Complicating Management in a Child with COVID-19 and Multiorgan System Failure: A Novel Use for Furosemide

Judicious balance of fluids is needed for optimal management of acute respiratory distress syndrome (ARDS). Achieving optimal fluid balance is difficult in patients with disorders of fluid homeostasis such as diabetes insipidus (DI). There is little data on the use of Furosemide to aid in balancing fluid and electrolytes in patients with DI. Here, we present a critically ill 11-year-old female with developmental delay, septo-optic dysplasia, central DI, and respiratory failure secondary to COVID-19 ARDS. She required careful titration of a Vasopressin infusion in addition to IV Furosemide for successful management of fluid and electrolyte derangements. On admission, she demonstrated high-volume urine output with mild hypernatremia (serum sodium 156 mmol/L). Despite her maximum Vasopressin infusion rate of 8 mU/kg/hr, by day two of admission, she voided a total of 4 L resulting in severe hypernatremia (serum sodium 171 mmol/L). With continually high Vasopressin infusion rates, her overall fluid balance became increasingly net positive, although her hypernatremia persisted. Her ARDS continued to worsen. After 48 hours of the addition of intermittent Furosemide, successful diuresis along with resolution of hypernatremia was achieved. The combination of IV Furosemide with Vasopressin infusion resulted in tailored diuresis and more controlled titration of serum sodium levels than adjustment in Vasopressin and fluids alone. These results are in contradistinction to the published literature, which focuses on the use of thiazide diuretics in managing DI. This experience highlights the potential for loop diuretics to aid in establishing a desired fluid and electrolyte status in managing patients with both DI and ARDS.

An Unusual Case of Transient Diabetes Insipidus After Prolonged Vasopressin Infusion

Background: Vasopressin is a hormone produced in the hypothalamus and secreted by the posterior pituitary. Underproduction or resistance to vasopressin can lead to diabetes insipidus (DI) resulting in the imbalance of fluid status and serum sodium levels. Synthetic vasopressin is a common second line agent used in the critical care setting for its vasopressor effects with an added clinical benefit by increasing cerebral perfusion pressure. There have been reported cases of transient DI after discontinuation of vasopressin in neurosurgical patients, however only few cases have been reported in septic shock patients without neurological involvement. We present a case of transient DI during treatment for septic shock after attempts to wean off vasopressin infusion. Presentation: A 41-year-old female with history of type 2 diabetes mellitus, quadriplegia following a motor vehicle accident at age 11 was admitted to the surgical intensive care unit for urosepsis after placement of right ureteral stent. The patient was started on broad spectrum intravenous (IV) antibiotics and vasopressors norepinephrine and vasopressin. After 8 days of vasopressin treatment, with each effort to wean IV vasopressin, the patient was noted to have significant polyuria with urine output reaching as much as 800 mL/hr and increase in her serum sodium to a maximum of 148 mmol/L (n 145 mmol/L). During episodes of excessive diuresis, urine sodium reached 87 mmol/L, urine osmolality was 72 mOsm/kg (50-1400 mOsm/kg), and serum osmolality was 288 mOsm/kg (n 300 mOsm/kg). The patient received three doses of 1 microgram of desmopressin 24 hours apart while weaning off vasopressin. This helped slow excessive diuresis while also maintaining normal serum sodium levels. Urine output decreased to approximately 150 mL/hr after each administration of desmopressin. The serum sodium levels eventually stabilized between 135-140 mmol/L and urine output held steady around 200 cc/hr. The patient did not require additional desmopressin and was hemodynamically stable off all vasopressors. Discussion: The pathophysiology behind transient diabetes insipidus following vasopressin infusion is still unclear. It is known that in septic shock, there is depletion of vasopressin stores which suggests central DI. Yet, pharmacologic doses of vasopressin are speculated to downregulate V2 receptors in the renal distal convoluted tubules and collecting ducts which suggests nephrogenic DI. Our patient responded to desmopressin which indicates that she at least had a central component of DI. There is no consensus on the duration of vasopressin required to precipitate transient DI, but vasopressin infusion was administered for at least 24 hours in other cases prior to onset. We present a rare case of transient diabetes insipidus after prolonged vasopressin infusion that clinicians should be aware of in the critical care setting.

The Effect of Early Vasopressin Use on Patients With Septic Shock: A Systematic Review and Meta-analysis

Background: The effect of early vasopressin initiation on clinical outcomes in patients with septic shock is uncertain. A systematic review and meta-analysis was performed to evaluate the impact of early start of vasopressin support within 6 hours after the diagnosis on clinical outcomes in septic shock patients.Methods: We searched the PubMed, Cochrane, and Embase databases for randomized controlled trials (RCTs) and cohort studies from inception to the 1st of October 2020. We included studies involving adult patients (> 16 years)with septic shock. All authors reported our primary outcome of short-term mortality and in the experimental group patients in the studies receiving vasopressin infusion within 6 hours after diagnosis of septic shock and in the control group patients in the studies receiving no vasopressin infusion or vasopressin infusion 6 hours after diagnosis of septic shock, clearly comparing with clinically relevant secondary outcomes(use of renal replacement therapy(RRT),new onset arrhythmias, ICU length of stay and length of hospitalization). Results were expressed as odds ratio (OR) and mean difference (MD) with accompanying 95% confidence interval (CI).Results: Five studies including 788 patients were included. The primary outcome of this meta-analysis showed that short-term mortality between the two groups was no difference (odds ratio [OR] = 1.09; 95% CI, 0.8 to 1.48; P =0.6; χ2 =0.83; I2 = 0%). Secondary outcomes demonstrated that the use of RRT was less in the experimental group than that of the control group (OR =0.63; 95% CI, 0.44 to 0.88; P =0.007; χ2 =3.15; I2 =36%).The new onset arrhythmias between the two groups was no statistically significant difference (OR =0.59; 95% CI, 0.31 to 1.1; P =0.10; χ2 =4.7; I2 =36%). There was no statistically significant difference in the ICU length of stay(mean difference = 0.16; 95% CI, - 0.91 to 1.22; P = 0.77; χ2 = 6.08; I2 =34%) and length of hospitalization (mean difference = -2.41; 95% CI, -6.61 to 1.78; P = 0.26; χ2 = 8.57; I2 =53%) between the two groups.Conclusions: Early initiation of vasopressin in patients within 6 hours of septic shock onset was not associated with decreased short-term mortality, new onset arrhythmias, shorter ICU length of stay and length of hospitalization, but can reduce the use of RRT. Further large-scale RCTs are still needed to evaluate the benefit of starting vasopressin in the early phase of septic shock.