Sex- and Gender-Based Analysis on Norepinephrine Use in Septic Shock: Why Is It Still a Male World?

Sex and gender are fundamental health determinants and their role as modifiers of treatment response is increasingly recognized. Norepinephrine is a cornerstone of septic shock management and its use is based on the highest level of evidence compared to dopamine. The related 2021 Surviving Sepsis Campaign (SCC) recommendation is presumably applicable to both females and males; however, a sex- and gender-based analysis is lacking, thus not allowing generalizable conclusions. This paper was aimed at exploring whether sex- and gender-disaggregated data are available in the evidence supporting this recommendation. For all the studies underpinning it, four pairs of authors, including a woman and a man, extracted data concerning sex and gender, according to the Sex and Gender Equity in Research guidelines. Nine manuscripts were included with an overall population of 2126 patients, of which 43.2% were females. No sex analysis was performed and gender was never reported. In conclusion, the present manuscript highlighted that the clinical studies underlying the SCC recommendation of NE administration in septic shock have neglected the likely role of sex and gender as modifiers of treatment response, thus missing the opportunity of sex- and gender-specific guidelines.

Reversible Cerebral Vasoconstriction Syndrome Secondary to Loperamide Ingestion: A Case Report

Reversible cerebral vasoconstriction syndrome (RCVS) is a cerebrovascular disorder highlighted by diffuse and multifocal vasoconstriction of the cerebral circulation. This syndrome has been reported to be associated with provoking vasoactive agents, and the identification of such offenders is quite challenging. In our case, the patient's RCVS was caused by the ingestion of loperamide. Although being reported in the cardiac literature, cerebral vasoconstriction due to loperamide has not been reported yet.

Effects of vasoactive substances on biomechanics of small resistance arteries of male and female Dahl salt-sensitive rats

Changes in vascular biomechanics leading to increase in arterial stiffness play a pivotal role in circulatory dysfunction. Our objectives were to examine sex-specific pharmacological changes related to the biomechanics and any structural modifications in small resistance arteries of Dahl salt-sensitive male and female rats. The composite Young modulus (CYM) was determined using pressure myograph recordings, and immunohistochemistry was used for the evaluation of any structural changes in the third-order mesenteric arteries (n = 6). Animals on high-salt diet developed hypertension with significant elevation in central and peripheral blood pressures and pulse wave velocity compared to those on regular diet. There were no significant differences observed in the CYM between any of the groups (i.e., males and females) in vehicle-treated time-control studies. The presence of verapamil (0.3 μM) significantly reduced CYM in hypertensive males without changes within females compared to vehicle. This effect was abolished by phenylephrine (0.3 μM). BaCl2 (100 μM), ouabain (100 μM), and L-NAME (0.3 μM) combined significantly increased CYM in vessels from in normotensive males and females but not in hypertensive males compared to vehicle. The increase in CYM was abolished in the presence of phenylephrine. Sodium nitroprusside (0.3 μM), in the presence of phenylephrine, significantly reduced CYM in male normotensive versus hypertensive, with no differences within females. Significant differences were observed in immunohistochemical assessment of biomechanical markers of arterial stiffness between males and females. Our findings suggest sex possibly due to pressure differences to be responsible for adaptive changes in biomechanics, and varied pharmacological responses in hypertensive state.

Optimizing Vasopressin Use and Initiation Timing in Septic Shock: A Narrative Review

TOPIC IMPORTANCE

This review discusses the rationale for vasopressin use, summarizes the results of clinical trials evaluating vasopressin, and focuses on the timing of vasopressin initiation to provide clinicians guidance for optimal adjunctive vasopressin initiation in patients with septic shock.

REVIEW FINDINGS

Patients with septic shock require vasoactive agents to restore adequate tissue perfusion. After norepinephrine, vasopressin is the suggested second-line adjunctive agent in patients with persistent inadequate mean arterial pressure. Vasopressin use in practice is heterogeneous likely because of inconsistent clinical trial findings, the lack of specific recommendations for when it should be used, and the high drug acquisition cost. Despite these limitations, vasopressin has demonstrated price inelastic demand, and its use in the United States has continued to increase. However, questions remain regarding optimal vasopressin use in patients with septic shock, particularly regarding patient selection and the timing of vasopressin initiation.

SUMMARY

Experimental studies evaluating the initiation timing of vasopressin in patients with septic shock are limited, and recent observational studies have revealed an association between vasopressin initiation at lower norepinephrine-equivalent doses or lower lactate concentrations and lower mortality.

Evaluation of the Addition of Angiotensin II in Patients With Shock After Cardiac Surgery at a Veterans Affairs Medical Center

BACKGROUND

Vasoplegic shock occurs in up to 37% of cardiac surgery patients. We investigated the use of angiotensin II for treating vasoplegic shock in these patients.

OBJECTIVES

We assessed clinical outcomes and mortality in patients undergoing cardiac surgery at our center between March 1, 2018 and October 31, 2020 who developed vasoplegic shock, comparing those who received angiotensin II with those who did not.

METHODS

This was a retrospective chart review. Response to angiotensin II was defined as increase in or maintenance of mean arterial pressure (MAP) and decrease in background vasopressor dosage.

RESULTS

Angiotensin II was administered to 7 patients (postoperatively in 4 patients [57.1%]) with vasoplegic shock and baseline norepinephrine equivalent (NEE) of 0.49 ± 0.08 μg/kg/min; 12 patients with vasoplegic shock did not receive angiotensin II. Within 3 hours of angiotensin II administration, NEE decreased by 38.0 ± 33.1%. Angiotensin patients were more likely to newly require renal replacement therapy (66.7% vs 9.1%, P = 0.03) and had a longer, although not statistically significant, postoperative stay (23.1 vs 14.0 days, P = 0.16). Despite higher NEE requirements at baseline (0.49 vs 0.30, P = 0.03) and over the next 48 hours in the angiotensin group, no between-group differences in 7-day mortality (14.3% vs 0.0%, P = 0.37) or 30-day mortality (28.6% vs 8.3%, P = 0.52) were noted.

CONCLUSION AND RELEVANCE

In patients who developed vasoplegic shock after cardiac surgery, angiotensin II administration allowed immediate dosage reductions of other vasopressors while maintaining MAP. Despite its small sample size, this study adds to the paucity of data in these patients and highlights future research needs.

Vasoactive Biomarkers in Patients With Vasovagal Syncope During Head-Up Tilt Test: A Case-Control Study

Background:

Vasovagal syncope (VVS) is the most common cause of syncope. Some stages of its pathophysiological mechanisms remain unclear. Vasoactive substances such as nitric oxide metabolites (NOx) and endothelin (ET) may be involved during acute orthostatic stress.

Objective:

To analyze plasma changes in NOx and ET and heart rate variability (HRV) in the supine positions (T1) and during the head-up tilt test (HUTT) (T2), in patients with VVS (case group) and control group.

Methods:

Thirty-seven patients (17 in the case group and 20 in the control group), matched for age and sex (mean aged 31.8 years) underwent HUTT with simultaneous HRV recording and venipuncture. Blood samples were collected during phases T1 and T2 and the analysis was performed without knowledge of the HUTT result.

Results:

In the total sample, there was an increase in NOx values (P = .014), however there was no increase in ET values from phase T1 to phase T2. Patients with VVS tended to increase plasma NOx values (P = .057) and had significantly higher plasma values compared to ET (P = .033) between phases T1 to T2. In the control group, there was no significant change in the values of these vasoactive substances. Regarding HRV, there were a decrease in the component HF (high frequency) and increased of the LF (low frequency)/HF ratio during HUTT.

Conclusions:

There was an increase in ET during HUTT occurred only in the case group. These patients are more likely to have an imbalance between antagonistic vasoactive biomarkers during orthostatic stress.

Evaluation of the safety of a novel peripheral vasopressor pilot program and the impact on central line placement in medical and surgical intensive care units

Purpose

The purpose of this quality improvement project was to evaluate the safety and feasibility of peripheral vasopressor administration in an attempt to minimize the placement and improve early removal of unnecessary central lines to reduce central line–associated bloodstream infection (CLABSI) rates.

Methods

A retrospective chart review was conducted on patients who received vasopressors via peripheral infusion over 3 months, starting at the time of guideline implementation.

Results

We identified 129 vasopressor orders among 79 patients that were administered peripherally. Among these orders, 3 events were documented as possible extravasation events. Forty-five patients (57%) did not require central line placement due to increasing vasopressor requirements. Standard utilization ratio data suggest minimal central line impact of the protocol implementation. December 2020 to February 2021 was associated with a large second peak of coronavirus disease 2019 (COVID-19) in our region. Utilization of central lines was less than predicted in December 2020 to February 2021 in 2 of our 3 intensive care units (ICUs); however, the differences were statistically significant on only 3 occasions. In the third ICU, utilization was greater than predicted, but this unit housed a majority of the most critically ill patients with COVID-19.

Conclusion

This study suggests that short-term use of select vasopressors at conservative doses is safe for peripheral administration and points toward efficacy at preventing central line placement. Further analysis is required to confirm efficacy.

Clinical Utilization of Stress Dose Hydrocortisone in Adult Patients With Septic Shock: A Retrospective Observational Study at a Large Academic Medical Center

Background: The use of stress dose corticosteroids, specifically, hydrocortisone, in septic shock is heterogeneous, and current clinical trials yield conflicting results. Regardless, they are still recommended by guidelines for vasopressor-dependent septic shock. Objectives: This study sought to characterize current practice of hydrocortisone use in patients with septic shock and secondarily to compare clinical outcomes of those who received hydrocortisone to those who did not. Methods: This single center, retrospective cohort study evaluated patients with septic shock admitted to a tertiary care center between 2012 and 2017. Patients receiving hydrocortisone for at least two doses were compared to those without. Results: 3411 septic shock patients were included; 1593 (47%) received hydrocortisone and 1818 (53%) did not. Patients who received hydrocortisone had higher lactate (4.0 vs 3.4 mmol/L; P < .01) and Acute Physiology and Chronic Health Evaluation (APACHE) III scores (104.1 vs 91.0; P < .01). Vasopressor duration was 1.7 days longer in the hydrocortisone group (P < .01), and the hydrocortisone group had higher hospital mortality (52% vs 38%; P < .01). A propensity score-matched population was conducted in patients with APACHE scores >100: vasopressor duration was longer in those who received hydrocortisone (3.9 vs 2.0 days; P < .01), and hospital mortality was higher (59.3% vs 53.1%; P = .036); however, after multivariable adjustment, no association between receipt of hydrocortisone and hospital mortality was detected (OR 1.2 [95% CI .9-1.6]). Conclusions: Patients who received hydrocortisone were more severely ill than those that did not, making retrospective evaluation of this question challenging. These results highlight the wide variability and heterogeneity in hydrocortisone use in clinical practice.

The Surviving Sepsis Campaign: Fluid Resuscitation and Vasopressor Therapy Research Priorities in Adult Patients

OBJECTIVE

Expand upon the priorities of fluid resuscitation and vasopressor therapy research priorities identified by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

DATA SOURCES

Original article, literature search.

STUDY SELECTION

Several members of the original task force with expertise specific to the area of fluid resuscitation and vasopressor therapy.

DATA EXTRACTION

None.

DATA SYNTHESIS

None.

CONCLUSION

In the second of a series of manuscripts subsequent to the original article, members with expertise in the subjects expound upon the three identified priorities related to fluid resuscitation and vasopressor therapies. This analysis summarizes what is known and what were identified as ongoing and future research.

Comparison of Vasopressor Duration in Septic Shock Patients With and Without Cirrhosis

BACKGROUND

Patients with cirrhosis have immune dysfunction, altered inflammatory response, and hemodynamic changes which increase risk of septic shock and potentially prolong management with fluids, vasopressors, and other therapies. Due to limited available guidance, this study aimed to characterize vasopressor use in patients with cirrhosis in relation to patients without cirrhosis in septic shock.

METHODS

This was a retrospective matched cohort analysis of 122 patients admitted to the intensive care unit (ICU) at an academic medical center from January 2015 to November 2017. Patients were grouped based on the presence or absence of cirrhosis and matched based on severity of illness scoring. The primary outcome was vasopressor duration. Secondary comparisons included total vasopressor requirement, length of hospital and ICU stay, in-hospital mortality, change in organ function, and discharge disposition.

RESULTS

The group with cirrhosis had significantly longer median (interquartile range [IQR]) durations of vasopressor therapy compared with the group without cirrhosis (86.0 [42.0-164.5] vs 39.0 [14.5-82.0] hours; P = 0.003) leading to increased median (IQR) vasopressor exposure (71.7 [15.5-239.5] vs 24.7 [5.3-77.9] mg norepinephrine [NE] equivalents; P = 0.003). No difference was found in in-hospital mortality between groups. However, regression analysis showed vasopressor exposure was associated with in-hospital mortality.

CONCLUSION AND RELEVANCE

Patients with cirrhosis in septic shock have increased vasopressor durations and overall requirements compared with patients without cirrhosis. Increased durations and requirements is associated with poorer outcomes independent of presence of cirrhosis. Future studies are needed to improve vasopressor treatment strategies and end points utilized in cirrhosis.

Vasoactive Agent Use in Septic Shock: Beyond First-Line Recommendations

Septic shock is a life-threatening disorder associated with high mortality rates requiring rapid identification and intervention. Vasoactive agents are often required to maintain goal hemodynamics and preserve tissue perfusion. However, guidance regarding the proper administration of adjunct agents for the management of septic shock is limited in patients who are refractory to norepinephrine. This review summarizes vasopressor agents and describes the nuanced application of these agents in patients with septic shock, specifically focusing on clinical scenarios with limited guidance including patients who are nonresponsive to first-line agents and individuals with mixed shock states, tachyarrhythmias, obesity, valvular abnormalities, or other comorbid conditions.

Effectiveness of Treatments and Diagnostic Tools and Declining Mortality in Patients With Severe Sepsis: A 12-Year Population-Based Cohort Study

Sepsis is a major cause of morbidity and mortality worldwide. With the advance of medical care, the mortality of sepsis has decreased in the past decades. Many treatments and diagnostic tools still lack supporting evidence. We conducted a retrospective population-based cohort study with propensity score matched subcohorts based on a prospectively collected national longitudinal health insurance database in Taiwan. Severe sepsis-associated hospital admissions from 2000 to 2011 based on International Classification of Diseases, Ninth Revision, Clinical Modification codes of infections and acute organ dysfunction were identified. To compare the effectiveness of treatment and diagnostic tool, propensity scores were generated to match the comparable control groups. During the 12-year period, 33 375 patients and 50 465 hospitalizations of severe sepsis were identified. The age-standardized 28-day in-hospital mortality decreased significantly from 21% in 2008 to 15% in 2011 with increasingly implemented treatment and diagnostic tool. After propensity score matching, procalcitonin (odds ratio [OR]: 0.70, 95% confidence interval [95% CI]: 0.61-0.81) and lactate testing (OR: 0.90, 95% CI: 0.84-0.97, respectively), transfusion of packed red blood cell (OR: 0.60, 95% CI: 0.52-0.69), albumin (OR: 0.72, 95% CI: 0.55-0.93), balanced crystalloid (OR: 0.29, 95% CI: 0.20-0.41), and use of dopamine (OR: 0.44, 95% CI: 0.39-0.49) were found to be significantly associated with lower mortality rate. However, inconsistent findings need to be further validated.

Norepinephrine Administration Is Associated with Higher Mortality in Dialysis Requiring Acute Kidney Injury Patients with Septic Shock

(1) Background: Norepinephrine (NE) is the first-line vasoactive agent used in septic shock patients; however, the effect of norepinephrine on dialysis-required septic acute kidney injury (AKI-D) patients is uncertain. (2) Methods: To evaluate the impact of NE on 90-day mortality and renal recovery in septic AKI-D patients, we enrolled patients in intensive care units from 30 hospitals in Taiwan. (3) Results: 372 patients were enrolled and were divided into norepinephrine users and non-users. After adjustment by Inverse probability of treatment weighted (IPTW), there was no significant difference of baseline comorbidities between the two groups. NE users had significantly higher 90-day mortality rate and using NE is a strong predictor of 90-day mortality in the multivariate Cox regression (HR = 1.497, p = 0.027) after adjustment. The generalized additive model disclosed norepinephrine alone exerted a dose–dependent effect on 90-day mortality, while other vasoactive agents were not. (4) Conclusion: Using norepinephrine in septic AKI-D patients is associated with higher 90-day mortality and the effect is dose-dependent. Further study to explore the potential mechanism is needed.

Iatrogenic Takotsubo Cardiomyopathy Secondary to Norepinephrine by Continuous Infusion for Shock

Takotsubo cardiomyopathy is a condition characterized by transient left ventricular systolic and diastolic dysfunction, with a possible direct causal role of catecholamine in its pathophysiology. We present a case of a woman with shock and adrenal insufficiency in whom Takotsubo cardiomyopathy developed after treatment with norepinephrine. This case confirms the direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy. An 82-year-old woman presented with asthenia, anorexia, nausea and abdominal pain. The patient had been on chronic corticosteroid therapy until 3 months before, when she underwent abdominal surgery and corticosteroids were stopped. She now presented with acute kidney injury, hyponatremia and hyperkalemia and shock. A norepinephrine continuous infusion was administered to maintain a mean arterial pressure over 65 mmHg. An echocardiogram showed severe hypokinesis in the apical segments and hyperdynamic basal segments, with an ejection fraction of 25%. Plasma cortisol level was 4.5 μg/dL (reference range 5-25). Corticosteroid therapy was begun and norepinephrine was tapered and stopped. A new echocardiogram showed normalization of cardiac wall motion and an ejection fraction of 70%. This case highlights the importance of the correction of the cause of shock, as well as the risks associated with the use of norepinephrine if hypotension is severe or if it persists despite fluid administration, as usually recommended. It also confirms the direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy. To the best of our knowledge, this is the first report of stress-induced cardiomyopathy secondary to norepinephrine by continuous infusion for shock.

LEARNING POINTS

Takotsubo cardiomyopathy is a condition characterized by transient left ventricular dysfunction of the apex and midventricle in the absence of attributable coronary artery disease.In patients with shock and adrenal insufficiency, who can be erroneously interpreted as septic shock, Takotsubo cardiomyopathy can develop after treatment with norepinephrine.In the management of shock, there are risks associated with recommending the use of norepinephrine if hypotension is severe or if it persists despite fluid administration, when the cause of shock is other than septic shock and is not corrected.There is a direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy.

Vasopressors in Sepsis

BACKGROUND

Sepsis accounts for 10% of intensive care unit admissions and significant healthcare costs. Although the mortality rate from sepsis has been decreasing with better critical care, early identification of septic patients, and prompt interventions, the mortality rate remains 20%-30%.

METHOD

Review of the English-language literature.

RESULTS

Norepinephrine is the first-line vasopressor in shock and is associated with a lower mortality rate as well as fewer adverse effects. Dopamine has similar actions but is associated with significantly more tachydysrhythmias and should be reserved for patients with bradycardia. Epinephrine and vasopressin are appropriate second-line vasopressors and may enable use of lower doses of norepinephrine while improving hemodynamics. Inotropes may be added in patients with cardiac dysfunction.

CONCLUSION

Appropriate treatment of sepsis includes prompt identification, early antimicrobial drug therapy, appropriate fluid resuscitation, and initiation of vasopressors in the presence of continued septic shock. Further research needs to be done to better understand the ideal timing of the addition of a second agent and the optimal combinations of vasopressors for individual patients.

Vascular Hyperpermeability Response in Animals Systemically Exposed to Arsenic

The mechanisms underlying cardiovascular diseases induced by chronic exposure to arsenic remain unclarified. The objectives of this study were to investigate whether increased vascular leakage is induced by inflammatory mustard oil in mice systemically exposed to various doses of arsenic and whether an increased vascular leakage response is still present in arsenic-fed mice after arsenic discontinuation for 2 or 6 months. ICR mice were fed water or various doses of sodium arsenite (10, 15, or 20 mg/kg/day; 5 days/week) for 8 weeks. In separate experiments, the mice were treated with sodium arsenite (20 mg/kg) for 2 or 8 weeks, followed by arsenic discontinuation for 2 or 6 months. Vascular permeability to inflammatory mustard oil was quantified using Evans blue (EB) techniques. Both arsenic-exposed and water-fed (control) mice displayed similar basal levels of EB leakage in the ears brushed with mineral oil, a vehicle of mustard oil. The levels of EB leakage induced by mustard oil in the arsenic groups fed with sodium arsenite (10 or 15 mg/kg) were similar to those of water-fed mice. However, increased levels of EB leakage in response to mustard oil stimulation were significantly higher in mice treated with sodium arsenite (20 mg/kg; high dose) than in arsenic-fed (10 or 15 mg/kg; low and middle doses) or control mice. After arsenic discontinuation for 2 or 6 months, mustard oil-induced vascular EB leakage in arsenic-fed (20 mg/kg) mice was similar to that in control mice. Dramatic increases in mustard oil-induced vascular leakage were only present in mice systemically exposed to the high arsenic dose, indicating the synergistic effects of the high arsenic dose and mustard oil.

Factors relating caesarean section to persistent pulmonary hypertension of the newborn

BACKGROUND

Several studies have clearly demonstrated a significantly higher incidence of persistent pulmonary hypertension of the newborn (PPHN) in neonates delivered by caesarean section (CS) compared to those delivered vaginally. The pathophysiological factors underlying the link between CS and PPHN are still poorly understood. In this review, we describe the mechanisms that could explain the association between CS delivery and subsequent PPHN, as well as potential preventive measures.

DATA SOURCES

A literature search was conducted by electronic scanning of databases such as PubMed and Web of Science using the key words "persistent pulmonary hypertension of the newborn", "caesarean section", "iatrogenic prematurity", "oxidative stress", "late preterm", "labor" and "vasoactive agents".

RESULTS

Iatrogenic prematurity, higher rates of late preterm delivery and lack of physiological changes of labor play an important role in the association between CS and PPHN. CS delivery also results in limited endogenous pulmonary vasodilator synthesis and lower levels of protective anti-oxidants in the neonates. In addition, CS delivery exposes infants to a higher risk of respiratory distress syndrome and its concomitant increase in endothelin-1 levels, which might indirectly lead to a higher risk of developing PPHN. We believe that neonates delivered by CS are exposed to a combination of these pathophysiological events, culminating in an endpoint of respiratory distress, hypoxia, acidosis, and delayed transition and thereby increased risks of PPHN. The use of antenatal corticosteroids prior to elective CS in late preterm deliveries, promoting accurate informedconsent process, delaying elective CS to 39 weeks of gestation or beyond and antenatal maternal anti-oxidant supplementation could potentially mitigate the effects of CS delivery and minimize CS-related PPHN.

CONCLUSIONS

The link between CS delivery and PPHN is complex. In view of the rising rates of CS worldwide, there is an urgent need to further explore the mechanisms linking CS to PPHN and experimentally test therapeutic options in order to allow effective targeted interventions.

Safety of Enteral Feedings in Critically Ill Children Receiving Vasoactive Agents

BACKGROUND

The objective of this retrospective study was to evaluate the safety of enteral feeding in children receiving vasoactive agents (VAs).

METHODS

Patients aged 1 month to 18 years with a pediatric intensive care unit stay for ≥96 hours during 2007 and 2008 who received any VA (epinephrine, norepinephrine, vasopressin, milrinone, dopamine, and dobutamine) were included and categorized into fed and nonfed groups. Their demographics, clinical characteristics, type and dose of VA, and presence of gastrointestinal (GI) outcomes were obtained. GI outcomes were compared between the groups by the χ(2) test, Mann-Whitney test, and logistic regression.

RESULTS

In total, 339 patients were included. Of these, 55% were in the fed group and 45% in the nonfed group. Patients in the fed group were younger (median age, 1.05 vs 2.75 years, respectively; P < .001) and tended to have a lower Pediatric Index of Mortality 2 (PIM2) risk of mortality (ROM) than those in the nonfed group (median, 3.33% vs 3.52%, respectively; P = .106). Mortality was lower in the fed group than the nonfed group (6.9% vs 15.9%, respectively; odds ratio [OR], 0.39; 0.18-0.84; P < .01, 95% CI), while GI outcomes did not differ between the groups. The vasoactive-inotropic score (VIS) did not differ between the groups except on day 1 (P = .017). The ROM did not differ between the groups after adjusting for age, PIM2 ROM, and VIS on day 1 (OR, 0.58; 0.26-1.28; P = .18, 95% CI).

CONCLUSIONS

Enteral feeding in patients receiving VAs is associated with no difference in GI outcomes and a tendency towards lower mortality. Prospective studies are required to confirm the safety of enteral feedings in patients receiving VAs.

Cardiovascular Drug Shortages: Predominant Etiologies, Clinical Implications, and Management Strategies

OBJECTIVE

To review the literature surrounding the incidence, significance, and management of cardiovascular (CV) drug shortages.

DATA SOURCES

A literature search was conducted using all available indexing databases from January 1996 to August 2013, coupled with assessments of the ASHP (American Society of Health System Pharmacists) and Food and Drug Administration Web sites designated to drug shortages. Data were also gathered through a review of listservs discussing this topic.

DATA SYNTHESIS

CV drug shortages are among the top 5 national drug class shortages that are posing a threat to patient care and public health. When a drug shortage occurs, it requires modifications to prescribing and the method medications are processed by the pharmacy. These necessary yet cumbersome changes can potentially result in less-than-desirable prescribing options and increases in personnel time because of administrative and dispensing obstacles. Any one of these has the potential to increase costs and/or lead to worse outcomes. Several factors have been shown to contribute to these shortages, including manufacturing delays, increased demand, medication discontinuations, and lack of raw materials. In this article, we review 13 of the critical CV drug shortages, describe their role in therapy, discuss the reasons for the shortage, define their impact on patient care, and recommend alternative therapies.

CONCLUSIONS

CV drug shortages are common and can potentially lead to deleterious patient outcomes. Institutions should develop plans for early identification, management, and resolution to minimize the clinical sequelae associated with drug shortages.

Endothelin-3-dependent pulmonary vasoconstriction in monocrotaline-induced pulmonary arterial hypertension

Blockade of the endothelin (ET) system is beneficial in pulmonary arterial hypertension (PAH). The contribution of ET-3 and its interactions with ET receptors have never been evaluated in the monocrotaline (MCT)-induced model of PAH. Vasoreactivity of pulmonary arteries was investigated; ET-3 localization was determined by confocal imaging and gene expression of prepro-ET-3 quantified using RT-PCR. ET-3 plasma levels tended to increase in PAH. ET-3 localized in the media of pulmonary arteries, where gene expression of prepro-ET-3 was reduced in PAH. ET-3 induced similar pulmonary vasoconstrictions in sham and PAH rats. In sham rats, the ET(A) antagonist A-147627 (10nmol/l) significantly reduced the maximal response to ET-3 (E(max) 77+/-1 to 46+/-2%, mean+/-S.E.M., P<0.001), while the ET(B) antagonist A-192621 (1mumol/l) reduced the sensitivity (EC(50) 21+/-7 to 59+/-16nmol/l, P<0.05) without affecting E(max). The combination of both antagonists completely abolished ET-3-induced pulmonary vasoconstriction. In PAH, the ET(A) antagonist further reduced the maximal response to ET-3 and shifted the EC(50) (E(max) 23+/-2%, P<0.001, EC(50) 104+/-24nmol/l, P<0.05), while the ET(B) antagonist only shifted the EC(50) (123+/-36nmol/l, P<0.05) without affecting the E(max). In PAH, dual ET receptor inhibition did not further reduce constriction compared to selective ET(A) inhibition. ET-3 significantly contributes to pulmonary vasoconstriction by activating the ET(B) at low concentration, and the ET(A) at high concentration. The increased inhibitory effect of the ET(A) antagonist in PAH suggests that the contribution of ET(B) to ET-3-induced vasoconstriction is reduced. Although ET-3 is a potent pulmonary vasoconstrictor in PAH, its potential pathophysiologic contribution remains uncertain.

L-type voltage-dependent Ca2+ channels in cerebral microvascular endothelial cells and ET-1 biosynthesis

We investigated the role of intracellular calcium concentration ([Ca2+]i) in endothelin-1 (ET-1) production, the effects of potential vasospastic agents on [Ca2+]i, and the presence of L-type voltage-dependent Ca2+ channels in cerebral microvascular endothelial cells. Primary cultures of endothelial cells isolated from piglet cerebral microvessels were used. Confluent cells were exposed to either the thromboxane receptor agonist U-46619 (1 microM), 5-hydroxytryptamine (5-HT; 0.1 mM), or lysophosphatidic acid (LPA; 1 microM) alone or after pretreatment with the Ca2+-chelating agent EDTA (100 mM), the L-type Ca2+ channel blocker verapamil (10 microM), or the antagonist of receptor-operated Ca2+ channel SKF-96365 HCl (10 microM) for 15 min. ET-1 production increased from 1.2 (control) to 8.2 (U-46619), 4.9 (5-HT), or 3.9 (LPA) fmol/microg protein, respectively. Such elevated ET-1 biosynthesis was attenuated by verapamil, EDTA, or SKF-96365 HCl. To investigate the presence of L-type voltage-dependent Ca2+ channels in endothelial cells, the [Ca2+]i signal was determined fluorometrically by using fura 2-AM. Superfusion of confluent endothelial cells with U-46619, 5-HT, or LPA significantly increased [Ca2+]i. Pretreatment of endothelial cells with high K+ (60 mM) or nifedipine (4 microM) diminished increases in [Ca2+]i induced by the vasoactive agents. These results indicate that 1) elevated [Ca2+]i signals are involved in ET-1 biosynthesis induced by specific spasmogenic agents, 2) the increases in [Ca2+]i induced by the vasoactive agents tested involve receptor as well as L-type voltage-dependent Ca2+ channels, and 3) primary cultures of cerebral microvascular endothelial cells express L-type voltage-dependent Ca2+ channels.

The effect of long-term streptozotocin-induced diabetes on contractile and relaxation responses of coronary arteries: selective attenuation of CGRP-induced relaxations

1. This study investigates the effect of partially metabolic controlled long-term (34 weeks) streptozotocin (STZ)-induced diabetes on relaxation and contractile responses of isolated coronary arteries to seven different vasoactive agents. 2. The average fasting and non-fasting blood glucose concentrations (mM) were significantly elevated in STZ-induced diabetic rats (P<0.0001; 10.4+/-0.4 and 16. 6+/-1.1, n=15) compared to those (4.3+/-0.03 and 4.7+/-0.18, n=11) in age-matched controls. The level of glycated haemoglobin (HbA(1)) was also significantly (P<0.0001) increased in STZ-induced diabetic rats. In STZ-induced diabetic rats, the HbA(1) levels were significantly correlated with the non-fasting blood glucose concentrations (r=0.76; P=0.003; n=13). In both groups, there was no significant correlation between the HbA(1) levels and maximal responses or sensitivities to the vasoactive agents. 3. The maximal relaxation induced by rat-alphacalcitonin gene-related peptide (rat-alphaCGRP) was significantly attenuated in the coronary arteries of STZ-induced diabetic rats (P<0.05; 40+/-7%, n=15) compared to that in age-matched controls (63+/-3%, n=11). However, there was no significant difference in the sensitivity to rat-alphaCGRP between the two groups. 4. There was no significant difference in either maximal response or sensitivity to any of the six other vasoactive agents between STZ- induced diabetic rats (n=15) and age-matched controls (n=11). 5. Our results show that partially metabolic controlled long-term (34 weeks) STZ-induced diabetes causes a selective depression of rat-alphaCGRP-induced relaxation in the intramural coronary arteries of Wistar rats.

Ultrastructural localisation of nitric oxide synthase, endothelin and binding sites of lectin (from Bandeirea simplicifolia) in the rat carotid artery after balloon catheter injury

An immunocytochemical and cytochemical study has been made on the ultrastructural localisation of type III (endothelial) nitric oxide synthase, endothelin-1 and the binding sites of lectin from Bandeirea simplicifolia to the endothelium surface-associated glycoproteins in the rat left common carotid artery at 1 and 28 d after Fogarty embolectomy balloon catheter-induced injury. Controls were carotid arteries from sham operated rats. In the controls, the immunoreactivity to nitric oxide synthase-III and endothelin-1 was localised in different proportions in vascular endothelial cells (36.9% +/- 4.3 and 7.6% +/- 2.7, respectively); immunoreactivity was confined to the cytoplasm and the membranes of intracellular organelles and structures. In contrast, staining with lectin was localised on the luminal surface of all endothelial cells. 1 d after injury, platelets were adherent to the endothelium-denuded intima. Some of the platelets displayed, immunoreactivity to nitric oxide synthase-III and endothelin-1 and were stained with lectin. 28 d after injury, a neointimal thickening of substantial size was present. Subpopulations of the regrown endothelial cells covering the luminal surface of the neointima showed positive immunoreactivity to nitric oxide synthase-III and endothelin-1 but there was a significant decrease in the proportion of nitric oxide synthase-III-containing endothelial cells (17.2% +/- 1.9; P < 0.001) and a significant increase in the proportion of endothelin-1-containing endothelial cells (36.9% +/- 4.7; P < 0.001) compared with the controls. Staining with lectin was associated with the cell membrane of all endothelial cells and in addition with cells located 'deeper' in the neointima which showed lectin-positive plasmalemma, Golgi complex and multivesicular bodies/lysosomes. In conclusion, regenerated endothelial cells of the neointima showed reduced population (2-fold) of nitric oxide synthase-III-and increased population (5-fold) endothelin-1-positive cells. The subendothelial location of some lectin-stained cells after balloon catheter injury indicates the heterogeneity of the neointima and suggests that some of these cells are involved in early angiogenesis. 24 h and 28 d after injury some platelets showed positive immunoreactivity for nitric oxide synthase-III and endothelin-1.