Vasoconstrictor responses to vasopressor agents in human pulmonary and radial arteries: an in vitro study. Anesthesiology. 2014;121:930-936. [PMID: 25198173 DOI: 10.1097/aln.0000000000000430]

Severe pulmonary hypertension in weaning from cardiopulmonary bypass following double Ozaki procedure: a case report

BACKGROUND

Ozaki surgery, which reconstructs cardiac valves using autologous pericardium, is commonly performed for aortic valve replacement and offers benefits such as avoiding anticoagulation and reducing valve degeneration. However, its application to pulmonary valve replacement remains rare, and anesthetic management for such cases is not well documented.

CASE PRESENTATION

A 71-year-old woman with severe aortic and pulmonary valve stenosis underwent double valve replacement using the Ozaki procedure and coronary artery bypass grafting. Post-cardiopulmonary bypass, she developed severe pulmonary hypertension and systemic hypotension. Norepinephrine exacerbated pulmonary hypertension, while arginine vasopressin effectively stabilized systemic pressure without worsening pulmonary pressure.

CONCLUSIONS

This is the first reported case of anesthetic management for double valve replacement using the Ozaki procedure. Adequate use of vasopressin led to ameliorating pulmonary hypertension after cardiopulmonary bypass. Assessing preoperative right ventricular pressure and selecting appropriate vasopressors are crucial in mitigating perioperative pulmonary hypertension.

2024 EACTS/EACTAIC/EBCP Guidelines on cardiopulmonary bypass in adult cardiac surgery

Clinical practice guidelines consolidate and evaluate all pertinent evidence on a specific topic available at the time of their formulation. The goal is to assist physicians in determining the most effective management strategies for patients with a particular condition. These guidelines assess the impact on patient outcomes and weigh the risk-benefit ratio of various diagnostic or therapeutic approaches. While not a replacement for textbooks, they provide supplementary information on topics relevant to current clinical practice and become an essential tool to support the decisions made by specialists in daily practice. Nonetheless, it is crucial to understand that these recommendations are intended to guide, not dictate, clinical practice, and should be adapted to each patient's unique needs. Clinical situations vary, presenting a diverse array of variables and circumstances. Thus, the guidelines are meant to inform, not replace, the clinical judgement of healthcare professionals, grounded in their professional knowledge, experience and comprehension of each patient's specific context. Moreover, these guidelines are not considered legally binding; the legal duties of healthcare professionals are defined by prevailing laws and regulations, and adherence to these guidelines does not modify such responsibilities. The European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) and the European Board of Cardiovascular Perfusion (EBCP) constituted a task force of professionals specializing in cardiopulmonary bypass (CPB) management. To ensure transparency and integrity, all task force members involved in the development and review of these guidelines submitted conflict of interest declarations, which were compiled into a single document available on the EACTS website (https://www.eacts.org/resources/clinical-guidelines). Any alterations to these declarations during the development process were promptly reported to the EACTS, EACTAIC and EBCP. Funding for this task force was provided exclusively by the EACTS, EACTAIC and EBCP, without involvement from the healthcare industry or other entities. Following this collaborative endeavour, the governing bodies of EACTS, EACTAIC and EBCP oversaw the formulation, refinement, and endorsement of these extensively revised guidelines. An external panel of experts thoroughly reviewed the initial draft, and their input guided subsequent amendments. After this detailed revision process, the final document was ratified by all task force experts and the leadership of the EACTS, EACTAIC and EBCP, enabling its publication in the European Journal of Cardio-Thoracic Surgery, the British Journal of Anaesthesia and Interdisciplinary CardioVascular and Thoracic Surgery. Endorsed by the EACTS, EACTAIC and EBCP, these guidelines represent the official standpoint on this subject. They demonstrate a dedication to continual enhancement, with routine updates planned to ensure that the guidelines remain current and valuable in the ever-progressing arena of clinical practice.

Autonomic control of the pulmonary circulation: Implications for pulmonary hypertension

The autonomic regulation of the pulmonary vasculature has been under-appreciated despite the presence of sympathetic and parasympathetic neural innervation and adrenergic and cholinergic receptors on pulmonary vessels. Recent clinical trials targeting this innervation have demonstrated promising effects in pulmonary hypertension, and in this context of reignited interest, we review autonomic pulmonary vascular regulation, its integration with other pulmonary vascular regulatory mechanisms, systemic homeostatic reflexes and their clinical relevance in pulmonary hypertension. The sympathetic and parasympathetic nervous systems can affect pulmonary vascular tone and pulmonary vascular stiffness. Local afferents in the pulmonary vasculature are activated by elevations in pressure and distension and lead to distinct pulmonary baroreflex responses, including pulmonary vasoconstriction, increased sympathetic outflow, systemic vasoconstriction and increased respiratory drive. Autonomic pulmonary vascular control interacts with, and potentially makes a functional contribution to, systemic homeostatic reflexes, such as the arterial baroreflex. New experimental therapeutic applications, including pulmonary artery denervation, pharmacological cholinergic potentiation, vagal nerve stimulation and carotid baroreflex stimulation, have shown some promise in the treatment of pulmonary hypertension.

Intraoperative Hemodynamic Instability in a Patient With Ebstein's Anomaly Complicated With Eisenmenger Syndrome

Ebstein's anomaly is a rare congenital displacement of the tricuspid valve resulting in atrialization of the right ventricle. About half of the patients with Ebstein's anomaly also have atrial septal defects, which may lead to chronic shunting and development of Eisenmenger syndrome. We describe a case of a sexagenarian male patient with a history of Ebstein's anomaly complicated with Eisenmenger syndrome undergoing robotic laparoscopic adrenalectomy who presented hemodynamic instability, hypoxemia, and likely right-to-left shunting intraoperatively, as well as the actions taken to correct it and have a successful outcome. Perioperative management of adult patients with congenital heart defects is complex and requires careful monitoring. When available, intraoperative transesophageal echocardiography is strongly recommended. To prevent right-to-left shunting, maintaining elevated systemic vascular resistance with the use of vasopressors and low positive end-expiratory pressure (PEEP) ventilation is critical.

Hemodynamic Management with Vasopressin for Cardiovascular Surgery

Background and Objectives: Vasopressin increases blood pressure through aquaporin-2-mediated water retention and is useful for managing hemodynamics after surgery. However, even after decades of study, clear clinical guidelines on doses and ideal use cases after cardiovascular surgery remain unclear. Here, the existing literature is synthesized on vasopressin use for cardiac surgeries and coupled with real-world clinical experience to outline a clearer clinical path for vasopressin use. Materials and Methods: Literature from 1966 to the present was searched, and information on surgical outcomes for cardiovascular surgery was extracted. Clinicians from the University of Tsukuba with extensive vasopressin experience in pediatric cardiovascular patients were consulted for general use guidelines. Results: Vasopressin response after cardiovascular surgery is multifaceted, and low-power trials, plus conflicting study reports, generally render it as a secondary choice behind norepinephrine. Clinical experience indicates that low doses of 0.2-0.3 mU/kg/min with constant blood pressure and oxygen monitoring for response are required. Although sole use is not recommended, vasopressin may aid in controlling hemodynamics when given with other volemic or osmolal drugs. Conclusions: Vasopressin may work in a select population of first-line non-responders, but relevant response factors remain unanalyzed and clear guidelines for use remain unestablished. Future, large-scale studies are needed to delineate temporal and demographic characteristics that affect response to vasopressin for the purpose of managing post-surgical capillary leakage and hemodynamics.

Management Strategies for Acute Pulmonary Embolism in the ICU

TOPIC IMPORTANCE

Acute pulmonary embolism (PE) is a common disease encountered by pulmonologists, cardiologists, and critical care physicians throughout the world. For patients with high-risk acute PE (defined by systemic hypotension) and intermediate high-risk acute PE (defined by the absence of systemic hypotension, but the presence of numerous other concerning clinical and imaging features), intensive care often is necessary. Initial management strategies should focus on optimization of right ventricle (RV) function while decisions about advanced interventions are being considered.

REVIEW FINDINGS

We reviewed the existing literature of various vasoactive agents, IV fluids and diuretics, and pulmonary vasodilators in both animal models and human trials of acute PE. We also reviewed the potential complications of endotracheal intubation and positive pressure ventilation in acute PE. Finally, we reviewed the data of venoarterial extracorporeal membrane oxygenation use in acute PE. The above interventions are discussed in the context of the underlying pathophysiologic features of acute RV failure in acute PE with corresponding illustrations.

SUMMARY

Norepinephrine is a reasonable first choice for hemodynamic support with vasopressin as an adjunct. IV loop diuretics may be useful if evidence of RV dysfunction or volume overload is present. Fluids should be given only if concern exists for hypovolemia and absence of RV dilatation. Supplemental oxygen administration should be considered even without hypoxemia. Positive pressure ventilation should be avoided if possible. Venoarterial extracorporeal membrane oxygenation cannulation should be implemented early if ongoing deterioration occurs despite these interventions.

Ten take-home messages on vasopressin use in critically ill patients

The most used vasopressors in critically ill patients are exogenous catecholamines, mainly norepinephrine. Their use can be associated with serious adverse events and even increased mortality, especially if administered at high doses. In recent years, the addition of vasopressin has been proposed to counteract the deleterious effects of high doses of catecholamines (decatecholaminization) with the intention of improving the prognosis of these patients. Currently, vasopressin has two main indications: septic shock and vasoplegic shock in the postoperative period of cardiac surgery. In septic shock, current evidence favors its early initiation before reaching high doses of norepinephrine. In the postoperative period of cardiac surgery, the different benefits of the use of vasopressin have been studied, especially in patients with atrial fibrillation and pulmonary hypertension. When used properly, vasopressin is a safe an effective drug for the indications described above.

Hemodynamic Support in Sepsis

This review discusses recent evidence in managing sepsis-induced hemodynamic alterations and how it can be integrated with previous knowledge for actionable interventions in adult patients.

Management of high-risk pulmonary embolism in the emergency department: A narrative review

BACKGROUND

High-risk pulmonary embolism (PE) is a complex, life-threatening condition, and emergency clinicians must be ready to resuscitate and rapidly pursue primary reperfusion therapy. The first-line reperfusion therapy for patients with high-risk PE is systemic thrombolytics (ST). Despite consensus guidelines, only a fraction of eligible patients receive ST for high-risk PE.

OBJECTIVE

This review provides emergency clinicians with a comprehensive overview of the current evidence regarding the management of high-risk PE with an emphasis on ST and other reperfusion therapies to address the gap between practice and guideline recommendations.

DISCUSSION

High-risk PE is defined as PE that causes hemodynamic instability. The high mortality rate and dynamic pathophysiology of high-risk PE make it challenging to manage. Initial stabilization of the decompensating patient includes vasopressor administration and supplemental oxygen or high-flow nasal cannula. Primary reperfusion therapy should be pursued for those with high-risk PE, and consensus guidelines recommend the use of ST for high-risk PE based on studies demonstrating benefit. Other options for reperfusion include surgical embolectomy and catheter directed interventions.

CONCLUSIONS

Emergency clinicians must possess an understanding of high-risk PE including the clinical assessment, pathophysiology, management of hemodynamic instability and respiratory failure, and primary reperfusion therapies.

Sepsis-Induced myocardial dysfunction: heterogeneity of functional effects and clinical significance

Sepsis is a life-threatening disease state characterized by organ dysfunction and a dysregulated response to infection. The heart is one of the many organs affected by sepsis, in an entity termed sepsis-induced cardiomyopathy. This was initially used to describe a reversible depression in ejection fraction with ventricular dilation but advances in echocardiography and introduction of new techniques such as speckle tracking have led to descriptions of other common abnormalities in cardiac function associated with sepsis. This includes not only depression of systolic function, but also supranormal ejection fraction, diastolic dysfunction, and right ventricular dysfunction. These reports have led to inconsistent definitions of sepsis-induced cardiomyopathy. Just as there is heterogeneity among patients with sepsis, there is heterogeneity in the cardiac response; thus resuscitating these patients with a single approach is likely suboptimal. Many factors affect the heart in sepsis including inflammatory mediators, catecholamine responsiveness, and pathogen related toxins. This review will discuss different functional effects characterized by echocardiographic changes in sepsis and their prognostic and management implications.

Postoperative care after left ventricular assist device implantation: considerations for the cardiac surgical intensivist

Heart failure is a leading cause of morbidity and mortality, the incidence of which is predicted to continue to increase as the population ages. Left ventricular assist devices (LVADs) in particular have emerged as important therapies for the support of patients with advanced heart failure needing short- or long-term mechanical circulatory support. With over 5000 implantations per year, LVADs are the most commonly used durable devices worldwide. In this article, we provide an overview of the intensive care management of patients with LVADs during the early post-implantation period.

Neuraxial anesthesia in Lutembacher's syndrome? Yes, we can!

Lutembacher's syndrome is a rare congenital cardiac syndrome comprising of a combination of an atrial septal defect complicated by congenital or acquired mitral stenosis. The applied physiology of the patient depends upon the severity and the interactions of the lesions. They pose certain difficulties to the administration of both general or neuraxial anesthesia. A preference of one form of anesthesia over the other should be based on the understanding of the physiology of the patient. There should not be an orthodox avoidance of neuraxial anesthesia in complex cardiac pathologies as general anesthesia can be associated with certain complications of its own. Here, we report our successful experience of neuraxial anesthesia being administered in a patient with Lutembacher's syndrome.

Individualizing Fluid Management in Patients with Acute Respiratory Distress Syndrome and with Reduced Lung Tissue Due to Surgery—A Narrative Review

Fluids are the cornerstone of therapy in all critically ill patients. During the last decades, we have made many steps to get fluid therapy personalized and based on individual needs. In patients with lung involvement—acute respiratory distress syndrome—finding the right amount of fluids after lung surgery may be extremely important because lung tissue is one of the most vulnerable to fluid accumulation. In the current narrative review, we focus on the actual perspectives of fluid therapy with the aim of showing the possibilities to tailor the treatment to a patient’s individual needs using fluid responsiveness parameters and other therapeutic modalities.

[Intensive Care in Heart Surgery - is All Now Different?]

With approximately 100000 operations performed in Germany per year, cardiac surgery is among the surgical specialties that require intensive care tratment most frequently. Although all therapeutic aspects of ICU treatment are of high importance among cardiac surgery patients, there is a focus on hemodynamics with the overarching goal of sufficient oxygen delivery. Patients undergoing cardiac surgery are particularily prone to hemodynamic instability and low cardiac output syndrome, potentially culminating into cardiogenic shock. This article presents an overview of essential elements of intensive care medicine in cardiac surgery, paying special attention to hemodynamic monitoring, low cardiac output syndrome, inotropy, cardiac arrhyhmia, perioperative myocardial infarction, and patient blood management.

Right heart failure: A narrative review for emergency clinicians

INTRODUCTION

Right heart failure (RHF) is a clinical syndrome with impaired right ventricular cardiac output due to a variety of etiologies including ischemia, elevated pulmonary arterial pressure, or volume overload. Emergency department (ED) patients with an acute RHF exacerbation can be diagnostically and therapeutically challenging to manage.

OBJECTIVE

This narrative review describes the pathophysiology of right ventricular dysfunction and pulmonary hypertension, the methods to diagnose RHF in the ED, and management strategies.

DISCUSSION

Right ventricular contraction normally occurs against a low pressure, highly compliant pulmonary vascular system. This physiology makes the right ventricle susceptible to acute changes in afterload, which can lead to RHF. Patients with acute RHF may present with an acute illness and have underlying chronic pulmonary hypertension due to left ventricular failure, pulmonary arterial hypertension, chronic lung conditions, thromboemboli, or idiopathic conditions. Patients can present with a variety of symptoms resulting from systemic edema and hemodynamic compromise. Evaluation with electrocardiogram, laboratory analysis, and imaging is necessary to evaluate cardiac function and end organ injury. Management focuses on treating the underlying condition, optimizing oxygenation and ventilation, treating arrhythmias, and understanding the patient's hemodynamics with bedside ultrasound. As RHF patients are preload dependent they may require fluid resuscitation or diuresis. Hypotension should be rapidly addressed with vasopressors. Cardiac contractility can be augmented with inotropes. Efforts should be made to support oxygenation while trying to avoid intubation if possible.

CONCLUSIONS

Emergency clinician understanding of this condition is important to diagnose and treat this life-threatening cardiopulmonary disorder.

Potential of Endogenous Oxytocin in Endocrine Treatment and Prevention of COVID-19

Coronavirus disease 2019 or COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a significant threat to the health of human beings. While wearing mask, maintaining social distance and performing self-quarantine can reduce virus spreading passively, vaccination actively enhances immune defense against COVID-19. However, mutations of SARS-CoV-2 and presence of asymptomatic carriers frustrate the effort of completely conquering COVID-19. A strategy that can reduce the susceptibility and thus prevent COVID-19 while blocking viral invasion and pathogenesis independent of viral antigen stability is highly desirable. In the pathogenesis of COVID-19, endocrine disorders have been implicated. Correspondingly, many hormones have been identified to possess therapeutic potential of treating COVID-19, such as estrogen, melatonin, corticosteroids, thyroid hormone and oxytocin. Among them, oxytocin has the potential of both treatment and prevention of COVID-19. This is based on oxytocin promotion of immune-metabolic homeostasis, suppression of inflammation and pre-existing comorbidities, acceleration of damage repair, and reduction of individuals' susceptibility to pathogen infection. Oxytocin may specifically inactivate SARS-COV-2 spike protein and block viral entry into cells via angiotensin-converting enzyme 2 by suppressing serine protease and increasing interferon levels and number of T-lymphocytes. In addition, oxytocin can promote parasympathetic outflow and the secretion of body fluids that could dilute and even inactivate SARS-CoV-2 on the surface of cornea, oral cavity and gastrointestinal tract. What we need to do now is clinical trials. Such trials should fully balance the advantages and disadvantages of oxytocin application, consider the time- and dose-dependency of oxytocin effects, optimize the dosage form and administration approach, combine oxytocin with inhibitors of SARS-CoV-2 replication, apply specific passive immunization, and timely utilize efficient vaccines. Meanwhile, blocking COVID-19 transmission chain and developing other efficient anti-SARS-CoV-2 drugs are also important. In addition, relative to the complex issues with drug applications over a long term, oxytocin can be mobilized through many physiological stimuli, and thus used as a general prevention measure. In this review, we explore the potential of oxytocin for treatment and prevention of COVID-19 and perhaps other similar pathogens.

Considerations for Inotrope and Vasopressor Use in Critically Ill Patients With Pulmonary Arterial Hypertension

ABSTRACT

Pulmonary arterial hypertension (PAH) is a rare and progressive cardiopulmonary disease, characterized by pulmonary vasculopathy. The disease can lead to increase pulmonary arterial pressures and eventual right ventricle failure due to elevated afterload. The prevalence of PAH in patients admitted to the intensive care unit (ICU) is unknown, and pulmonary hypertension (PH) in the ICU is more commonly the result of left heart disease or hypoxic lung injury (PH due to left heart disease and PH due to lung diseases and/or hypoxia, respectively), as opposed to PAH. Management of patients with PAH in the ICU is complex as it requires a careful balance to maintain perfusion while optimizing right-sided heart function. A comprehensive understanding of the underlying physiology and underlying hemodynamics is crucial for the management of this population. In this review, we summarized the evidence for use of vasopressors and inotropes in the management of PH and extrapolated the data to patients with PAH. We strongly believe that the understanding of the hemodynamic consequences of inotropes and vasopressors, especially from data in the PH population, can lead to better management of this complex patient population.

Vasopressin and Breathing: Review of Evidence for Respiratory Effects of the Antidiuretic Hormone

Vasopressin (AVP) is a key neurohormone involved in the regulation of body functions. Due to its urine-concentrating effect in the kidneys, it is often referred to as antidiuretic hormone. Besides its antidiuretic renal effects, AVP is a potent neurohormone involved in the regulation of arterial blood pressure, sympathetic activity, baroreflex sensitivity, glucose homeostasis, release of glucocorticoids and catecholamines, stress response, anxiety, memory, and behavior. Vasopressin is synthesized in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus and released into the circulation from the posterior lobe of the pituitary gland together with a C-terminal fragment of pro-vasopressin, known as copeptin. Additionally, vasopressinergic neurons project from the hypothalamus to the brainstem nuclei. Increased release of AVP into the circulation and elevated levels of its surrogate marker copeptin are found in pulmonary diseases, arterial hypertension, heart failure, obstructive sleep apnoea, severe infections, COVID-19 due to SARS-CoV-2 infection, and brain injuries. All these conditions are usually accompanied by respiratory disturbances. The main stimuli that trigger AVP release include hyperosmolality, hypovolemia, hypotension, hypoxia, hypoglycemia, strenuous exercise, and angiotensin II (Ang II) and the same stimuli are known to affect pulmonary ventilation. In this light, we hypothesize that increased AVP release and changes in ventilation are not coincidental, but that the neurohormone contributes to the regulation of the respiratory system by fine-tuning of breathing in order to restore homeostasis. We discuss evidence in support of this presumption. Specifically, vasopressinergic neurons innervate the brainstem nuclei involved in the control of respiration. Moreover, vasopressin V1a receptors (V1aRs) are expressed on neurons in the respiratory centers of the brainstem, in the circumventricular organs (CVOs) that lack a blood-brain barrier, and on the chemosensitive type I cells in the carotid bodies. Finally, peripheral and central administrations of AVP or antagonists of V1aRs increase/decrease phrenic nerve activity and pulmonary ventilation in a site-specific manner. Altogether, the findings discussed in this review strongly argue for the hypothesis that vasopressin affects ventilation both as a blood-borne neurohormone and as a neurotransmitter within the central nervous system.

Radial-to-femoral pressure gradient quantification in cardiac surgery

Background

A radial-to-femoral pressure gradient (RFPG) can occur in roughly one-third of cardiac surgical patients. Such a gradient has been associated with smaller stature and potentially smaller radial artery diameter. We hypothesized that preoperative radial artery diameter could be a predictor of RFPG. We also investigated the clinical impact of using a femoral versus a radial arterial catheter in terms of vasoactive support.

Methods

Using ultrasound, we measured the bilateral radial artery diameters of 160 cardiac surgical patients. All arterial pressure values were continuously recorded. Significant RFPG was defined as ≥25 mm Hg in systolic and/or ≥10 mm Hg in mean arterial pressure. One hundred and forty-nine additional patients were used to validate the impact of our observations.

Results

Using 78,013 pressure datapoints in 129 patients, 34.8% of patients had an RFPG with a mean duration of 54 ± 48 minutes. Patients with a radial artery diameter <1.8 mm were more likely to have an RFPG (n = 14 [48.3%] vs 12 [22.2%]; P = .042). Patients with only a radial catheter received more phenylephrine (P = .016) despite undergoing shorter and less complex procedures. In the validation cohort, similar observations were made, and patients with a radial artery catheter received a longer duration of vasoactive support in the intensive care unit.

Conclusions

A significant RFPG occurs in one-third of cardiac surgical patients and in 48% of those with a radial artery diameter <1.8 mm. The use of a single radial arterial catheter instead of dual radial and femoral catheters was associated with greater vasopressor requirements in the operating room and in the intensive care unit. We do not recommend the use of a single radial artery catheter in cardiac surgery.

Non-invasive detection of a femoral-to-radial arterial pressure gradient in intensive care patients with vasoactive agents

BACKGROUND

In patient requiring vasopressors, the radial artery pressure may underestimate the true central aortic pressure leading to unnecessary interventions. When using a femoral and a radial arterial line, this femoral-to-radial arterial pressure gradient (FR-APG) can be detected. Our main objective was to assess the accuracy of non-invasive blood pressure (NIBP) measures; specifically, measuring the gradient between the NIBP obtained at the brachial artery and the radial artery pressure and calculating the non-invasive brachial-to-radial arterial pressure gradient (NIBR-APG) to detect an FR-APG. The secondary objective was to assess the prevalence of the FR-APG in a targeted sample of critically ill patients.

METHODS

Adult patients in an intensive care unit requiring vasopressors and instrumented with a femoral and a radial artery line were selected. We recorded invasive radial and femoral arterial pressure, and brachial NIBP. Measurements were repeated each hour for 2 h. A significant FR-APG (our reference standard) was defined by either a mean arterial pressure (MAP) difference of more than 10 mmHg or a systolic arterial pressure (SAP) difference of more than 25 mmHg. The diagnostic accuracy of the NIBR-APG (our index test) to detect a significant FR-APG was estimated and the prevalence of an FR-APG was measured and correlated with the NIBR-APG.

RESULTS

Eighty-one patients aged 68 [IQR 58-75] years and an SAPS2 score of 35 (SD 7) were included from which 228 measurements were obtained. A significant FR-APG occurred in 15 patients with a prevalence of 18.5% [95%CI 10.8-28.7%]. Diabetes was significantly associated with a significant FR-APG. The use of a 11 mmHg difference in MAP between the NIBP at the brachial artery and the MAP of the radial artery led to a specificity of 92% [67; 100], a sensitivity of 100% [95%CI 83; 100] and an AUC ROC of 0.93 [95%CI 0.81-0.99] to detect a significant FR-APG. SAP and MAP FR-APG correlated with SAP (r2 = 0.36; p < 0.001) and MAP (r2 = 0.34; p < 0.001) NIBR-APG.

CONCLUSION

NIBR-APG assessment can be used to detect a significant FR-APG which occur in one in every five critically ill patients requiring vasoactive agents.

Efficacy of Whole-Blood Del Nido Cardioplegia Compared with Diluted Del Nido Cardioplegia in Coronary Artery Bypass Grafting: A Retrospective Monocentric Analysis of Pakistan

Background and Objectives: Cardioplegia is one of the most significant components used to protect the myocardium during cardiac surgery. There is a paucity of evidence regarding the utilization of whole-blood Del Nido cardioplegia (WB-DNC) on clinical outcomes in coronary artery bypass grafting (CABG). The purpose of this retrospective cross-sectional study is to compare the effectiveness of diluted (blood to crystalloid; 1:4) Del Nido cardioplegia (DNC) with WB-DNC in patients who underwent elective CABG in a tertiary care hospital in Lahore-Pakistan. Materials and Methods: This was a retrospective descriptive study conducted at the Department of Cardiovascular Surgery, King Edward Medical University, Lahore. The medical database of all consecutive patients admitted from January 2018 to March 2020 and who fulfilled the inclusion criteria were reviewed. Results: Out of 471 patients admitted during the study period, 450 underwent various elective cardiac surgeries. Out of 450, 321 patients (71.33%) were operated on for CABG. Only 234/321 (72.89%) CABG patients fulfilled our inclusion criteria; 120 (51.28%) patients received WB-DNC, while 114 (48.71%) patients were administered with DNC. The former group presented with better clinical outcomes compared with the latter in terms of lesser requirements of inotropic support, low degree of hemodilution, shorter in-hospital stay, improved renal function, and cost-effectiveness. Peak values of serum Troponin-T (Trop-T), creatine kinase-myocardial band (CK-MB) release, and activated clotting time (ACT) were also lower in the WB-DNC group compared with the DNC group. Conclusions: The WB-DNC conferred better myocardial protection, improved early clinical outcomes, and also proved to be economical for patients undergoing elective CABG compared with classical crystalloid cardioplegia solution.

Effects of different vasopressors on the contraction of the superior mesenteric artery and uterine artery in rats during late pregnancy

Background

Hypotension after neuraxial anaesthesia is one of the most common complications during caesarean section. Vasopressors are the most effective method to improve hypotension, but which of these drugs is best for caesarean section is not clear. We assessed the effects of vasopressors on the contractile response of uterine arteries and superior mesenteric arteries in pregnant rats to identify a drug that increases the blood pressure of the systemic circulation while minimally affecting the uterine and placental circulation.

Methods

Isolated ring segments from the uterine and superior mesenteric arteries of pregnant rats were mounted in organ baths, and the contractile responses to several vasopressor agents were studied. Concentration-response curves for norepinephrine, phenylephrine, metaraminol and vasopressin were constructed.

Results

The contractile response of the mesenteric artery to norepinephrine, as measured by the pEC50 of the drug, was stronger than the uterine artery (5.617 ± 0.11 vs. 4.493 ± 1.35, p = 0.009), and the contractile response of the uterine artery to metaraminol was stronger than the mesenteric artery (pEC50: 5.084 ± 0.17 vs. 4.92 ± 0.10, p = 0.007). There was no statistically significant difference in the pEC50 of phenylephrine or vasopressin between the two blood vessels.

Conclusions

In vitro experiments showed that norepinephrine contracts peripheral blood vessels more strongly and had the least effect on uterine artery contraction. These findings support the use of norepinephrine in mothers between the time of neuraxial anaesthesia and the delivery of the foetus.

Opposing responses of the rat pulmonary artery and vein to phenylephrine and other agents in vitro

Background

Different from current cognition, our study demonstrated that adrenergic receptors agonist phenylephrine significantly relaxed isolated pulmonary artery but constricted pulmonary veins. Through comparing differences in the effects of commonly used vasoactive drugs on pulmonary artery and veins, the study aimed to improve efficiency and accuracy of isolated pulmonary vascular experiments, and to provide experimental basis for clinical drug use.

Methods

The contractile responses of pulmonary arteries and veins from twelve-week-old Male Sprague-Dawley rats to phenylephrine, arginine vasopressin (AVP), U46619, endothelin-1, and potassium chloride (KCl) were recorded, as well as the relaxation in response to phenylephrine, AVP, acetylcholine. To further explore the mechanism, some vessels was also pre-incubated with adrenergic receptors antagonists propranolol, prazosin and nitric oxide synthesis inhibitor N[gamma]-nitro-L-arginine methyl ester (L-NAME) before addition of the experimental drugs.

Results

Phenylephrine constricted pulmonary veins directly, but constricted pulmonary artery only after incubation with propranolol or/and L-NAME. The pulmonary artery exhibited significant relaxation to AVP with or without L-NAME incubation. AVP more clearly constricted the veins after incubation with L-NAME. Changes in vascular tension also varied from pulmonary artery to veins for KCl stimulation. Different from phenomena presented in veins, acetylcholine did not relax pulmonary artery preconstricted by KCl, U46619, and endothelin-1.

Conclusions

According to the results, phenylephrine, KCl, AVP, and acetylcholine could be used to distinguish pulmonary arteries and pulmonary veins in vitro. This also suggested that the pulmonary arteries and pulmonary veins have great differences in physiology and drug reactivity.

Perioperative Management of the Fontan Patient for Cardiac and Noncardiac Surgery

The Fontan circulation is the single-ventricle approach to surgical palliation of complex congenital heart disease wherein biventricular separation and function cannot be safely achieved. Incremental improvements in this surgical technique, along with improvements in the long-term medical management of these patients, have led to greater survival of these patients and a remarkably steady increase in the number of adults living with this unusual circulation and physiology. This has implications for healthcare providers who now have a greater chance of encountering Fontan patients during the course of their practice. This has particularly important implications for anesthesiologists because the effects of their interventions on the finely balanced Fontan circulation may be profound. The American Heart Association and American College of Cardiology recommend that, when possible, elective surgery should be performed in an adult congenital heart disease center, although this may not be feasible in the provision of true emergency care. This review article summarizes the pathophysiology pertinent to the provision of anesthesia in this complex patient group and describes important modifications to anesthetic technique and perioperative management.

Vasopressin in vasoplegic shock: A systematic review

BACKGROUND

Vasoplegic shock is a challenging complication of cardiac surgery and is often resistant to conventional therapies for shock. Norepinephrine and epinephrine are standards of care for vasoplegic shock, but vasopressin has increasingly been used as a primary pressor in vasoplegic shock because of its unique pharmacology and lack of inotropic activity. It remains unclear whether vasopressin has distinct benefits over standard of care for patients with vasoplegic shock.

AIM

To summarize the available literature evaluating vasopressin vs non-vasopressin alternatives on the clinical and patient-centered outcomes of vasoplegic shock in adult intensive care unit (ICU) patients.

METHODS

This was a systematic review of vasopressin in adults (≥ 18 years) with vasoplegic shock after cardiac surgery. Randomized controlled trials, prospective cohorts, and retrospective cohorts comparing vasopressin to norepinephrine, epinephrine, methylene blue, hydroxocobalamin, or other pressors were included. The primary outcomes of interest were 30-d mortality, atrial/ventricular arrhythmias, stroke, ICU length of stay, duration of vasopressor therapy, incidence of acute kidney injury stage II-III, and mechanical ventilation for greater than 48 h.

RESULTS

A total of 1161 studies were screened for inclusion with 3 meeting inclusion criteria with a total of 708 patients. Two studies were randomized controlled trials and one was a retrospective cohort study. Primary outcomes of 30-d mortality, stroke, ventricular arrhythmias, and duration of mechanical ventilation were similar between groups. Conflicting results were observed for acute kidney injury stage II-III, atrial arrhythmias, duration of vasopressors, and ICU length of stay with higher certainty of evidence in favor of vasopressin serving a protective role for these outcomes.

CONCLUSION

Vasopressin was not found to be superior to alternative pressor therapy for any of the included outcomes. Results are limited by mixed methodologies, small overall sample size, and heterogenous populations.

The right ventricle

The healthy right ventricle (RV) has a thin-walled structure compared to the thick-walled left ventricle (LV). It has a complex shape that appears crescentic when viewed in cross section and triangular when viewed from the side.

Risk of Major Complications After Perioperative Norepinephrine Infusion Through Peripheral Intravenous Lines in a Multicenter Study

BACKGROUND

Continuous infusions of norepinephrine to treat perioperative hypotension are typically administered through a central venous line rather than a peripheral venous catheter to avoid the risk of localized tissue necrosis in case of drug extravasation. There is limited literature to estimate the risk of skin necrosis when peripheral norepinephrine is used to counteract anesthesia-associated hypotension in elective surgical cases. This study aimed to estimate the rate of occurrence of drug-related adverse effects, including skin necrosis requiring surgical management when norepinephrine peripheral extravasation occurs.

METHODS

This retrospective cohort study used the perioperative databases of the University Hospitals in Amsterdam and Utrecht, the Netherlands, to identify surgical patients who received norepinephrine peripheral intravenous infusions (20 µg/mL) between 2012 and 2016. The risk of drug-related adverse effects, including skin necrosis, was estimated. Particular care was taken to identify patients who needed plastic surgical or medical attention secondary to extravasation of dilute, peripheral norepinephrine.

RESULTS

A total of 14,385 patients who received norepinephrine peripheral continuous infusions were identified. Drug extravasation was observed in 5 patients (5/14,385 = 0.035%). The 95% confidence interval (CI) for infusion extravasation was 0.011%-0.081%, indicating an estimated risk of 1-8 events per every 10,000 patients. There were zero related complications requiring surgical or medical intervention, resulting in a 95% CI of 0%-0.021% and indicating a risk of approximately 0-2 events per 10,000 patients.

CONCLUSIONS

In the current database analysis, no significant association was found between the use of peripheral intravenous norepinephrine infusions and adverse events.

Angiotensin II and Vasopressin for Vasodilatory Shock: A Critical Appraisal of Catecholamine-Sparing Strategies

Vasodilatory shock is a serious medical condition that increases the morbidity and mortality of perioperative and critically ill patients. Norepinephrine is an established first-line therapy for this condition, but at high doses, it may lead to diminishing returns. Oftentimes, secondary noncatecholamine agents are required in those whose hypotension persists. Angiotensin II and vasopressin are both noncatecholamine agents available for the treatment of hypotension in vasodilatory shock. They have distinct modes of action and unique pharmacologic properties when compared to norepinephrine. Angiotensin II and vasopressin have shown promise in certain subsets of the population, such as those with acute kidney injury, high Acute Physiology and Chronic Health Evaluation II scores, or those receiving cardiac surgery. Any benefit from these drugs must be weighed against the risks, as overall mortality has not been shown to decrease mortality in the general population. The aims of this narrative review are to provide insight into the historical use of noncatecholamine vasopressors and to compare and contrast their unique modes of action, physiologic rationale for administration, efficacy, and safety profiles.

Pharmacologic Agents for the Treatment of Vasodilatory Shock

Vasodilatory shock is a life-threatening syndrome in critically ill patients and is characterized by severe hypotension and resultant tissue hypoperfusion. This shock state requires the use of vasopressor agents to restore adequate vascular tone. Norepinephrine is still recommended as first-line vasopressor in the management of critically ill patients suffering from severe vasodilation. In the recent time, catecholaminergic vasopressor drugs have been associated with possible side effects at higher dosages. This so-called catecholamine toxicity has focused on alternative noncatecholaminergic vasopressors or the use of moderate doses of multiple vasopressors with complementary mechanisms of action. Besides vasopressin and terlipressin, angiotensin II may be a promising drug for the management of vasodilatory shock. In addition, adjunctive drugs, such as hydrocortisone, methylene blue or ascorbic acid can be added to conventional vasopressor therapy. The objective of this review is to give an overview of the current available vasopressor agents used in vasodilatory shock. A thorough search of PubMed was conducted in order to identify the majority of studies related to the subject. Data on the outcome of several drugs and future perspective of possible management strategies for the therapy of vasodilatory shock are discussed.

Monitored Anesthesia Care of Two Patients with Highly Elevated Subpulmonic Ventricular Pressure due to Adult Congenital Heart Disease

Procedural sedation and analgesia for patients with adult congenital heart disease (ACHD) and highly elevated subpulmonic ventricular pressure require proper anesthesia care to prevent a pulmonary hypertensive crisis. We describe the monitored anesthesia care (MAC) of two patients with ACHD (a complete atrioventricular septal defect and congenitally corrected transposition of the great arteries) and highly elevated subpulmonic ventricular pressure. In both patients, preprocedural transthoracic echocardiography was useful for detecting severely elevated subpulmonic ventricular pressure. The MAC involved the infusion of propofol, dexmedetomidine, and fentanyl. Norepinephrine was continuously administered from the preanesthetic period. No hemodynamic instability or respiratory depression was observed during the MAC. Continuous administration of norepinephrine from the preinduction period was helpful for preventing hypotension. We added dexmedetomidine to our MAC regimen of propofol and fentanyl because it exerts both sedative and analgesic effects. Dexmedetomidine does not cause respiratory depression; thus, our MAC regimen is believed to be theoretically safe for patients with ACHD and elevated subpulmonic ventricular pressure. Our findings suggest that safe MAC for patients with ACHD and highly elevated subpulmonic ventricular pressure may require careful consideration of the anesthetic regimen and close observation by adequately trained personnel, which is best provided at regional ACHD centers.

Scoliosis Correction with One Ventricle: A Multispecialty Approach

BACKGROUND

Patients with single-ventricle congenital heart disease may present for scoliosis correction. These patients undergo a series of cardiac operations that create a novel circulation that has a significant impact on the management of their spinal surgery.

CASE DESCRIPTION

A 21-year-old man with severe scoliosis presented for posterior T4-L3 spinal fusion. He was born with complex congenital heart disease that resulted in his having a single functioning ventricle. He underwent a series of operations culminating in a Fontan procedure to palliate his heart disease. Both the surgical procedure and the anesthetic plan were modified based on his abnormal physiology, which led to a successful correction with no complications.

CONCLUSIONS

Patients who have undergone a Fontan procedure can successfully undergo a lengthy scoliosis correction, but it requires multidisciplinary planning.

Modulation of Peroxynitrite Reduces Norepinephrine Requirements in Ovine MRSA Septic Shock

Vascular hypo-responsiveness to vasopressors during septic shock is a challenging problem. This study is to test the hypothesis that reactive nitrogen species (RNS), such as peroxynitrite, are major contributing factors to vascular hypo-responsiveness in septic shock. We hypothesized that adjunct therapy with peroxynitrite decomposition catalyst (PDC) would reduce norepinephrine requirements in sepsis resuscitation. Fourteen female Merino sheep were subjected to a "two-hit" injury (smoke inhalation and endobronchial instillation of live methicillin-resistant Staphylococcus aureus [1.6-2.5 × 10 CFUs]). The animals were randomly allocated to control: injured, fluid resuscitated, and titrated norepinephrine, n = 7; or PDC: injured, fluid resuscitated, titrated norepinephrine, and treated with PDC, n = 7. One-hour postinjury, an intravenous injection of PDC (0.1 mg/kg) was followed by a continuous infusion (0.04 mg/kg/h). Titration of norepinephrine started at 0.05 mcg/kg/min based on their mean arterial pressure. All animals were mechanically ventilated and monitored in the conscious state for 24 h. The mean arterial pressure was well maintained in the PDC with significantly less norepinephrine requirement from 7 to 23 h after injury compared with control. Total norepinephrine dose, the highest norepinephrine rate, and time on norepinephrine support were also significantly lower in PDC. Modified sheep organ failure assessment scores at 6 to 18 h postinjury were significantly lower in PDC compared with control. PDC improved survival rate at 24 h (71.4% vs. 28.6%). PDC treatment had no adverse effects. In conclusion, the modulation of RNS may be considered an effective adjunct therapy for septic shock, in the case of hypo-responsiveness to norepinephrine.

Arginine vasopressin modulates electrical activity and calcium homeostasis in pulmonary vein cardiomyocytes

Background

Atrial fibrillation (AF) frequently coexists with congestive heart failure (HF) and arginine vasopressin (AVP) V1 receptor antagonists are used to treat hyponatremia in HF. However, the role of AVP in HF-induced AF still remains unclear. Pulmonary veins (PVs) are central in the genesis of AF. The purpose of this study was to determine if AVP is directly involved in the regulation of PV electrophysiological properties and calcium (Ca²⁺) homeostasis as well as the identification of the underlying mechanisms.

Methods

Patch clamp, confocal microscopy with Fluo-3 fluorescence, and Western blot analyses were used to evaluate the electrophysiological characteristics, Ca²⁺ homeostasis, and Ca²⁺ regulatory proteins in isolated rabbit single PV cardiomyocytes incubated with and without AVP (1 μM), OPC 21268 (0.1 μM, AVP V1 antagonist), or OPC 41061 (10 nM, AVP V2 antagonist) for 4–6 h.

Results

AVP (0.1 and 1 μM)-treated PV cardiomyocytes had a faster beating rate (108 to 152%) than the control cells. AVP (1 μM) treated PV cardiomyocytes had higher late sodium (Na⁺) and Na⁺/Ca²⁺ exchanger (NCX) currents than control PV cardiomyocytes. AVP (1 μM) treated PV cardiomyocytes had smaller Ca²⁺_i transients, and sarcoplasmic reticulum (SR) Ca²⁺ content as well as higher Ca²⁺ leak. However, combined AVP (1 μM) and OPC 21268 (0.1 μM) treated PV cardiomyocytes had a slower PV beating rate, larger Ca²⁺_i transients and SR Ca²⁺ content, smaller late Na⁺ and NCX currents than AVP (1 μM)-treated PV cardiomyocytes. Western blot experiments showed that AVP (1 μM) treated PV cardiomyocytes had higher expression of NCX and p-CaMKII, and a higher ratio of p-CaMKII/CaMKII.

Conclusions

AVP increases PV arrhythmogenesis with dysregulated Ca²⁺ homeostasis through vasopressin V1 signaling.

Peroxynitrite decomposition catalyst reduces vasopressin requirement in ovine MRSA sepsis

Background

Sepsis is one of the most frequent causes of death in the intensive care unit. Host vascular hypo-responsiveness to vasopressors during septic shock is one of the challenging problems. This study tested the hypothesis that adjunct therapy with peroxynitrite decomposition catalyst (WW-85) would reduce arginine vasopressin (AVP) requirements during sepsis resuscitation, using ovine sepsis model.

Methods

Thirteen adult female Merino sheep, previously instrumented with multiple vascular catheters, were subjected to “two-hit” (cotton smoke inhalation and intrapulmonary instillation of live methicillin-resistant Staphylococcus aureus; 3.5 × 10¹¹ colony-forming units) injury. Post injury, animals were awakened and randomly allocated to the following groups: (1) AVP: injured, fluid resuscitated, and titrated with AVP, n = 6 or (2) WW-85 + AVP: injured, fluid resuscitated, treated with WW-85, and titrated with AVP, n = 7. One-hour post injury, a bolus intravenous injection of WW-85 (0.1 mg/kg) was followed by a 23-h continuous infusion (0.02 mg/kg/h). Titration of AVP started at a dose of 0.01 unit/min, when mean arterial pressure (MAP) decreased by 10 mmHg from baseline, despite aggressive fluid resuscitation, and the rate was further adjusted to maintain MAP. After the injury, all animals were placed on a mechanical ventilator and monitored in the conscious state for 24 h.

Results

The injury induced severe hypotension refractory to aggressive fluid resuscitation. High doses of AVP were required to partially attenuate the sepsis-induced hypotension. However, the cumulative AVP requirement was significantly reduced by adjunct treatment with WW-85 at 17–24 h after the injury (p < 0.05). Total AVP dose and the highest AVP rate were significantly lower in the WW-85 + AVP group compared to the AVP group (p = 0.02 and 0.04, respectively). Treatment with WW-85 had no adverse effects. In addition, the in vitro effects of AVP on isolated artery diameter changes were abolished with peroxynitrite co-incubation.

Conclusions

The modulation of reactive nitrogen species, such as peroxynitrite, may be considered as a novel adjunct treatment option for septic shock associated with vascular hypo-responsiveness to vasopressors.

[Acute right heart failure on the intensive care unit : Pathophysiology, monitoring and management]

Right ventricular heart failure is a frequent and serious but often undetected and complex clinical challenge on the intensive care unit. The commonest causes include acute decompensation of pulmonary hypertension, pulmonary embolism, sepsis, acute respiratory distress, and cardiothoracic surgery. The gold standard of bedside diagnosis is a combination of clinical symptoms, biochemical markers (NT-proBNP) and echocardiography. For the purposes of hemodynamic monitoring and treatment management, the indication to place a pulmonary artery catheter should be made generously. The major components of management include treating the underlying disease and triggering factors, reducing pulmonary vascular resistance, increasing contractility, volume optimization, and maintenance of adequate perfusion. Mechanical circulatory support should be considered before irreversible end-organ failure develops.

Dysrhythmias and heart failure complicating acute myocardial infarction: An emergency medicine review

INTRODUCTION

Patients with acute myocardial infarction (AMI) may suffer several complications after the acute event, including dysrhythmias and heart failure (HF). These complications place patients at risk for morbidity and mortality.

OBJECTIVE

This narrative review evaluates literature and guideline recommendations relevant to the acute emergency department (ED) management of AMI complicated by dysrhythmia or HF, with a focus on evidence-based considerations for ED interventions.

DISCUSSION

Limited evidence exists for ED management of dysrhythmias in AMI due to relatively low prevalence and frequent exclusion of patients with active cardiac ischemia from clinical studies. Management decisions for bradycardia in the setting of AMI are determined by location of infarction, timing of the dysrhythmia, rhythm assessment, and hemodynamic status of the patient. Atrial fibrillation is common in the setting of AMI, and caution is warranted in acute rate control for rapid ventricular rate given the possibility of compensation for decreased ventricular function. Regular wide complex tachycardia in the setting of AMI should be managed as ventricular tachycardia with electrocardioversion in the majority of cases. Management directed towards HF from left ventricular dysfunction in AMI consists of noninvasive positive pressure ventilation, nitroglycerin therapy, and early cardiac catheterization. Norepinephrine is the first line vasopressor for patients with cardiogenic shock and hypoperfusion on clinical examination. Early involvement of a multi-disciplinary team is recommended when caring for patients in cardiogenic shock.

CONCLUSIONS

This review discusses considerations of ED management of dysrhythmias and HF associated with AMI.

Right-to-Left Shunt During Transseptal Mitral Valve-in-Valve Replacement: A Case Report

The following case report details an 88-year-old woman with severe mitral stenosis and moderate mitral regurgitation who presented with worsening dyspnea on exertion. The patient had undergone 4-vessel coronary artery bypass graft and mitral valve replacement 14 years before and was deemed high risk for redo sternotomy. A transseptal mitral valve-in-valve replacement was performed which resulted in intraoperative hypoxia and hypotension after atrial septal defect creation for valve deployment. A right-to-left shunt had developed due to the patient's underlying pulmonary hypertension. Successful atrial septal defect closure resolved the hypoxia and hypotension. The patient had a brief and uncomplicated postoperative course.

Critical Care of Patients After Pulmonary Thromboendarterectomy

Pulmonary thromboendarterectomy (PTE) remains the only curative surgery for patients with chronic thromboembolic pulmonary hypertension (CTEPH). Postoperative intensive care unit care challenges providers with unique disease physiology, operative sequelae, and the potential for detrimental complications. Central concerns in patients with CTEPH immediately after PTE relate to neurologic, pulmonary, hemodynamic, and hematologic aspects. Institutional experience in critical care for the CTEPH population, a multidisciplinary team approach, patient risk assessment, and integration of current concepts in critical care determine outcomes after PTE surgery. In this review, the authors will focus on specific aspects unique to this population, with integration of current available evidence and future directions. The goal of this review is to provide the cardiac anesthesiologist and intensivist with a comprehensive understanding of postoperative physiology, potential complications, and contemporary intensive care unit management immediately after pulmonary endarterectomy.

Effects of vasopressin during a pulmonary hypertensive crisis induced by acute hypoxia in a rat model of pulmonary hypertension

BACKGROUND

A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.

METHODS

Four weeks after MCT 60 mg kg^-1 administration i.v., right ventricular systolic pressure (RVSP), systolic BP (SBP), mean BP (MBP), cardiac index (CI), and pulmonary vascular resistance index (PVRI) were measured. PHC defined as an RVSP exceeding or equal to SBP was induced by changing the fraction of inspiratory oxygen to 0.1. Rats were subsequently treated by vasopressin, phenylephrine, or norepinephrine, followed by assessment of systemic haemodynamics, isometric tension of femoral and pulmonary arteries, cardiac function, blood gas composition, and survival.

RESULTS

PHC was associated with increased RV dilatation and paradoxical septal motion. Vasopressin increased MBP [mean (standard error)] from 52.6 (3.8) to 125.0 (8.9) mm Hg and CI from 25.4 (2.3) to 40.6 (1.8) ml min^-1 100 g^-1 while decreasing PVRI. Vasopressin also improved RV dilatation, oxygenation, and survival in PHC. In contrast, phenylephrine increased MBP from 54.8 (2.3) to 96.8 (3.2) mm Hg without improving cardiac pump function. Norepinephrine did not alter MBP. Vasopressin contracted femoral but not pulmonary arteries, whereas phenylephrine contracted both arterial beds. Hence, improvements with vasopressin in PHC might be associated with decreased PVRI and selective systemic vasoconstriction.

CONCLUSIONS

In this rat model of a PHC, vasopressin, but not phenylephrine or norepinephrine, resulted in better haemodynamic and vascular recovery.