Pharmacologic management of perioperative pulmonary hypertension

Comparison of Nebulized Versus Intravenous Milrinone on Reducing Pulmonary Arterial Pressure in Patients with Pulmonary Hypertension Candidate for Open-cardiac Surgery: A Double-Blind Randomized Clinical Trial

Background

Regardless of the cause, pulmonary hypertension can increase patient complications and mortality. This study compared the effect of nebulized versus intravenous (IV) milrinone on reducing pulmonary arterial pressure in patients with pulmonary hypertension candidates for open-cardiac surgery.

Methods

This double-blind, randomized clinical trial was performed on 32 patients undergoing elective on-pump cardiac surgery during January 2021-January 2022 in the Cardiac Operating Room of Golestan Hospital, Ahvaz, Iran. Patients were randomly divided into test groups nebulize milrinone (N = 16) and IV milrinone (N = 16). The medication was administered after the cross-clamp of the aorta opening. The outcome variables included hemodynamic data, cardiac output, cardiac index, stroke volume, mean arterial pressure (MAP), central venous pressure, mean pulmonary artery pressure (mPAP), systemic vascular resistance, pulmonary vascular resistance, MAP/mPAP ratio, time until extubation, duration of hospitalization in the Intensive Care Unit (ICU), and duration of hospital stay.

Results

In the nebulized group, MAP and MAP/mPAP were significantly higher than in the IV milrinone group (P = 0.09 and P < 0.0001, respectively). The time of extubation (P = 0.001), duration of hospitalization in the ICU (P = 0.009), and duration of hospital stay (P = 0.026) in the nebulized milrinone group were significantly shorter than in the IV milrinone group.

Conclusions

Nebulized milrinone administration before weaning off cardiopulmonary bypass (CPB) can be accelerated and facilitate weaning off CPB. Moreover, despite maintaining MAP, nebulized milrinone significantly reduces mPAP. According to the results of this study, nebulized milrinone is recommended in patients undergoing cardiac surgery with pulmonary hypertension.

Perioperative approach to precapillary pulmonary hypertension in non-cardiac non-obstetric surgery

Pulmonary hypertension (PH) confers a significant challenge in perioperative care. It is associated with substantial morbidity and mortality. A considerable amount of information about management of patients with PH has emerged over the past decade. However, there is still a paucity of information to guide perioperative evaluation and management of these patients. Yet, a satisfactory outcome is feasible by focusing on elaborate disease-adapted anaesthetic management of this complex disease with a multidisciplinary approach. The cornerstone of the peri-anaesthetic management of patients with PH is preservation of right ventricular (RV) function with attention on maintaining RV preload, contractility and limiting increase in RV afterload at each stage of the patient's perioperative care. Pre-anaesthetic evaluation, choice of anaesthetic agents, proper fluid management, appropriate ventilation, correction of hypoxia, hypercarbia, acid-base balance and pain control are paramount in this regard. Essentially, the perioperative management of PH patients is intricate and multifaceted. Unfortunately, a comprehensive evidence-based guideline is lacking to navigate us through this complex process. We conducted a literature review on patients with PH with a focus on the perioperative evaluation and suggest management algorithms for these patients during non-cardiac, non-obstetric surgery.

Perioperative Management of Pulmonary Hypertension. a Review

Pulmonary hypertension is a rare and progressive pathology defined by abnormally high pulmonary artery pressure mediated by a diverse range of aetiologies. It affects up to twenty-six individuals per one million patients currently living in the United Kingdom (UK), with a median life expectancy of 2.8 years in idiopathic pulmonary hypertension. The diagnosis of pulmonary hypertension is often delayed due to the presentation of non-specific symptoms, leading to a delay in referral to specialists services. The complexity of treatment necessitates a multidisciplinary approach, underpinned by a diverse disease aetiology from managing the underlying disease process to novel specialist treatments. This has led to the formation of dedicated specialist treatment centres within centralised UK cities. The article aimed to provide a concise overview of pulmonary hypertension's clinical perioperative management, including key definitions, epidemiology, pathophysiology, and risk stratification.

Influence of the aldehyde dehydrogenase 2 polymorphism on the vasodilatory effect of nitroglycerin in infants with congenital heart disease and pulmonary arterial hypertension

PURPOSE

The influence of the aldehyde dehydrogenase 2 (ALDH2) gene polymorphism on the pharmacokinetics and haemodynamics of nitroglycerin (GTN) was determined in human subjects.

METHODS

Eighteen infants (nine each with and without ALDH2 gene polymorphism) with congenital heart disease and pulmonary arterial hypertension participated in this study. GTN treatment started at a dose of 2 μg/kg/min, and the dose was escalated by 1-2 μg/kg/min until pulmonary vascular resistance (PVR) was reduced by more than 30%. The plasma GTN concentration and PVR were measured at the end of each infusion period.

RESULTS

Plasma GTN concentrations were significantly higher in patients with the ALDH2 gene polymorphism than in those without the polymorphism. Conversely, the reduction in PVR was smaller in patients with the ALDH2 gene polymorphism than in those without.

CONCLUSIONS

These data suggest that the ALDH2 gene polymorphism influences the pharmacokinetics and haemodynamics of GTN in human subjects.

Preoperative balloon pulmonary angioplasty enabled noncardiac surgery of a patient with chronic thromboembolic pulmonary hypertension (CTEPH): A case report

RATIONALE

Chronic thromboembolic pulmonary hypertension (CTEPH) is a disease with a poor prognosis, characterized by chronic thromboembolic obstruction of the pulmonary arteries and pulmonary hypertension. Balloon pulmonary angioplasty (BPA) is a newly emergent treatment for CTEPH, which may substitute pulmonary endarterectomy, the standard but more invasive treatment for CTEPH. Here, we report the case of a CTEPH patient who underwent 2 noncardiac surgeries without complications after preoperative intervention of BPA.

PATIENT CONCERNS

A 79-year-old man presented with severe osteoarthritis of bilateral knees, with adaptation of total knee arthroplasty (TKA). Transthoracic echocardiogram revealed severe pulmonary hypertension with estimated right ventricular systolic pressure of 140 mm Hg.

DIAGNOSIS

Pulmonary arteriography revealed total occlusion of the upper branch of the right pulmonary artery, and ventilation/perfusion scan showed multiple mismatched perfusion defects. His pulmonary artery pressure (PAP) was as high as 89/25 (46) mm Hg with normal range of pulmonary capillary wedge pressure. He was diagnosed with CTEPH.

INTERVENTIONS

Four BPA sessions for 8 branches of the bilateral pulmonary arteries were done, until the mean PAP (mPAP) went under 30 mm Hg. For the TKA, we selected spinal anesthesia in order to minimize intraoperative hemodynamic changes. Cardiac surgeons were standby in case extracorporeal membrane oxygenation (ECMO) initiation was required.

OUTCOMES

With appropriate pain management and use of intravenous vasopressors, intraoperative vital signs were stable. No symptoms of hemodynamic collapse were observed postoperatively. The patient was discharged on the 46th postoperative day following rehabilitation. Two years later, left-side unicompartment knee arthroplasty (UKA) was scheduled. Right heart catheterization study revealed the mPAP was 30 mm Hg, nearly the same value as the last study. The operation was performed under spinal anesthesia with continuous arterial pressure monitoring without need for intraoperative vasopressor. He was discharged without complications on the 24th postoperative day.

LESSONS

BPA can be an effective preoperative intervention for CTEPH patients undergoing noncardiac surgery.

The Pathophysiology of Nitrogen Dioxide During Inhaled Nitric Oxide Therapy

Administration of inhaled nitric oxide (NO) with the existing compressed gas delivery systems is associated with unavoidable codelivery of nitrogen dioxide (NO2), an unwanted toxic contaminant that forms when mixed with oxygen. The NO2 is generated when NO is diluted with O2-enriched air before delivery to the patient. When NO2 is inhaled by the patient, it oxidizes protective antioxidants within the epithelial lining fluid (ELF) and triggers extracellular damage in the airways. The reaction of NO2 within the ELF triggers oxidative stress (OS), possibly leading to edema, bronchoconstriction, and a reduced forced expiratory volume in 1 second. Nitrogen dioxide has been shown to have deleterious effects on the airways of high-risk patients including neonates, patients with respiratory and heart failure, and the elderly. Minimizing co-delivery of NO2 for the next generation delivery systems will be a necessity to fully optimize the pulmonary perfusion of NO because of vasodilation, whereas minimizing the negative ventilatory and histopathological effects of NO2 exposure during inhaled NO therapy.

Beyond the evidence: treating pulmonary hypertension in the intensive care unit

Most patients with pulmonary arterial hypertension succumb to their disease in the ICU; however, limited evidence-based information exists to guide treatment in those that present with advanced right ventricular failure. Critical care physicians should be aware of the complexities of the treatment of patients with pulmonary arterial hypertension and should develop a strategy for their care. Current management is based on the pathophysiology of the disease and involves a multidisciplinary team supported by institutional polices directed at optimizing patient safety.