Nitric Oxide and Milrinone: Combined Effect on Pulmonary Circulation After Fontan-Type Procedure: A Prospective, Randomized Study

Inhaled nitric oxide and postoperative outcomes in cardiac surgery with cardiopulmonary bypass: A systematic review and meta-analysis

Cardiac surgeries under cardiopulmonary bypass (CPB) are complex procedures with high incidence of complications, morbidity and mortality. The inhaled nitric oxide (iNO) has been frequently used as an important composite of perioperative management during cardiac surgery under CPB. We conducted a meta-analysis of published randomized clinical trials (RCTs) to assess the effects of iNO on reducing postoperative complications, including the duration of postoperative mechanical ventilation, length of intensive care unit (ICU) stay, length of hospital stay, mortality, hemodynamic improvement (the composite right ventricular failure, low cardiac output syndrome, pulmonary arterial pressure, and vasoactive inotropic score) and myocardial injury biomarker (postoperative troponin I levels). Subgroup analyses were performed to assess the effect of modification and interaction. These included iNO dosage, the timing and duration of iNO therapy, different populations (children and adults), and comparators (other vasodilators and placebo or standard care). A comprehensive search for iNO and cardiac surgery was performed on online databases. Twenty-seven studies were included after removing the duplicates and irrelevant articles. The results suggested that iNO could reduce the duration of mechanical ventilation, but had no significance in the ICU stay, hospital stay, and mortality. This may be attributed to the small sample size of the most included studies and heterogeneity in timing, dosage and duration of iNO administration. Well-designed, large-scale, multicenter clinical trials are needed to further explore the effect of iNO in improving postoperative prognosis in cardiovascular surgical patients.

Reassessing the role of milrinone in the treatment of heart failure and pulmonary hypertension in neonates and children: a systematic review and meta-analysis

To evaluate milrinone's impact on pediatric cardiac function, focusing on its specific role as an inotrope and lusitrope, while considering its systemic and pulmonary vasodilatory effects. Search of PubMed, EMBASE, and the Cochrane Library up to August 2023. We included all studies that evaluated milrinone in children under 18 years old in neonatal, pediatric, or cardiac intensive care units. We excluded case reports, studies that did not provide tabular information on milrinone's outcomes, and studies focused on non-intensive care populations. We extracted data on the research design, objectives, study sample, and results of each study, including the impact of milrinone and any associated factors. We screened a total of 9423 abstracts and 41 studies were ultimately included. Milrinone significantly improved left ventricular ejection fraction (WMD 3.41 [95% CI 0.61 - 6.21]), left ventricle shortening fraction (WMD 4.25 [95% CI 3.43 - 5.08]), cardiac index (WMD 0.50 [95% CI 0.32 to 0.68]), left ventricle output (WMD 55.81 [95% CI 4.91 to 106.72]), serum lactate (WMD -0.59 [95% CI -1.15 to -0.02]), and stroke volume index (WMD 2.95 [95% CI 0.09 - 5.82]). However, milrinone was not associated with improvements in ventricular myocardial performance index (WMD -0.01 [95% CI -0.06 to 0.04]) and ventricular longitudinal strain (WMD -2.14 [95% CI -4.56 to 0.28]). Furthermore, milrinone was not associated with isovolumetric relaxation time reduction (WMD -8.87 [95% CI -21.40 to 3.66]).

CONCLUSION

Our meta-analysis suggests potential clinical benefits of milrinone by improving cardiac function, likely driven by its systemic vasodilatory effects. However, questions arise about its inotropic influence and the presence of a lusitropic effect. Moreover, milrinone's pulmonary vasodilatory effect appears relatively weaker compared to its systemic actions. Further research is needed to elucidate milrinone's precise mechanisms and refine its clinical applications in pediatric practice.

WHAT IS KNOWN

• Milrinone is a phosphodiesterase III inhibitor that has been used to treat a variety of pediatric and neonatal conditions. • Milrinone is believed to exert its therapeutic effects by enhancing cardiac contractility and promoting vascular relaxation.

WHAT IS NEW

• Milrinone may not have a significant inotropic effect. • Milrinone's pulmonary vasodilatory effect is less robust than its systemic vasodilatory effect.

Outcome of obstructed total anamalous pulmonary venous connection (TAPVC) repair patients with milrinone versus milrinone and inhaled nitric oxide (INO): A prospective randomized observational study

Background

Obstructed total anomalous pulmonary venous connection (TAPVC) typically present with severe cardiovascular decompensation and requires urgent surgical management. Pulmonary arterial hypertension (PAH) is a major risk factor affecting mortality. Perioperative management focuses on providing inotropic support and managing potential pulmonary hypertensive episodes. Milrinone and inhaled nitric oxide (iNO) efficiently reduce pulmonary artery pressure (PAP) and help to improve the outcome. The aim was to determine the outcome of patients with high PAP with milrinone alone and a combination of iNO and milrinone.

Material and Method

After ethical committee approval, the study was conducted over a period of 3 years in 80 patients with obstructed TAPVC repair. A total of 80 patients having severe PAH (supra systemic arterial pressure) randomly divided into two groups with 40 patients in each (M & MN). Group M (milrinone) patients received milrinone and Group MN (milrinone & iNO) patients received both milrinone (after opening aortic cross clamp) and iNO (post operative ICU). Ventilation time, hospital stay, ICU stay, complications, in hospital mortality were compared between both groups.

Result

Ventilation time, Intensive Care Unit (ICU) stay, hospital stay for group M was 8.02 ± 5.74 days, 11.25 ± 7.33 day, 14.92 ± 8.55 days, respectively, and for group MN was 5.02 ± 1.78 days, 8.27 ± 3.24 days, 10.3 ± 3.18 days, respectively. In hospital mortality for group M and MN was 10% and 2.5%, respectively. P value for each variable was significant < 0.05 (except mortality).

Conclusion

Most of the patients with obstructed TAPVC had severe PAH. Management of severe PAH with a combination of milrinone with iNO had a better outcome than milrinone alone.

Home Milrinone in Pediatric Hospice Care of Children with Heart Failure

CONTEXT

The symptom profile of children dying from cardiac disease, especially heart failure, differs from those with cancer and other non-cardiac conditions. Treatment with vasoactive infusions at home may be a superior therapy for symptom control for these patients, rather than traditional pain and anxiety management with morphine and benzodiazepines.

OBJECTIVES

We report our experience using outpatient milrinone in children receiving hospice care for end-stage heart failure.

METHODS

Retrospective review of a contemporary cohort of all patients at Lucile Packard Children's Hospital, Stanford who were discharged on intravenous milrinone and hospice care between 2008 and 2021. Clinical data, including cardiac diagnosis, milrinone dose and route of administration, total milrinone days, symptoms reported, rehospitalization rates, concurrent therapies and complications were analyzed.

RESULTS

Among 8 patients, median duration of home milrinone infusion was 191 (33, 572) days with the longest support duration 1,054 days. All (100%) patients were also receiving diuretics at the time of death. Five (63%) were receiving no other pain control medications until the active phase of dying. From milrinone initiation to last outpatient assessment, a reduction in the number of patients reporting respiratory discomfort, abdominal pain, weight loss/lack of appetite, and fatigue was observed. Six (75%) died at home.

CONCLUSION

We used milrinone with oral diuretics effectively for symptom control in children with heart failure on palliative care. Our experience was that this combination can be used safely in the outpatient setting for long-term use without the addition of opiates, benzodiazepines, or supplemental oxygen in most cases.

Postoperative Inhaled Nitric Oxide Use and Early Outcomes after Fontan Surgery Completion

A considerable number of patients after the Fontan operation require prolonged hospitalization due to significant perioperative morbidities. The early postoperative morbidity can be attributed to elevated pulmonary vascular resistance. We hypothesized that the postoperative outcomes would improve with the routine use of inhaled nitric oxide (iNO) to decrease pulmonary vascular resistance. From January 2015 to November 2017 (Group 1), 37 patients underwent Fontan operation, and from December 2017 to December 2019 (Group 2), 34 patients underwent Fontan operation. All patients in Group 2 received iNO in the immediate perioperative period as part of a standardized postoperative pathway. There was no statistically significant difference in demographics or single ventricle subtype between the two groups. All patients underwent an extracardiac Fontan, and Group 2 had a higher number of fenestration (p< 0.01). Pre-Fontan hemodynamics showed no statistically significant difference in Glenn pressure, transpulmonary gradient, or systemic arterial and venous saturation. Both groups had a median length of stay of 13 days (p = 0.5), median chest tube placement of 7 days (p = 0.5), and there was no statistically significant difference in major complications. Readmission within 1 month of discharge occurred in five patients in Group 1 and six patients in Group 2 (p = 0.7). Routine use of iNO in the early postoperative period after Fontan operation did not reduce the length of stay, chest tube duration, rate of complications, or readmission.

Perioperative Management of an Adolescent Fontan Patient with Narrowing of the Aortopulmonary Space for Posterior Scoliosis Surgery

Congenital cardiac patients who received neonatal reconstructive aortic arch surgery are at risk of aortopulmonary space narrowing with compression of the left pulmonary artery and left main bronchus (LMB) later in life. We discuss a challenging adolescent single ventricle patient who presented for surgical treatment of a non-idiopathic thoracic scoliosis (posterior spinal fusion) with severe stenosis of the LMB and left pulmonary artery due to a narrow aortopulmonary space. Careful preoperative imaging, evaluation, and decision making resulted in successful surgical treatment and uneventful perioperative course.

A systematic review of clinical study evidence for pulmonary vasodilator therapy following surgery with cardiopulmonary bypass in children with CHD

OBJECTIVES

Complications from pulmonary hypertension are one of the leading contributors to morbidity and mortality post-cardiopulmonary bypass surgery in children with CHD. Pulmonary vasodilator therapies are commonly used post-operatively, but the optimal target patient population, therapy choice, timing of therapy initiation, and duration of therapy are not well defined.

METHODS

We used PubMed and EMBASE to identify studies from 2000 to 2020 investigating the use of pulmonary vasodilator therapy post-cardiopulmonary bypass in children aged 0-18 years. To ensure eligibility criteria, studies were systematically reviewed by two independent reviewers.

RESULTS

We identified 26 studies of 42,971 children across four medication classes; 23 were single centre, 14 were prospective, and 11 involved randomisation (four of which employed a placebo-control arm). A disproportionate number of children were from a single retrospective study of 41,872 patients. Definitions varied, but change in pulmonary haemodynamics was the most common primary outcome, used in 14 studies. Six studies had clinical endpoints, with mortality the primary endpoint for two studies. Treatment with inhaled nitric oxide, iloprost, and sildenafil all resulted in improved haemodynamics in specific cohorts of children with post-operative pulmonary hypertension, although improved outcomes were not consistently demonstrated across all treated children. Iloprost may be a cheaper alternative to inhaled nitric oxide with similar haemodynamic response.

CONCLUSION

Studies were predominantly single-centre, a control arm was rarely used in randomised studies, and haemodynamic endpoints varied significantly. Further research is needed to reduce post-operative morbidity and mortality from pulmonary hypertension in children with CHD.

Improving respiratory outcomes after pediatric cardiac surgery: New uses for nitric oxide

BACKGROUND

This month's issue of Journal of Cardiac Surgery features a retrospective study on the effect of combining inhaled nitric oxide with high frequency oscillator ventilation to rescue infants who have failed conventional ventilation after congenital heart surgery.

AIMS

This commentary aims to place that study within the context of available published literature on the topic.

MATERIALS AND METHODS

The PubMed database was queried for all English-language entries between 1995 and 2021 with the terms nitric oxide, congenital heart disease, oscillator, and respiratory failure. The results were then assessed for relevance and impact by the author.

RESULTS

From these results, 15 articles were selected for use in this review. The cost of prolonged mechanical ventilation is described. The use of nitric oxide has been used to improve outcomes in hypoxic respiratory failure. High-frequency oscillator ventilation has also been studied in pediatric patients with ARDS. To date, no studies have been published showing the benefit of combining these two modalities in pediatric cardiac surgical patients.

DISCUSSION

The results of this month's study on nitric oxide and high frequency oscillator ventilation are placed in the context of current literature and suggestions for further study are presented.

CONCLUSION

Pediatric patients with hypoxic respiratory failure following congenital heart surgery have a new treatment strategy that appears effective. Further studies to confirm this should be undertaken.

Long-Term Outcomes After Fenestration Closure in High-Risk Fontan Candidates

The study aimed to assess the long-term outcomes after fenestration closure in patients at risk for Fontan failure. Of 119 patients who underwent Fontan operation between 1995 and 2004, fenestration was not created in 89 patients (NF group) and created in 30 patients with hypoplastic left heart syndrome, heterotaxy syndrome, high pulmonary arterial pressure, high systemic ventricular end-diastolic pressure, low ventricular ejection fraction, or atrioventricular valve regurgitation. All fenestrations were closed spontaneously or by catheter/surgical interventions, excepting two patients, and therefore, they were excluded. In fenestration group, patients with pre-Fontan mean pulmonary arterial pressure ≥ 15 mmHg or systemic atrioventricular valve regurgitation ≥ moderate were classified as high-risk Fontan candidates (F-HR group, n = 16), and the remaining patients were as standard-risk (F-SR group, n = 12). Protein-losing enteropathy-free survival rates did not differ among the three groups (p = 0.72). Serial follow-up catheter examinations after Fontan operation were completed in 69 patients in NF group and 11 patients in both F-SR and F-HR groups. Cardiac index and pulmonary vascular resistance significantly and similarly decreased over time in all groups, though the F-HR group showed lowest arterial oxygen saturation, lowest cardiac index, and highest pulmonary vascular resistance. The F-HR group also showed much veno-venous collaterals (p = 0.049), low peak oxygen consumption (p = 0.019), and low anaerobic threshold (p = 0.023) as compared to those in the F-SR group. In F-HR group, cyanosis remained after fenestration closure due to transformation from fenestration to veno-venous collaterals, which resulted in elevation of pulmonary vascular resistance, low cardiac index, and deterioration of exercise tolerance.

The pulmonary vascular bed in patients with functionally univentricular physiology and a Fontan circulation

Fontan palliation represents one of the most remarkable surgical advances in the management of individuals born with functionally univentricular physiology. The operation secures adult survival for all but a few with unfavourable anatomy and/or physiology. Inherent to the physiology is passive transpulmonary blood flow, which produces a vulnerability to adequate filling of the systemic ventricle at rest and during exertion. Similarly, the upstream effects of passive flow in the lungs are venous congestion and venous hypertension, especially marked during physical activity. The pulmonary vascular bed has emerged as a defining character on the stage of Fontan circulatory behaviour and clinical outcomes. Its pharmacologic regulation and anatomic rehabilitation therefore seem important strategic therapeutic targets. This review seeks to delineate the important aspects of pulmonary artery development and maturation in functionally univentricular physiology patients, pulmonary artery biology, pulmonary vascular reserve with exercise, and pulmonary artery morphologic and pharmacologic rehabilitation.

Perioperative and long-term management of Fontan patients

A Fontan circulation requires a series of three-staged operations aimed to palliate patients with single-ventricle CHD. Currently, the most frequent technique is the extracardiac total cavopulmonary connection, an external conduit connecting the IVC and right pulmonary artery, bypassing the right side of the heart. Fontan candidates must meet strict criteria; they are assessed utilising both cardiac catheterisation and cardiac magnetic resonance. Postoperatively, treatment protocols prioritise antibiotic prophylaxis, diuretics, angiotensin-converting enzyme inhibitors, anticoagulation, and oxygen therapy with fluid restriction and a low-fat diet. These measures aim to reduce length of stay in the ICU and hospital by preventing acute complications such as infection, venous thromboembolism, low cardiac output, pleural effusion, and acute kidney injury. Late complications of a Fontan procedure include circulation failure, protein-losing enteropathy, plastic bronchitis, and Fontan-associated liver disease. The definitive management is cardiac transplantation, with promising innovations in selective embolisation of lymphatic vessels and Fontan-specific ventricular assist devices. Further research assessing current protocols in the perioperative management of Fontan patients would be beneficial for standardising current practice and improving outcomes.

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.

Congenital Heart Disease-Associated Pulmonary Hypertension

Presently, with increasing survival of patients with congenital heart disease (CHD), pulmonary arterial hypertension (PAH) associated with CHD is commonly encountered in children and adults. This increased prevalence is seen despite significant advances in early diagnosis and surgical correction of patients with structural CHD. PAH is the cause of significant morbidity and mortality in these patients and comes in many forms. With the increased availability of targeted therapies for PAH, there is hope for improved hemodynamics, exercise capacity, quality of life, and possibly survival for these patients. There may also be opportunities for combined medical and interventional/surgical approaches for some.

Fontan procedure in patients with preoperative mean pulmonary artery pressure over 15 mmHg

BACKGROUND

Several factors affect the long-term outcome of Fontan procedure, but a high pulmonary artery pressure is still one of the most important limitation for proceeding to a Fontan circulation. Herein, we present our experience in Fontan patients with high preoperative pulmonary artery pressures.

METHODS

A retrospective analysis was performed to evaluate Fontan patients with a preoperative pulmonary artery pressure >15 mmHg between 2009 and 2020. Sixteen patients were operated on with a mean preoperative pulmonary artery pressure of 17.5 ± 2.1 mmHg.

RESULTS

Mean age at the time of Fontan procedure was 7.8 ± 5.6 years. All the patients had stage 2 cavopulmonary anastomosis before Fontan completion, with a mean interstage period of 4 ± 2.6 years. Fontan completion was achieved with a polytetrafluorethylene tubular conduit, two of which were intra-extracardiac. Fenestration was performed in five (31%) cases. Postoperative pulmonary artery pressures and arterial oxygen saturation levels were 11.2 ± 2.8 and 97.8 ± 2 mmHg, respectively. Mean duration of pleural drainage was 3.9 ± 5.3 days. Any morbidity and mortality were not encountered during a mean follow-up period of 4.8 ± 7.7 years.

CONCLUSIONS

The midterm results of stage 3 Fontan completion in patients with pulmonary artery >15 mmHg are encouraging. Not only the mean pulmonary artery pressure but also the pulmonary vascular resistance may be helpful in order to identify the high risk patients before Fontan completion.

Efficacy of phosphodiesterase type 5 inhibitors in univentricular congenital heart disease: the SV-INHIBITION study design

Aims

In univentricular hearts, selective lung vasodilators such as phosphodiesterase type 5 (PDE5) inhibitors would decrease pulmonary resistance and improve exercise tolerance. However, the level of evidence for the use of PDE5 inhibitors in patients with a single ventricle (SV) remains limited. We present the SV‐INHIBITION study rationale, design, and methods.

Methods and results

The SV‐INHIBITION trial is a nationwide multicentre, randomized, double blind, placebo‐controlled, Phase III study, aiming to evaluate the efficacy of sildenafil on the ventilatory efficiency during exercise, in teenagers and adult patients (>15 years old) with an SV. Patients with a mean pulmonary arterial pressure >15 mmHg and a trans‐pulmonary gradient >5 mmHg, measured by cardiac catheterization, will be eligible. The primary outcome is the variation of the VE/VCO₂ slope, measured by a cardiopulmonary exercise test, between baseline and 6 months of treatment. A total of 50 patients are required to observe a decrease of 5 ± 5 points in the VE/VCO₂ slope, with a power of 90% and an alpha risk of 5%. The secondary outcomes are clinical outcomes, oxygen saturation, 6 min walk test, SV function, NT‐proBNP, peak VO₂, stroke volume, mean pulmonary arterial pressure, trans‐pulmonary gradient, SF36 quality of life score, safety, and acceptability.

Conclusions

The SV‐INHIBITION study aims to answer the question whether PDE5 inhibitors should be prescribed in patients with an SV. This trial has been built focusing on the three levels of research defined by the World Health Organization: disability (exercise tolerance), deficit (SV function), and handicap (quality of life).

Post-Extubation Inhaled Nitric Oxide Therapy via High-Flow Nasal Cannula After Fontan Procedure

In 2014, our hospital introduced inhaled nitric oxide (iNO) therapy combined with high-flow nasal cannula (HFNC) oxygen therapy after extubation following the Fontan procedure in patients with unstable hemodynamics. We report the benefits of HFNC-iNO therapy in these patients. This was a single-center, retrospective review of 38 patients who underwent the Fontan procedure between January 2010 and June 2016, and required iNO therapy before extubation. The patients were divided into two groups: patients in Epoch 1 (n = 24) were treated between January 2010 and December 2013, receiving only iNO therapy; patients in Epoch 2 (n = 14) were treated between January 2014 and June 2016, receiving iNO therapy and additional HFNC-iNO therapy after extubation. There were no significant differences between Epoch 1 and 2 regarding preoperative cardiac function, age at surgery, body weight, initial diagnosis (hypoplastic left heart syndrome, 4 vs. 2; total anomalous pulmonary venous return, 5 vs. 4; heterotaxy, 7 vs. 8), intraoperative fluid balance, or central venous pressure upon admission to the intensive care unit. Epoch 2 had a significantly shorter duration of postoperative intubation [7.2 (3.7-49) vs. 3.5 (3.0-4.6) hours, p = 0.033], pleural drainage [23 (13-34) vs. 9.5 (8.3-18) days, p = 0.007], and postoperative hospitalization [36 (29-49) vs. 27 (22-36) days, p = 0.017]. Two patients in Epoch 1 (8.3%), but none in Epoch 2, required re-intubation. Our results suggest that HFNC-iNO therapy reduces the duration of postoperative intubation, pleural drainage, and hospitalization.

The efficacy and safety of pulmonary vasodilators in patients with Fontan circulation: a meta-analysis of randomized controlled trials

No previous meta-analysis has evaluated the efficacy and safety of pulmonary vasodilators in Fontan physiology. Recent relative trials have obtained conflicting results regarding improvements in peak oxygen consumption; the relatively small number of patients in each study may be a limiting factor. We aimed to evaluate the efficacy and safety of pulmonary vasodilators in Fontan patients. Relevant studies were identified by searching the PubMed, Embase, and Cochrane Library databases. Pooled outcomes were determined to assess the efficacy and safety of pulmonary vasodilators in Fontan patients. Nine randomized controlled studies involving 381 patients with Fontan circulation were included. Pulmonary vasodilator therapy led to significant improvement (mean difference = -0.39, 95% CI: [-0.72, -0.05]) in the New York Heart Association (NYHA) functional class. The 6-minute walking distance (6MWD) was significantly increased by 134 m (95% CI: [86.07, 181.94]), and the peak VO2 was also significantly improved (mean difference = 1.42 ml·(kg·min)-1, 95% CI: [0.21, 2.63]). Additionally, the mean pulmonary artery pressure (mPAP) was significantly reduced (mean difference = -2.25 mmHg, 95% CI: [-3.00, -1.50]). No significant change was found in mortality or in brain natriuretic peptide (BNP) or N-terminal pronatriuretic peptide (NT-proBNP). Four studies reported no side effects and good drug tolerance, and two studies reported mild adverse effects. The present meta-analysis indicated that pulmonary vasodilators (primarily the PDE-5 inhibitor and endothelin-1 receptor antagonist) significantly improved the hemodynamics of Fontan patients, reduced the NYHA functional class and increased the 6MWD. The peak oxygen consumption was also improved. No significant change was observed in mortality or in the BNP or NT-proBNP level. Overall, the pulmonary vasodilators were well tolerated. This finding needs to be confirmed in future studies.

Assessment of the effect of two regimens of milrinone infusion in pediatric patients undergoing fontan procedure: A randomized study

Objective:

The aim of the study was to compare the effect of two different regimens of milrinone on hemodynamics and oxygen saturation in pediatric patients undergoing Fontan procedure.

Design:

This was a randomized study.

Setting:

Cardiac centers.

Patients:

This study included 116 patients undergoing Fontan procedure.

Material and Methods:

Group E: Milrinone was started as infusion 0.5 μg/kg/min without a loading dose at the beginning of cardiopulmonary bypass (CPB) followed by infusion 0.5–0.75 μg/kg/min in the pediatric cardiac surgical intensive care unit (PSICU). Group L: Milrinone was started as a loading dose 50 μg/kg over 10 min before weaning from CPB followed by infusion 0.5–0.75 μg/kg/min in the PSICU.

Measurements:

Heart rate, mean arterial blood pressure, central venous pressure, transpulmonary pressure, cardiac index, pharmacological support, lactate level, urine output, oxygen saturation, ICU, and hospital length of stay.

Main Results:

There were no changes in the heart rate and mean arterial blood pressure (P > 0.05). The increase in the postoperative central venous pressure, transpulmonary pressure and lactate level was lower in Group E than Group L (P < 0.05). The increase in the postoperative cardiac index, oxygen saturation, and urine output was higher in Group E than Group L (P < 0.05). The requirement for pharmacological support was lower in the Group E (P < 0.05). The ICU and hospital length of stay were shorter in the Group E than Group L (P < 0.05).

Conclusion:

Early use of milrinone during Fontan procedure facilitated the weaning from CPB, decreased the elevation in the central venous pressure, transpulmonary gradient pressure, and the requirement for pharmacological support. Furthermore, it increased the cardiac index and arterial oxygen saturation.

Nitric Oxide in Cardiac Surgery: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To investigate the efficacy and safety of perioperative administration of nitric oxide in cardiac surgery.

DESIGN

Meta-analysis of randomized controlled trials (RCTs).

PARTICIPANTS

Cardiac surgery patients.

INTERVENTIONS

A search of Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and MEDLINE for RCTs that compared nitric oxide with placebo or other comparators.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit (ICU) stay, and secondary outcomes were mortality, duration of mechanical ventilation, and reduction of mean pulmonary artery pressure. The study included 18 RCTs comprising 958 patients. The authors calculated the pooled odds ratio (OR) and the mean difference (MD) with random-effects model. Quantitative synthesis of data demonstrated a clinically negligible reduction in the length of ICU stay (MD -0.38 days, confidence interval CI [-0.65 to -0.11]; p = 0.005) and mechanical ventilation duration (MD -4.81 hours, CI [-7.79 to -1.83]; p = 0.002) compared with all control interventions with no benefit on mortality.

CONCLUSIONS

Perioperative delivery of inhaled nitric oxide resulted to be of no or minimal benefit in patients with pulmonary hypertension undergoing cardiac surgery. Large, randomized trials are needed to further assess its effect on major clinical outcomes and its cost-effectiveness.

The Perspective of the Intensivist on Inotropes and Postoperative Care Following Pediatric Heart Surgery: An International Survey and Systematic Review of the Literature

Introduction:

Inotropes are frequently being used in children undergoing heart surgery to prevent or treat low cardiac output syndrome (LCOS). There is only limited evidence that inotropes actually positively influence postoperative outcome. Our aim was to describe the current international practice variation in the use of inotropes following congenital heart surgery.

Methods:

We developed an online survey regarding the postoperative use of inotropes. We sent an invitation to all 197 registered members of the Pediatric Cardiac Intensive Care Society (PCICS) to participate in the survey. We also performed a systematic review of the literature.

Results:

Ninety-eight people (50%) responded, representing 62 international centers. Milrinone is routinely used perioperatively by 90 respondents (97%). Adrenaline/epinephrine is routinely used by 43%, dopamine by 36%, dobutamine by 11%, and levosimendan by 6%. Steroids are used routinely by 54% before initiating cardiopulmonary bypass. Vasopressin is used by 44% of respondents. The development of LCOS is monitored with lactate in 99% of respondents, physical examination (98%), intermittent mixed venous saturation (76%), continuous mixed venous saturation (13%), echocardiography (53%), core–peripheral temperature gap (29%), near-infrared spectrometry (25%), and 4% use cardiac output monitors (PiCCO, USCOM). To improve cardiac output, 42% add/increase milrinone, 37% add adrenaline, and 15% add dopamine. Rescue therapy is titrated individually, based on the patients’ pathophysiology. A systematic review of the literature failed to show compelling evidence with regard to the benefit of inotropes.

Conclusions:

Despite the lack of sufficient evidence, milrinone is used by the vast majority of caregivers following congenital heart surgery.

Fontan's circulation with dextrocardia, recent pulmonary embolism, and inferior vena cava filter: Anesthetic challenges for urgent hysterectomy

Fontan's circulation is a unique challenge for the anesthesiologist. Venous pressure is the only source of blood flow for the pulmonary circulation. Patients with such circulation are extremely sensitive to progression of cyanosis (decreased pulmonary blood flow) or circulatory failure. Any major venous compression can compromise the pulmonary blood flow worsening cyanosis; simultaneously, an increased afterload can precipitate circulatory failure. We present a rare patient of surgically corrected Ivemark syndrome with Fontan's physiology with dextrocardia who developed a large uterine fibroid compressing inferior vena cava (IVC). As a result of compression, not only the pulmonary circulation was compromised but she also developed stasis-induced venous thrombosis in the lower limbs that lead to pulmonary embolism (PE) (increased afterload). In addition to oral anticoagulation an IVC filter was inserted to prevent ongoing recurrent PE. Further, to prevent both circulatory compromise and deep venous thrombosis an urgent myomectomy/hysterectomy was planned. In the present case, we discuss the issues involved in the anesthetic management of such patients and highlight the lacunae in the present guidelines for managing perioperative anticoagulation these situations.

Clinical-Physiological Considerations in Patients Undergoing Staged Palliation for a Functionally Single Ventricle

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the circulation with a functionally univentricular heart, with a focus on the unique physiologic characteristics, which provide the underpinnings for the management of these complex patients.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

The circulation of the patient with a functionally univentricular heart displays unique physiologic characteristics, which are quite different from those of the normal biventricular circulation. There are profound differences within the heart itself in terms of ventricular function, interventricular interactions, and myocardial architecture, which are likely to have significant implications for the efficiency of ventricular ejection and metabolism. The coupling between the systemic ventricle and the aorta also displays unique features. The 3D orientation of the Fontan anastomosis itself can profoundly impact cardiac output, although the "portal" pulmonary arterial bed is a crucial determinant of overall cardiovascular function. As a result, disease-specific approaches to improve cardiovascular function are required at all stages during the care of these complex patients.

Pulmonary Hypertension

OBJECTIVES

To review the clinical classification, diagnosis, and pathophysiology of pulmonary hypertension in children, emphasizing the role of right ventricular function, ventricular interaction, and congenital heart disease in the evolution and progression of disease, as well as management strategies and therapeutic options.

DATA SOURCE

MEDLINE, PubMed.

CONCLUSIONS

Critically ill children with pulmonary hypertension associated with congenital heart disease are a high-risk population. Congenital cardiac defects resulting in either increased pulmonary blood flow or impaired pulmonary venous drainage predispose patients to developing structural and functional aberrations of the pulmonary vasculature. Mortality from pulmonary hypertension is most directly related to right ventricular failure.

Milrinone in Enterovirus 71 Brain Stem Encephalitis

Enterovirus 71 (EV71) was implicated in a widespread outbreak of hand-foot-and-mouth disease (HFMD) across the Asia Pacific area since 1997 and has also been reported sporadically in patients with brain stem encephalitis. Neurogenic shock with pulmonary edema (PE) is a fatal complication of EV71 infection. Among inotropic agents, milrinone is selected as a therapeutic agent for EV71- induced PE due to its immunopathogenesis. Milrinone is a type III phosphodiesterase inhibitor that has both inotropic and vasodilator effects. Its clinical efficacy has been shown by modulating inflammation, reducing sympathetic over-activity, and improving survival in patients with EV71-associated PE. Milrinone exhibits immunoregulatory and anti-inflammatory effects in the management of systemic inflammatory responses in severe EV71 infection.

Pulmonary vasodilator therapy and early postoperative outcome after modified Fontan operation

Although mortality is low after the modified Fontan procedure, there is a significant percentage of patients with prolonged postoperative recovery. The objective of this study is to evaluate the usefulness of postoperative administration of oral sildenafil and inhaled nitric oxide on early postoperative outcome. A prospective interventional and comparison study with a historical cohort was conducted. Between January, 2010 and March, 2013, 16 patients received oral sildenafil during immediate modified Fontan postoperative period. Inhaled nitric oxide was also administered if the patient was kept intubated 12 hours after surgery. Early postoperative outcome was compared with a historical cohort of 32 patients on whom the modified Fontan procedure was performed between March, 2000 and December, 2009. Postoperative administration of sildenafil and nitric oxide had no influence on early postoperative outcome after the modified Fontan procedure in terms of duration of pleural effusions, mechanical ventilation time, length of stay in the ICU, and length of hospital stay.

Prophylactic milrinone for the prevention of low cardiac output syndrome and mortality in children undergoing surgery for congenital heart disease

BACKGROUND

Children with congenital heart disease often undergo heart surgery at a young age. They are at risk for postoperative low cardiac output syndrome (LCOS) or death. Milrinone may be used to provide inotropic and vasodilatory support during the immediate postoperative period.

OBJECTIVES

This review examines the effectiveness of prophylactic postoperative use of milrinone to prevent LCOS or death in children having undergone surgery for congenital heart disease.

SEARCH METHODS

Electronic and manual literature searches were performed to identify randomised controlled trials. We searched CENTRAL, MEDLINE, EMBASE and Web of Science in February 2014 and conducted a top-up search in September 2014 as well as clinical trial registries and reference lists of published studies. We did not apply any language restrictions.

SELECTION CRITERIA

Only randomised controlled trials were selected for analysis. We considered studies with newborn infants, infants, toddlers, and children up to 12 years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data according to a pre-defined protocol. We obtained additional information from all study authors.

MAIN RESULTS

Three of the five included studies compared milrinone versus levosimendan, one study compared milrinone with placebo, and one compared milrinone verus dobutamine, with 101, 242, and 50 participants, respectively. Three trials were at low risk of bias while two were at higher risk of bias. The number and definitions of outcomes were non-uniform as well. In one study comparing two doses of milrinone and placebo, there was some evidence in an overall comparison of milrinone versus placebo that milrinone lowered risk for LCOS (risk ratio (RR) 0.52, 95% confidence interval (CI) 0.28 to 0.96; 227 participants). The results from two small studies do not provide enough information to determine whether milrinone increases the risk of LCOS when compared to levosimendan (RR 1.22, 95% CI 0.32 to 4.65; 59 participants). Mortality rates in the studies were low, and there was insufficient evidence to draw conclusions on the effect of milrinone compared to placebo or levosimendan or dobutamine regarding mortality, the duration of intensive care stay, hospital stay, mechanical ventilation, or maximum inotrope score (where available). Numbers of patients requiring mechanical cardiac support were also low and did not allow a comparison between studies, and none of the participants of any study received a heart transplantation up to the end of the respective follow-up period. Time to death within three months was not reported in any of the included studies. A number of adverse events was examined, but differences between the treatment groups could not be proven for hypotension, intraventricular haemorrhage, hypokalaemia, bronchospasm, elevated serum levels of liver enzymes, or a reduced left ventricular ejection fraction < 50% or reduced left ventricular fraction of shortening < 28%. Our analysis did not prove an increased risk of arrhythmias in patients treated prophylactically with milrinone compared with placebo (RR 3.59, 95% CI 0.83 to 15.42; 238 participants), a decreased risk of pleural effusions (RR 1.78, 95% CI 0.92 to 3.42; 231 participants), or a difference in risk of thrombocytopenia on milrinone compared with placebo (RR 0.86, 95% CI 0.39 to 1.88; 238 participants). Comparisons of milrinone with levosimendan or with dobutamine, respectively, did not clarify the risk of arrhythmia and were not possible for pleural effusions or thrombocytopenia.

AUTHORS' CONCLUSIONS

There is insufficient evidence of the effectiveness of prophylactic milrinone in preventing death or low cardiac output syndrome in children undergoing surgery for congenital heart disease, compared to placebo. So far, no differences have been shown between milrinone and other inodilators, such as levosimendan or dobutamine, in the immediate postoperative period, in reducing the risk of LCOS or death. The existing data on the prophylactic use of milrinone has to be viewed cautiously due to the small number of small trials and their risk of bias.

Pediatric split liver transplantation after Fontan procedure in left isomerism combined with biliary atresia: a case report

LI is a subset of the heterotaxy syndrome and a rare birth defect that involves the heart and other organs. It can be combined with extracardiac abnormalities, especially BA. CHD can be associated with LI in up to 15% of cases, although it is rare in BA. Pediatric LT for a child with ESLD due to BA combined with LI and CHD is a challenging issue for a transplant surgeon. Herein, we report a successful split LT on a three-yr-old boy with LI who survived after a Fontan procedure due to single ventricle, but who suffered from HPS associated with BA.

Inhaled Nitric Oxide for Elevated Cavopulmonary Pressure and Hypoxemia After Cavopulmonary Operations

Background. Elevated cavopulmonary pressure early after surgical creation of cavopulmonary connections is an important hemodynamic problem with grave prognostic significance. We examined the effect of administration of inhaled nitric oxide (iNO) to patients with elevated cavopulmonary pressure in the early postoperative period. Methods. We retrospectively reviewed data pertaining to all 14 patients with superior (n = 6) and total (n = 8) cavopulmonary connections who were treated with iNO in the early postoperative period during an interval of six years. Changes in the cavopulmonary pressure, the transpulmonary gradient, and the oxygen saturation after the institution of iNO were evaluated. The preoperative characteristics of the patients were compared to those of a control group of patients with cavopulmonary operations not treated with iNO postoperatively. Results. Twelve hours after the initiation of iNO therapy, significant reduction in the cavopulmonary pressure (16.6 ± 3.5 mm Hg vs 18.1 ± 2.3 mm Hg, P = .006), reduction in the cavopulmonary gradient (7.0 ± 3.5 mm Hg vs 9.8 ± 3.7 mm Hg, P = .009), and elevation of the arterial oxygen saturation (84.5% ± 6.0% vs 78.7% ± 5.9%, P = .001) were observed. Linear correlation analysis confirmed tendencies for reduction in the cavopulmonary pressure ( P = .13), reduction in the cavopulmonary gradient ( P = .02), and elevation of the oxygen saturation ( P = .10). Compared to the control group, the treated patients tended to have higher preoperative pulmonary arterial pressures (PAPs) 17 (11-30) mm Hg versus 12 (10-25) mm Hg, P = .10; higher pulmonary vascular resistance (PVR) 2.04 (0.27-6.94) Wood units versus 1.02 (0.49-5.20) Wood units, P = .37; and longer bypass times 154 (41-218) versus 91 (15-276) minutes, P = .13. Conclusions. Administration of iNO was associated with diminuition of cavopulmonary pressure and transpulmonary gradient and increasing oxygen saturation in our small group of patients. In our experience selected patients with preoperatively elevated PAP above 17 mm and PVR above 2 Wood units can undergo cavopulmonary operations with iNO treatment early postoperatively.

Urgent cesarean delivery and prolonged ventilatory support in a parturient with Fontan circulation and undiagnosed pseudocholinesterase deficiency

A parturient with Fontan circulation required general anesthesia for urgent cesarean delivery and subsequent prolonged postoperative ventilation for newly-diagnosed pseudocholinesterase deficiency. Anesthetic management necessitated a thorough understanding of the hemodynamic principles of the Fontan circulation and physiologic adaptations during surgical delivery and recovery in the intensive care unit.

Pediatric pulmonary arterial hypertension: current and emerging therapeutic options

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a rare disease in neonates, infants and children that is associated with significant morbidity and mortality. An adequate understanding of the controlling pathophysiologic mechanisms is lacking and although mortality has decreased as therapeutic options have increased over the past several decades, outcomes remain unacceptable.

AREAS COVERED

This review summarizes the currently available therapies for neonates, infants and children with PAH and describes emerging therapies in the context of what is known about the underlying pathophysiology of the disease.

EXPERT OPINION

All of the currently approved PAH therapies impact one of three endothelial-based pathways: nitric oxide-guanosine-3'-5'cyclic monophosphate, prostacyclin or endothelin-1. The beneficial effects of these agents may relate to their impact on pulmonary vascular tone, and/or their antiproliferative and antithrombotic properties. Fundamental advances in PAH therapy are likely to relate to: i) a better understanding of PAH subpopulations, allowing for therapies to be better tailored to individual patients and pathophysiologic processes; and ii) therapies that promote the regression of advanced structural remodeling.

Phosphodiesterases: emerging therapeutic targets for neonatal pulmonary hypertension

Pulmonary hypertension in the neonate is associated with multiple underlying problems such as respiratory distress syndrome, meconium aspiration syndrome, congenital diaphragmatic hernia, bronchopulmonary dysplasia, sepsis, or congenital heart disease. Because of the heterogeneous group of disorders, the therapeutic approach and response often depends on the underlying disease. In many of these conditions, there is evidence that cyclic nucleotide signaling and specifically phosphodiesterases (PDEs) are disrupted. PDE inhibitors represent an emerging class of pulmonary vasodilators in adults. Studies are now under way to evaluate the utility, efficacy, and safety of such therapies in infants with pulmonary hypertension.

Current and future therapeutic options for persistent pulmonary hypertension in the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a potentially life-threatening condition that is characterized by supra-systemic pulmonary vascular resistance causing right-to-left shunting through the ductus arteriosus and/or foramen ovale, leading to a vicious cycle of hypoxemia, acidosis and further pulmonary vasoconstriction. Advances in neonatology including surfactant instillation, high-frequency ventilation, extracorporeal membrane oxygenation and, most importantly, inhaled nitric oxide (INO), have revolutionized the management of PPHN. However, given that INO does not improve oxygenation in a significant proportion (30-40%) of cases, there is an urgent need to consider other therapeutic options for PPHN. The issue is more important for developing nations with a higher PPHN-related health burden and limited resources. This article discusses the evidence about INO in term and preterm neonates in brief, and focuses mainly on the potential alternative drugs in the management of PPHN.

Postoperative use of oral sildenafil in pediatric patients with congenital heart disease

We sought to determine the efficacy of postoperative oral sildenafil therapy (OST) in pediatric patients with congenital heart disease (CHD). A retrospective review of 45 postoperative patients with CHD who received OST was performed. Patients were categorized into three groups according to clinical indications: (1) to stabilize pulmonary vascular reactivity after biventricular repair (group 1 [n = 15]), (2) to lower pulmonary vascular resistance after bidirectional cavopulmonary shunt (group 2 [n = 12]), and (3) to improve post-Fontan hemodynamics (group 3 [n = 18]). Thirty-four patients (34 of 45 [75.6%]) had received inhaled nitric oxide (iNO) while on OST. Mean pulmonary arterial pressure (mPAP), mean systemic blood pressure (mSBP), and peripheral oxygen saturation (SpO(2)) were recorded during the first 24 hours after the initiation of OST. In group 1, the baseline mPAP/mSBP ratio (0.60 +/- 0.17) decreased significantly after the second (0.46 +/- 0.14, p = 0.004) and fourth (0.50 +/- 0.18, p = 0.025) doses of OST. In group 2, baseline SpO(2) (71.0 +/- 12.3%) increased after the fourth dose (75.1 +/- 12.3%, p = 0.04) of OST, without significant changes in mPAP. In group 3, baseline mPAP (14.8 +/- 3.3 mmHg) decreased significantly after the first (13.9 +/- 2.8 mmHg, p = 0.025) and second (13.3 +/- 1.9 mmHg, p = 0.016) doses of OST, without changes in SpO(2). In thirty-one (31 of 34 [92%]) subjects, iNO was discontinued within a median of 2 days after the initiation of OST, without rebound phenomena. There were no OST-related complications. Sildenafil citrate can be used safely in postoperative pediatric patients with CHD. Benefits from OST may be manifested differently in various clinical settings.

Inhaled nitric oxide and related therapies

Children with congenital heart defects are at risk for perioperative pulmonary hypertension if they require corrective or palliative surgery in the first week of life or if they have defects associated with significant pulmonary overcirculation. In addition, children undergoing cavopulmonary connections for single ventricle lesions require low pulmonary vascular resistance for surgical success. Treatment of perioperative pulmonary hypertension with inhaled nitric oxide has become standard therapy in many centers. Related drugs that increase nitric oxide synthesis, including arginine and citrulline, have also been studied in the perioperative period. In this article, previous clinical trials of inhaled nitric oxide, intravenous arginine, and intravenous and oral citrulline in children with perioperative pulmonary hypertension or elevated pulmonary vascular resistance after a cavopulmonary connection are reviewed. In addition, recommendations are presented for each agent on the clinical use in the perioperative setting including clinical indications, assessment of clinical effect, and length of therapy.