Management of pulmonary hypertension: physiological and pharmacological considerations for anesthesiologists

Obstructive Sleep Apnea, Obesity Hypoventilation Syndrome, and Pulmonary Hypertension: A State-of-the-Art Review

The pathophysiological interplay between sleep-disordered breathing (SDB) and pulmonary hypertension (PH) is complex and can involve a variety of mechanisms by which SDB can worsen PH. These mechanistic pathways include wide swings in intrathoracic pressure while breathing against an occluded upper airway, intermittent and/or sustained hypoxemia, acute and/or chronic hypercapnia, and obesity. In this review, we discuss how the downstream consequences of SDB can adversely impact PH, the challenges in accurately diagnosing and classifying PH in the severely obese, and review the limited literature assessing the effect of treating obesity, obstructive sleep apnea, and obesity hypoventilation syndrome on PH.

A single institution anesthetic experience with catheterization of pediatric pulmonary hypertension patients

Cardiac catheterization remains the gold standard for the diagnosis and management of pediatric pulmonary hypertension (PH). There is lack of consensus regarding optimal anesthetic and airway regimen. This retrospective study describes the anesthetic/airway experience of our single center cohort of pediatric PH patients undergoing catheterization, in which obtaining hemodynamic data during spontaneous breathing is preferential. A total of 448 catheterizations were performed in 232 patients. Of the 379 cases that began with a natural airway, 274 (72%) completed the procedure without an invasive airway, 90 (24%) received a planned invasive airway, and 15 (4%) required an unplanned invasive airway. Median age was 3.4 years (interquartile range [IQR] 0.7-9.7); the majority were either Nice Classification Group 1 (48%) or Group 3 (42%). Vasoactive medications and cardiopulmonary resuscitation were required in 14 (3.7%) and eight (2.1%) cases, respectively; there was one death. Characteristics associated with use of an invasive airway included age <1 year, Group 3, congenital heart disease, trisomy 21, prematurity, bronchopulmonary dysplasia, WHO functional class III/IV, no PH therapy at time of case, preoperative respiratory support, and having had an intervention (p < 0.05). A composite predictor of age <1 year, Group 3, prematurity, and any preoperative respiratory support was significantly associated with unplanned airway escalation (26.7% vs. 6.9%, odds ratio: 4.9, confidence interval: 1.4-17.0). This approach appears safe, with serious adverse event rates similar to previous reports despite the predominant use of natural airways. However, research is needed to further investigate the optimal anesthetic regimen and respiratory support for pediatric PH patients undergoing cardiac catheterization.

Left Ventricular Diastolic Dysfunction and Pulmonary Hypertension: Outcomes in SAVR

BACKGROUND

Severe pulmonary hypertension (PH) and left ventricular diastolic dysfunction (LVDD) are independently associated with poor outcomes in cardiac surgery. We evaluated the relationship of several measures of LVDD, PH, and hemodynamic subtypes of PH including precapillary pulmonary hypertension(pcPH) and isolated post-capillary pulmonary hypertension(ipcPH) and combined pre and post capillary pulmonary hypertension(cpcPH) capillary PH to postoperative outcomes in a cohort of patients who underwent elective isolated-AVR.

METHODS

We evaluated (n = 206) patients in our local STS database who underwent elective isolated-AVR between 2014 and 2018, with transthoracic echocardiogram (n = 177) or right heart catheterization (n = 183) within 1 year of operation (or both, n = 161). The primary outcome was a composite end point of death, prolonged ventilation, ICU readmission, and hospital stay >14 days.

RESULTS

Severe PH was associated with worse outcomes (moderate: OR, 1.1, p = 0.09; severe: OR, 1.28, p = 0.01), but degree of LVDD was not associated with worse outcomes. Across hemodynamic subtypes of PH, odds of composite outcome were similar (p = 0.89), however, patients with cpcPH had more postoperative complications (67 vs. 36%, p = 0.06) and patients with ipcPH had greater all-cause mortality at 1 (8 vs. 1%, p = 0.03) and 3 years (27 vs. 4%, p = 0.008).

CONCLUSION

Severe PH conferred modestly greater risk of adverse events, and both LVDD grade and the combination of severe PH and LVDD were not associated with worse outcomes. However, hemodynamic stratification of PH revealed higher postoperative complications and worse long-term outcomes for those with cpcPH and ipcPH. Preoperative stratification of PH by hemodynamic subtype in valve replacement surgery may improve our risk stratification in this heterogenous condition. Further evaluation of the significance of LVDD and PH in other cardiac operations is warranted.

Vasoplegic syndrome in patients undergoing heart transplantation

Objectives

To summarize the risk factors, onset time, and treatment of vasoplegic syndrome in patients undergoing heart transplantation.

Methods

The PubMed, OVID, CNKI, VIP, and WANFANG databases were searched using the terms "vasoplegic syndrome," "vasoplegia," "vasodilatory shock," and "heart transplant*," to identify eligible studies. Data on patient characteristics, vasoplegic syndrome manifestation, perioperative management, and clinical outcomes were extracted and analyzed.

Results

Nine studies enrolling 12 patients (aged from 7 to 69 years) were included. Nine (75%) patients had nonischemic cardiomyopathy, and three (25%) patients had ischemic cardiomyopathy. The onset time of vasoplegic syndrome varied from intraoperatively to 2 weeks postoperatively. Nine (75%) patients developed various complications. All patients were insensitive to vasoactive agents.

Conclusions

Vasoplegic syndrome can occur at any time during the perioperative period of heart tranplantation, especially after the discontinuation of bypass. Methylene blue, angiotensin II, ascorbic acid, and hydroxocobalamin have been used to treat refractory vasoplegic syndrome.

Pulmonary hypertension associated with cardiopulmonary bypass and cardiac surgery

BACKGROUND AND AIM

Pulmonary hypertension (PH) is frequently associated with cardiovascular surgery and is a common complication that has been observed after surgery utilizing cardiopulmonary bypass (CPB). The purpose of this review is to explain the characteristics of PH, the mechanisms of PH induced by cardiac surgery and CPB, treatments for postoperative PH, and future directions in treating PH induced by cardiac surgery and CPB using up-to-date findings.

METHODS

The PubMed database was utilized to find published articles.

RESULTS

There are many mechanisms that contribute to PH after cardiac surgery and CPB which involve pulmonary vasomotor dysfunction, cyclooxygenase, the thromboxane A2 and prostacyclin pathway, the nitric oxide pathway, inflammation, and oxidative stress. Furthermore, there are several effective treatments for postoperative PH within different types of cardiac surgery.

CONCLUSIONS

By possessing a deep understanding of the mechanisms that contribute to PH after cardiac surgery and CPB, researchers can develop treatments for clinicians to use which target the mechanisms of PH and ultimately reduce and/or eliminate postoperative PH. Additionally, learning about the most up-to-date studies regarding treatments can allow clinicians to choose the best treatments for patients who are undergoing cardiac surgery and CPB.

Preoperative 2D-echocardiographic assessment of pulmonary arterial pressure in subgroups of liver transplantation recipients

BACKGROUND

The clinical efficacy of preoperative 2D-echocardiographic assessment of pulmonary arterial pressure (PAP) has not been evaluated fully in liver transplantation (LT) recipients.

METHODS

From October 2010 to February 2017, a total of 344 LT recipients who underwent preoperative 2D-echocardiography and intraoperative right heart catheterization (RHC) was enrolled and stratified according to etiology, disease progression, and clinical setting. The correlation of right ventricular systolic pressure (RVSP) on preoperative 2D-echocardiography with mean and systolic PAP on intraoperative RHC was evaluated, and the predictive value of RVSP > 50 mmHg to identify mean PAP > 35 mmHg was estimated.

RESULTS

In the overall population, significant but weak correlations were observed (R = 0.27; P < 0.001 for systolic PAP, R = 0.24; P < 0.001 for mean PAP). The positive and negative predictive values of RVSP > 50 mmHg identifying mean PAP > 35 mmHg were 37.5% and 49.9%, respectively. In the subgroup analyses, correlations were not significant in recipients of deceased donor type LT (R = 0.129; P = 0.224 for systolic PAP, R = 0.163; P = 0.126 for mean PAP) or in recipients with poorly controlled ascites (R = 0.215; P = 0.072 for systolic PAP, R = 0.21; P = 0.079 for mean PAP).

CONCLUSIONS

In LT recipients, the correlation between RVSP on preoperative 2D-echocardiography and PAP on intraoperative RHC was weak; thus, preoperative 2D-echocardiography might not be the optimal tool for predicting intraoperative PAP. In LT candidates at risk of pulmonary hypertension, RHC should be considered.

Perioperative right ventricular function and dysfunction in adult cardiac surgery-focused review (part 1-anatomy, pathophysiology, and diagnosis)

Right ventricle (RV) dysfunction and failure are now increasingly recognized as an important cause of perioperative morbidity and mortality after cardiac surgery. Although RV dysfunction is common, RV failure is very rare (0.1%) after routine cardiac surgery. However, it occurs in 3% of patients after heart transplantation and in up to 30% of patients after left ventricular assist device implantation. Significant RV failure after cardiac surgery has high mortality. Knowledge of RV anatomy and physiology are important for understanding RV dysfunction and failure. Echocardiography and haemodynamic monitoring are the mainstays in the diagnosis of RV dysfunction and failure. While detailed echocardiography assessment of right heart function has been extensively studied and validated in the elective setting, gross estimation of RV chamber size, function, and some easily obtained quantitative parameters on transesophageal echocardiography are useful in the perioperative setting. However, detailed knowledge of echocardiography parameters is still useful in understanding the differences in contractile pattern, ventriculo-arterial coupling, and interventricular dependence that ensue after open cardiac surgery.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12055-021-01240-y.

Risk factors associated with pulmonary hypertension in obesity hypoventilation syndrome

STUDY OBJECTIVES

Pulmonary hypertension (PH) is prevalent in obesity hypoventilation syndrome (OHS). However, there is a paucity of data assessing pathogenic factors associated with PH. Our objective is to assess risk factors that may be involved in the pathogenesis of PH in untreated OHS.

METHODS

In a post-hoc analysis of the Pickwick trial, we performed a bivariate analysis of baseline characteristics between patients with and without PH. Variables with a p value ≤0.10 were defined as potential risk factors and were grouped by theoretical pathogenic mechanisms in several adjusted models. Similar analysis was carried out for the two OHS phenotypes, with and without severe concomitant obstructive sleep apnea (OSA).

RESULTS

Of 246 patients with OHS, 122 (50%) had echocardiographic evidence of PH defined as systolic pulmonary artery pressure ≥40 mmHg. Lower levels of awake PaO₂ and higher body mass index (BMI) were independent risk factors in the multivariate model, with a negative and positive adjusted linear association, respectively (adjusted odds ratio 0.96; 95% CI 0.93 to 0.98; p = 0.003 for PaO₂, and 1.07; 95% CI 1.03 to 1.12; p = 0.001 for BMI). In separate analyses, BMI and PaO₂ were independent risk factors in the severe OSA phenotype, whereas BMI and peak in-flow velocity in early (E)/late diastole (A) ratio were independent risk factors in the non-severe OSA phenotype.

CONCLUSIONS

This study identifies obesity per se as a major independent risk factor for PH, regardless of OHS phenotype. Therapeutic interventions targeting weight loss may play a critical role in improving PH in this patient population.

CLINICAL TRIALS REGISTRATION

Registry: Clinicaltrial.gov; Identifier: NCT01405976.

Periprocedural safety and outcome after pump implantation for intravenous treprostinil administration in patients with pulmonary arterial hypertension

Methods

In this retrospective observational study, we analyzed all patients with pulmonary arterial hypertension undergoing LenusPro® pump implantation between November 2013 and October 2019 at our center. Periprocedural safety was assessed by describing all complications that occurred within 28 days after surgery; complications that occurred later were described to assess long-term safety. Clinical outcomes were measured by comparison of clinical parameters and echocardiographic measurements of right ventricular function from baseline to 6-months-follow-up.

Results

Fifty-four patients underwent LenusPro® pump implantation for intravenous treprostinil treatment during the investigation period. Periprocedural complications occurred in 5 patients; the only anesthesia-related complication (right heart failure with recovery after prolonged intensive care and death in the further course) occurred in the only patient who underwent general anesthesia. All other patients underwent local anesthesia with or without short-acting (analgo-) sedation. Eighteen long-term complications occurred in 15 patients, most notably pump pocket or catheter related problems. Transplant-free survival rates at 1, 2, and 3 years were 77 %, 56 %, and 48 %, respectively.

Conclusions

Subcutaneous pump implantation under local anesthesia and conscious analgosedation while avoiding intubation and mechanical ventilation is feasible in patients with advanced PAH. Controlled studies are needed to determine the safest anesthetic approach for this procedure.

Background/Objectives

Intravenous treprostinil treatment via a fully implantable pump is a treatment option for patients with advanced pulmonary arterial hypertension. However, there is no consensus on the preferred anesthetic approach for the implantation procedure. Primary objective was to assess periprocedural safety with particular attention to feasibility of local anesthesia and conscious analgosedation instead of general anesthesia. Long-term safety and clinical outcomes were secondary endpoints.

Inhaled versus intravenous milrinone in mitral stenosis with pulmonary hypertension

OBJECTIVE

To evaluate and compare the hemodynamic effects of intraoperative intravenous milrinone versus inhalational milrinone at two timepoints in patients with severe pulmonary hypertension undergoing mitral valve surgery.

METHODS

A prospective observational study was performed in 100 patients with severe rheumatic mitral stenosis (with/without regurgitation) and right ventricular systolic pressure > 50 mm Hg. They were divided into two groups based on the strategy used to reduce pulmonary hypertension. Fifty patients had inhalational milrinone after sternotomy until initiation of cardiopulmonary bypass and after release of the aortic crossclamp until weaning off cardiopulmonary bypass. The other 50 patients received an intravenous loading dose of milrinone 50 µg·kg^-1 over 10 min on release of the aortic crossclamp. Both groups received intravenous milrinone 0.5 µg·kg^-1 during weaning from cardiopulmonary bypass. Hemodynamic data were evaluated at the 3 timepoints.

RESULTS

Pulmonary artery pressures, central venous pressure, and pulmonary capillary wedge pressure decreased significantly in the inhalational milrinone group compared to the intravenous milrinone group. Systemic vascular resistance index and cardiac index were significantly higher and pulmonary vascular resistance index was significantly lower in the inhalational milrinone group. The mean arterial pressure-to-mean pulmonary artery pressure ratio was significantly lower in the intravenous milrinone group. Tricuspid annular plane systolic excursion and right ventricular fractional area change were increased significantly in the inhalational milrinone group.

CONCLUSION

Intraoperative inhalational milrinone before and after cardiopulmonary bypass is safe, easy to administer, and results in significant improvements in right ventricular hemodynamics, right ventricular function, and systemic hemodynamics.

Management of Right Ventricular Failure in Pulmonary Embolism

Acute right ventricular failure remains the leading cause of mortality associated with acute pulmonary embolism (PE). This article reviews the pathophysiology behind acute right ventricular failure and strategies for managing right ventricular failure in acute PE. Immediate clot reduction via systemic thrombolytics, catheter based procedures, or surgery is always advocated for unstable patients. While waiting to mobilize these resources, it often becomes necessary to support the RV with vasoactive medications. Clinicians should carefully assess volume status and use caution with volume resuscitation. Right ventricular assist devices may have an expanding role in the future.

Noncardiac surgery in patients with a left ventricular assist device

Left ventricular assist devices are implanted in patients with chronic left heart failure refractory to maximal medical therapy. These devices were initially meant as bridge-to-transplant therapy, but with technological advances they are now also used as destination therapy. With improved survival, many patients with implanted devices need noncardiac surgery. We present three representative cases of noncardiac surgery in such patients to highlight the issues involved in their management. We also review the contemporary literature on various aspects of perioperative management. Anesthesia for noncardiac surgery in these patients was initially the domain of cardiac anesthesiologists, but with an increasing number of such patients needing surgery, general anesthesiologists are frequently tasked to provide anesthetic care. An understanding of left ventricular assist device physiology and issues unique to these patients is essential for safe management of these cases.

[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.

Efficacy of different analgesic or sedative drug therapies in pediatric patients with congenital heart disease undergoing surgery: a network meta-analysis

BACKGROUND

Surgery is an effective therapy for congenital heart disease (CHD) and the management after surgery poses challenges for the clinical workers. We performed this network meta-analysis to enhance the corresponding evidence with respect to the relative efficacy of different drug treatments applied after the CHD surgery.

METHODS

Embase and PubMed were systematically retrieved to identify all published controlled trials investigating the effectiveness of drugs for patients up to 25 August, 2018. Mean differences (MD), odds ratios and their 95% credible intervals (CrIs) were used to evaluate multi-aspect comparisons. Surface under cumulative ranking curve (SUCRA) was used to analyze the relative ranking of different treatments in each endpoint.

RESULTS

Compared to saline, all the drugs achieved better preference under the efficacy endpoints except fentanyl in JET. As for ventilator time, all drugs were more effective than saline while only the difference of dexmedetomidine was statistically obvious (MD = 6.92, 95% CrIs 1.77-12.54). Under the endpoint of ICU time, dexmedetomidine was superior to saline as well (MD = 1.26, 95% CrIs 0.11-2.45). When all the endpoints were taken into consideration and with the help of ranking probabilities and SUCRA values, fentanyl combined with dexmedetomidine was one of the recommended drugs due to its shorter time on ventilator and stay in hospital as well as lower mortality.

CONCLUSIONS

Overall, based on the comprehensive consideration of all the endpoints, fentanyl combined with dexmedetomidine was considered to be the best-recommended clinical interventions among all the methods.

Adaptation to acute pulmonary hypertension in pigs

The extent of right ventricular compensation compared to the left ventricle is restricted and varies among individuals, which makes it difficult to define. While establishing a model of acute pulmonary hypertension in pigs we observed two different kinds of compensation in our animals. Looking deeper into the hemodynamic data we tried to delineate why some animals could compensate and others could not. Pulmonary hypertension (mean pressure 45 mmHg) was induced gradually by infusion of a stable thromboxane A₂ analogue U46619 in a porcine model (n = 22). Hemodynamic data (pressure‐volume loops, strain‐analysis of echocardiographic data and coronary flow measurements) were evaluated retrospectively for the short‐term right ventricular compensatory mechanisms and limits (Roehl et al. [2012] Acta Anaesthesiol. Scand., 56:449–58) 10 animals showed stable arterial blood pressures, whereas 12 pigs exhibited a significant drop of 16.4 ± 9.9 mmHg. Cardiac output and heart rate were comparable in both groups. In contrast, right ventricular contractility and coronary flow only rose in the stable group. The unchanging values in the decrease group correlated with an increasing ST‐segment depression and a loss of ventricular synchronism and resulted in a larger septum bulging to the right ventricle. Simultaneously, a reduced left‐ventricular end‐diastolic volume and a missing improvement in contractility in the posterior septal and inferior free wall of the left ventricle have been observed. Our findings suggest that right ventricular compensation during acute pulmonary hypertension is strongly dependent on the individual capability to increase coronary flow. The cause for inter‐individual variability could be the dimension and reactivity of the coronary system.

Spectrum of postoperative complications in pulmonary hypertension and obesity hypoventilation syndrome

PURPOSE OF REVIEW

The purpose of this review is to identify chronic pulmonary conditions which may often not be recognized preoperatively especially before elective noncardiac surgery and which carry the highest risk of perioperative morbidity and mortality.

RECENT FINDINGS

This review discusses some of the most recent studies that highlight the perioperative complications, and their prevention and management strategies.

SUMMARY

Pulmonary hypertension is a well recognized risk factor for postoperative complications after cardiac surgery but the literature surrounding noncardiac surgery is sparse. Pulmonary hypertension was only recently classified as an independent risk factor for postoperative complications in the American Heart Association/American College of Cardiology Foundation Practice Guideline for noncardiac surgery. Spinal anesthesia should be avoided in most surgeries on patients with pulmonary hypertension because of it's rapid sympatholytic effects. The presence of significant right ventricle dysfunction and marked hypoxemia should prompt re-evaluation of the need for elective surgery. Obesity hypoventilation syndrome is even harder to recognize preoperatively as arterial blood gases are generally not obtained prior to elective noncardiac surgery. Amongst patients with obstructive sleep apnea this group of patients carries much higher risk of postoperative respiratory and congestive heart failure.

Perioperative Considerations for Patients Diagnosed With Pulmonary Hypertension Undergoing Noncardiac Surgery

The prevalence of pulmonary hypertension (PH) has risen in adults of all races, genders, and ethnicities. PH is a fatal disease that presents many challenges to the perioperative health care team. Through increased knowledge of PH pathophysiological changes and anesthesia medications' effect on PH, perioperative health care teams can conduct a detailed preoperative evaluation to determine appropriate therapies to administer. This will assist the perioperative health care team in reducing the pulmonary vascular resistance, optimizing the matching of right ventricle and pulmonary circulations, and reduce the incidence of intraoperative and postoperative complications.

Pulmonary Circulation Transvascular Fluid Fluxes Do Not Change during General Anesthesia in Dogs

General anesthesia (GA) can cause abnormal lung fluid redistribution. Pulmonary circulation transvascular fluid fluxes (J_VA) are attributed to changes in hydrostatic forces and erythrocyte volume (EV) regulation. Despite the very low hydraulic conductance of pulmonary microvasculature it is possible that GA may affect hydrostatic forces through changes in pulmonary vascular resistance (PVR), and EV through alteration of erythrocyte transmembrane ion fluxes (_ionJ_VA). Furosemide (Fur) was also used because of its potential to affect pulmonary hydrostatic forces and _ionJ_VA. A hypothesis was tested that J_VA, with or without furosemide treatment, will not change with time during GA. Twenty dogs that underwent castration/ovariectomy were randomly assigned to Fur (n = 10) (4 mg/kg IV) or placebo treated group (Con, n = 10). Baseline arterial (BL) and mixed venous blood were sampled during GA just before treatment with Fur or placebo and then at 15, 30 and 45 min post-treatment. Cardiac output (Q) and pulmonary artery pressure (P_AP) were measured. J_VA and _ionJ_VA were calculated from changes in plasma protein, hemoglobin, hematocrit, plasma and whole blood ions, and Q. Variables were analyzed using random intercept mixed model (P < 0.05). Data are expressed as means ± SE. Furosemide caused a significant volume depletion as evident from changes in plasma protein and hematocrit (P < 0.001). However; Q, P_AP, and J_VA were not affected by time or Fur, whereas erythrocyte fluid flux was affected by Fur (P = 0.03). Furosemide also affected erythrocyte transmembrane K⁺ and Cl⁻, and transvascular Cl⁻ metabolism (P ≤ 0.05). No other erythrocyte transmembrane or transvascular ion fluxes were affected by time of GA or Fur. Our hypothesis was verified as J_VA was not affected by GA or ion metabolism changes due to Fur treatment. Furosemide and 45 min of GA did not cause significant hydrostatic changes based on Q and P_AP. Inhibition of Na⁺/K⁺/2Cl⁻ cotransport caused by Fur treatment, which can alter EV regulation and J_VA, was offset by the Jacobs Stewart cycle. The results of this study indicate that the Jacobs Stewart cycle/erythrocyte Cl⁻ metabolism can also act as a safety factor for the stability of lung fluid redistribution preserving optimal diffusion distance across the blood gas barrier.

Perioperative events in children with pulmonary hypertension undergoing non-cardiac procedures

Prior limited research indicates that children with pulmonary hypertension (PH) have higher rates of adverse perioperative outcomes when undergoing non-cardiac procedures and cardiac catheterizations. We examined a single-center retrospective cohort of children with active or pharmacologically controlled PH who underwent cardiac catheterization or non-cardiac surgery during 2006–2014. Preoperative characteristics and perioperative courses were examined to determine relationships between the severity or etiology of PH, type of procedure, and occurrence of major and minor events. We identified 77 patients who underwent 148 procedures at a median age of six months. The most common PH etiologies were bronchopulmonary dysplasia (46.7%), congenital heart disease (29.9%), and congenital diaphragmatic hernia (14.3%). Cardiac catheterizations (39.2%), and abdominal (29.1%) and central venous access (8.9%) were the most common procedures. Major events included failed planned extubation (5.6%), postoperative cardiac arrest (4.7%), induction or intraoperative cardiac arrest (2%), and postoperative death (1.4%). Major events were more frequent in patients with severe baseline PH (P = 0.006) and the incidence was associated with procedure type (P = 0.05). Preoperative inhaled nitric oxide and prostacyclin analog therapies were associated with decreased incidence of minor events (odds ratio [OR] = 0.32, P = 0.046 and OR = 0.24, P = 0.008, respectively), but no change in the incidence of major events. PH etiology was not associated with events (P = 0.24). Children with PH have increased risk of perioperative complications; cardiac arrest and death occur more frequently in patients with severe PH and those undergoing thoracic procedures. Risk may be modified by using preoperative pulmonary vasodilator therapy and lends itself to further prospective studies.

Pulmonary Vasodilators and Anesthesia Considerations

Pulmonary hypertension (PH) is a complex disease process of the pulmonary vasculature system characterized by elevated pulmonary arterial pressures. Patients with PH are at increased risk for morbidity and mortality, including intraoperatively and postoperatively. Appreciation by the clinical anesthesiologist of the pathophysiology of PH is warranted. Careful and meticulous strategy using appropriate anesthetic medications, pulmonary vasodilator and inotropic agents, and careful fluid management all increase the likelihood of the best possible outcome in this challenging patient population.

Management of Pulmonary Hypertension in the Operating Room

Pulmonary artery hypertension is defined as persistent elevation of mean pulmonary artery pressure > 25 mm Hg with pulmonary capillary wedge pressure < 15 mm Hg or elevation of exercise mean pulmonary artery pressure > 35 mm Hg. Although mild pulmonary hypertension rarely impacts anesthetic management, severe pulmonary hypertension and exacerbation of moderate hypertension can lead to acute right ventricular failure and cardiogenic shock. Knowledge of anesthetic drug effects on the pulmonary circulation is essential for anesthesiologists. Intraoperative management should include prevention of exacerbating factors such as hypoxemia, hypercarbia, acidosis, hypothermia, hypervolemia, and increased intrathoracic pressure; monitoring and optimizing right ventricular function; and treatment with selective pulmonary vasodilators. Recent advances in pharmacology provide anesthesiologists with a wide variety of options for selective pulmonary vasodilatation. Pulmonary hypertension is a major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement.

The internal mammary artery as a shunt in a noncyanotic infant with hemitruncus: surgical and anesthetic management

The internal mammary artery (IMA) has been used as a systemic-to-pulmonary artery shunt in selected patients with congenital heart disease. Growth and development of hypoplastic pulmonary arteries have been described. We discuss the surgical and anesthetic management of an infant with an atretic-thrombosed right pulmonary artery originating from the ascending aorta in whom the IMA was used to create a systemic-to-pulmonary artery shunt after failure of a previous shunt and later successful pulmonary artery reconstruction. The IMA should be considered as an alternative conduit in patients requiring a systemic-to-pulmonary artery shunt for growth of pulmonary arteries.

A Practical Clinical Approach to the Diagnosis and Treatment of Patients with Pulmonary Hypertension

Pulmonary hypertension is defined by a mean pulmonary artery pressure of >25 mmHg at rest or 30 mmHg during exercise. There are many causes and currently diseases causing the condition are classified into five groups. The greatest elevation in pulmonary arterial pressure is found among those disorders in group 1 (known as pulmonary arterial hypertension [PAH]) and research and targeted therapy has focused on this group in particular, although patients in group 4 (chronic thromboembolic PH [CTEPH]) also receive advanced pulmonary vasodilator therapy. The symptoms of PH are often vague and the diagnosis is frequently missed or delayed. Efforts are therefore being made to improve awareness of PH among clinicians to enable prompt referral to a PH unit to confirm the diagnosis and instigate appropriate therapy. Multi-disciplinary team (MDT) discussion is necessary if patients with PH require surgical intervention or become pregnant. For patients in the other PH groups, treatment is usually concentrated on the primary disorder. A small number of patients with PAH will respond to calcium-channel-blocking agents. Specific targeted therapy is often given in combination depending on the patients functional performance status. Available agents include phosphodiesterase type V inhibitors, endothelin receptor antagonists, prostglandin analogues and nitric oxide. Many novel agents are under review. For carefully selected patients surgical options, include lung transplantation, pulmonary thromboendarterectomy and atrial septostomy.

Pulmonary Protective Effects of Remote Ischaemic Preconditioning with Postconditioning in Patients Undergoing Cardiac Surgery Involving Cardiopulmonary Bypass: A Substudy of the Remote Ischaemic Preconditioning with Postconditioning Outcome trial

BACKGROUND

The RISPO (Remote Ischemic Preconditioning with Postconditioning Outcome) trial evaluated whether remote ischaemic preconditioning (RIPC) combined with remote ischaemic postconditioning (RIPostC) improves the clinical outcomes of patients undergoing cardiac surgery. This substudy of the RISPO trial aimed to evaluate the effect of RIPC with RIPostC on pulmonary function in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

Sixty-five patients were enrolled (32: control and 33: RIPC-RIPostC). In the RIPC-RIPostC group, four cycles of 5min ischaemia and 5min reperfusion were administered before and after CPB to the upper limb. Peri-operative PaO2/FIO2 ratio, intra-operative pulmonary shunt, and dynamic and static lung compliance were determined.

RESULTS

The mean PaO2/ FIO2 was significantly higher in the RIPC-RIPostC group at 24h after surgery [290 (96) vs. 387 (137), p=0.001]. The incidence of mechanical ventilation for longer than 48h was significantly higher in the control group (23% vs. 3%, p<0.05). However, there were no significant differences in other pulmonary profiles, post-operative mechanical ventilation time, and duration of intensive care unit stay.

CONCLUSIONS

In our study, RIPC-RIPostC improved the post-operative 24h PaO2/FIO2 ratio. Remote ischaemic preconditioning-Remote ischaemic postconditioning has limited and delayed pulmonary protective effects in cardiac surgery patients with CPB.

Cardiopulmonary parameters in propofol- or thiopental-anesthetized dogs induced to pulmonary hypertension by serotonin

ABSTRACTThe cardiopulmonary changes in propofol- or thiopental-anesthetized dogs induced to pulmonary hypertension (PH) were evaluated. Twenty adult animals were randomly assigned to two groups: propofol group (PG) and thiopental group (TG). In PG, propofol was used for induction (8(0.03mg.kg-1) and anesthesia maintenance (0.8mg.kg-1.minute-1), while, in TG, thiopental was used (22±2.92mg.kg-1; 0.5mg.kg-1.minute-1, respectively). Mechanical ventilation using time cycle was started. PH was induced by administration of serotonin (5HT) (10µg.kg-1 and 1mg.kg-1.hour-1) through a thermodilution catheter positioned in the pulmonary artery. The measurements were performed before administration of 5HT (T0), after 30 minutes (T30), then at 15-minute intervals (T45, T60, T75 and T90). No differences between groups were registered for systolic (sPAP) and mean pulmonary arterial pressure (mPAP), mean arterial pressure (MAP), total peripheral resistance index (TPRI) and pulmonary vascular resistance index (PVRI). In PG, sPAP and mPAP increased from T30. While in TG, sPAP and mPAP increased from T75. In PG, heart rate (HR) increased from T30, in which PG was higher than TG. The TPRI values decreased from T30 in PG, and in TG, at T45, T60 and T90. In PG, at T0, PVRI was lower than at other times. In PG, arterial partial pressures of oxygen (PaO2) decreased from T60 and alveolar-arterial oxygen gradient (PA-aO2) increased at T60. In TG, at T0 PaO2 was higher than at T30, T45, T60 and T90, while PA-aO2 at T0 was lower than at T90. From T30 to T90, TG showed higher PaO2 means and lower arterial partial pressures of carbon dioxide (PaCO2) values when compared to PG. In PG, from T30, PaCO2 increased, while in TG this parameter was stable. In conclusion, thiopental anesthesia attenuated the cardiopulmonary changes resulting from serotonin-induced PH, probably by attenuation of vasoconstriction and bronchoconstriction.

[Catecholamine-secreting paraganglioma in a patient with Eisenmenger syndrome and a single ventricle. Nitric oxide administration and minimally invasive haemodynamic monitoring]

Surgery for catecholamine-secreting neuroendocrine tumours poses a high anaesthetic risk that might increase due to coexisting congenital heart diseases, such as a single ventricle and Eisenmenger syndrome. This report emphasises the usefulness of pulse range haemodynamic monitoring over thermodilution in a patient with a single ventricle. In addition, the importance of nitric oxide is stressed in the management of respiratory problems associated to surgical-related pulmonary hypertension. As to the anaesthetic techniques, none is preferred as long as the one chosen has no haemodynamic repercussions.

Cardiorespiratory effects of recruitment maneuvers and positive end expiratory pressure in an experimental context of acute lung injury and pulmonary hypertension

Background

Recruitment maneuvers (RM) and positive end expiratory pressure (PEEP) are the cornerstone of the open lung strategy during ventilation, particularly during acute lung injury (ALI). However, these interventions may impact the pulmonary circulation and induce hemodynamic and respiratory effects, which in turn may be critical in case of pulmonary hypertension (PHT). We aimed to establish how ALI and PHT influence the cardiorespiratory effects of RM and PEEP.

Methods

Rabbits control or with monocrotaline-induced PHT were used. Forced oscillatory airway and tissue mechanics, effective lung volume (ELV), systemic and right ventricular hemodynamics and blood gas were assessed before and after RM, during baseline and following surfactant depletion by whole lung lavage.

Results

RM was more efficient in improving respiratory elastance and ELV in the surfactant-depleted lungs when PHT was concomitantly present. Moreover, the adverse changes in respiratory mechanics and ELV following ALI were lessened in the animals suffering from PHT.

Conclusions

During ventilation with open lung strategy, the role of PHT in conferring protection from the adverse respiratory consequences of ALI was evidenced. This finding advocates the safety of RM and PEEP in improving elastance and advancing lung reopening in the simultaneous presence of PHT and ALI.

Successful Liver Transplant Complicated by Severe Portopulmonary Hypertension After an Initial Aborted Attempt: Case Report and Review of Treatment Options

Good right ventricular function and responsiveness to vasodilator therapy are the most important prerequisites for successful liver transplant in patients with portopulmonary hypertension. A patient with portopulmonary hypertension and good right ventricular function presented for deceased-donor liver transplant. Pulmonary arterial pressure was controlled with epoprostenol and sildenafil preoperatively. After anesthesia induction, pulmonary arterial pressure increased significantly and the procedure was aborted. Additional medical treatment included aggressive vasodilator therapy and the transplant was successfully performed 1 month later. During the procedure, elevations in pulmonary arterial pressure responded to a combination of inhaled nitric oxide, intravenous milrinone and nitroglycerin, and optimization of mechanical ventilation.

A retrospective comparison of dexmedetomidine versus midazolam for pediatric patients with congenital heart disease requiring postoperative sedation

We hypothesized that postoperative sedation with dexmedetomidine/fentanyl would be effective in infants and neonates with congenital heart disease and pulmonary arterial hypertension (PAH). Children who were <36 months of age, had congenital heart disease with PAH, and had been treated at our hospital between October 2011 and April 2013 (n = 187) were included in this retrospective study. Either dexmedetomidine/fentanyl (Group Dex) or midazolam/fentanyl (Group Mid) was used for postoperative sedation. The main outcome variables included delirium scores, supplemental sedative/analgesic drugs, ventilator use, and sedation time. Baseline demographics and clinical characteristics were similar between the two groups. The Pediatric Anesthesia Emergence Delirium scale (5.2 ± 5.3 vs. 7.1 ± 5.2 in the Dex and Mid groups, respectively; P = 0.016) and the incidence of delirium (18.2 vs. 32.0 % in the Dex and Mid groups, respectively; P = 0.039) were significantly lower in the Dex group than in the Mid group. Total sufentanil, midazolam, and propofol doses given during the operation did not differ between the two groups. Group Dex patients required significantly lower doses of adjunctive sedative/analgesic drugs than group Mid patients in the cardiac intensive care unit (CICU; midazolam, P = 0.007; morphine, P < 0.001). In conclusion, we found no differences between dexmedetomidine/fentanyl and midazolam/fentanyl in terms of the duration of sedation, mechanical ventilator use, and CICU stay in children with PAH. However, patients in the Dex group required a lower additional sedative/analgesic drugs and had a lower incidence of delirium than patients in the Mid group.

Comparison of the effect of inhaled anaesthetic with intravenous anaesthetic on pulmonary vascular resistance measurement during cardiac catheterisation

BACKGROUND

Children with pulmonary hypertension routinely undergo pulmonary vascular resistance studies to assess the disease severity and vasodilator responsiveness. It is vital that results are accurate and reliable and are not influenced by the choice of anaesthetic agent. However, there are anecdotal data to suggest that propofol and inhalational agents have different effects on pulmonary vascular resistance.

METHODS

A total of 10 children with pulmonary hypertension were selected sequentially to be included in the study. To avoid confounding because of baseline anatomic or demographic details, a crossover protocol was implemented, using propofol or isoflurane, with time for washout in between each agent and blinding of the interventionalist.

RESULTS

Pulmonary and systemic vascular resistance were not significantly different when using propofol or isoflurane. However, the calculated resistance fraction - ratio of pulmonary resistance to systemic resistance - was significantly lower when using propofol than when using isoflurane.

CONCLUSIONS

Although no difference in pulmonary vascular resistance was demonstrated, this pilot study suggests that the choice of anaesthetic agent may affect the calculation of relative pulmonary and systemic vascular resistance, and provides some preliminary evidence to favour propofol over isoflurane. These findings require replication in a larger study, and thus they should be considered in future calculations to make informed decisions about the management of children with pulmonary hypertension.

Perioperative management of patients with severe pulmonary hypertension in major orthopedic surgery: experience-based recommendations

Introduction: It is known that pulmonary hypertension is associated with worse outcome in both cardiac and non-cardiac surgery. The aims of our retrospective analysis were to evaluate the outcomes of our patients with pulmonary hypertension undergoing major orthopedic surgery and to give experience-based recommendations for the perioperative management.

Material and methods: From 92 patients with pulmonary hypertension undergoing different kinds of surgical procedures from 2011–2014 in a tertiary academic hospital we evaluated 16 patients with major orthopedic surgery for perioperative morbidity and mortality.

Results: Regarding the in-hospital morbidity and mortality, one patient died postoperatively due to pulmonary infection and right heart failure (6.25%) and 6 patients suffered significant postoperative complications (37.5%; bleeding = 1, infection = 1, wound healing deficits = 3; dysrhythmia = 1).

Conclusion: Our data show that major orthopedic surgery is feasible with satisfactory outcome even in cases of severe pulmonary hypertension by an individualized, disease-adapted interdisciplinary treatment concept.

Current clinical management of pulmonary arterial hypertension

During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field.

Perioperative management of the patient with pulmonary hypertension

Patients with pulmonary hypertension are at increased risk for perioperative morbidity and mortality. Elective surgery is generally discouraged in this patient population; however, there are times when surgery is deemed necessary. Currently, there are no guidelines for the preoperative risk assessment or perioperative management of subjects with pulmonary hypertension. The majority of the literature evaluating perioperative risk factors and mortality rates is observational and includes subjects with multiple etiologies of pulmonary hypertension. Subjects with pulmonary arterial hypertension, also referred to as World Health Organization group I pulmonary hypertension, and particularly those receiving pulmonary arterial hypertension-specific therapy may be at increased risk. Perioperative management of these patients requires a solid understanding and careful consideration of the hemodynamic effects of anesthetic agents, positive pressure ventilation and volume shifts associated with surgery in order to prevent acute right ventricular failure. We reviewed the most recent data regarding perioperative morbidity and mortality for subjects with pulmonary hypertension in an effort to better guide preoperative risk assessment and perioperative management by a multidisciplinary team.

[Management of patients with pulmonary hypertension]

Due to the increased survival of patients with pulmonary hypertension, even non-cardiac anesthesiologists will see these patients more frequently for anesthesia. The hemodynamic goal in the perioperative period is to avoid an increase in pulmonary vascular resistance (PVR) and to reduce a possibly pre-existing elevated PVR. Acute increases of chronically elevated PVR may result from hypoxia, hypercapnia, acidosis, hypothermia, elevated sympathetic output and also release of endogenous or application of exogenous pulmonary vasoconstrictors. Early recognition and treatment of these changes might be life saving in these patients. Drug interventions to perioperatively reduce PVR include administration of pulmonary vasodilators, such as oxygen, prostacyclines (epoprostenol, iloprost), phosphodiesterase III (milrinone) and V (sildenafil) inhibitors, as well as nitrates and nitric oxide. Along with the concept of selective pulmonary vasodilation inhalative administration of pulmonary vasodilators has benefits compared to intravenous administration. New therapeutic strategies, such as inhalational iloprost, inhalational milrinone and intravenous sildenafil can be introduced without significant technical support even in smaller departments.