Effects of commercial air travel on patients with pulmonary hypertension air travel and pulmonary hypertension

Symposium review: high altitude travel with pulmonary vascular disease

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension are the main precapillary forms of pulmonary hypertension (PH) summarized as pulmonary vascular diseases (PVD). PVDs are characterized by exertional dyspnoea and oxygen desaturation, and reduced quality of life and survival. Medical therapies improve life expectancy and physical performance of PVD patients, of whom many wish to participate in professional work and recreational activities including traveling to high altitude. The exposure to the hypobaric hypoxic environment of mountain regions incurs the risk of high altitude adverse events (AEHA) due to severe hypoxaemia exacerbating symptoms and further increase in pulmonary artery pressure, which may lead to right heart decompensation. Recent prospective and randomized trials show that altitude-induced hypoxaemia, pulmonary haemodynamic changes and impairment of exercise performance in PVD patients are in the range found in healthy people. The vast majority of optimally treated stable PVD patients who do not require long-term oxygen therapy at low altitude can tolerate short-term exposure to moderate altitudes up to 2500 m. PVD patients that reveal persistent severe resting hypoxaemia (S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$  <80% for >30 min) at 2500 m respond well to supplemental oxygen therapy. Although there are no accurate predictors for AEHA, PVD patients with unfavourable risk profiles at low altitude, such as higher WHO functional class, lower exercise capacity with more pronounced exercise-induced desaturation and more severely impaired haemodynamics, are at increased risk of AEHA. Therefore, doctors with experience in PVD and high-altitude medicine should counsel PVD patients before any high-altitude sojourn. This review aims to summarize recent literature and clinical recommendations about PVD patients travelling to high altitude.

Air travel in patients suffering from pulmonary hypertension-A prospective, multicentre study

The PEGASUS study is the first multicentric and prospective assessment of the safety of air travel flying in pulmonary hypertension (PH) (NCT03051763). Data of air travel from 60 patients with PH was available. No severe adverse events occurred. Nine patients self-reported mild adverse events during flight (13%), while after landing, 12 patients reported events (20%). Solely one patient (2%) had an adverse event leading to medical consultation. In patients with PH and World Health Organization functional classes II and III, air travel was safe.

Air Transportation Impact on a Late Preterm Neonate

BACKGROUND: Neonatal air transportation is a crucial means of moving critically ill or sick neonates to specialized neonatal intensive care units or medical centers for consultation, regardless of distance or geographical limits. Proper preparation and consideration of air transport can help alleviate medical emergencies and ensure safe delivery. However, crewmembers and neonates may face stress during transportation. To date, there are few studies on neonatal air transportation in Taiwan.CASE REPORT: We present the case of a late preterm neonate born with neonatal respiratory distress syndrome and polycythemia, who was also diagnosed with patent ductus arteriosus and mild pulmonary arterial hypertension on echocardiography. Due to disease progression, the neonate underwent endotracheal intubation and was subsequently transported to a medical center in Taiwan via a rotary-wing aircraft at 3 d of age. During takeoff and landing, a temporary oxygen desaturation event occurred. The physiological changes in these patients have seldom been discussed. This case emphasizes the important considerations of neonatal transport in Taiwan.DISCUSSION: The air transport process could be influenced by both the patient's medical condition and environmental factors. In preterm infants with cardiopulmonary conditions, thorough assessment is necessary for ensuring safe transportation.Li S-P, Hsu P-C, Huang C-Y, Wu P-W, Fang H-H. Air transportation impact on a late preterm neonate. Aerosp Med Hum Perform. 2024; 95(4):219-222.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare and progressive disease characterised by remodelling of the pulmonary arteries and progressive narrowing of the pulmonary vasculature. This leads to a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure and, if left untreated, to right ventricular failure and death. A correct diagnosis requires a complete work-up including right heart catheterisation performed in a specialised centre. Although our knowledge of the epidemiology, pathology and pathophysiology of the disease, as well as the development of innovative therapies, has progressed in recent decades, PAH remains a serious clinical condition. Current treatments for the disease target the three specific pathways of endothelial dysfunction that characterise PAH: the endothelin, nitric oxide and prostacyclin pathways. The current treatment algorithm is based on the assessment of severity using a multiparametric risk stratification approach at the time of diagnosis (baseline) and at regular follow-up visits. It recommends the initiation of combination therapy in PAH patients without cardiopulmonary comorbidities. The choice of therapy (dual or triple) depends on the initial severity of the condition. The main treatment goal is to achieve low-risk status. Further escalation of treatment is required if low-risk status is not achieved at subsequent follow-up assessments. In the most severe patients, who are already on maximal medical therapy, lung transplantation may be indicated. Recent advances in understanding the pathophysiology of the disease have led to the development of promising emerging therapies targeting dysfunctional pathways beyond endothelial dysfunction, including the TGF-β and PDGF pathways.

Pre-Flight Hypoxemia Challenge Testing in Bronchopulmonary Dysplasia

BACKGROUND AND OBJECTIVES

Former premature infants with bronchopulmonary dysplasia (BPD) are at risk for hypoxemia during air travel, but it is unclear until what age. We aimed to determine pass rates for high altitude simulation testing (HAST) by age in children with BPD and identify risks for failure.

METHODS

Retrospective, observational analysis of HAST in children with BPD at Boston Children's Hospital, using interval censoring to estimate the time-to-event curve of first pass. Curves were stratified by neonatal risk factors. Pass was considered lowest Spo2 ≥ 90%, or ≥94% for subjects with ongoing pulmonary hypertension (PH).

RESULTS

Ninety four HAST studies were analyzed from 63 BPD subjects; 59 studies (63%) were passed. At 3 months corrected gestational age (CGA), 50% of subjects had passed; at 6 months CGA, 67% has passed; at 12 and 18 months CGA, 72% had passed; and at 24 months CGA, 85% had passed. Neonatal factors associated with delayed time-to-pass included postnatal corticosteroid use, respiratory support at NICU discharge, and tracheostomy. BPD infants who did not require respiratory support at 36 weeks were likely to pass (91%) at 6 months CGA. At 24 months, children least likely to pass included those with a history of PH (63%) and those discharged from the NICU with oxygen or respiratory support (71%).

CONCLUSIONS

Children with BPD on respiratory support at 36 weeks should be considered for preflight hypoxemia challenges through at least 24 months CGA, and longer if they had PH or went home from NICU on respiratory support.

Allgemeine Therapie der pulmonalarteriellen Hypertonie nach den neuen Leitlinien

In den neuen Leitlinien (LL) für pulmonalarterielle Hypertonie (PAH) sind die allgemeinen Maßnahmen ein integraler Bestandteil der Behandlung der Patienten. Auch die systemischen Auswirkungen der pulmonalen Hypertonie und Rechtsherzinsuffizienz sollten angemessen berücksichtigt und behandelt werden. Im folgenden Artikel werden die in den LL genannten Maßnahmen unter Berücksichtigung des bestehenden Empfehlungsgrads und der Evidenzen beschrieben. Leider sind die meisten Allgemeinmaßnahmen, wie die Gabe von Diuretika, Sauerstoff, psychosozialer Support und Impfungen, nicht oder unzureichend in randomisierten, kontrollierten Studien untersucht worden. So haben sie zwar einen hohen I-Empfehlungsgrad, aber einen niedrigen Evidenzgrad C. Nur bei dem spezialisierten körperlichen Training liegen bislang insgesamt 7 randomisierte, kontrollierte Studien und 5 Metaanalysen vor, die eine Verbesserung der Sauerstoffaufnahme, körperlichen Belastbarkeit, der Beschwerden (WHO-Funktionsklasse), Lebensqualität und Hämodynamik nachgewiesen haben (daher neu IA-Empfehlung). Auch weitere Maßnahmen wie die Antikoagulation, Eisensubstitution und andere werden im Folgenden besprochen.

Underlying lung disease and exposure to terrestrial moderate and high altitude: personalised risk assessment

Once reserved for the fittest, worldwide altitude travel has become increasingly accessible for ageing and less fit people. As a result, more and more individuals with varying degrees of respiratory conditions wish to travel to altitude destinations. Exposure to a hypobaric hypoxic environment at altitude challenges the human body and leads to a series of physiological adaptive mechanisms. These changes, as well as general altitude related risks have been well described in healthy individuals. However, limited data are available on the risks faced by patients with pre-existing lung disease. A comprehensive literature search was conducted. First, we aimed in this review to evaluate health risks of moderate and high terrestrial altitude travel by patients with pre-existing lung disease, including chronic obstructive pulmonary disease, sleep apnoea syndrome, asthma, bullous or cystic lung disease, pulmonary hypertension and interstitial lung disease. Second, we seek to summarise for each underlying lung disease, a personalized pre-travel assessment as well as measures to prevent, monitor and mitigate worsening of underlying respiratory disease during travel.

High altitude simulation testing in patients with congenital diaphragmatic hernia

AIM OF STUDY

Congenital Diaphragmatic Hernia (CDH) is associated with lung hypoplasia and pulmonary hypertension. Many patients receive care in specialty centers requiring air travel upon discharge and for subsequent follow-up care. Premature infants can experience significant hypoxia in flight, but this has not been studied in the CDH population. This report describes our center's experience with simulated altitude testing among CDH patients.

METHODS

In a single center retrospective cohort study, CDH patients who underwent a High Altitude Simulation Test (HAST) from 2006 to 2019 were analyzed. HAST simulates increased altitude by reducing oxygen tension to an FIO2 of 0.15. Patients were tested only when flight was anticipated. Patients requiring oxygen were challenged on their baseline requirement. To pass, patients had to maintain oxygen saturation > 90%, and 94% if diagnosed with pulmonary hypertension. Supplemental oxygen was titrated as needed to achieve this goal.

RESULTS

Of twenty patients tested, only six (30%) passed on their first attempt. Ten (50%) eventually passed, after an average of 3.2 additional attempts over 1.8 years. No patient passed initially who utilized ECMO support, diaphragmatic agenesis, or had elevated right ventricular pressure on echocardiogram. All patients achieved the targeted SpO2 with supplemental oxygen.

CONCLUSION

CDH patients experience hypoxia when exposed to the simulated hypobaric nature of air travel and therefore may become hypoxic in flight, requiring oxygen supplementation. Disease severity seems to correlate with risk of in-flight hypoxia. This data suggests that CDH patients should be screened to assess their need for supplemental oxygen to ensure safe air travel.

LEVEL OF EVIDENCE

Level 4 case series.

Altitude exposure in pediatric pulmonary hypertension-are we ready for (flight) recommendations?

Patients with congenital heart disease are surviving further into adulthood and want to participate in multiple activities. This includes exposure to high altitude by air travel or recreational activities, such as hiking and skiing. However, at an altitude of about 2,500 m, the barometric environmental pressure is reduced and the partial pressure of inspired oxygen drops from 21% to 15% (hypobaric hypoxia). In physiologic response to high-altitude-related hypoxia, pulmonary vasoconstriction is induced within minutes of exposure followed by compensatory hyperventilation and increased cardiac output. Even in healthy children and adults, desaturation can be profound and lead to a significant rise in pulmonary pressure and resistance. Individuals with already increased pulmonary pressure may be placed at risk during high-altitude exposure, as compensatory mechanisms may be limited. Little is known about the physiological response and risk of developing clinically relevant events on altitude exposure in pediatric pulmonary hypertension (PAH). Current guidelines are, in the absence of clinical studies, mainly based on expert opinion. Today, healthcare professionals are increasingly faced with the question, how best to assess and advise on the safety of individuals with PAH planning air travel or an excursion to mountain areas. To fill the gap, this article summarises the current clinical knowledge on moderate to high altitude exposure in patients with different forms of pediatric PAH.

Can a patient with pulmonary hypertension travel safely by plane?

Air travel is known as the safest way of transportation. Therefore, patients with health problems prefer to travel by air; however, those with heart or lung issues, who do not have any problems under normal conditions, may experience some problems in high altitude and different environmental conditions. In this review, we have described the points to be considered during air travel in patients with pulmonary hypertension.

Orbital Fractures and Air Travel

Previous surveys indicate that the majority of clinicians recommend avoidance of air travel for a period of time following an acute orbital fracture. This advice has largely been based on the theoretical risk that in-flight pressure variation may exacerbate orbital emphysema and produce visual compromise, though no previous reviews have been conducted on the evidence underpinning this advice. The purpose of this study was, therefore, to conduct a systematic review of the literature pertaining to the safety of air travel in the setting of an acute orbital fracture. A systematic review of the OVID Medline database - and of cases referenced as providing evidence for adverse outcomes due to flying with an orbital fracture - was carried out.Two articles were identified from the literature with data specific to patients who undertook air travel following orbital fractures. A large case series identified no complications in patients exposed to both pressurized and unpressurized air travel, and only a single case report detailed an adverse outcome requiring intervention. The remainder of the articles that had previously been cited as evidence against air travel involved additional factors such as intra-ocular pathologies. There is, therefore, a paucity of evidence to support the conventional advice regarding avoidance of air travel, though clinicians should exclude the possibility of an associated intra-ocular injury, advise against nose-blowing in flight, and provide advice regarding alternative methods to the Valsalva maneuver for equalizing middle ear pressure in flight.

LEVEL OF EVIDENCE

IV.

Social and environmental risks as contributors to the clinical course of heart failure

Heart failure is a major contributor to healthcare expenditures. Many clinical risk factors for the development and exacerbation of heart failure had been reported, including diabetes, renal dysfunction, and respiratory disease. In addition to these clinical parameters, the effects of social factors, such as occupation or lifestyle, and environmental factors may have a great impact on disease development and progression of heart failure. However, the current understanding of social and environmental factors as contributors to the clinical course of heart failure is insufficient. To present the knowledge of these factors to date, this comprehensive review of the literature sought to identify the major contributors to heart failure within this context. Social factors for the risk of heart failure included occupation and lifestyle, specifically in terms of the effects of specific occupations, occupational exposure to toxicities, work style, and sleep deprivation. Socioeconomic factors focused on income and education level, social status, the neighborhood environment, and marital status. Environmental factors included traffic and noise, air pollution, and other climate factors. In addition, psychological stress and behavior traits were investigated. The development of heart failure may be closely related to these factors; therefore, these data should be summarized for the context to improve their effects on patients with heart failure. The present study reviews the literature to summarize these influences.

Commercial Air Travel for Passengers With Cardiovascular Disease: Recommendations for Less Common Conditions, Considerations for Venous Thromboembolism, and General Guidance

The accelerated growth of commercial flights has resulted in a huge upswing of air travelers over the last few decades, including passengers with a wide range of cardiovascular conditions. Notwithstanding the ongoing COVID-19 pandemic that has set back the aviation industry for the next 1-2 years, air travel is expected to rebound fully by 2024. Guidelines and evidence-based recommendations for safe air travel in this group vary, and physicians often encounter situations where opinions and assessments on fitness for flights are sought. This article aims to provide an updated suite of recommendations for the aeromedical disposition of passenger with uncommon cardiovascular conditions, such as congenital heart diseases, inflammatory cardiac conditions (endocarditis/pericarditis/myocarditis), pulmonary hypertension, and venous thromboembolism. In addition, the article also aims to provide practical general guidance for the aeromedical examiner in evaluating, preparing, and optimizing the cardiac status of the patient with cardiovascular ailments for air travel.

Assessing Patients for Air Travel

Advising patients before air travel is a frequently overlooked, but important, role of the physician, particularly primary care providers and pulmonary specialists. Although physiologic changes occur in all individuals during air travel, those with underlying pulmonary disease are at increased risk of serious complications and require a specific approach to risk stratification. We discuss the available tools for assessment of preflight risk and strategies to minimize potential harm. We also present a case discussion to illustrate our approach to assessing patients for air travel and discuss the specific conditions that should prompt a more thorough preflight workup.

Exercise-induced hypoxia predicts hypobaric hypoxia during flight in patients after Fontan operation

BACKGROUND

Hypobaric hypoxia (HH) during flight might be more detrimental to pulmonary circulation in Fontan patients compared healthy individuals. This study was designed to clarify whether exercise-induced hypoxia could predict HH during flight in Fontan patients.

METHODS AND RESULTS

Percutaneous oxygen saturation (SpO₂) was analyzed during flight in 11 Fontan patients and eight volunteers. SpO₂ was measured before taking off (S1), at the initial (S2), the end of stabilization (S3), and after landing (S4). The SpO₂-dynamics were compared with SpO₂-dynamics during cardiopulmonary exercise testing (CPX), pulmonary function, and hemodynamics in the Fontan patients. At all measurements, SpO₂ was lower in the Fontan patients than the volunteers during flight. The total SpO₂ decline from S1 to S3 was greater in the Fontan patients than the volunteers. While SpO₂ change from S2 to S3 was negative in the Fontan patients, it was stable in the volunteers. In the Fontan patients, the median value of exercise-induced SpO₂ decline (Ex-dSpO₂), SpO₂ at rest, and SpO₂ at peak was -6%, 93%, and 88%, respectively. In addition to exercise capacity and pulmonary function, the Ex-dSpO₂ was correlated strongly with SpO₂ at all phases during flight (r = 0.75-0.98, p < 0.01 for all). Flight-associated adverse events occurred in two patients with SpO₂ < 80% at S3.

CONCLUSIONS

Both the Fontan patients and the volunteers demonstrated similar SpO₂-dynamics during flight with a greater HH in the Fontan patients. CPX with SpO₂ monitoring is useful in predicting SpO₂-dynamics and adverse events during flight in these patients.

Exertion during a hypoxia altitude simulation test helps identify potential cardiac decompensation

A 64-year-old female with a history of chronic thromboembolic pulmonary arterial hypertension (CTEPH), moderate airway obstruction (forced expiratory volume in 1 second (FEV1) 58% predicted), and resting oxygen saturation below the normal range (SaO2 94%) underwent a hypoxic challenge test (HCT) to determine suitability for long-haul air travel. The HCT showed only a mild decrease in SaO2 (89% at 0.15 fraction of inspired oxygen (FIO2)) at rest. However, a HCT coupled with mild exercise at two metabolic equivalents demonstrated significant hypoxia (SpO2 77%) with worsening right ventricular impairment and an inability to increase cardiac output measured with echocardiography. The case highlights the importance of the evaluating cardiac and pulmonary reserve during hypoxic stress. Resting measures alone may not identify risk, and the addition of an exercise component was essential in this case.

Acute hemodynamic changes by breathing hypoxic and hyperoxic gas mixtures in pulmonary arterial and chronic thromboembolic pulmonary hypertension

BACKGROUND

There is insufficient evidence to counsel patients with pulmonary hypertension undergoing altitude or air travel. We thus aimed to study hemodynamic response of patients with pulmonary arterial or chronic thromboembolic pulmonary hypertension (PAH/CTEPH) during changes in inspiratory oxygen partial pressure.

METHODS AND RESULTS

Consecutive patients undergoing right heart catheterization had hemodynamic assessments whilst breathing ambient air (normoxia, FiO₂ 0.21, at altitude 490 m), nitrogen-enriched air (hypoxia, FiO₂ 0.16, simulated altitude 2600 m) and oxygen (hyperoxia, FiO₂ 1.0), each for 10 min. Data from patients with PAH/CTEPH with mean pulmonary artery pressure (mPAP) ≥25 mmHg, pulmonary artery wedge pressure ≤15 mmHg, were compared to data from controls, mPAP <20 mmHg. 28 PAH/CTEPH-patients, 15 women, median age (quartiles) 62y (49;73), mPAP 35 mmHg (31;44), PaO₂ 7.1 kPa (6.8;9.3) and 16 controls, 12 women, 60y (52;69), mPAP 18 mmHg (16;18), PaO₂ 9.5 kPa (8.5;10.6) were included. Hypoxia reduced the PaO₂ in PAH/CTEPH-patients by median of 2.3 kPa, in controls by 3.3 kPa, difference (95%CI) in change 1.0 (0.02 to 1.9), p < 0.05. Corresponding changes in pulmonary vascular resistance, mPAP and cardiac output were nonsignificant in both groups. Hyperoxia decreased mPAP in PAH/CTEPH-patients by 4 mmHg (2 to 6), in controls by 2 mmHg (0 to 3), difference in change 3 mmHg (0 to 5), p < 0.05.

CONCLUSIONS

In patients with PAH/CTEPH, very short-term exposure to moderate hypoxia similar to 2600 m altitude or during commercial air travel did not deteriorate hemodynamics. These results encourage studying the response of PAH/CTEPH during daytrips to the mountain or air travel.

Fitness to fly in the paediatric population, how to assess and advice

The number of children on commercial aircrafts is rising steeply and poses a need for their treating physicians to be aware of the physiologic effects and risks of air travel. The most important risk factors while flying are a decrease in partial oxygen pressure, expansion of trapped air volume, low cabin humidity, immobility, recirculation of air and limited options for medical emergencies. Because on-board medical emergencies mostly concern exacerbations of chronic disease, the medical history, stability of current disease and previous flight experience should be assessed before flight. If necessary, hypoxia altitude simulation testing can be performed to simulate the effects of in-flight hypoxia. Although the literature on paediatric safety of air travel is sparse, recommendations for many different situations can be given.

CONCLUSION

We present an overview of the most up to date recommendations to ensure the safety of children during flight. What is Known: • Around 65% of on-board medical emergencies are complications of underlying disease. • In children, the three most common emergencies during flight concern respiratory, neurological and infectious disease. What is New: • Although studies are scarce, some advices to ensure safe air travel can be given for most underlying medical conditions in children, based on physiology, studies in adults and expert opinions. • In former preterm infants without chronic lung disease, hypoxia altitude simulation testing to rule out in-flight desaturation is not recommended.

Effect of hypoxia and hyperoxia on exercise performance in healthy individuals and in patients with pulmonary hypertension: a systematic review

Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension (PH), exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange, and, presumably, these limitations are more pronounced at altitude. In studies performed near sea level in healthy subjects, as well as in patients with PH, maximal performance during progressive ramp exercise and endurance of submaximal constant-load exercise were substantially enhanced by breathing oxygen-enriched air. Both in healthy individuals and in PH patients, these improvements were mediated by a better arterial, muscular, and cerebral oxygenation, along with a reduced sympathetic excitation, as suggested by the reduced heart rate and alveolar ventilation at submaximal isoloads, and an improved pulmonary gas exchange efficiency, especially in patients with PH. In summary, in healthy individuals and in patients with PH, alterations in the inspiratory Po₂ by exposure to hypobaric hypoxia or normobaric hyperoxia reduce or enhance exercise performance, respectively, by modifying oxygen delivery to the muscles and the brain, by effects on cardiovascular and respiratory control, and by alterations in pulmonary gas exchange. The understanding of these physiological mechanisms helps in counselling individuals planning altitude or air travel and prescribing oxygen therapy to patients with PH.

Navigating air travel and cardiovascular concerns: Is the sky the limit?

As the population ages and our ability to care for patients with cardiac disease improves, an increasing number of passengers with cardiovascular conditions will be traveling long distances. Many have had cardiac symptoms, recent interventions, devices, or surgery. Air travel is safe for most individuals with stable cardiovascular disease. However, a thorough understanding of the physiologic changes during air travel is essential given the potential impact on cardiovascular health and the risk of complications in passengers with preexisting cardiac conditions. It is important for clinicians to be aware of the current recommendations and precautions that need to be taken before and during air travel for passengers with cardiovascular concerns.

Right heart function during simulated altitude in patients with pulmonary arterial hypertension

OBJECTIVE

Patients with pulmonary arterial hypertension (PAH) are often recommended supplemental oxygen for altitude travel due to the possible deleterious effects of hypoxia on pulmonary haemodynamics and right heart function. This includes commercial aircraft travel; however, the direct effects and potential risks are unknown.

METHODS

Doppler echocardiography and gas exchange measures were investigated in group 1 patients with PAH and healthy patients at rest breathing room air and while breathing 15.1% oxygen, at rest for 20 min and during mild exertion.

RESULTS

The 14 patients with PAH studied were clinically stable on PAH-specific therapy, with functional class II (n=11) and III (n=3) symptoms when tested. Measures of right ventricular size and function were significantly different in the PAH group at baseline as compared to 7 healthy patients (p<0.04). There was no evidence of progressive right ventricular deterioration during hypoxia at rest or under exertion. Pulmonary arterial systolic pressure (PASP) increased in both groups during hypoxia (p<0.01). PASP in hypoxia correlated strongly with baseline PASP (p<0.01). Pressure of arterial oxygen correlated with PASP in hypoxia (p<0.03) but not at baseline, with three patients with PAH experiencing significant desaturation. The duration and extent of hypoxia in this study was tolerated well despite a mild increase in symptoms of breathlessness (p<0.01).

CONCLUSIONS

Non-invasive measures of right heart function in group 1 patients with PAH on vasodilator treatment demonstrated a predictable rise in PASP during short-term simulated hypoxia that was not associated with a deterioration in right heart function.

Digital Health: Tracking Physiomes and Activity Using Wearable Biosensors Reveals Useful Health-Related Information

A new wave of portable biosensors allows frequent measurement of health-related physiology. We investigated the use of these devices to monitor human physiological changes during various activities and their role in managing health and diagnosing and analyzing disease. By recording over 250,000 daily measurements for up to 43 individuals, we found personalized circadian differences in physiological parameters, replicating previous physiological findings. Interestingly, we found striking changes in particular environments, such as airline flights (decreased peripheral capillary oxygen saturation [SpO2] and increased radiation exposure). These events are associated with physiological macro-phenotypes such as fatigue, providing a strong association between reduced pressure/oxygen and fatigue on high-altitude flights. Importantly, we combined biosensor information with frequent medical measurements and made two important observations: First, wearable devices were useful in identification of early signs of Lyme disease and inflammatory responses; we used this information to develop a personalized, activity-based normalization framework to identify abnormal physiological signals from longitudinal data for facile disease detection. Second, wearables distinguish physiological differences between insulin-sensitive and -resistant individuals. Overall, these results indicate that portable biosensors provide useful information for monitoring personal activities and physiology and are likely to play an important role in managing health and enabling affordable health care access to groups traditionally limited by socioeconomic class or remote geography.

A review of therapeutic agents for the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an uncommon, progressive and life threatening disease characterized by a proliferative vasculopathy of the small muscular pulmonary arterioles resulting in elevated pulmonary vascular resistance and eventually right ventricular failure. An increasing understanding of the pathobiology of PAH and its natural history has led to the development of numerous targeted therapies. Despite these advances there is significant progression of disease and the survival rate remains low. This article reviews the agents currently available for the medical management of PAH.

Pediatric Pulmonary Hypertension: Guidelines From the American Heart Association and American Thoracic Society

Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension.

Pharmacologic therapy for pulmonary arterial hypertension in adults: CHEST guideline and expert panel report

OBJECTIVE

Choices of pharmacologic therapies for pulmonary arterial hypertension (PAH) are ideally guided by high-level evidence. The objective of this guideline is to provide clinicians advice regarding pharmacologic therapy for adult patients with PAH as informed by available evidence.

METHODS

This guideline was based on systematic reviews of English language evidence published between 1990 and November 2013, identified using the MEDLINE and Cochrane Library databases. The strength of available evidence was graded using the Grades of Recommendations, Assessment, Development, and Evaluation methodology. Guideline recommendations, or consensus statements when available evidence was insufficient to support recommendations, were developed using a modified Delphi technique to achieve consensus.

RESULTS

Available evidence is limited in its ability to support high-level recommendations. Therefore, we drafted consensus statements to address many clinical questions regarding pharmacotherapy for patients with PAH. A total of 79 recommendations or consensus statements were adopted and graded.

CONCLUSIONS

Clinical decisions regarding pharmacotherapy for PAH should be guided by high-level recommendations when sufficient evidence is available. Absent higher level evidence, consensus statements based upon available information must be used. Further studies are needed to address the gaps in available knowledge regarding optimal pharmacotherapy for PAH.

Physiology in Medicine: Acute altitude exposure in patients with pulmonary and cardiovascular disease

Travel is more affordable and improved high-altitude airports, railways, and roads allow rapid access to altitude destinations without acclimatization. The physiology of exposure to altitude has been extensively described in healthy individuals; however, there is a paucity of data pertaining to those who have reduced reserve. This Physiology in Medicine article discusses the physiological considerations relevant to the safe travel to altitude and by commercial aircraft in patients with pulmonary and/or cardiac disease.