Predictors and outcomes of withholding and withdrawal of life-sustaining treatments in intensive care units in Singapore: a multicentre observational study

BACKGROUND

Clinical practice guidelines on limitation of life-sustaining treatments (LST) in the intensive care unit (ICU), in the form of withholding or withdrawal of LST, state that there is no ethical difference between the two. Such statements are not uniformly accepted worldwide, and there are few studies on LST limitation in Asia. This study aimed to evaluate the predictors and outcomes of withholding and withdrawal of LST in Singapore, focusing on the similarities and differences between the two approaches.

METHODS

This was a multicentre observational study of patients admitted to 21 adult ICUs across 9 public hospitals in Singapore over an average of three months per year from 2014 to 2019. The primary outcome measures were withholding and withdrawal of LST (cardiopulmonary resuscitation, invasive mechanical ventilation, and vasopressors/inotropes). The secondary outcome measure was hospital mortality. Multivariable generalised mixed model analysis was used to identify independent predictors for withdrawal and withholding of LST and if LST limitation predicts hospital mortality.

RESULTS

There were 8907 patients and 9723 admissions. Of the former, 80.8% had no limitation of LST, 13.0% had LST withheld, and 6.2% had LST withdrawn. Common independent predictors for withholding and withdrawal were increasing age, absence of chronic kidney dialysis, greater dependence in activities of daily living, cardiopulmonary resuscitation before ICU admission, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score, and higher level of care in the first 24 h of ICU admission. Additional predictors for withholding included being of Chinese race, the religions of Hinduism and Islam, malignancy, and chronic liver failure. The additional predictor for withdrawal was lower hospital paying class (with greater government subsidy for hospital bills). Hospital mortality in patients without LST limitation, with LST withholding, and with LST withdrawal was 10.6%, 82.1%, and 91.8%, respectively (p < 0.001). Withholding (odds ratio 13.822, 95% confidence interval 9.987-19.132) and withdrawal (odds ratio 38.319, 95% confidence interval 24.351-60.298) were both found to be independent predictors of hospital mortality on multivariable analysis.

CONCLUSIONS

Differences in the independent predictors of withholding and withdrawal of LST exist. Even after accounting for baseline characteristics, both withholding and withdrawal of LST independently predict hospital mortality. Later mortality in patients who had LST withdrawn compared to withholding suggests that the decision to withdraw may be at the point when medical futility is recognised.

Correction: Expanding the utility of the ROX index among patients with acute hypoxemic respiratory failure

[This corrects the article DOI: 10.1371/journal.pone.0261234.].

Real-world outcomes of Selexipag for treatment of pulmonary hypertension in an Asian population

Funding Acknowledgements

Type of funding sources: None.

Introduction

Selexipag is an oral selective prostacyclin IP receptor agonist indicated for treatment of pulmonary arterial hypertension (PAH). Data on its real-world safety and efficacy in Asians is lacking.

Purpose

We sought to evaluate the clinical characteristics, treatment regimens and outcomes of patients initiated on selexipag in a tertiary cardiac centre in Asia.

Methods

This was a retrospective study on all patients initiated on selexipag from January 2017 to December 2020. Baseline and follow up characteristics including demographics, functional status and clinical data were collected. Clinical outcomes evaluated included hospitalisation for PH related complications and all-cause mortality. Patients were risk stratified using the COMPERA 2.0 risk scores.

Results

A total of 36 PAH patients were treated with selexipag. At baseline, most patients were WHO functional class II or III (36.4% and 51.5% respectively), with a NT-proBNP of 1335 pg/ml (557 – 2918) and 6 minute walk test (6MWT) duration of 327.5 ±126.4 meters. Selexipag was initiated at 200mcg twice daily dosage for all except one patient (started at 200mcg once daily) and the maximum tolerated dose ranged from 200mcg twice daily to 1400mcg twice daily, with majority tolerating up to a dose of 600mcg twice daily (58.3%). Side effects were reported in 23 patients (63.9%), of which headache (27.8%), diarrhea (30.6%) or musculoskeletal symptoms (27.8%) were predominant. After a median follow up duration of 25.9 ± 23.1 months, selexipag was stopped in 20 patients (55.6%), of which eight patients were due to PAH progression requiring alternative therapy, and 12 patients due to side effects from selexipag. At baseline, patients were classified into low (8.3%), intermediate-low (30.6%), intermediate-high (33.3%) and high risk (27.8%) respectively. Patients who continued on selexipag at follow up showed no change (46.2%), improvement (15.4%) and deterioration (38.5%) in risk score. In the overall cohort of 36 patients, majority (75%) had at least one hospitalisation for PAH related complications and 15 patients (41.7%) demised.

Conclusion

In this real-world study, while selexipag was associated with a stable or improved PAH risk scores in majority of patients, there was a subset of patients with disease progression or intolerance to the medication. Further studies are warranted to identify patients who will benefit most from this therapy.

Impending spontaneous tracheal rupture due to steroid use

A spontaneous tracheal rupture is rare and life-threatening. We postulate that long-term steroid administration is an under-reported risk factor. We present a case of an impending spontaneous tracheal rupture in a 51-year-old female with a significant medical history of systemic lupus erythematosus and interstitial lung disease, and a drug history of chronic steroid intake for 9 months. An impending tracheal rupture was diagnosed by computed tomography, which prompted surgery. A right thoracotomy, followed by a posterior tracheal repair via an intercostal muscle flap, was done, with venovenous extracorporeal membrane oxygenation support throughout the operation.

Intravenous epoprostenol therapy in the treatment of pulmonary arterial hypertension: the Singapore experience

Funding Acknowledgements

Type of funding sources: None.

Background

Pulmonary arterial hypertension (PAH) is a progressive disease with significant morbidity and mortality. While intravenous (IV) Epoprostenol, a prostacyclin analogue, has been shown to improve exercise tolerance, symptoms, hemodynamics and survival, there are challenges with initiation and maintenance of this IV therapy.

Purpose

We aim to describe our local experience of the use of IV Epoprostenol in the treatment of PAH patients in Singapore, highlighting various issues and challenges.

Methods

From 2016, patients at a tertiary cardiac institution diagnosed with Group 1 PAH and remaining in intermediate to high risk class with progressive symptoms (despite being on maximum tolerable doses of PhosphoDiEsterase-5 inhibitors and Endothelin-1 receptor antagonists) were assessed and counselled for initiation of Epoprostenol therapy. With a fixed set of local protocols, comprehensive assessment and support of a multi-disciplinary team including physicians, specialist nurses and pharmacists, suitable patients were started on this treatment.

Results

A total of 12 patients (11 female, mean age 42.8 +/- 11.0 years) were included. The average New York Heart Association class of the patients initiated on Epoprostenol was II-III. The pulmonary artery pressures and pulmonary vascular resistance on right heart catheterization prior to initiation was 52.5 (IQR 47.0-54.0) mmHg and 12.6 (IQR 10.0-14.2) Woods respectively. The duration from diagnosis to time of initiating Epoprostenol was 89 (IQR 62-140) months. Epoprostenol was generally well tolerated. The most common side effect experienced was diarrhea (5/12 patients) followed by headache and musculoskeletal complains (3/12 patients each). Of the 12 patients, 6 passed away after 12 (IQR 10-16) months of Epoprostenol therapy. Of the remaining 6, PAH was diagnosed 110 (IQR 104-136) months ago and Epoprostenol therapy has been continued for 17 (IQR 14-27) months. Of those who survived, right ventricle size and PA pressures on echocardiography remained relatively stable as compared to those who passed on. 2 patients had line related infections requiring a line change 1 and 2 times respectively.

Conclusion

While not without its challenges, the establishment of concrete protocols with the support of a multidisciplinary team allows for the introduction of IV Epoprostenol as an additional potential line of effective therapy for PAH patients in Singapore.

Risk stratification and prognosis in pulmonary arterial hypertension: the Singapore experience

Funding Acknowledgements

Type of funding sources: None.

Aims & Background: Guidelines recommend the risk stratification of patients with pulmonary arterial hypertension (PAH) at baseline and on follow-up, so as to guide the management and titration of therapy in these patients.  This approach has been validated in various pulmonary hypertension registries in the West.  We aim to study the value of risk stratification on the prognosis of PAH patients in Asia.

Methods

A retrospective review of all PAH patients from 2002 to 2018 from a single tertiary cardiac centre was performed. Inclusion criteria was the availability of both initial visit and follow-up data. Patients were classified into low-, medium-, and high-risk groups in both initial and follow-up visits based on the variables in the 2015 ESC/ERS PH risk stratification table  according to the "score and average" method used by SPAHR and COMPERA registries (total score divided by number of variables assessed and rounded to nearest integer). An average score of 1, 2 and 3 was defined as low, medium and high risk respectively. The primary outcomes was all-cause mortality.

Results

 A total of 102 patients (mean age 57 ± 18 years old, 82 females) were included. Survival was significantly affected by PAH subtype and risk profile. On multivariate analysis, baseline risk did not impact on mortality. Follow-up risk stage impacted on prognosis, with significantly poorer prognosis noted in both intermediate- (adj HR 3.12, 95% CI 1.03 – 9.48, p = 0.045) and high-risk (adj HR = 7.84, 95% CI 2.22 – 27.64, p = 0.001) groups. Patients who improved their risk groups to low risk on follow-up had  similar survival to stable low-risk patients, but those patients whose risk group worsened on follow-up had significantly worse prognosis (adj HR = 5.44, 95% CI 1.26 – 13.75, p = 0.02).

Conclusion

Risk stratification is useful in prognosticating Asian PAH patients. There is potential survival benefit in optimising treatment to achieve a low-risk profile.

Expanding the utility of the ROX index among patients with acute hypoxemic respiratory failure

BACKGROUND

Delaying intubation in patients who fail high-flow nasal cannula (HFNC) may result in increased mortality. The ROX index has been validated to predict HFNC failure among pneumonia patients with acute hypoxemic respiratory failure (AHRF), but little information is available for non-pneumonia causes. In this study, we validate the ROX index among AHRF patients due to both pneumonia or non-pneumonia causes, focusing on early prediction.

METHODS

This was a retrospective observational study in eight Singapore intensive care units from 1 January 2015 to 30 September 2017. All patients >18 years who were treated with HFNC for AHRF were eligible and recruited. Clinical parameters and arterial blood gas values at HFNC initiation and one hour were recorded. HFNC failure was defined as requiring intubation post-HFNC initiation.

RESULTS

HFNC was used in 483 patients with 185 (38.3%) failing HFNC. Among pneumonia patients, the ROX index was most discriminatory in pneumonia patients one hour after HFNC initiation [AUC 0.71 (95% CI 0.64-0.79)], with a threshold value of <6.06 at one hour predicting HFNC failure (sensitivity 51%, specificity 80%, positive predictive value 61%, negative predictive value 73%). The discriminatory power remained moderate among pneumonia patients upon HFNC initiation [AUC 0.65 (95% CI 0.57-0.72)], non-pneumonia patients at HFNC initiation [AUC 0.62 (95% CI 0.55-0.69)] and one hour later [AUC 0.63 (95% CI 0.56-0.70)].

CONCLUSION

The ROX index demonstrated moderate discriminatory power among patients with either pneumonia or non-pneumonia-related AHRF at HFNC initiation and one hour later.

Association between lung compliance phenotypes and mortality in COVID-19 patients with acute respiratory distress syndrome

ABSTRACT Introduction: Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with a high mortality rate, though outcomes of the different lung compliance phenotypes are unclear. We aimed to measure lung compliance and examine other factors associated with mortality in COVID-19 patients with ARDS. Methods: Adult patients with COVID-19 ARDS who required invasive mechanical ventilation at 8 hospitals in Singapore were prospectively enrolled. Factors associated with both mortality and differences between high (<40mL/cm H2O) and low (<40mL/cm H2O) compliance were analysed. Results: A total of 102 patients with COVID-19 who required invasive mechanical ventilation were analysed; 15 (14.7%) did not survive. Non-survivors were older (median 70 years, interquartile range [IQR] 67–75 versus median 61 years, IQR 52–66; P<0.01), and required a longer duration of ventilation (26 days, IQR 12–27 vs 8 days, IQR 5–15; P<0.01) and intensive care unit support (26 days, IQR 11–30 vs 11.5 days, IQR 7–17.3; P=0.01), with a higher incidence of acute kidney injury (15 patients [100%] vs 40 patients [46%]; P<0.01). There were 67 patients who had lung compliance data; 24 (35.8%) were classified as having high compliance and 43 (64.2%) as having low compliance. Mortality was higher in patients with high compliance (33.3% vs 11.6%; P=0.03), and was associated with a drop in compliance at day 7 (-9.3mL/cm H2O (IQR -4.5 to -15.4) vs 0.2mL/cm H2O (4.7 to -5.2) P=0.04). Conclusion: COVID-19 ARDS patients with higher compliance on the day of intubation and a longitudinal decrease over time had a higher risk of death. Keywords: ARDS, COVID-19-associated respiratory failure, high-flow nasal cannula therapy, HFNC, post-intubation, ventilation strategies

High-flow nasal cannula therapy: A multicentred survey of the practices among physicians and respiratory therapists in Singapore

BACKGROUND

Use of high-flow nasal cannula (HFNC) has become a regular intervention in the intensive care units especially in patients coming in with hypoxaemic respiratory failure. Clinical practices may differ from published literature.

OBJECTIVES

The objective of this study was to determine the clinical practices of physicians and respiratory therapists (RTs) on the use of HFNC.

METHODS

A retrospective observational study looking at medical records on HFNC usage from January 2015 to September 2017 was performed and was followed by a series of questions related to HFNC practices. The survey involved physicians and RTs in intensive care units from multiple centres in Singapore from January to April 2018. Indications and thresholds for HFNC usage with titration and weaning practices were compared with the retrospective observational study data.

RESULTS

One hundred twenty-three recipients (69.9%) responded to the survey and reported postextubation (87.8%), pneumonia in nonimmunocompromised (65.9%), and pneumonia in immunocompromised (61.8%) patients as the top three indications for HFNC. Of all, 39.8% of respondents wanted to use HFNC for palliative intent. Similar practices were observed in the retrospective study with the large cohort of 63% patients (483 of the total 768 patients) where HFNC was used for acute hypoxaemic respiratory failure and 274 (35.7%) patients to facilitate extubation. The survey suggested that respondents would initiate HFNC at a lower fraction of inspired oxygen (FiO₂), higher partial pressure of oxygen to FiO₂ ratio, and higher oxygen saturation to FiO₂ ratio for nonpneumonia patients than patients with pneumonia. RTs were less likely to start HFNC for patients suffering from pneumonia and interstitial lung disease than physicians. RTs also preferred adjustment of FiO₂ to improve oxygen saturations and noninvasive ventilation for rescue.

CONCLUSIONS

Among the different intensive care units surveyed, the indications and thresholds for the initiation of HFNC differed in the clinical practices of physicians and RTs.

Managing respiratory complications in Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

In the recently published guidelines by the Society of Dermatology Hospitalists on the management of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), a brief section was included on airway management. These recommendations provide an easy reference on how to manage respiratory complications of the disease. Understanding the evidence that underlies these recommendations would offer physicians greater clarity on the considerations behind every decision and treatment offered. We present a review of the literature on respiratory manifestations associated with SJS and TEN. In addition, we aim to address specific concerns regarding the respiratory management of these patients. These include issues such as the indications and optimal timing of intubation, tracheostomy, role of flexible nasoendoscopy, bronchoscopy, ventilation strategies, and management of chronic respiratory complications.

Singapore Advanced Cardiac Life Support Guidelines 2021

Advanced cardiac life support (ACLS) emphasises the use of advanced airway management and ventilation, circulatory support and the appropriate use of drugs in resuscitation, as well as the identification of reversible causes of cardiac arrest. Extracorporeal cardiopulmonary resuscitation and organ donation, as well as special circumstances including drowning, pulmonary embolism and pregnancy are addressed. Resuscitation does not end with ACLS but must continue in post-resuscitation care. ACLS also covers the recognition and management of unstable pre-arrest tachy- and bradydysrhythmias that may deteriorate further.

Predictors and outcomes of high-flow nasal cannula failure following extubation: A multicentre observational study

INTRODUCTION

Despite adhering to criteria for extubation, up to 20% of intensive care patients require re-intubation, even with use of post-extubation high-flow nasal cannula (HFNC). This study aims to identify independent predictors and outcomes of extubation failure in patients who failed post-extubation HFNC.

METHODS

We conducted a multicentre observational study involving 9 adult intensive care units (ICUs) across 5 public hospitals in Singapore. We included patients extubated to HFNC following spontaneous breathing trials. We compared patients who were successfully weaned off HFNC with those who failed HFNC (defined as re-intubation ≤7 days following extubation). Generalised additive logistic regression analysis was used to identify independent risk factors for failed HFNC.

RESULTS

Among 244 patients (mean age: 63.92±15.51 years, 65.2% male, median APACHE II score 23.55±7.35), 41 (16.8%) failed HFNC; hypoxia, hypercapnia and excessive secretions were primary reasons. Stroke was an independent predictor of HFNC failure (odds ratio 2.48, 95% confidence interval 1.83-3.37). Failed HFNC, as compared to successful HFNC, was associated with increased median ICU length of stay (14 versus 7 days, P<0.001), ICU mortality (14.6% versus 2.0%, P<0.001) and hospital mortality (29.3% versus 12.3%, P=0.006).

CONCLUSION

Post-extubation HFNC failure, especially in patients with stroke as a comorbidity, remains a clinical challenge and predicts poorer clinical outcomes. Our observational study highlights the need for future prospective trials to better identify patients at high risk of post-extubation HFNC failure.

Clinical features and predictors of severity in COVID-19 patients with critical illness in Singapore

We aim to describe a case series of critically and non-critically ill COVID-19 patients in Singapore. This was a multicentered prospective study with clinical and laboratory details. Details for fifty uncomplicated COVID-19 patients and ten who required mechanical ventilation were collected. We compared clinical features between the groups, assessed predictors of intubation, and described ventilatory management in ICU patients. Ventilated patients were significantly older, reported more dyspnea, had elevated C-reactive protein and lactate dehydrogenase. A multivariable logistic regression model identified respiratory rate (aOR 2.83, 95% CI 1.24–6.47) and neutrophil count (aOR 2.39, 95% CI 1.34–4.26) on admission as independent predictors of intubation with area under receiver operating characteristic curve of 0.928 (95% CI 0.828–0.979). Median APACHE II score was 19 (IQR 17–22) and PaO2/FiO2 ratio before intubation was 104 (IQR 89–129). Median peak FiO2 was 0.75 (IQR 0.6–1.0), positive end-expiratory pressure 12 (IQR 10–14) and plateau pressure 22 (IQR 18–26) in the first 24 h of ventilation. Median duration of ventilation was 6.5 days (IQR 5.5–13). There were no fatalities. Most COVID-19 patients in Singapore who required mechanical ventilation because of ARDS were extubated with no mortality.

Rationale and significance of patient selection in awake prone positioning for COVID-19 pneumonia

We read with interest the research letter by Nget al. [1], which described their experience in prone positioning (PP) for awake patients with coronavirus disease 2019 (COVID-19) pneumonia, and concluded that this manoeuvre could delay or reduce the need for intensive care. We agree that the authors demonstrated safety and feasibility of PP in COVID-19 pneumonia patients. However, we humbly suggest a few crucial points be addressed before drawing conclusions on the efficacy of PP.

COVID-19 is increasingly recognised to manifest phenotypic diversity in clinical presentation, severity and trajectory. As such, treatment, e.g. awake prone positioning, should be personalised and guided by the primary pathophysiology and immunopathology.https://bit.ly/2ZneHlF

Early prediction of high flow nasal cannula therapy outcomes using a modified ROX index incorporating heart rate

Background

The ROX index (ratio of pulse oximetry/FIO₂ to respiratory rate) has been validated to predict high flow nasal cannula therapy (HFNC) outcomes in patients with pneumonia. We evaluated a modified ROX index incorporating heart rate (HR) in patients initiated on HFNC for acute hypoxemic respiratory failure and as a preventative treatment following planned extubation.

Methods

We performed a prospective observational cohort study of 145 patients treated with HFNC. ROX-HR index was defined as the ratio of ROX index over HR (beats/min), multiplied by a factor of 100. Evaluation was performed using area under the receiving operating characteristic curve (AUROC) and cutoffs assessed for prediction of HFNC failure: defined as the need for mechanical ventilation.

Results

Ninety-nine (68.3%) and 46 (31.7%) patients were initiated on HFNC for acute hypoxemic respiratory failure and following a planned extubation, respectively. The majority (86.9%) of patients had pneumonia as a primary diagnosis, and 85 (56.6%) patients were immunocompromised. Sixty-one (42.1%) patients required intubation (HFNC failure). Amongst patients on HFNC for acute respiratory failure, HFNC failure was associated with a lower ROX and ROX-HR index recorded at time points between 1 and 48 h. Within the first 12 h, both indices performed with the highest AUROC at 10 h as follows: 0.723 (95% CI 0.605–0.840) and 0.739 (95% CI 0.626–0.853) for the ROX and ROX-HR index respectively. A ROX-HR index of > 6.80 was significantly associated with a lower risk of HFNC failure (hazard ratio 0.301 (95% CI 0.143–0.663)) at 10 h. This association was also observed at 2, 6, 18, and 24h, even with correction for potential confounding factors. For HFNC initiated post-extubation, only the ROX-HR index remained significantly associated with HFNC failure at all recorded time points between 1 and 24 h. A ROX-HR > 8.00 at 10 h was significantly associated with a lower risk of HFNC failure (hazard ratio 0.176 (95% CI 0.051–0.604)).

Conclusion

While validation studies are required, the ROX-HR index appears to be a promising tool for early identification of treatment failure in patients initiated on HFNC for acute hypoxemic respiratory failure or as a preventative treatment after a planned extubation.

Potential role of statins in COVID-19

Patients with COVID-19 infection have an increased risk of cardiovascular complications and thrombotic events. Statins are known for their pleiotropic anti-inflammatory, antithrombotic and immunomodulatory effects. They may have a potential role as adjunctive therapy to mitigate endothelial dysfunction and dysregulated inflammation in patients with COVID-19 infection.

Practical Considerations for Solid Organ Transplantation During the COVID-19 Global Outbreak: The Experience from Singapore

The current coronavirus disease 2019 (COVID-19) pandemic has not only caused global social disruptions but has also put tremendous strain on healthcare systems worldwide. With all attention and significant effort diverted to containing and managing the COVID-19 outbreak (and understandably so), essential medical services such as transplant services are likely to be affected. Closure of transplant programs in an outbreak caused by a highly transmissible novel pathogen may be inevitable owing to patient safety. Yet program closure is not without harm; patients on the transplant waitlist may die before the program reopens. By adopting a tiered approach based on outbreak disease alert levels, and having hospital guidelines based on the best available evidence, life-saving transplants can still be safely performed. We performed a lung transplant and a liver transplant successfully during the COVID-19 era. We present our guidelines and experience on managing the transplant service as well as the selection and management of donors and recipients. We also discuss clinical dilemmas in the management COVID-19 in the posttransplant recipient.

Clinical Updates on the Diagnosis and Management of Chronic Thromboembolic Pulmonary Hypertension

Introduction: Chronic thromboembolic pulmonary hypertension (CTEPH) is a known sequela after acute pulmonary embolism (PE). It is a debilitating disease, and potentially fatal if left untreated. This review provides a clinically relevant overview of the disease and discusses the usefulness and limitations of the various investigational and treatment options. Methods: A PubMed search on articles relevant to pulmonary embolism, pulmonary hypertension, chronic thromboembolic pulmonary hypertension, pulmonary endarterectomy, and balloon pulmonary angioplasty were performed. A total of 68 articles were found to be relevant and were reviewed. Results: CTEPH occurs as a result of non-resolution of thrombotic material, with subsequent fibrosis and scarring of the pulmonary arteries. Risk factors have been identified, but the underlying mechanisms have yet to be fully elucidated. The cardinal symptom of CTEPH is dyspnoea on exertion, but the diagnosis is often challenging due to lack of awareness. The ventilation/perfusion scan is recommended for screening for CTEPH, with other modalities (eg. dual energy computed tomography pulmonary angiography) also being utilised in expert centres. Conventional pulmonary angiography with right heart catherisation is important in the final diagnosis of CTEPH. Conclusion: Operability assessment by a multidisciplinary team is crucial for the management of CTEPH, as pulmonary endarterectomy (PEA) remains the guideline recommended treatment and has the best chance of cure. For inoperable patients or those with residual disease post-PEA, medical therapy or balloon pulmonary angioplasty are potential treatment options. Keywords: Balloon pulmonary angioplasty, Chronic thromboembolic pulmonary hypertension, Pulmonary embolism, Pulmonary endarterectomy, Pulmonary hypertension

Clinical Updates on the Diagnosis and Management of Chronic Thromboembolic Pulmonary Hypertension

INTRODUCTION

Chronic thromboembolic pulmonary hypertension (CTEPH) is a known sequela after acute pulmonary embolism (PE). It is a debilitating disease, and potentially fatal if left untreated. This review provides a clinically relevant overview of the disease and discusses the usefulness and limitations of the various investigational and treatment options.

METHODS

A PubMed search on articles relevant to PE, pulmonary hypertension, CTEPH, pulmonary endarterectomy, and balloon pulmonary angioplasty were performed. A total of 68 articles were found to be relevant and were reviewed.

RESULTS

CTEPH occurs as a result of non-resolution of thrombotic material, with subsequent fibrosis and scarring of the pulmonary arteries. Risk factors have been identified, but the underlying mechanisms have yet to be fully elucidated. The cardinal symptom of CTEPH is dyspnoea on exertion, but the diagnosis is often challenging due to lack of awareness. The ventilation/perfusion scan is recommended for screening for CTEPH, with other modalities (eg. dual energy computed tomography pulmonary angiography) also being utilised in expert centres. Conventional pulmonary angiography with right heart catheterisation is important in the final diagnosis of CTEPH.

CONCLUSION

Operability assessment by a multidisciplinary team is crucial for the management of CTEPH, as pulmonary endarterectomy (PEA) remains the guideline recommended treatment and has the best chance of cure. For inoperable patients or those with residual disease post-PEA, medical therapy or balloon pulmonary angioplasty are potential treatment options.

Mortality and Neurological Outcomes in Out-of-Hospital Cardiac Arrest Patients With and Without Targeted Temperature Management in a Multiethnic Asian Population

INTRODUCTION

The use of targeted temperature management (TTM) is increasing although adoption is still variable. We describe our 6-year experience and compare the mortality and neurological outcomes of out-of-hospital cardiac arrest (OHCA) patients with and without the use of TTM in a multiethnic Asian population.

MATERIALS AND METHODS

We performed a retrospective observational study at a tertiary academic medical centre. OHCA survivors admitted to our hospital between April 2010‒December 2016 were included. Outcomes of interest were 30-day mortality postresuscitation, Cerebral Performance Category (CPC) and Overall Performance Category (OPC) scores.

RESULTS

A total of 121 of 261 patients (46.3%) underwent TTM. TTM patients were younger (TTM 60.0 years old vs no TTM 63.7 years old, P = 0.047). There was no difference in the initial arrest rhythm of shockable origin between the 2 groups (P = 0.289). There was suggestion of lower 30-day mortality (TTM 24.3% vs no TTM 31.4%, P = 0.214), higher and good CPC/OPC scores (TTM 19.0% vs no TTM 15.7%, P = 0.514) with TTM although this did not reach statistical significance. On multivariable logistic regression analysis, TTM was not associated with 30-day mortality (P = 0.07). However, older age, initial non-shockable rhythm and increased duration from arrest to return of spontaneous circulation were associated with increased mortality. Malay ethnicity was associated with a poorer CPC/ OPC score.

CONCLUSION

Adoption and outcomes of TTM postresuscitation is variable and there is still a need to optimise management of the identified predictors of survival and good neurological outcomes while TTM is being used.

Therapeutic temperature management (TTM): post-resuscitation care for adult cardiac arrest, with recommendations from the National TTM Workgroup

Therapeutic temperature management (TTM) was strongly recommended by the 2015 International Liaison Committee on Resuscitation as a component of post-resuscitation care. It has been known to be effective in improving the survival rate and neurologic functional outcome of patients after cardiac arrest. In an effort to increase local adoption of TTM as a standard of post-resuscitation care, this paper discusses and makes recommendations on the treatment for local providers.

Randomized controlled trial of internal and external targeted temperature management methods in post- cardiac arrest patients

BACKGROUND

Targeted temperature management post-cardiac arrest is currently implemented using various methods, broadly categorized as internal and external. This study aimed to evaluate survival-to-hospital discharge and neurological outcomes (Glasgow-Pittsburgh Score) of post-cardiac arrest patients undergoing internal cooling verses external cooling.

METHODOLOGY

A randomized controlled trial of post-resuscitation cardiac arrest patients was conducted from October 2008-September 2014. Patients were randomized to either internal or external cooling methods. Historical controls were selected matched by age and gender. Analysis using SPSS version 21.0 presented descriptive statistics and frequencies while univariate logistic regression was done using R 3.1.3.

RESULTS

23 patients were randomized to internal cooling and 22 patients to external cooling and 42 matched controls were selected. No significant difference was seen between internal and external cooling in terms of survival, neurological outcomes and complications. However in the internal cooling arm, there was lower risk of developing overcooling (p=0.01) and rebound hyperthermia (p=0.02). Compared to normothermia, internal cooling had higher survival (OR=3.36, 95% CI=(1.130, 10.412), and lower risk of developing cardiac arrhythmias (OR=0.18, 95% CI=(0.04, 0.63)). Subgroup analysis showed those with cardiac cause of arrest (OR=4.29, 95% CI=(1.26, 15.80)) and sustained ROSC (OR=5.50, 95% CI=(1.64, 20.39)) had better survival with internal cooling compared to normothermia. Cooling curves showed tighter temperature control for internal compared to external cooling.

CONCLUSION

Internal cooling showed tighter temperature control compared to external cooling. Internal cooling can potentially provide better survival-to-hospital discharge outcomes and reduce cardiac arrhythmia complications in carefully selected patients as compared to normothermia.

Pulmonary Function Test: Spirometry

Spirometry is a useful tool in assessing the physiological lung function of a patient, and can be helpful in differentiating the etiology of the patient's symptoms. Indications for the test and the actual procedure are as described. Validity of a spirometry depends on patient co-operation and criteria for acceptability and repeatability must be met for useful interpretation of the results. Commonly measured parameters are described and a simple logarithm for interpretation of a spirometry result is given. Physicians must be mindful when interpreting the result in the context of extreme of ages, size or differing ethnicity as reference values for these groups of individuals are often extrapolated and not validated.