Diaphragm Ultrasound in the Evaluation of Diaphragmatic Dysfunction in Lung Disease

The diaphragm is the most important respiratory muscle, and its function may be limited by acute and chronic diseases. A diaphragmatic ultrasound, which quantifies dysfunction through different approaches, is useful in evaluating work of breathing and diaphragm atrophy, predicting successful weaning, and diagnosing critically ill patients. This technique has been used to determine reduced diaphragmatic function in patients with chronic obstructive pulmonary disease and interstitial diseases, while in those with COVID-19, diaphragmatic ultrasound has been used to predict weaning failure from mechanical ventilation.

High Flow Nasal Cannula as Support in Immunocompromised Patients with Acute Respiratory Failure: A Retrospective Study

Introduction: High Flow Nasal Cannula (HFNC) is a novel technique for respiratory support that improves oxygenation. In some patients, it may reduce the work of breathing. In immunocompromised patients with Acute Respiratory Failure (ARF), Non-Invasive Ventilation (NIV) is the main support recommended strategy, since invasive mechanical ventilation could increase mortality rates. NIV used for more than 48 hours may be associated with increased in-hospital mortality and hospital length of stay. Therefore HFNC seems like a respiratory support alternative. Objective: To describe clinical outcomes of immunocompromised patients with ARF HFNC-supported. Methods: Retrospective study in patients admitted with ARF and HFNC-supported. 25 adult patients were included, 21 pharmacologically and 4 non- pharmacologically immunosuppressed. Median age of the patients was 64 [60-76] years, APACHE II 15 [11-19], and PaO2:FiO2 218 [165-248]. Demographic information, origin of immunosuppression, Respiratory Rate (RR), Heart Rate (HR), Mean Arterial Pressure (MAP), oxygen saturation (SpO2) and PaO2:FiO2 ratio were extracted from clinical records of our HFNC local protocol. Data acquisition was performed before and after the first 24 hours of connection. In addition, the need for greater ventilatory support after HFNC, orotracheal intubation, in-hospital mortality and 90 days out-patients’ mortality was recorded. Results: Mean RR before the connection was 25±22 breaths/min and 22±4 breaths/min after the first 24 hours of HFNC use (95% CI; p=0.02). HR mean before connection to HFNC was 96±22 beats/min, and after, it was 86±15 beats/min (95%CI; p=0.008). Previous mean MAP was 86±15 mmHg, and after HFNC, it was 80±12 mmHg (95%CI; p=0.09); mean SpO2 after was 93±5% and before it was 95±4% (95% CI; p=0.13); and previous PaO2:FiO2 mean was 219±66, and after it was 324±110 (95%CI; p=0.52). In-hospital mortality was 28% and 90 days out-patients’ mortality was 32%. Conclusion: HFNC in immunosuppressed ARF subjects significantly decreases HR and RR, being apparently an effective alternative to decrease work of breathing. In-hospital mortality in ARF immunosuppressed patients was high even though respiratory support was used. Better studies are needed to define the role of HFNC-support in ARF.

Dilated Cardiomyopathy (DCM) in an Infant Due to Primary Carnitine Deficiency (PCD); A Rare Case

Dilated cardiomyopathy (DCM) is known to have ventricular dilatation and dysfunction in myocardium. Primary carnitine deficiency (PCD) is a not common but a reversible autosomal recessive phenomenon with supplementation of carnitine. Case presentation- 11-month male child was brought with complain of fever, cough, cold since 7 days and increased work of breathing for 15 days. 2 D echo was done suggestive of dilated cardiomyopathy. His initial investigations; chest Xray revealed significant cardiomegaly electrocardiography, (ECG) showed prolonged QT interval fraction. Patient was treated with syrup carnitine syrup empirically, as there is no way to determine a fatty acid oxidation profile. Repeated 2D echocardiogram (2 D ECHO) was suggestive of recovery. Conclusions: Carnitine deficiency could be the cause of cardiomyopathy and so treatment of carnitine supplementation can be considered empirically to avoid life-threatening complication related to cardiomyopathy.

Awake prone position reduces work of breathing in patients with COVID-19 ARDS supported by CPAP

Background The use of awake prone position concomitant to non-invasive mechanical ventilation in acute respiratory distress syndrome (ARDS) secondary to COVID-19 has shown to improve gas exchange, whereas its effect on the work of breathing remain unclear. The objective of this study was to evaluate the effects of awake prone position during helmet continuous positive airway pressure (CPAP) ventilation on inspiratory effort, gas exchange and comfort of breathing. Methods Forty consecutive patients presenting with ARDS due to COVID-19 were prospectively enrolled. Gas exchange, esophageal pressure swing (ΔPes), dynamic transpulmonary pressure (dTPP), modified pressure time product (mPTP), work of breathing (WOB) and comfort of breathing, were recorded on supine position and after 3 h on prone position. Results The median applied PEEP with helmet CPAP was 10 [8–10] cmH2O. The PaO2/FiO2 was higher in prone compared to supine position (Supine: 166 [136–224] mmHg, Prone: 314 [232–398] mmHg, p < 0.001). Respiratory rate and minute ventilation decreased from supine to prone position from 20 [17–24] to 17 [15–19] b/min (p < 0.001) and from 8.6 [7.3–10.6] to 7.7 [6.6–8.6] L/min (p < 0.001), respectively. Prone position did not reduce ΔPes (Supine: − 7 [− 9 to − 5] cmH2O, Prone: − 6 [− 9 to − 5] cmH2O, p = 0.31) and dTPP (Supine: 17 [14–19] cmH2O, Prone: 16 [14–18] cmH2O, p = 0.34). Conversely, mPTP and WOB decreased from 152 [104–197] to 118 [90–150] cmH2O/min (p < 0.001) and from 146 [120–185] to 114 [95–151] cmH2O L/min (p < 0.001), respectively. Twenty-six (65%) patients experienced a reduction in WOB of more than 10%. The overall sensation of dyspnea was lower in prone position (p = 0.005). Conclusions Awake prone position with helmet CPAP enables a reduction in the work of breathing and an improvement in oxygenation in COVID-19-associated ARDS.

Paediatric pneumonia: deriving a model to identify severe disease

BackgroundCommunity-acquired pneumonia (CAP) is a leading cause of childhood hospitalisation. Limited data exist on factors predicting severe disease with no paediatric-specific predictive tools.MethodsRetrospective cohort (2011–2016) of hospitalised CAP cases. We analysed clinical variables collected at hospital presentation against outcomes. Stratified outcomes were mild (hospitalised), moderate (invasive drainage procedure, intensive care) or severe (mechanical ventilation, vasopressors, death).ResultsWe report 3330 CAP cases, median age 2.0 years (IQR 1–5 years), with 2950 (88.5%) mild, 305 (9.2%) moderate and 75 (2.3%) severe outcomes. Moderate-severe outcomes were associated with hypoxia (SaO2 <90%; OR 6.6, 95% CI 5.1 to 8.5), increased work of breathing (severe vs normal OR 5.8, 95% CI 4.2 to 8.0), comorbidities (4+ comorbidities vs nil; OR 8.8, 95% CI 5.5 to 14) and being indigenous (OR 4.7, 95% CI 2.6 to 8.4). Febrile children were less likely than afebrile children to have moderate-severe outcomes (OR 0.57 95% CI 0.44 to 0.74). The full model receiver operating characteristic (ROC) area under the curve (AUC) was 0.78. Sensitivity analyses showed similar results with clinical or radiological CAP definitions. We derived a clinical tool to stratify low, intermediate or high likelihood of severe disease (AUC 0.72). High scores (≥5) had nearly eight times higher odds of moderate-severe disease than those with a low (≤1) score (OR 7.7 95% CI 5.6 to 10.5).ConclusionsA clinical risk prediction tool is needed for child CAP. We have identified risk factors and derived a simple clinical tool using clinical variables at hospital presentation to determine a child’s risk of invasive or intensive care treatment with an ROC AUC comparable with adult pneumonia tools.

Airway luminal area and the resistive work of breathing during exercise in healthy young females and males

We examined the relationship between the work of breathing (Wb) during exercise and in vivo measures of airway size in healthy females and males. We hypothesized that sex-differences in airway luminal area (Ai) would explain the larger resistive Wb during exercise in females. Healthy participants (n=11 females and n=11 males; 19-30 y) completed a cycle exercise test to exhaustion where Wb was assessed using an esophageal balloon catheter. On a separate day, participants underwent a bronchoscopy procedure for optical coherence tomography measures of airways in the left (n=3) and right (n=4) lung. In vivo measures of Ai were made for the 4th-8th airway generations. A composite index of airway size was calculated as the sum of the Ai for each generation and the total area was calculated based on Weibel's model. We found that index of airway size (males: 37.4±6.3 mm2 vs. females: 27.5±7.4 mm2) and airway area calculated based on Weibel's model (males: 2274±557 mm2 vs. females: 1594±389 mm2) were significantly larger in males (both p=0.003). When minute ventilation was greater than ~60 l·min-1, the resistive Wb was higher in females. At the highest equivalent flow achieved by all subjects, resistance to inspired flow was larger in females and significantly associated with two measures of airway size: index of airway size (r=0.559, p=0.007) and Weibel area (r=0.541, p=0.009). Our findings suggest that innate sex-differences in Ai result in a greater resistive Wb during exercise in females compared to males.

Integrated oxygen therapy consisting of non invasive ventilation and nasal cannulae in respiratory failure secondary to COVID-19 pneumonia: Case series

Patients with moderate to severe COVID-19 disease develop hypoxemic respiratory failure demonstrating profound degrees of hypoxia with little or no distress. This has put the conventional management consisting of an early intubation in question. In this case series, we attempted an integrated oxygen strategy utilizing non invasive ventilation with standard oxygen therapy (SO) via nasal cannula. We managed both the patients with successful outcomes, without the need of intubation. Hence, integrated oxygen therapy was successfully utilized for the ventilatory management of moderate to severe COVID-19 patients by improving oxygenation, making patients more comfortable and reducing the work of breathing. By complete avoidance of intubation, this technique might help in preservation of much-needed critical care ventilators and help improve patient outcomes in the areas hit hard by the pandemic.

P169 Comparison of Work of Breathing: Heart failure versus Interstitial Lung Disease

Background Heart failure with central sleep apnoea and Cheyne Stokes respiration (HF-CSA-CSR) and interstitial lung disease (ILD) are characterised by tachypnoea, reflecting an increased work of breathing (WOB). Whilst tachypnoea is continuous in ILD, it is periodic in HF-CSA-CSF. Our hypothesis is that the periodicity reflects adaptive efficiency. Methods We assessed polysomnograms of male patients attending for either heart transplant or ILD assessment. WOB during non-REM sleep was estimated by the breath to breath interval (BBI), from which respiratory rate (RR) was calculated. An age matched control group with snoring, AHI&lt;5 and neither HF or ILD was included. Progress to date: Four patients (mean age 70 years) were identified in each group. The HF-CSA-CSR and ILD groups had similar awake PaCO2. The HF-CSA-CSR group had a lower LVEF and higher TLCO than the ILD group. There was similar BBI in the HF-CSA-CSR group during hyperpneic phase mean = 3.4±0.1 seconds and ILD group mean = 3.5±0.3 seconds, p=0.31. However, the RR during slow wave sleep was significantly lower in the HF-CSA-CSR group compared with ILD and control groups: HF-CSA-CSR mean = 10.3±0.8 breaths/min, control mean = 14.3±1.0 breaths/min, ILD mean 18.2±2.3 breaths/min, P=0.0002. Intended outcome and Impact: This data would suggest that both HF-CSA-CSR and ILD have similar severities of tachypnoea (aka work of breathing) compared with controls, however the RR is significantly lower in the HF-CSA-CSR group compared with ILD, despite similar PaCO2. This would indicate HF-CSA-CSR has similar WOB, yet greater efficiency, than ILD during non-REM sleep.