Functional availability of medical oxygen for the management of hypoxaemia in Cameroon: A nationwide facility-based cross-sectional survey.

Background: Medical oxygen is essential for managing hypoxaemia, which has a multifactorial origin, including acute and chronic lung diseases such as pneumonia, asthma, and severe malaria. The coronavirus disease 2019 (COVID-19) revealed substantial gaps in the availability and accessibility of safe medical oxygen, especially in low- and middle-income countries (LMICs). This study aimed to assess the availability and sources, as well as the barriers to the availability of functional medical oxygen in hospitals in Cameroon. Methods: This was a nationwide cross-sectional descriptive study conducted from 26 March to 1 June 2021. Using a convenient sampling technique, we sampled accredited public and private COVID-19 treatment centres in all ten regions in Cameroon. Representatives from the selected hospitals were provided with a pre-designed questionnaire assessing the availability, type, and state of medical oxygen in their facilities. All analyses were performed using R. Results: In total, 114 hospitals were included in this study, with functional medical oxygen available in 65% (74/114) of the hospitals. About 85% (23/27) of the reference hospitals and only 59% (51/87) of the district hospitals had available functional medical oxygen. Compared to district hospitals, reference hospitals were more likely to have central oxygen units (reference vs. district: 10 vs. 0%), oxygen cylinders (74 vs. 42%), and oxygen concentrators (79 vs. 51%). The most common barriers to the availability of medical oxygen were inadequate oxygen supply to meet needs (district vs. reference hospitals: 55 vs. 30%), long delays in oxygen bottle refills (51 vs. 49%), and long distances from oxygen suppliers (57 vs. 49%). Conclusions: The availability of medical oxygen in hospitals in Cameroon is suboptimal and more limited in districts compared to reference hospitals. The cost of medical oxygen, delays related to refills and supplies, and long distances from medical sources were the most common barriers to availability in Cameroon.

Effect of immediate initiation of invasive ventilation on mortality in acute hypoxemic respiratory failure: a target trial emulation.

PURPOSE: Invasive ventilation is a fundamental treatment in intensive care but its precise timing is difficult to determine. This study aims at assessing the effect of initiating invasive ventilation versus waiting, in patients with hypoxemic respiratory failure without immediate reason for intubation on one-year mortality. METHODS: Emulation of a target trial to estimate the benefit of immediately initiating invasive ventilation in hypoxemic respiratory failure, versus waiting, among patients within the first 48-h of hypoxemia. The eligible population included non-intubated patients with SpO2/FiO2 ≤ 200 and SpO2 ≤ 97%. The target trial was emulated using a single-center database (MIMIC-IV) which contains granular information about clinical status. The hourly probability to receive mechanical ventilation was continuously estimated. The hazard ratios for the primary outcome, one-year mortality, and the secondary outcome, 30-day mortality, were estimated using weighted Cox models with stabilized inverse probability weights used to adjust for measured confounding. RESULTS: 2996 Patients fulfilled the inclusion criteria of whom 792 were intubated within 48 h. Among the non-invasive support devices, the use of oxygen through facemask was the most common (75%). Compared to patients with the same probability of intubation but who were not intubated, intubation decreased the hazard of dying for the first year after ICU admission HR 0.81 (95% CI 0.68-0.96, p = 0.018). Intubation was associated with a 30-day mortality HR of 0.80 (95% CI 0.64-0.99, p = 0.046). CONCLUSION: The initiation of mechanical ventilation in patients with acute hypoxemic respiratory failure reduced the hazard of dying in this emulation of a target trial.

PaCO2 is nonlinearly associated with NIV failure in patients with hypoxemic respiratory failure.

OBJECTIVE: To explore the association between PaCO2 and noninvasive ventilation (NIV) failure in patients with hypoxemic respiratory failure. METHODS: A retrospective study was performed in a respiratory ICU of a teaching hospital. Patients admitted to ICU between 2011 and 2019 were screened. We enrolled the patients with hypoxemic respiratory failure. However, patients who used NIV due to acute-on-chronic respiratory failure or heart failure were excluded. Data before the use of NIV were collected. Requirement of intubation was defined as NIV failure. RESULTS: A total of 1029 patients were enrolled in final analysis. The rate of NIV failure was 45% (461/1029). A nonlinear relationship between PaCO2 and NIV failure was found by restricted cubic splines (p = 0.03). The inflection point was 32 mmHg. The rate of NIV failure was 42% (224/535) in patients with PaCO2 >32 mmHg. However, it increased to 48% (237/494) in those with PaCO2 ≤ 32 mmHg. The crude and adjusted hazard ratio (HR) for NIV failure was 1.36 (95%CI:1.13-1.64) and 1.23(1.01-1.49), respectively, if the patients with PaCO2 >32 mmHg were set as reference. In patients with PaCO2 ≤ 32 mmHg, one unit increment of PaCO2 was associated with 5% reduction of NIV failure. However, it did not associate with NIV failure in patients with PaCO2 >32 mmHg. CONCLUSIONS: PaCO2 and NIV failure was nonlinear relationship. The inflection point was 32 mmHg. Below the inflection point, lower PaCO2 was associated with higher NIV failure. However, it did not associate with NIV failure above this point.

High-Flow Nasal Cannula Versus Noninvasive Ventilation as Initial Treatment in Acute Hypoxia: A Propensity Score-Matched Study.

IMPORTANCE: Patients presenting to the emergency department (ED) with hypoxemia often have mixed or uncertain causes of respiratory failure. The optimal treatment for such patients is unclear. Both high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) are used. OBJECTIVES: We sought to compare the effectiveness of initial treatment with HFNC versus NIV for acute hypoxemic respiratory failure. DESIGN SETTING AND PARTICIPANTS: We conducted a retrospective cohort study of patients with acute hypoxemic respiratory failure treated with HFNC or NIV within 24 hours of arrival to the University of Michigan adult ED from January 2018 to December 2022. We matched patients 1:1 using a propensity score for odds of receiving NIV. MAIN OUTCOMES AND MEASURES: The primary outcome was major adverse pulmonary events (28-d mortality, ventilator-free days, noninvasive respiratory support hours) calculated using a win ratio. RESULTS: A total of 1154 patients were included. Seven hundred twenty-six (62.9%) received HFNC and 428 (37.1%) received NIV. We propensity score matched 668 of 1154 (57.9%) patients. Patients on NIV versus HFNC had lower 28-day mortality (16.5% vs. 23.4%, p = 0.033) and required noninvasive treatment for fewer hours (median 7.5 vs. 13.5, p < 0.001), but had no difference in ventilator-free days (median [interquartile range]: 28 [26, 28] vs. 28 [10.5, 28], p = 0.199). Win ratio for composite major adverse pulmonary events favored NIV (1.38; 95% CI, 1.15-1.65; p < 0.001). CONCLUSIONS AND RELEVANCE: In this observational study of patients with acute hypoxemic respiratory failure, initial treatment with NIV compared with HFNC was associated with lower mortality and fewer composite major pulmonary adverse events calculated using a win ratio. These findings underscore the need for randomized controlled trials to further understand the impact of noninvasive respiratory support strategies.

Hypoxia-Induced Piglet Model of Cardiac Arrest with Assisted Resuscitation by Extracorporeal Membrane Oxygenation.

The mortality rate of newborns with severe congenital heart disease (CHD) has significantly decreased over the past few decades. However, many of these children experience neurological impairments, particularly following a hypoxic cardiac arrest. The use of extracorporeal membrane oxygenation (ECMO) has been considered an effective treatment for severe hypoxia in CHD cases. Various clinical studies have examined the use of ECMO for resuscitation after hypoxic cardiac arrest, but the results have been contradictory, showing a significant incidence of both mortality and morbidity in some studies while others report good outcome. In order to investigate the mechanisms behind brain injury associated with extracorporeal circulation, we have developed a neonatal porcine model of hypoxia-induced cardiac arrest followed by veno-arterial ECMO therapy.

[Value of transnasal high-flow oxygen therapy and noninvasive ventilation in the management of acute respiratory distress syndrome].

Acute respiratory distress syndrome (ARDS) is one of the most common syndromes in the intensive care unit, with a high mortality and morbidity. Refractory hypoxia is the typical feature of ARDS, and improving hypoxia is the key to the treatment of ARDS. Due to the rapid progression of ARDS, invasive ventilation is usually used to improve hypoxia. But in recent years, with the extending of the understanding of ARDS and the development of non-invasive oxygen therapy, high flow nasal oxygen (HFNO) and non-invasive ventilation (NIV) are gradually used in ARDS. Therefore, we reviewed the role of HFNO and NIV in ARDS in this paper.

Post-pandemic acute respiratory distress syndrome: A New Global Definition with extension to lower-resource regions.

Acute respiratory distress syndrome (ARDS), first described in 1967, is characterized by acute respiratory failure causing profound hypoxemia, decreased pulmonary compliance, and bilateral CXR infiltrates. After several descriptions, the Berlin definition was adopted in 2012, which established three categories of severity according to hypoxemia (mild, moderate and severe), specified temporal aspects for diagnosis, and incorporated the use of non-invasive ventilation. The COVID-19 pandemic led to changes in ARDS management, focusing on continuous monitoring of oxygenation and on utilization of high-flow oxygen therapy and lung ultrasound. In 2021, a New Global Definition based on the Berlin definition of ARDS was proposed, which included a category for non-intubated patients, considered the use of SpO2, and established no particular requirement for oxygenation support in regions with limited resources. Although debates persist, the continuous evolution seeks to adapt to clinical and epidemiological needs, and to the search of personalized treatments.

[Best evidence summary for awake prone positioning in treating hypoxemic due to COVID-19 infection].

Objective: To retrieve, evaluate, and summarize the best evidence for the treatment of hypoxemia in patients with COVID-19 infection using the awake prone positioning, with the aim of guiding healthcare professionals in the standardized implementation of this therapy. Methods: A systematic search was conducted in databases including UpToDate, BMJ Best Practice, JBI Evidence-Based Healthcare Center, American Association of Critical-Care Nurses, Intensive Care Society, European Respiratory Society, World Health Organization website, Cochrane Library, PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang. The retrieved literature was subjected to quality assessment and evidence extraction. Results: A total of ten publications were included, consisting of one thematic evidence summary, one guideline, two systematic reviews, three randomized controlled trials, and three expert consensus statements. This summary synthesizes thirty key pieces of evidence in five categories: organizational management and training, risk assessment, preparatory operations, implementation key points, and risk control. Conclusions: Awake prone positioning is beneficial for improving hypoxemia in patients with COVID-19 and is easy to implement. Medical institutions should develop nursing management systems, operational standards, and best practices for awake prone positioning based on evidence-based evidence in order to improve the quality of care management for such patients.

Occurrence of hyperoxia during iNO treatment for persistent pulmonary hypertension of the newborn: a cohort study.

High concentrations of oxygen are often needed to optimize oxygenation in infants with persistent pulmonary hypertension (PPHN), but this can also increase the risk of hyperoxemia. We determined the occurrence of hyperoxemia in infants treated for PPHN. Medical records of infants ≥ 34 + 0 weeks gestational age (GA) who received inhaled nitric oxide (iNO) were retrospectively reviewed for oxygenation parameters during iNO therapy. Oxygen was manually titrated to target arterial oxygen tension (PaO2) 10-13 kPa and peripheral oxygen saturation (SpO2) 92-98%. The main study outcomes were the incidence and duration of hyperoxemia and hypoxemia and the fraction of inspired oxygen (FiO2). A total of 181 infants were included. The median FiO2 was 0.43 (IQR 0.34-0.56) and the maximum FiO2 was 1.0 in 156/181 (86%) infants, resulting in at least one PaO2 > 13 kPa in 149/181 (82%) infants, of which 46/149 (31%) infants had minimal one PaO2 > 30 kPa. SpO2 was > 98% in 179/181 (99%) infants for 17.7% (8.2-35.6%) of the iNO time. PaO2 < 10 kPa occurred in 160/181 (88%) infants, of which 81/160 (51%) infants had minimal one PaO2 < 6.7 kPa. SpO2 was < 92% in 169/181 (93%) infants for 1.6% (0.5-4.3%) of the iNO time.    Conclusion: While treatment of PPHN is focused on preventing and reversing hypoxemia, hyperoxemia occurs inadvertently in most patients. What is Known: • High concentrations of oxygen are often needed to prevent hypoxemia-induced deterioration of PPHN, but this can also increase the risk of hyperoxemia. • Infants with persistent pulmonary hypertension may be particularly vulnerable to the toxic effects of oxygen, and hyperoxemia could further induce pulmonary vasoconstriction, potentially worsening the condition. What is New: • Hyperoxemia occurs in the majority of infants with PPHN during treatment with iNO. • Infants with PPHN spent a considerably longer period with saturations above the target range compared to saturations below the target range.

Effectiveness of bubble continuous positive airway pressure for treatment of children aged 1-59 months with severe pneumonia and hypoxaemia in Ethiopia: a pragmatic cluster-randomised controlled trial.

BACKGROUND: The safety and efficacy of bubble continuous positive airway pressure (bCPAP) for treatment of childhood severe pneumonia outside tertiary care hospitals is uncertain. We did a cluster-randomised effectiveness trial of locally made bCPAP compared with WHO-recommended low-flow oxygen therapy in children with severe pneumonia and hypoxaemia in general hospitals in Ethiopia. METHODS: This open, cluster-randomised trial was done in 12 general (secondary) hospitals in Ethiopia. We randomly assigned six hospitals to bCPAP as first-line respiratory support for children aged 1-59 months who presented with severe pneumonia and hypoxaemia and six hospitals to standard low-flow oxygen therapy. Cluster (hospital) randomisation was stratified by availability of mechanical ventilation. All children received treatment in paediatric wards (in a dedicated corner in front of a nursing station) with a similar level of facilities (equipment for oxygen therapy and medications) and staffing (overall, one nurse per six patients and one general practitioner per 18 patients) in all hospitals. All children received additional care according to WHO guidelines, supervised by paediatricians and general practitioners. The primary outcome was treatment failure (defined as any of the following: peripheral oxygen saturation <85% at any time after at least 1 h of intervention plus signs of respiratory distress; indication for mechanical ventilation; death during hospital stay or within 72 h of leaving hospital against medical advice; or leaving hospital against medical advice during intervention). The analysis included all children enrolled in the trial. We performed both unadjusted and adjusted analyses of the primary outcome, with the latter adjusted for the stratification variable and for the design effect of cluster randomisation, as well as selected potentially confounding variables, including age. We calculated effectiveness as the relative risk (RR) of the outcomes in the bCPAP group versus low-flow oxygen group. This trial is registered with ClinicalTrial.gov, NCT03870243, and is completed. FINDINGS: From June 8, 2021, to July 27, 2022, 1240 children were enrolled (620 in hospitals allocated to bCPAP and 620 in hospitals allocated to low-flow oxygen). Cluster sizes ranged from 103 to 104 children. Five (0·8%) of 620 children in the bCPAP group had treatment failure compared with 21 (3·4%) of 620 children in the low-flow oxygen group (unadjusted RR 0·24, 95% CI 0·09-0·63, p=0·0015; adjusted RR 0·24, 0·07-0·87, p=0·030). Six children died during hospital stay, all of whom were in the low-flow oxygen group (p=0·031). No serious adverse events were attributable to bCPAP. INTERPRETATION: In Ethiopian general hospitals, introduction of locally made bCPAP, supervised by general practitioners and paediatricians, was associated with reduced risk of treatment failure and in-hospital mortality in children with severe pneumonia and hypoxaemia compared with use of standard low-flow oxygen therapy. Implementation research is required in higher mortality settings to consolidate our findings. FUNDING: SIDA Sweden and Grand Challenges Ethiopia.

Nocturnal oxygen therapy in obstructive sleep apnoea: a systematic review and meta-analysis.

Obstructive sleep apnoea is characterised by recurrent reduction of airflow during sleep leading to intermittent hypoxia. Continuous positive airway pressure is the first-line treatment but is limited by poor adherence. Nocturnal oxygen therapy may be an alternative treatment for obstructive sleep apnoea but its effects remain unclear. This meta-analysis evaluates the effects of nocturnal oxygen therapy on both obstructive sleep apnoea severity and blood pressure.A literature search was performed based on the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. Peer-reviewed, randomised studies that compared the effect of nocturnal oxygen therapy to sham in obstructive sleep apnoea patients were included. The main outcomes were the apnoea-hypopnoea index and systolic and diastolic blood pressure.The search strategy yielded 1295 citations. Nine studies with 502 participants were included. When nocturnal oxygen therapy was compared to sham/air, it significantly reduced the apnoea-hypopnoea index (mean difference (MD) -15.17 events·h-1, 95% CI -19.95- -10.38 events·h-1, p<0.00001). Nocturnal oxygen therapy had no significant effect on blood pressure at follow-up without adjustment for baseline values, but did, where available, significantly attenuate the change in blood pressure from baseline to follow-up for both systolic blood pressure (MD -2.79 mmHg, 95% CI -5.45- -0.14 mmHg, p=0.040) and diastolic blood pressure (MD -2.20 mmHg, 95% CI -3.83- -0.57 mmHg, p=0.008).Nocturnal oxygen therapy reduced the apnoea-hypopnoea index severity and the change in (but not absolute) systolic and diastolic blood pressure, compared to sham. This suggests that nocturnal oxygen therapy may be a treatment option for obstructive sleep apnoea. Further studies with longer-term follow-up and standardised measurements are needed.

Outcomes and Functional Deterioration in Hospital Admissions with Acute Hypoxemia.

BACKGROUND: Many hospitalized patients decline in functional status after discharge, but functional decline in emergency admissions with hypoxemia is unknown. The primary aim of this study was to study functional outcomes as a clinical endpoint in a cohort of patients with acute hypoxemia. METHODS: A multicenter prospective observational study was conducted in patients with new-onset hypoxemia emergently admitted to two respiratory departments at a university hospital and an academic teaching hospital. Using the WHO scale, the patients' functional status 4 weeks before admission and at hospital discharge was assessed. The type and duration of oxygen therapy, hospital length of stay and survival and risk of hypercapnic failure were recorded. RESULTS: A total of 151 patients with a median age of 74 were included. Two-thirds declined in functional status by at least one grade at discharge. A good functional status (OR 4.849 (95% CI 2.209-10.647)) and progressive cancer (OR 6.079 (1.197-30.881)) were more associated with functional decline. Most patients were treated with conventional oxygen therapy (n = 95, 62%). The rates of in-hospital mortality and need for intubation were both 8%. CONCLUSIONS: Patients with acute hypoxemia in the emergency room have a poorer functional status after hospital discharge. This decline may be of multifactorial origin.

Lower vs Higher Oxygenation Target and Days Alive Without Life Support in COVID-19: The HOT-COVID Randomized Clinical Trial.

Importance: Supplemental oxygen is ubiquitously used in patients with COVID-19 and severe hypoxemia, but a lower dose may be beneficial. Objective: To assess the effects of targeting a Pao2 of 60 mm Hg vs 90 mm Hg in patients with COVID-19 and severe hypoxemia in the intensive care unit (ICU). Design, Setting, and Participants: Multicenter randomized clinical trial including 726 adults with COVID-19 receiving at least 10 L/min of oxygen or mechanical ventilation in 11 ICUs in Europe from August 2020 to March 2023. The trial was prematurely stopped prior to outcome assessment due to slow enrollment. End of 90-day follow-up was June 1, 2023. Interventions: Patients were randomized 1:1 to a Pao2 of 60 mm Hg (lower oxygenation group; n = 365) or 90 mm Hg (higher oxygenation group; n = 361) for up to 90 days in the ICU. Main Outcomes and Measures: The primary outcome was the number of days alive without life support (mechanical ventilation, circulatory support, or kidney replacement therapy) at 90 days. Secondary outcomes included mortality, proportion of patients with serious adverse events, and number of days alive and out of hospital, all at 90 days. Results: Of 726 randomized patients, primary outcome data were available for 697 (351 in the lower oxygenation group and 346 in the higher oxygenation group). Median age was 66 years, and 495 patients (68%) were male. At 90 days, the median number of days alive without life support was 80.0 days (IQR, 9.0-89.0 days) in the lower oxygenation group and 72.0 days (IQR, 2.0-88.0 days) in the higher oxygenation group (P = .009 by van Elteren test; supplemental bootstrapped adjusted mean difference, 5.8 days [95% CI, 0.2-11.5 days]; P = .04). Mortality at 90 days was 30.2% in the lower oxygenation group and 34.7% in the higher oxygenation group (risk ratio, 0.86 [98.6% CI, 0.66-1.13]; P = .18). There were no statistically significant differences in proportion of patients with serious adverse events or in number of days alive and out of hospital. Conclusion and Relevance: In adult ICU patients with COVID-19 and severe hypoxemia, targeting a Pao2 of 60 mm Hg resulted in more days alive without life support in 90 days than targeting a Pao2 of 90 mm Hg. Trial Registration: ClinicalTrials.gov Identifier: NCT04425031.

The occurrence of pressure injuries and related risk factors in patients undergoing extracorporeal membrane oxygenation for respiratory failure: A retrospective single centre study.

INTRODUCTION: Limited data is available regarding the incidence of pressure injuries in patients who have undergone Extracorporeal Membrane Oxygenation (ECMO), a life-saving technique that provides respiratory support for hypoxemia that does not respond to conventional treatment. AIM: To assess the incidence of pressure injuries and identify the risk factors in Acute Respiratory Distress Syndrome patients receiving ECMO. METHODS: A retrospective observational study utilizing prospectively collected data was performed in an Italian intensive care unit, between 1 January 2012 and 30 April 2022 enrolling all consecutive patients with Acute Respiratory Distress Syndrome who underwent ECMO. RESULTS: One hundred patients were included in this study. 67 patients (67%) developed pressure injuries during their intensive care unit stay, with a median of 2 (1-3) sites affected. The subgroup of patients with pressure injuries was more hypoxic before ECMO implementation, received more frequent continuous renal replacement therapy and prone positioning, and showed prolonged ECMO duration, intensive care unit and hospital length of stay compared to patients without pressure injuries. The logistic model demonstrated an independent association between the pO2/FiO2 ratio prior to ECMO initiation, the utilization of the prone positioning during ECMO, and the occurrence of pressure injuries. CONCLUSIONS: The incidence of pressure injuries was elevated in patients with Adult Respiratory Distress Syndrome who received ECMO. The development of pressure injuries was found to be independently associated with hypoxemia before ECMO initiation and the utilization of prone positioning during ECMO. IMPLICATIONS FOR CLINICAL PRACTICE: Patients who require ECMO for respiratory failure are at a high risk of developing pressure injuries. To ensure optimal outcomes during ECMO implementation and treatment, it is vital to implement preventive measures and to closely monitor skin health in at-risk areas.