Evaluation of inpatient oxygen therapy in hypercapnic chronic obstructive pulmonary disease

Implementing Oxygen Therapy in Medical Wards-A Scoping Review to Understand Health Services Protocols and Procedures

Background/Objectives: Conventional oxygen therapy (COT) is the cornerstone of management for hypoxaemia associated with acute respiratory failure (ARF) in wards. COT implementation guidance is provided in local health guidance documents (LHGDs). This study aimed to identify ward-delivered adult COT implementation LHGDs in Australian health services and assess their content and accuracy. Methods: A scoping review was conducted on 1 May 2022 and updated on 19 December 2023 to identify public health services COT LHGDs. Data were extracted and analysed regarding COT initiation, monitoring, maintenance and weaning, and management of clinical deterioration. Results: Thirty-seven included LHGDs, and eleven referenced the Australian COT guidelines. A definition in the LHGDs for hypoxaemia is that any oxygen saturation (SpO2) or arterial blood gas (ABG) is rare. None required ABG prior to COT initiation. Twenty-nine provided target SpO2 aims for initiation and maintenance. Fifteen did not specify the criteria for clinical review. Nine LHGDs provided guidance on weaning. Conclusions: There was considerable variation in the structure and content of COT LHGDs in Australian health services. Variations and limited guideline concordance of LHGDs may impact the quality and safety of health care. Considerations for future research include the development and implementation of standardised core LHGD recommendations for COT, as well as conducting a national oxygen audit to better measure and benchmark the safety and quality of care.

Oxygen-induced hypercapnia: physiological mechanisms and clinical implications

Oxygen is probably the most commonly prescribed drug in the emergency setting and is a life-saving modality as well. However, like any other drug, oxygen therapy may also lead to various adverse effects. Patients with chronic obstructive pulmonary disease (COPD) may develop hypercapnia during supplemental oxygen therapy, particularly if uncontrolled. The risk of hypercapnia is not restricted to COPD only; it has also been reported in patients with morbid obesity, asthma, cystic fibrosis, chest wall skeletal deformities, bronchiectasis, chest wall deformities, or neuromuscular disorders. However, the risk of hypercapnia should not be a deterrent to oxygen therapy in hypoxemic patients with chronic lung diseases, as hypoxemia may lead to life-threatening cardiovascular complications. Various mechanisms leading to the development of oxygen-induced hypercapnia are the abolition of ‘hypoxic drive’, loss of hypoxic vasoconstriction and absorption atelectasis leading to an increase in dead-space ventilation and Haldane effect. The international guideline recommends a target oxygen saturation of 88% to 92% in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and other chronic lung diseases at risk of hypercapnia.  Oxygen should be administered only when oxygen saturation is below 88%. We searched PubMed, EMBASE, and the CINAHL from inception to June 2022. We used the following search terms: “Hypercapnia”, “Oxygen therapy in COPD”, “Oxygen-associated hypercapnia”, “oxygen therapy”, and “Hypoxic drive”. All types of study are selected. This review will focus on the physiological mechanisms of oxygen-induced hypercapnia and its clinical implications.

Post-acute care for asthma patients presenting to an Australian hospital network

We evaluated post-acute care in 1273 asthma patients presenting to our hospital network. Patients with respiratory unit admission (n = 413) or consultation from the respiratory service (n = 45) were more likely to have guideline adherent care compared with patients without respiratory input (n = 153). Patients aged greater than 60 years had higher rates of representation within 90 days and lower rates of asthma action plans. Post-acute care of asthma at our centre falls short of guideline recommendations, and subspecialist involvement should be expanded.

Determination of oxygen saturation compared to a prescribed target range using continuous pulse oximetry in acutely unwell medical patients

BACKGROUND

Both inadequate and excessive administration of oxygen to acutely unwell patients results in risk of harm. Guidelines recommend titration of oxygen to achieve a target oxygen saturation (SpO2) range. Information regarding whether this is being achieved is limited.

METHODS

In this two-centre non-interventional study we used continuous pulse oximetry in acutely unwell medical patients over a 24-h period to determine the proportion of time spent with SpO2 within the prescribed target range and whether this is influenced by the target range, age, care in a high-dependency area and the number of oxygen adjustments.

RESULTS

Eighty participants were included in the analysis. The mean (SD) proportion of time spent in target range was 55.6% (23.6), this was lower in those with a reduced hypercapnic target range (88-92% or below) compared to those with a range of 92-96%; difference - 13.1% (95% CI - 3.0 to - 23.2), P = 0.012. The proportion of time spent above range was 16.2% (22.9); this was higher in those with a reduced hypercapnic range; difference 21.6% (31.4 to 12), P < 0.001. The proportion of time below range was 28.4% (25.2); there was no difference between target ranges. The proportion of time spent in range was higher for those in a high dependency area in the multivariate model; difference 15.5% (95% CI 2.3 to 28.7), P = 0.02.

CONCLUSIONS

Medical patients receiving oxygen in a ward setting spend significant periods of time with SpO2 both above and below the prescribed target range while receiving oxygen therapy.