Oxygen for relief of dyspnea: what is the evidence?

Peripheral oxygen saturation levels as a guide to avoid hyperoxia: an observational study

BACKGROUND

As iatrogenic hyperoxia has been related to adverse outcomes in critically ill patients, guidelines advise to titrate oxygen to physiological levels. In the prehospital setting where partial arterial oxygen (PaO2) values are often not readily available, titration of oxygen is based on peripheral oxygen saturations (SpO2). In this study we aimed to investigate the efficacy of SpO2 guided oxygen titration in the prevention of hyperoxia.

METHODS

In a retrospective observational cohort study of patients included in the Acutelines data- and biobank of the University Medical Center Groningen between September 2020 and March 2023, we collected blood gas samples and triage data of sequentially included patients who received oxygen at the moment they were presented in the emergency department (ED). PaO2 values were compared to (concurrently measured) SpO2 values, and to patient- and treatment characteristics and P/F ratios were calculated in order to investigate the efficacy of SpO2 based oxygen titration for various subgroups.

RESULTS

Blood gas samples were obtained for 1042 patients, of which 178 (17.1%) had hyperoxia (PaO2 levels > 13.5 kPa). SpO2 readings were available for 170 of these, 68 of which (40%) had SpO2 values above the recommended target range (94-98%; 88-92% for patients with COPD) whereas 102 patients (60%) had SpO2 values within- or even below the recommended target range. Many of these patients (44.1%) received oxygen through a low-flow device (nasal canula), and these patients almost invariably (84.4%) were not compromised in their ventilation (P/F ratio's > 300).

CONCLUSION

When oxygen is titrated based on SpO2 levels, this results in hyperoxemia in a significant proportion of the patients. Health care providers should especially be reluctant to administer (low flow) oxygen as a standard of care to patients who do not have clear respiratory compromise, as these patients are at a high risk of developing (occult) hyperoxia.

Evaluation of diagnostic and treatment approaches to acute dyspnea in a palliative care setting among medical doctors with different educational levels

Background

Dyspnea is common in patients with advanced cancer. Diagnostic procedures in patients with dyspnea are mandatory but often time-consuming and hamper rapid treatment of the underlying refractory symptoms. Opioids are the first-line drugs for the treatment of refractory dyspnea in palliative care patients with advanced lung cancer.

Methods

To evaluate the knowledge levels of medical doctors with different educational levels on the diagnosis of and treatment options for dyspnea in patients with advanced lung cancer in a palliative care setting, a case report and survey were distributed to physicians at the University Hospital Krems, describing acute dyspnea in a 64-year-old stage IV lung cancer patient. A total of 18 diagnostic and 22 therapeutic options were included in the survey. The physicians were asked to suggest and rank in order of preference their diagnosis and treatment options. Statistical analyses of the data were performed, including comparison of the responses of the senior doctors and the physicians in training.

Results

A total of 106 surveys were completed. The respondents were 82 senior physicians and 24 physicians in training (response rates of 86% and 80%, respectively). Regarding diagnostic investigations, inspection and reading the patient’s chart were the most important diagnostic tools chosen by the respondents. The choices of performing blood gas analysis (p = 0.01) and measurement of oxygen saturation (p = 0.048) revealed a significant difference between the groups, both investigations performed more frequently by the physicians in training. As for non-pharmacological treatment options, providing psychological support was one of the most relevant options selected. A significant difference was seen in choosing the option of improving a patient’s position in relation to level of training (65.9% senior physicians vs. 30.4% physicians in training, p = 0.04). Regarding pharmacological treatment options, oxygen application was the most chosen approach. The second most frequent drug chosen was a ß-2 agonist. Only 9.8% of the senior physicians and 8.7% of the physicians in training suggested oral opioids as a treatment option, whereas intravenous opioids were suggested by 43.9% of the senior physicians and 21.7% of the physicians in training (p = 0.089). For subcutaneous application of opioids, the percentage of usage was significantly higher for the physicians in training than for the senior physicians (78.3% vs. 48.8%, p = 0.017, respectively).

Conclusion

The gold standard treatment for treating refractory dyspnea in patients with advanced lung cancer is opioids. Nevertheless, this pharmacological treatment option was not ranked as the most important. Discussing hypothetical cases of patients with advanced lung cancer and refractory dyspnea with experienced doctors as well as doctors at the beginning of their training may help improve symptom control for these patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00520-022-06996-6.

Clinician Strategies to Improve the Care of Patients Using Supplemental Oxygen

This article reviews four key clinician strategies to improve the care of adult patients receiving supplemental oxygen in the outpatient setting in the United States. The current barriers to adequate oxygen services are substantial and complex and include decreased reimbursement to durable medical equipment (DME) companies; a substantially lower number of available DME suppliers; difficult communication with DME suppliers; rigid patient testing, prescription, and documentation requirements; and unclear patient benefit and adherence. Recent data documenting frequent and varied problems reflect the significant impact of supplemental oxygen therapy on patients and caregivers. Areas where clinicians can improve patient oxygen experiences are highlighted in this review and include understanding Centers for Medicare and Medicaid Services oxygen prescription requirements, matching oxygen equipment to patient needs, providing essential patient education, and understanding mechanisms for patients and clinicians to report unresolved oxygen problems.

Long-term oxygen therapy

Long-term oxygen therapy (LTOT) has been shown to reduce pulmonary hypertension and improve survival in patients with chronic obstructive pulmonary disease and resting hypoxemia (reduced arterial partial pressure of oxygen ≤55 mmHg). However, the benefit of its use for chronic pulmonary diseases other than chronic obstructive pulmonary disease as well as for nonpulmonary conditions is debatable. Its role in patients with mild hypoxemia (reduced arterial partial pressure of oxygen >55 mmHg at rest) is presently being investigated in the LOTT. A meta-analysis of four controlled trials reporting the role of LTOT in patients with either nocturnal desaturation or daytime moderate hypoxemia found no difference in survival between patients on LTOT than those without. Advances in oxygen delivery and conservation devices have made domiciliary oxygen therapy more practical and popular for patients. There still remain concerns with the actual compliance of therapy among the needy patients.

Oxygen is nonbeneficial for most patients who are near death

CONTEXT

Clinicians prescribe and administer oxygen in response to reports of dyspnea, in the face of dropping oxygen saturation, as a "routine" comfort intervention, or to support anxious family members. Oxygen may produce nasal irritation and increase the cost of care.

OBJECTIVES

To determine the benefit of administering oxygen to patients who are near death.

METHODS

A double-blind, repeated-measure observation with the patient as his/her own control was conducted. The Respiratory Distress Observation Scale(©) measured presence and intensity of distress at baseline and at every gas or flow change. Medical air, oxygen, and no flow were randomly alternated every 10 minutes via nasal cannula with patients who were near death, at risk for respiratory distress, with no distress at the baseline of testing. Each patient had two encounters under each condition, yielding six encounters per patient.

RESULTS

Patients were 66% female, 34% white, and 66% African American, and ages 56-97 years. Patients had heart failure (25%), chronic obstructive pulmonary disease (34%), pneumonia (41%), or lung cancer (9%). Most (91%) patients tolerated the protocol with no change in respiratory comfort. Three patients (9%) displayed distress and were restored to baseline oxygen; one patient died during the protocol while displaying no distress. Repeated-measure analysis of variance revealed no differences in the Respiratory Distress Observation Scale under changing gas and flow conditions.

CONCLUSION

The routine application of oxygen to patients who are near death is not supported. The n-of-1 trial of oxygen in clinical practice is appropriate in the face of hypoxemic respiratory distress.

Interventions for alleviating cancer-related dyspnea: a systematic review and meta-analysis

BACKGROUND

Dyspnea is commonly encountered by many cancer patients in the terminal stage of their disease and it severely hampers their quality of life. We aimed to evaluate the role of interventions to alleviate dyspnea.

METHODS

Systematic review and meta-analysis of randomized controlled trials assessing all interventions for dyspnea palliation in cancer patients, and searched the Cochrane Library, MEDLINE, conference proceedings, and references.

RESULTS

Our search yielded 18 trials. Eight studies evaluated opioids in any route of administration, seven studies evaluated the use of oxygen, two studies assessed the role of benzodiazepines and two studies evaluated the role of furosemide in alleviating cancer-related dyspnea. Weighted mean difference (WMD) was calculated for continuous variables that were reported on the same scale. For continuous data reported in different scales, standardized mean difference (SMD) was calculated. Meta-analysis of three trials yielded a positive effect for opioid administration, WMD -1.31[95% CI (-2.49)-(- 0.13)]. Meta-analysis of the six studies showed lack of benefit to oxygen to improve dyspnea, SMD -0.3[95% CI -1.06-0.47]. The role of benzodiazepines remains unclear, furosemide was not beneficial.

CONCLUSIONS

Our systematic review and meta-analysis demonstrate a beneficial effect to opioids in alleviating cancer-related dyspnea, and no advantage for the use of oxygen.

Effect of palliative oxygen versus room air in relief of breathlessness in patients with refractory dyspnoea: a double-blind, randomised controlled trial

BACKGROUND

Palliative oxygen therapy is widely used for treatment of dyspnoea in individuals with life-limiting illness who are ineligible for long-term oxygen therapy. We assessed the effectiveness of oxygen compared with room air delivered by nasal cannula for relief of breathlessness in this population of patients.

METHODS

Adults from outpatient clinics at nine sites in Australia, the USA, and the UK were eligible for enrolment in this double-blind, randomised controlled trial if they had life-limiting illness, refractory dyspnoea, and partial pressure of oxygen in arterial blood (PaO(2)) more than 7.3 kPa. Participants were randomly assigned in a 1:1 ratio by a central computer-generated system to receive oxygen or room air via a concentrator through a nasal cannula at 2 L per min for 7 days. Participants were instructed to use the concentrator for at least 15 h per day. The randomisation sequence was stratified by baseline PaO(2) with balanced blocks of four patients. The primary outcome measure was breathlessness (0-10 numerical rating scale [NRS]), measured twice a day (morning and evening). All randomised patients who completed an assessment were included in the primary analysis for that data point (no data were imputed). This study is registered, numbers NCT00327873 and ISRCTN67448752.

FINDINGS

239 participants were randomly assigned to treatment (oxygen, n=120; room air, n=119). 112 (93%) patients assigned to receive oxygen and 99 (83%) assigned to receive room air completed all 7 days of assessments. From baseline to day 6, mean morning breathlessness changed by -0.9 points (95% CI -1.3 to -0.5) in patients assigned to receive oxygen and by -0.7 points (-1.2 to -0.2) in patients assigned to receive room air (p=0.504). Mean evening breathlessness changed by -0.3 points (-0.7 to 0.1) in the oxygen group and by -0.5 (-0.9 to -0.1) in the room air group (p=0.554). The frequency of side-effects did not differ between groups. Extreme drowsiness was reported by 12 (10%) of 116 patients assigned to receive oxygen compared with 14 (13%) of 108 patients assigned to receive room air. Two (2%) patients in the oxygen group reported extreme symptoms of nasal irritation compared with seven (6%) in the room air group. One patient reported an extremely troublesome nose bleed (oxygen group).

INTERPRETATION

Since oxygen delivered by a nasal cannula provides no additional symptomatic benefit for relief of refractory dyspnoea in patients with life-limiting illness compared with room air, less burdensome strategies should be considered after brief assessment of the effect of oxygen therapy on the individual patient.

FUNDING

US National Institutes of Health, Australian National Health and Medical Research Council, Duke Institute for Care at the End of Life, and Doris Duke Charitable Foundation.