Automated audit of hospital oxygen use devised during the COVID-19 pandemic

BACKGROUND

The British Thoracic Society (BTS) has organised intermittent audits of hospital oxygen use in UK hospitals since 2008. Manual audits are time-consuming and subject to human errors. Oxygen prescribing and bedside observations including National Early Warning Scores (NEWS2 scores) are undertaken within an integrated electronic medical record (EMR) at this hospital.

METHODS

The hospital's Business Information team were commissioned in late 2019 to devise a bespoke automated audit of oxygen prescribing and use. A summary report displays the oxygen saturation alongside the oxygen prescription status of every patient in the hospital except for critical care units which do not use NEWS2. The display has a 'traffic-light' colour scheme (green within target range, amber or red if below range or if above range on supplemental oxygen), with a graph showing oxygen use and saturation levels for patients with each prescribed target range. Clinicians can access raw data including oxygen saturation, oxygen device and flow rate for each individual patient.

RESULTS

Over 51 audits involving 34 352 sets of observations, an average of 6.0% involved use of oxygen and 88.6% of these had a valid oxygen prescription. During the first wave of the COVID-19 pandemic in spring 2020, the monthly percentage of observations involving oxygen use increased to a peak of 10.4% followed by a rise to 10.6% during the second wave and 7.4% during the third (Omicron) wave. Oxygen use returned to baseline after each wave.

CONCLUSIONS

In hospitals with integrated EMRs, it is possible to automate all fundamental aspects of the BTS oxygen audits and to monitor oxygen use at individual patient level and a hospital-wide level. This could be particularly valuable during major events such as the COVID-19 pandemic. This methodology could be extended to other clinical audits where the audit questions relate to routinely collected EMR data.

Carcinoid heart disease of gonadal primary presenting with hypoxia: a case report

Background

Carcinoid heart disease is a potential sequela of metastatic neuroendocrine tumour that has characteristic valve appearances. Patients can present with symptoms of carcinoid syndrome or be relatively asymptomatic until symptoms of progressive heart failure manifest.

Case summary

We present a case of a 54-year-old male who was admitted to the hospital for investigation of hypoxia. Transthoracic echocardiogram was suggestive of carcinoid heart disease which subsequently led to a diagnosis of metastatic neuroendocrine (carcinoid) tumour of the testicular primary. Work-up revealed a patent foramen ovale with evidence of the right to left interatrial shunt from severe tricuspid regurgitation as the cause of his hypoxia. Prior to surgical excision of the primary tumour, percutaneous patent foramen ovale closure was performed resulting in improved arterial oxygen saturation and symptomatic improvement.

Discussion

Carcinoid heart disease typically affects the right-sided cardiac valves and the tricuspid valve appearances were critical in leading to a diagnosis of a metastatic neuroendocrine tumour in our patient. This case demonstrates that percutaneous patent foramen ovale closure can be an effective intervention for hypoxia in those not managed surgically. A high index of suspicion should be maintained for gonadal primary carcinoid tumour when there is carcinoid heart disease in the absence of liver metastases.

Implementing target range oxygen in critical care: A quality improvement pilot study

Background

Iatrogenic hyperoxaemia is common on critical care units and has been associated with increased mortality. We commenced a quality improvement pilot study to analyse the views and practice of critical care staff regarding oxygen therapy and to change practice to ensure that all patients have a prescribed target oxygen saturation range.

Methods

A baseline measurement of oxygen target range prescribing was undertaken alongside a survey of staff attitudes. We then commenced a programme of change, widely promoting an agreed oxygen target range prescribing policy. The analyses of target range prescribing and staff survey were repeated four to five months later.

Results

Thirty-three staff members completed the baseline survey, compared to 29 in the follow-up survey. There was no discernible change in staff attitudes towards oxygen target range prescribing. Fifty-four patients were included in the baseline survey and 124 patients were assessed post implementation of changes. The proportion of patients with an oxygen prescription with a target range improved from 85% to 95% (χ² = 5.17, p = 0.02) and the proportion of patients with an appropriate prescribed target saturation range increased from 85% to 91% (χ² = 1.4, p = 0.24). The improvement in target range prescribing was maintained at 96% 12 months later.

Conclusions

The introduction and promotion of a structured protocol for oxygen prescribing were associated with a sustained increase in the proportion of patients with a prescribed oxygen target range on this unit.

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve

Key Points

Educational Aims

To understand how oxygen is delivered to the tissues.

To understand the relationships between oxygen saturation, partial pressure, content and tissue delivery.

The clinical relevance of the haemoglobin–oxygen dissociation curve will be reviewed and we will show how a mathematical model of the curve, derived in the 1960s from limited laboratory data, accurately describes the relationship between oxygen saturation and partial pressure in a large number of routinely obtained clinical samples.

To understand the role of pulse oximetry in clinical practice.

To understand the differences between arterial, capillary and venous blood gas samples and the role of their measurement in clinical practice.

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S_O2) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin–oxygen dissociation curve, a graphical representation of the relationship between oxygen satur­ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S_O2 in blood from patients with normal pH and S_O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S_pO2) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S_aO2) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S_pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Understand the role of oximetry in clinical practice and how oxygen delivery, saturation and partial pressure relatehttp://ow.ly/R05hK

A rare complication of pneumonectomy: Diagnosis made by a literature search

This case describes platypnoea-orthodeoxia syndrome in a patient 2 months after a right pneumonectomy for adenocarcinoma of the lung. The patient complained of platypnoea (breathlessness in the upright position) and was noted to have orthodeoxia (arterial desaturation on standing) on clinical examination. This was due to anatomical changes after the pneumonectomy that resulted in direct blood flow from the inferior vena cava through a previously unrecognised atrial septal defect into the left atrium. The closure of this right to left shunt with an Amplatzer occluder produced immediate and striking symptomatic relief in the patient. The authors had no previous experience of this very rare complication of pneumonectomy. The diagnosis was made after a literature search using PubMed/Medline, underlining the direct clinical benefit provided by these databases.

Pre-medication for bronchoscopy: a randomised double blind trial comparing alfentanil with midazolam

This study was designed to compare the effects of alfentanil and midazolam pre-medication on patient comfort during and after flexible bronchoscopy. A randomised, double-blind study was performed; 40 patients received alfentanil and 29 midazolam. Subjects completed questionnaires about discomfort and adverse effects immediately post-procedure and 24 h later. The bronchoscopist also completed a questionnaire. No difference in patient discomfort was found immediately post-procedure and no differences were found for amount of topical lignocaine used or minimum oxygen saturation. Operators reported no overall difference between the agents for ease of procedure but about 20% less cough was reported in the alfentanil group (P = 0.02). Patient discomfort scores in the 24h questionnaire were significantly lower in patients given midazolam (P = 0.01 for nasal discomfort, P = 0.003 for throat discomfort) but drowsiness was commoner in this group (P = 0.04). There was no significant difference in patients' reports of cough, nausea or vomiting or their willingness to have a repeat procedure. In conclusion, cough during bronchoscopy was slightly less marked with alfentanil than midazolam pre-medication but this made no difference to the ease of procedure or to overall patient discomfort. Patients given midazolam reported less discomfort when asked about the test 24 h later.

Do all patients require supplemental oxygen during flexible bronchoscopy?

STUDY OBJECTIVES

Some respiratory units routinely administer supplemental oxygen to all patients during flexible bronchoscopy, but other units give oxygen only to those who desaturate (arterial oxygen saturation [SaO(2)], < 90%). We performed a study to examine both the requirement for supplemental oxygen and the effect of IV midazolam therapy on oxygenation during flexible bronchoscopy for patients with a known FEV(1).

DESIGN

Data on the SaO(2) of patients during flexible bronchoscopy were collected prospectively for all procedures performed in our respiratory unit for the period 1992 to 1997.

RESULTS

There were 1,051 flexible bronchoscopy procedures performed in which the patient had a known FEV(1) and was not receiving supplemental oxygen before the procedure. Supplemental oxygen was commenced during or immediately after the procedure in 151 cases (14.4%), while a further 101 cases (9.6%) had momentary desaturation (ie, < 20 s) not requiring oxygen therapy. The lower the FEV(1), the greater the risk of significant desaturation and the need for supplemental oxygen (p < 0.0001) [supplemental O(2) therapy was administered in 35% of cases if FEV(1) < 1.0 L, in 14% of cases if FEV(1) was 1.0 to 1.5 L, and in 7% of cases if FEV(1) > 1.5 L]. The use of low-to-moderate doses of midazolam as sedation did not affect the probability of the occurrence of significant desaturation (p = 0.204).

CONCLUSIONS

This study supports guidelines that suggest that all patients should be monitored by pulse oximetry during flexible bronchoscopy. Desaturation may occur at any FEV(1) level even without sedation. The majority of our patients did not require routine oxygen supplementation, especially the group with an FEV(1) above 1 L.