Among the 37,872 ESAIC members who received the email, 9517 opened the link to the survey, 999 members at least started the survey, and 798 anesthesiologists, mainly from Europe and the Americas, representing 2.1% of the total number of ESAIC members, responded to the survey (Table 1). Most respondents were board-certified in anesthesiology (n = 759; 95.1%), but many of them held additional certifications in intensive care medicine, critical emergency medicine, and pain therapy. The most common double certification was anesthesiology/intensive care medicine (n = 379; 47.5%), followed by anesthesiology/critical emergency medicine (n = 120; 15.0%), and anesthesiology/pain therapy (n = 79; 9.9%). Most respondents worked in university hospitals, heart centres, or another type of tertiary care facility. Hospital size varied from ≥500 beds (n = 383; 49.3%), to 100 to 499 beds (n = 334; 41.9%), and < 100 beds (n = 63; 7.9%). The majority of respondents worked in hospitals with ≤20 operation rooms.

Table 1 Characteristics of participants who completed the surveyOxygen therapy in general

More than 70% (n = 559) of respondents stated that they do not use specific protocols or guidelines for oxygen therapy, regardless of geographical location, board certifications status, and types of primary institution (Table 2).

Table 2 Oxygen therapy in general practice - Not using specific protocols or guidelinesUse of oxygen in the perioperative setting

As shown in Fig. 1, approximately 42% (n = 335) of respondents were not familiar with the current recommendations of the WHO on SSI prevention by perioperative oxygen therapy [8], while 13.8% (n = 110) knew but do not agree with them, 2.9% (n = 23) have never followed those recommendations, and 12.4% (n = 99) claim that recent studies diverge from them. Yet, 23.7% (n = 189) of participants knew and agreed with the recommendations.

Fig. 1

Respondent’s knowledge and acceptance of the recent guidelines of the World Health Organization

For induction of anesthesia, an FiO2 of 100% was preferred by the majority of respondents, but approximately one third of participants selected FiO2 between 80 and 100% (Fig. 2).

Fig. 2

Preferred inspiratory oxygen fraction (FiO2) for induction of anaesthesia

During maintenance of general anesthesia, the majority of respondents (n = 379; 47.5%) preferred FiO2 of 40–60%, followed by FiO2 of 21–40% (n = 295; 37.0%), with less than 10% (n = 81) of participants using FiO2 ≥ 60%.

During the emergence period, FiO2 between 80 and 100% was preferred by approximately 35% (n = 275) of participants, followed closely by FiO2 of 100% (n = 268; 33.8%). Analysis of FiO2 use for induction, maintenance, and emergence per geographical region is reported in an additional file in more detail (see Additional file 2). For induction of anesthesia, proportions were similarly distributed. During maintenance, FiO2 of 100% was selected statistically more often in Africa than in other regions. During emergence, 100% FiO2 was selected more often in South-East Asia and less frequently in Europe and Eastern Mediterranean regions.

More than the half of respondents replied also that supplemental oxygen is inconsistently used, that is, only sometimes (n = 220; 27.6%) or rarely (n = 217; 27.2%), when transferring patients from the operation room to the post-anesthesia care unit (PACU), as well as from the PACU to surgical wards (sometimes, n = 290; 36.3%; rarely, n = 301; 37.7%). While 37.7% (n = 301) claimed they do not distinguish between patients with diseased vs. non-diseased lungs regarding FiO2, 30.0% (n = 239) of the respondents preferred higher FiO2 and 24.2% (n = 193) used lower FiO2 during anesthesia.

Approximately 56% (n = 447) of all respondents recommended oxygen therapy postoperatively in the post-surgery ward depending on actual peripheral oxygen saturation (SpO2), while 19.8% (n = 158) prescribed this therapy for high-risk patients only, 8.7% (n = 69) recommend supplemental oxygen regularly, and 2.6% (n = 21) advocated it in patients who required proportionally high doses of opioids. Roughly 2% (n = 18) never recommend oxygen in the post-surgery ward.

Yet, 66.7% (n = 532) of respondents considered the monitoring of SpO2 during administration of oxygen in the ward mandatory, irrespective of risk. However, only 54.5% (n = 435) of participants informed that SpO2 is monitored regularly in all post-surgery patients, while 27.4% (n = 219) reported that their institutions monitor SpO2 in high-risk patients only. Among all respondents, 53.6% (n = 428) stated that SpO2 data is also documented in intervals in patient’s records when oxygen is administered in the post-surgery ward, while only 14.2% (n = 113) informed that those data are recorded automatically. Approximately 5% (n = 38) stated that their institutions never document SpO2 while administering oxygen in post-surgery wards. The main reason for not monitoring SpO2 postoperatively on wards was lack of devices (n = 389; 48.8%), followed by increased workload for nurses (n = 178; 22.3%), which was statistically similar between the analysed geographical regions, as shown in more detail in an additional table (see Additional file 3).

For roughly 31% (n = 249) of participants, supplemental oxygen therapy on the surgical ward should be prescribed upon patients’ comorbidities, while 14% (n = 112) of those colleagues did not guide oxygen therapy based on SpO2 thresholds. Physicians who used SpO2 to guide the decision on oxygen therapy more frequently, reported a preferred SpO2 threshold of 92% (n = 164; 20.6%), followed by 90% (n = 100; 12.5%), 95% (n = 67; 8.4%), and 85% (n = 21; 2.6%).

Use of oxygen in critical emergency medicine

The majority of respondents (n = 540; 67.7%) considered that supplemental oxygen reduces the risk of death in critical emergency medicine, while 9.3% (n = 74) claimed the opposite. In critical emergency patients aged ≥80 years, approximately 83% of physicians used supplemental oxygen, i.e. sometimes (n = 264; 33.1%), usually (n = 233; 29.2%), or almost always (n = 167; 20.9%).

Patients who presented with respiratory distress were treated almost always (n = 453; 56.8%), usually (n = 189; 23.7%), or sometimes (n = 40; 5.0%) with supplemental oxygen by participants in this survey.

In patients presenting with chronic obstructive pulmonary disease (COPD), more than 79% (n = 632) of respondents would use supplemental oxygen (sometimes, n = 343, 43%; usually, n = 188, 23.7%; almost always, n = 101, 12.66%).

In patients with acute myocardial infarction, supplemental oxygen was used almost always, sometimes, or usually by 42.0% (n = 335), 21.7% (n = 173), and 14.8% (n = 118) of respondents, respectively. In patients with stroke being treated by respondents, a similar pattern to myocardial infarction was reported (almost always, n = 260, 32.6%; sometimes, n = 199, 24.9%; usually, n = 173, 21.7%).

Respondents considered supplemental oxygen significantly less frequently in critical emergency patients presenting with any other than the following conditions ≥80 years old, respiratory distress, COPD, myocardial infarction, and stroke: Rarely, 22.0% (n = 151) and never, 3.1% (n = 21), whereas only 6.5% (n = 52) almost always administer oxygen to these patients (p < 0.001 for any other conditions vs. each of the afore-mentioned).

Use of oxygen in intensive care medicine

Approximately 26% (n = 209) of respondents stated they administer supplemental oxygen independently from SpO2 in spontaneously breathing ICU patients with healthy lungs, especially in high risk patients, while 51.4% (n = 410) supplied oxygen under a certain target SpO2. In these patients, SpO2 was mainly targeted at 94–96% (n = 214; 26.8%), closely followed by 92–94% (n = 174; 21.8%), 90–92% (n = 105; 13.2%), 97–100% (n = 65; 8.2%), and 88–90% (n = 31; 3.9%).

Figure 3 shows SpO2 targets in mechanically ventilated ICU patients. Most participants preferred targeting SpO2 at 92–96% in patients with healthy (n = 375; 47.0%) as well as non-healthy (n = 268; 33.6%) lungs. The second-preferred SpO2 target was 97–100% in patients with healthy lungs (n = 161; 20.2%), but 88–92% in patients with non-healthy lungs (n = 263; 33.0%). Less than 10% of participants reported they do not guide oxygen therapy according to SpO2 in this sub-population, independently of lung disease. According to the participants, SpO2 targets were reached in their ICUs most of the time (n = 462; 57.9%), sometimes (n = 133; 16.7%), or always (n = 35; 4.4%).

Fig. 3

Target SpO2 in mechanically ventilated patients with healthy (panel A) and diseased lungs (panel B)

More than half of the respondents (n = 441; 55.3%) were concerned about both hyperoxemia and hypoxemia in ICU patients. Nearly 15.0% (n = 120) feared rather hypoxemia and 8.8% (n = 70) are more afraid of hyperoxemia, whereas 2.9% (n = 23) had no major concerns regarding extremes of oxygen therapy. While arterial partial pressure of oxygen (PaO2) was used to detect hyperoxemia by more than 50% (n = 408) of participants, approximately 40% (n = 316) would rely on both SpO2 and PaO2 to detect hypoxemia. Yet, most respondents preferred monitoring oxygen treatment with PaO2 (n = 396; 49.6%), followed by SpO2 (n = 171; 21.4%), and arterial oxygen saturation (SaO2) (n = 80; 10.0%) in the ICU.

Awareness about oxygen toxicity

Approximately 55% (n = 436) of participants considered that FiO2 of 100% applied > 4 h can be toxic to the central nervous system, while 31.3% (n = 250) were concerned when using FiO2 of 80% for > 8 h. Virtually 35% (n = 279) believed that oxygen can be toxic at any concentration higher than normal under atmospheric pressure conditions.

Less than 13% (n = 100) of the participants in the survey saw a potential for lung toxicity when FiO2 is kept below 50%, but the percentage of physicians concerned about this harmful effect increased to 28.9% (n = 231), 48.0% (n = 383), and 66.5% (n = 531) when FiO2 of 60, 80, and 100% were used, respectively.

The main potential side effects of FiO2 > 50% in adults that respondents were concerned about were formation of atelectasis (n = 564; 70.7%), followed by degradation of lung surfactant (n = 419; 52.5%), decline in vital capacity (n = 384; 48.1%), and epigastric pain (n = 43; 5.4%). Yet, in preterm newborns, retinopathy, retrolental fibroplasia, bronchopulmonary dysplasia, and nephrotoxicity, were identified as possible complications of high oxygen therapy by 57.8% (n = 461), 53.5% (n = 427), 50.3% (n = 401), and 7.5% (n = 60) of participants, respectively.

Devices for administration of oxygen

Table 3 summarises the devices used to administer oxygen, as addressed in the survey. The five most frequently used devices by respondents within the last 4 weeks preceding survey completion were anesthetic facemask (n = 615), followed by nasal cannula (n = 612), simple facemask/‘Hudson’ mask (n = 543), ICU ventilators (n = 475), and resuscitation bag with mask (n = 453), respectively.

Table 3 Devices for oxygen administration used within four weeks prior to completing the survey