Difficult airway management resources and capnography use in Japanese intensive care units: a nationwide cross-sectional study

This nationwide cross-sectional study was conducted from September 2015 to February 2016. After approval by the institutional review boards of Fukushima Medical University (No. 2521), self-administered questionnaires were mailed to the directors of all ICUs (289 hospitals in 47 prefectures) registered as certified training facilities by the Japanese Society of Intensive Care Medicine (JSICM) in November, 2015. A complete list of these hospitals is available at: http://​www.​jsicm.​org/​senmon/​sisetu_​all.​html (in Japanese, accessed 7 February 2016). The criteria for a JSICM-certified ICU include: (1) an independent, central clinical division of the facility; (2) one or more dedicated JSICM board-certified intensivists on staff; and (3) more than four critical care beds (http://​www.​jsicm.​org/​pdf/​senmon_​sinsaisoku2016.​pdf, in Japanese, accessed 24 March 2016). JSICM-certified ICUs constitute approximately half of all critical care beds in Japan.

When selecting items in the questionnaire, we referred to previous studies conducted in other countries and addressing both similar settings (ICUs [20‐24], ORs [25‐28], and emergency departments [29‐31],) and different settings (pre-hospital emergency medical services [32‐34], and obstetrical units [35‐37]).

An English version of the Japanese questionnaire used in this study is available in the supplementary material (Online Resource 1). Survey items consisted of basic information regarding the numbers of hospital beds, ICU beds, annual ICU admissions in 2014, the types of ICU, and the availability of the following materials in the ICU: (1) direct laryngoscope and adjunct equipment (curved blade, straight blade, McCoy laryngoscope, stylet, gum elastic bougie, tube exchanger catheter, and local anesthetic spray); (2) alternate intubation equipment (rigid video laryngoscope, flexible fiberscope, retrograde intubation kit, and surgical airway equipment); (3) alternate ventilation equipment [supraglottic airway device (SGA), and oral and nasal airways]; (4) capnometry; (5) a portable packaged unit containing several DAM kits (DAM cart); and (6) neuromuscular blocking agents to facilitate endotracheal intubation and reversal agents (sugammadex, neostigmine, flumazenil, and naloxone). In this survey, we divided ICU types into (a) academic or community, (b) closed or not-closed, (c) high-volume or not, (d) emergency or surgical or other type including medical, mixed, and pediatric ICUs. Academic ICUs were defined as units in university-affiliated hospitals [38]. Closed ICUs were defined as units that transferred all patients to an intensive care team that directs patients’ care with primary responsibility for the therapeutic plan and patient care [39, 40]. Non-closed ICUs were defined as ICUs where the intensive care team provides expertise via elective or mandatory consultation without primary responsibility for the patient care [39, 40]. High-volume ICUs were defined as units in the upper tertile of annual patient admissions [38], and emergency ICUs were defined as units in which most patients were from an emergency room, and which were likely to receive patients suffering acute-onset medical conditions, or surgical illnesses including trauma, burns, intoxication, acute coronary disease, and stroke. We included coronary care units and stroke care units in the emergency category. Surgical ICUs were defined as units in which most patients were from ORs, and which were likely to provide post-operative intensive care.

The questionnaire also asked about the availability of direct laryngoscopes and alternate ventilation equipment in assorted sizes; the product name of the rigid video laryngoscopes and SGA used was also requested. Surgical airway equipment was categorized as a cricothyroidotomy kit, or a set containing a scalpel and hemostat. If capnometry was available, we asked whether: (a) capnometry was used to verify tube placement (routinely, sometimes, and never) [20], and (b) whether the ICU used continuous capnography monitoring for ventilator-dependent patients (routinely, sometimes, and never) [20]. If a dedicated DAM cart was present in the ICU, we asked respondents to specify the contents. We also requested information on: the usual number of on-duty staff ICU physician(s) during the day and overnight; whether in-house experienced (anesthetic or emergency medicine) back-up coverage can be called during overnight hours; and whether staff physicians were board-certified. We included senior residents (post-graduate year 3 or more) as staff ICU physicians, but not junior residents (post-graduate year 1 or 2). We deemed that “24-h in-house back-up coverage” was obtainable if: (a) two or more physicians were usually on duty, including overnight, or (b) in-house experienced back-up coverage was available overnight. Board-certified physicians were defined based on the Japanese Medical Specialty Board criteria (http://​www.​japan-senmon-i.​jp/​, in Japanese, accessed 7 February 2016). ICUs that did not respond to the initial survey were sent a repeat mailing on January 2016.

Outcomes of interest in this study were availability of: (1) 24-h in-house back-up coverage, (2) an SGA, (3) a DAM cart, (4) surgical airway equipment; and routine use of: (5) capnometry to confirm ETI, and (6) continuous capnography monitoring of ventilator-dependent patients. Of these, (1)–(4) are important DAM resources commonly endorsed by the JSA, ASA, and DAS airway management guidelines [10‐12]. The availability of “surgical airway equipment” was defined as a cricothyroidotomy kit or a scalpel and hemostat, present in the ICU.

During the planning of this study, we performed a power analysis using G*Power 3 for Windows (Heinrich Heine University, Düsseldorf, Germany). Because no previous study, to our knowledge, has examined the association between the type of ICU and DAM resources, we assumed an effect size using Cohen’s power table (Power primer) [41]. With an effect size, “w” of 0.3 (medium size [41]), 88 samples per group (total, 176) provided 80 % power at two-tailed α of 0.05.

Our results showed that only 55.6 % of ICUs routinely use capnometry for ETI verification, and the same percentage always monitor capnography in ventilator-dependent patients. However, this percentage was much higher than in previous studies conducted in other countries (Table 8). Our results suggest that ETCO₂ monitoring was successfully transferred from ORs to ICUs to a certain extent in Japan, but that there is still room for improvement.

The increased use of capnography in the ICU is the single change with the greatest potential to prevent deaths from airway complications in ICUs and elsewhere, outside the OR [14]. A national audit in the UK [8] found that failure to use capnometry in treating a difficult airway contributed to at least some of the fatal outcomes in ICUs. Jaber et al. [1] recently reported that after the introduction of an “intubation bundle” including the routine use of capnometry, ETI-related complications in critically ill patients were significantly reduced.

Displaced tracheostomy and tracheal tubes were the greatest cause of major morbidity and mortality in ICUs [8, 14]. In fact, failure to use capnography in ventilated patients likely contributed to more than 70 % of ICU deaths [8, 14]. Accordingly, further incorporation of ETCO₂ confirmation and continuous monitoring in Japanese ICUs would improve patient management by critical care medical staff.

In this study, an SGA was available in only 60.2 % of Japanese ICUs. In other nations, SGAs are available in 80–100 % of critical care departments (Table 8). Therefore, in Japan, SGAs have been undervalued as rescue ventilation devices in critical care settings. Our previous study found the same trend in the pre-hospital setting [16], which further supports this undervaluation. Each ICU must have back-up ventilation strategies [10‐12] because: (1) the consequences of failed intubation, especially in the ICU, can be devastating [8, 14]; and (2) airway difficulties are far more likely in the ICU than in the OR [2‐6]. Since the use of SGAs is well supported in rescue ventilation strategies [10‐12], the standardization of airway equipment, including SGAs, would be beneficial for Japanese ICUs.

Our survey results revealed that a dedicated DAM cart was present in 60.7 % of Japanese ICUs, and that the contents varied considerably. This percentage is smaller than previous reports (Table 8). In an ICU, the availability of a DAM cart may have an even greater impact than in the OR, because areas outside the OR, including critical care departments, may not otherwise have immediate access to equipment for airway management [24]. Generally, time is very limited in airway management of a critically ill patient, because these patients have very little physiological reserve. Therefore, every ICU should have immediate access to at least one DAM cart [8, 10‐12], which should have the same contents and layout as those used in that hospital’s OR [8]. Suggestions for the contents of DAM carts are in the JSA [10], ASA [11], and DAS [12] guidelines.

This study found a general trend showing that high-volume, closed, and academic ICUs had well-prepared DAM equipment. We also noted that capnometry was more likely to be used for ETI verification in closed ICUs, and continuous capnography monitoring was more likely in academic ICUs. It is well known that these types of ICUs have improved patient outcomes compared with other ICU types [38‐40, 42, 43]. Therefore, it is possible, at least in part, that having well-prepared DAM resources is responsible for improved outcomes. This fact, and our data, further support current recommendations that every ICU have DAM resources at the same level as that of hospital ORs [8, 13‐15]. We also observed that surgical ICUs were less likely to use capnometry for ETI verification, but we could not explain the reason for this finding, based on our survey results.

There are four major limitations to this study. First, we did not include non-JSICM certified ICUs, which comprise another 50 % of all critical-care beds in Japan. This is because a complete list of non-JSICM certified ICUs was not available. However, it is likely that DAM resources are less available and capnometry is used less often in non-JSICM-certified training facilities, because most such ICUs are not academic or closed units. Our recommendations regarding DAM resources and the use of capnometry can also be applied to non-JSICM-certified ICUs. Second, our survey did not determine the frequencies of difficult airways situations (i.e., cannot ventilate, cannot intubate), nor did our survey obtain information on the clinical protocols for DAM in Japanese ICUs. Third, because our questionnaire was self-administered, reporting bias is possible. Fourth, we did not clarify why SGAs and DAM carts were less available, nor why capnometry was under-used in Japanese ICUs. These points require further investigation. Despite these limitations, this study has several strengths. First, the response rate was quite high (196 of 289 surveyed ICUs responded), and our survey successfully captured the findings in various types of ICU from all geographic areas in Japan including closed, surgical, emergency, and other types. Our study provides an accurate depiction of the current state of advanced airway management in Japanese ICUs. Second, our findings provided the associations between ICU type, and DAM resources and the use of capnometry. To the best of our knowledge, this relationship has not been clarified previously. We believe that this study is a meaningful first approach to improve DAM in Japanese ICUs.

In conclusion, this nationwide cross-sectional study clarified the available DAM equipment in Japanese ICUs, as well as areas that warrant improving. Available best evidence clearly states that DAM resources in ICUs should be consistent with those in the OR [8, 13‐15], and the use of capnometry should meet the same standards that apply in the hospital’s OR [8, 13‐15]. Therefore, it would be helpful for many Japanese ICUs to standardize DAM equipment, including an SGA and a DAM cart, and to incorporate the routine use of capnometry into their clinical practices.