Year : 2023 | Volume
| Issue : 1 | Page : 12-17
Simulating high-fidelity emergency front-of-neck access: Training in an obstetric setting
Mai O'Sullivan1, Sarah Gaffney2, Ross Free3, Stephen Smith3
1 University Hospital Galway, Galway, Ireland
2 Saint James's Hospital, Dublin, Ireland
3 Coombe Womens and Infants University Hospital, Dublin, Ireland
University Hospital Galway, Newcastle Road, Galway, H91 YR71
Source of Support: None, Conflict of Interest: None
|Date of Submission||05-Jul-2022|
|Date of Acceptance||13-Jul-2022|
|Date of Web Publication||02-Jan-2023|
Introduction: In a cannot intubate, cannot oxygenate scenario (CICO), emergency front of neck access (eFONA) is the final lifesaving step in airway management to reverse hypoxia and prevent progression to brain injury, cardiac arrest and death. The Difficult Airway Society (DAS) guidelines advise the scalpel cricothyroidotomy method for eFONA. Anatomical and physiological changes in pregnancy exacerbate the already challenging obstetric airway. We aim to assess the impact made by introducing formal eFONA training to the perioperative medicine department of an obstetric hospital.
Methods: Ethical approval and written informed consent were obtained. 17 anesthetists participated, (two consultants, one senior registrar, four registrars and eight senior house officers). Study design was as follows: Initial participant survey and performance of a timed scalpel cricothyroidotomy on Limbs & Things AirSim Advance X cricothyroidotomy training mannikin. Difficulty of the attempt was rated on a Visual Analogue Scale (VAS). Participants then watched the DAS eFONA training video. They then re-performed a scalpel cricothyroidotomy and completed a repeat survey. The primary endpoint was duration of cricothyroidotomy attempt, measured as time from CICO declaration to lung inflation confirmed visually. After a three-month period, participants were reassessed.
Results: Four anesthetists had previous eFONA training with simulation, only one underwent training in the previous year. The mean time-to-lung inflation pre-intervention was 123.6 seconds and post-intervention was 80.8 seconds. This was statistically significant (p = 0.0192). All participants found training beneficial. Mean improvement of VAS was 3. All participants' confidence levels in identifying when to perform eFONA and ability to correctly identify anatomy improved. On repeat assessment, 11/13 participants successfully performed a surgical cricothyroidotomy, mean improvement from first attempt was 12 seconds (p = 0.68) which was not statistically significant.
Conclusion: This method of training is an easily reproducible way to teach a rarely performed skill in the obstetric population.
Keywords: Airway, eFONA, obstetric
|How to cite this article:|
O'Sullivan M, Gaffney S, Free R, Smith S. Simulating high-fidelity emergency front-of-neck access: Training in an obstetric setting. Saudi J Anaesth 2023;17:12-7
|How to cite this URL:|
O'Sullivan M, Gaffney S, Free R, Smith S. Simulating high-fidelity emergency front-of-neck access: Training in an obstetric setting. Saudi J Anaesth [serial online] 2023 [cited 2023 Mar 31];17:12-7. Available from: https://www.saudija.org/text.asp?2023/17/1/12/364861
| Introduction|| |
The defining feature of anesthetists is their expertize in management of the airway. While airway complications are rare, they are among the most life-threatening in medicine. The incidence of failed intubation is ~1: 2000 in the elective setting, ~1:300 in rapid sequence induction (RSI) in the obstetric setting and ~1:50-100 in the emergency department, pre-hospital setting, and intensive care unit. While a 'can't intubate, can't oxygenate' (CICO) situation occurs in less than 1:5,000 routine general anesthetics and requires an emergency surgical airway in ~1 in 50,000, it is associated with significant morbidity. Preparedness of both the individual and the institution are required to avoid airway complications. This involves careful assessment, planning, good judgment, teamwork, and communication. Some important components of preparation include knowledge and use of a range of techniques and devices, as well as a willingness to change or stop performing techniques when they are failing. In the event of a CICO scenario, correctly performed emergency cricothyroidotomy can be life-saving. However, as it is infrequently performed, there can be a lack of training and proficiency for this technique.
Planning for the event of difficult airway management is recommended by the Difficult Airway Society and the Obstetrics Anaesthetists' Association. In their most recent adult and obstetric guidelines (2015), a stepwise approach to airway management is described. 'Plan D' or a scalpel cricothyroidotomy is the suggested management in a CICO scenario. The recommended technique uses a 10-blade scalpel, bougie and a size 6 cuffed endotracheal tube. As CICO scenarios necessitating progression to emergency front of neck access are rare, it is difficult for anesthetists to train for this eventuality in day-to-day practice. Simulated environments provide an opportunity for anesthetists to practice this core skill, as unfamiliarity with equipment has been quoted as a likely contributing factor to the poor outcomes associated with CICO scenarios.,
The 2011 NAP 4 report of major complications of airway management in the United Kingdom provided recommendations for institutions to improve their preparedness for such events. It was advised that all anesthetists be trained in emergency cricothyroidotomy and subsequent maintenance training be undertaken., Simulator-based training has been demonstrated to improve adherence to CICO algorithms. However, skill retention in the technique has been shown to deteriorate six-to-nine months following initial training.
The obstetric airway presents further challenges to the anesthetist, in part arising from the normal physiological changes that occur during pregnancy., Parturients' reduced functional residual capacity (FRC) and expiratory reserve volume (ERV) lead to more rapid desaturation during apnoea., Elevated intra-gastric pressures predispose to greater risk of aspiration. Tracheal intubation can also be complicated by mucosal hyperaemia and enlarged breast tissue. Kodali et al. have shown that Mallampati scores can increase by one grade in up to 33% of women from pre- to post-labor, and up to two grades in 5%. With a failed intubation rate of 1:300 at RSI, the obstetric airway is proven to cause difficulty. Therefore, we must carefully plan airway management strategies and prepare for the rare event of failure in this unique population.
Our institution sought to implement the National Audit Project 4 (NAP 4) recommendations regarding eFONA training in a tertiary obstetric hospital in the Republic of Ireland, with approximately 8,500 births per year.
| Methods|| |
A 'before' and 'after' study design [Figure 1] was conducted in the Coombe Women and Infants University Hospital's perioperative medicine department. Ethical approval was obtained from the local ethics committee. Funding was obtained from the 'Friends of the Coombe Trust' to purchase a TruCorp 'AirSim® Advance X' airway management trainer [Figure 2]. Participants consisted of members of the perioperative medicine department with varying levels of experience from novice trainee to consultant anesthetist, totaling 17 individuals. Recruitment occurred during departmental teaching sessions and participation was voluntary. Written and informed consent was obtained.
At commencement of the study protocol [Figure 1], participants completed a paper-based 'pre-intervention questionnaire' in which they were asked about their level of experience, details of any formal eFONA training in the previous 12 months, what form of training model was used for such training, and whether they had encountered a CICO situation in their clinical practice. They were also rated their level of confidence in identifying the need for eFONA in a patient, and level of confidence in performing a surgical cricothyroidotomy in the presence of a palpable thyroid and cricoid cartilage.
Following completion of the questionnaire, participants were brought to a simulated operating theatre. They were familiarized with the airway trainer and standardized equipment available (scalpel, bougie, size 6 cuffed endotracheal tube, and self-inflating bag). They were provided with a standardized airway assistant. The participant was placed at the head of the airway trainer and informed that they could not intubate or oxygenate a patient and asked to perform a scalpel cricothyroidotomy. Primary outcome of the study was time-to-successful ventilation measured from declaration of CICO to successful inflation of the manikin's lungs. A failed attempt was defined as an attempt where successful ventilation did not occur or successful ventilation took over >240 seconds to perform. At the end of the attempt, each participant scored the ease of performance of the technique using a visual analogue scale (VAS). This consisted of a 10 cm line anchored by two descriptors, 0 = “Extremely Difficult” and 10 = “Extremely Easy”. A new skin collar and larynx was used with each participant so that previous participants' attempts did not confound results.
The intervention/airway training was as follows: Each participant watched a standardized 7 minute DAS eFONA training video which is freely available on the DAS website. Following this, participants repeated the proforma above. Time to successful ventilation was recorded and ease of the attempt was measured on the VAS. A post-simulation questionnaire was performed in which participants were asked to rate their confidence identifying when eFONA is required, preparedness post-intervention to perform a cricothyroidotomy if required and whether they found training to be beneficial. Confidence performing surgical cricothyroidotomy post-training was assessed. Participants were also asked if they felt regular six-monthly eFONA training was warranted in an obstetric hospital.
A sample of the participants was re-tested at three months. The study protocol was repeated and ease of performance was again measured using VAS. They were also asked to rate their confidence in performing a scalpel cricothyroidotomy in a real scenario.
Data was analysed using SPSS.
| Results|| |
17 anaesthetists participated, participants consisted of 4 consultants, 1 specialist registrar, 4 registrars, and 8 senior house officers. The mean experience of participants was 4.9 years.
One participant had received eFONA training in the previous six months. 29.4% of participants had received previous eFONA training, all had used a plastic mannikin in training sessions. No participant had previously performed a cricothyroidotomy on a patient or encountered a CICO scenario. When asked about confidence identifying the need for eFONA, 7/17 were very unconfident, 4/17 were confident and 6/17 were neither confident or unconfident. Confidence levels performing eFONA in the presence of palpable landmarks was as follows: 7/17 very unconfident, 2/17 unconfident, 7/17 neither confident or unconfident, and 1/17 was confident.
Performance of surgical cricothyroidotomy
In the first simulated CICO scenario (pre-intervention), 14 (82%) participants successfully ventilated the mannikin in <240 seconds. This increased to 16 (94.1%) post-intervention. The mean time to lung inflation pre-intervention was 123 seconds (SD 69.4) and post-intervention was 76 seconds (SD 46.3), this finding was statistically significant with a P value of 0.0192 using a paired t-test. Mean VAS pre-intervention was 4.13 (±2) which increased to 7.47 (±1.5), with a mean increase of 3.33. This was a statistically significant improvement with P < 0.0001. The cricothyroid membrane was correctly identified by 47% of participants pre-intervention, this was unchanged post-intervention.
All participants (17/17) felt that their confidence identifying when eFONA is required improved. 16 (94.1%) participants felt their preparedness to perform eFONA was improved post-intervention. 100% of participants found training to be beneficial and all felt that training should occur six monthly in our institution. 2 felt very confident in their ability to perform eFONA going forward, 11 were confident, 3 were neutral and 1 was very unconfident. The very unconfident outlier was the participant who was unsuccessful in achieving lung inflation within 240 seconds. This was remediated with further training outside of study protocol.
Following a three month interval, 13 anesthetists participated in the reassessment; 2 consultants, 1 specialist registrar, 2 registrars, and 8 senior house officers. 11 participants successfully ventilated the mannikin (84.6%). 2 participants' attempts lasted >240 seconds, one registrar and one senior house officer [Figure 3]. In those who successfully ventilated the mannikin at three months, mean time to lung inflation was 80.18 (SD 41.31). Time to successful ventilation during participants' first attempts was compared with repeat assessment at three months, the mean improvement was 12 seconds (p = 0.68). Of note, two of the participants who failed to ventilate the mannikin within 240 seconds had previously done so successfully. If these participants are excluded, a mean improvement of 38.72 seconds is seen in those who successfully ventilated the mannikin (p = 0.183), which was not statistically significant.
|Figure 3: Comparison of time from CICO declaration to lung inflation in participants between attempts 1, 2, and 3|
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On analysis of VAS from repeat assessment, the mean was 6.69 (SD = 2.59). There was a mean VAS improvement of +2.46 at the time of repeat assessment [Figure 4]. Confidence performing eFONA was similar at the time of reassessment to the time of completion of training [see [Figure 5]] with 1 participant very confident, 7 (53.8%) reporting confidence and 5 (38.4%) of participants being neither confident nor unconfident.
|Figure 4: Comparison between VAS scores in participants between attempt 1, attempt 2, and attempt 3 at scalpel cricothyroidotomy. 0 = “Extremely Difficult” and 10 = “Extremely Easy”|
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|Figure 5: Comparison of participant's confidence in performing eFONA. 5 = 'Very Confident', 4 = 'Confident'|
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| Discussion|| |
This study demonstrates that cricothyroidotomy time and success improved following a blended learning approach using both didactic instruction in the form of a standardized video and simulation-based training. Participants' confidence performing this procedure also improved following training.
Cricothyroidotomy is a life-saving skill in a CICO scenario. While improvements in equipment and airway management techniques have reduced the incidence of emergency cricothyroidotomy, it remains an important skill that must be learned by every airway practitioner. Poor education and training were identified as contributory factors to serious airway events in NAP 4. The training format described has been shown to aid participants' ability to identify when surgical cricothyroidotomy is indicated, as well as highlighting the time-sensitive nature of a CICO scenario to participants. It also serves to implement the DAS recommendation that CICO training be undertaken at six monthly intervals by anesthetists in our institution.
The obstetric airway presents its own unique challenges, rendering training in this setting of particular importance. The increased incidence of difficult and indeed failed intubation in this cohort may be partly explained by the presence of isolated junior staff performing the procedure out of hours, however this alone does not explain the challenges faced. There has also been a decrease in trainee exposure to general anesthesia in the obstetric patient., Physiological and anatomical changes in pregnancy may further contribute to the level of difficulty; increased breast size can obstruct insertion of the laryngoscope and airway mucosal oedema can worsen the view at laryngoscopy – particularly in the presence of pre-eclampsia. In addition to this, the airway changes throughout labor and delivery, with changes in Mallampati, oral volume and pharyngeal area having been well-described. With a known failure rate of 1/300 intubations in this population, anesthesia training and institutional preparedness for CICO scenarios is of utmost importance to ensure good outcomes in this population.,
Another important consideration is the challenges presented as a result of the physiological adaptations in pregnancy. At term, oxygen consumption and basal metabolic rate increase by up to 21% and 14%, respectively. FRC is also reduced in pregnancy., This combined with the increase in oxygen consumption, lowers oxygen reserves in parturients, leading to rapid desaturation during apnoea. The emphasis on pre-oxygenation in this population cannot be overstated, with both mother and fetus at risk of hypoxic encephalopathy in the event of hypoxia. In the adult population, when hypoxia occurs but cerebral blood flow is maintained, irreversible neuronal damage may occur within 4-15 minutes, depending on the degree and abruptness of the insult. In the event of hypoxia and ischaemia, irreversible neuronal damage can occur within 1-4 minutes. These time frames have not been extrapolated to the obstetric population; however, the message that 'time is brain' could not be more clear. Therefore, in training any airway practitioner to perform eFONA, procedural time must be emphasized alongside practical skills. Procedural time for scalpel cricothyroidotomy, when indicated, is advised to occur within 3-4 minutes. The outside limit of this is 240 seconds, which is the rationale behind choosing this timeframe as a cut-off in our study.
Identification of an optimal training interval is challenging. While the DAS recommend six monthly intervals, we noted decay in skillset among our small cohort within three months. Two participants who had previously successfully ventilated the mannikin successfully following training were unable to complete a scalpel cricothyroidotomy within 240 seconds at three months. Overall success rate fell from 94.1% to 84.6% between attempts 2 and 3, over a short period of time, well within the current recommended training period. Time to successful ventilation improved by only 12 seconds between attempt 1 and attempt 3. This swift decline in proficiency further demonstrates the challenges of deciding upon an optimal training interval.
While no interval may be optimal, one must be decided upon at a departmental level to implement this important training. Once this is determined, training programs such as ours require time, resources, and manpower to execute. In our institution, there is a turnover of junior staff at six-monthly intervals. This offers a natural waypoint for re-training of permanent staff and training junior anesthetists. It presents the question whether difficult airway courses where skills such as scalpel cricothyroidotomy and fibreoptic intubation should become mandatory, with anesthetists undergoing regular re-certification, as is the case with advanced cardiac life support (ACLS) which occurs twice yearly. This concept was previously explored by Baker et al. who felt that such lifelong learning throughout one's career should be seen as an ethical obligation by practising anesthetists.
Although many experience such events infrequently, anesthetists are well-placed to lead in a CICO scenario. Aintree University Hospital conducted a study in which 45 consultants from anesthesia, head and neck and general surgery departments participated in a high-fidelity simulation scenario in which a surgical airway was required in a CICO scenario. Primary outcome observed was time to ventilation. 44/45 consultants succeeded; however, anesthetists were significantly faster at achieving ventilation than general surgeons. A unique feature in the department in question is that all anesthetists were required to complete mandatory six-monthly eFONA training, and all participants were up to date. In comparison, the average time since general surgeons had practised the technique was 14 years. This further supports the doctrine that anesthetists regularly trained in eFONA should feel empowered to lead this procedure in the event of CICO scenarios. An area where this is of particular relevance is the standalone obstetric unit or peripheral hospital, where only general surgical colleagues are available. One such unit is our institution, where the only other speciality available for assistance with a surgical airway is obstetrics, many of whom have had no exposure to surgical airways in their training. For this reason, it will be mandatory for members of our anesthesia department to participate in six-monthly training. Going forward, there may be a role for multidisciplinary training in which our obstetric/nursing colleagues are trained alongside airway practitioners; however, this was outside the scope of our study.
The training modality we describe is easily implementable in any department. While initial setup costs required for the purchase of the manikin are not insignificant, the cost of consumables is low. Replacement larynxes and artificial skin pads would be required over time, however airway equipment such as a size 10 blade, bougie, size 6 cuffed endotracheal tube, and self-inflating bags are readily available within anesthesia, ICU, and emergency departments. Access to the training video is free of charge.
Our study is not without limitations. We describe a small sample size, limited by the small size of our department. This study was performed on a manikin model, not humans or cadavers. Human trials are difficult to conduct as the procedure is rarely performed, and is usually undertaken in emergency circumstances. As such, complications of this procedure that would be seen in human subjects, such as bleeding or oedema, are not accounted for. An emergency cricothyroidotomy is normally performed under extremely stressful circumstances and this environment is difficult to replicate in a simulated environment. Participants may have had increased familiarity with the manikin on their second and third attempts, potentially contributing to faster time to lung inflation. The AirSim® Advance X trainer has palpable landmarks (thyroid and cricothyroid cartilage) facilitating a stab approach that may not be possible in an obese patient, parturient, or other such patients with impalpable landmarks. Finally, no decision-making was required by participants in this study, only the participants' dexterity performing the skill. Non-technical and psychological skills in difficult airway management were not addressed in this study.
To conclude, front of neck access training on manikins led to improvements in cricothyroidotomy times and success rates. On their third attempt, following a three-month period 84.6% participants successfully performed a scalpel cricothyroidotomy in under 195 seconds. We advise that anesthetists working in obstetric hospitals be trained in emergency front of neck access and offer a reproducible method to carry out such training. The most appropriate training interval has not been determined for optimal skill retention; however, we demonstrate that skills are not retained by all participants within a six-month period.
Consent to participate
Patients' consent form: Available on request.
Obtained from SJH/TUH Joint Research Ethics Committee.
Financial support and sponsorship
1500 euro from 'Friends of the Coombe Trust' for the purchase of equipment.
Conflicts of interest
There are no conflicts of interest.
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