French pre-hospital physicians included the Easytube, which is similar to the Combitube, in their difficult airway algorithm. They describe the insertion method as:
“ ..inserted blindly, the patient’s head must be in neutral position. Manually opening the patient’s mouth and pressing the tongue gently toward the mandible, the tube is inserted parallel to the frontal axis of the patient until the proximal black ring mark is positioned at the level of the incisors. If the EzT is inserted blindly, the tip is likely to be positioned in the esophagus with a probability of more than 95% [3]. Ventilation of the patient should be performed using a colored lumen, and the transparent lumen can then be used to insert a gastric tube or to drain gastric contents.”
The authors suggest that the main advantages of the Ezt are: shorter insertion time for Ezt than for ETI, better protection against aspiration than a laryngeal mask and the possibility of blind insertion of the Ezt in patients trapped in a sitting position.
BACKGROUND: Securing the airway in emergency is among the key requirements of appropriate prehospital therapy. The Easytube (Ezt) is a relatively new device, which combines the advantages of both an infraglottic and supraglottic airway.
AIMS: Our goal was to evaluate the effectiveness and the safety of use of Ezt by emergency physicians in case of difficult airway management in a prehospital setting with minimal training.
METHODS: We performed a prospective multi-centre observational study of patients requiring airway management conducted in prehospital emergency medicine in France by 3 French mobile intensive care units from October 2007 to October 2008.
RESULTS: Data were available for 239 patients who needed airway management. Two groups were individualized: the “easy airway management” group (225 patients; 94%) and the “difficult airway management” group (14 patients; 6%). All patients had a successful airway management. The Ezt was used in eight men and six women; mean age was 64 years. It was used for ventilation for a maximum of 150 min and the mean time was 65 min. It was positioned successfully at first attempt, except for two patients, one needed an adjustment because of an air leak, and in the other patient the Ezt was replaced due to complete obstruction of the Ezt during bronchial suction.
CONCLUSION: The present study shows that emergency physicians in cases of difficult airway management can use the EzT safely and effectively with minimal training. Because of its very high success rate in ventilation, the possibility of blind intubation, the low failure rate after a short training period. It could be introduced in new guidelines to manage difficult airway in prehospital emergency.
The Easytube for airway management in prehospital emergency medicine
Resuscitation. 2010 Nov;81(11):1516-20
Tag Archives: RSI
Flying Docs and Airways
Flying Doctor Minh Le Cong describes the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team, comprising a doctor and flight nurse. It would be interesting to know how many more patients have been added to the registry since this was submitted. An important contribution to the literature in retrieval medicine.
Objective To describe the profile and success rates of emergency endotracheal intubation conducted by the Queensland Royal Flying Doctor Service aeromedical retrieval team comprising a doctor and flight nurse.
Method Each intubator completed a study questionnaire at the time of each intubation for indications, complications, overall success, drugs utilised and deployment of rescue airway devices/adjuncts.
Results 76 patients were intubated; 72 intubations were successful. None required surgical airway and three were managed with laryngeal mask airways; the remaining failure was managed with simple airway positioning for transport. There were two cardiac arrests during intubation. Thiopentone and suxamethonium were the predominant drugs used to facilitate intubation.
Conclusion Despite a low rate of endotracheal intubation, the high success rate was similar to other aeromedical organisations’ published airway data. This study demonstrates the utility of the laryngeal mask airway device in the retrieval and transport setting, in particular for managing a failed intubation.
Flying doctor emergency airway registry: a 3-year, prospective, observational study of endotracheal intubation by the Queensland Section of the Royal Flying Doctor Service of Australia
Emerg Med J. 2010 Sep 15. [Epub ahead of print]
Those interested in learning more about this registry, including how often capnography was used, more information about the asystolic arrests, and whether they tried a blind digital intubation, can check this link to a presentation about the registry.
Propofol and the heart
I don’t normally blog about animal studies, but on reading a review of recent(-ish) shock research I was interested in the following piece that describes the effect of diffrent induction agents on rat heart muscle:
Sedation is frequently necessary in patients with septic shock, and therefore Zausig and colleagues investigated the effects of dose-dependent effects of various induction agents (propofol, midazolam, s(+)-ketamine, methohexitone, etomidate) in a Langendorff heart preparation from rats rendered septic by CLP. Propofol exerted the most pronounced depressant effects on both the maximal systolic contraction and the minimal diastolic relaxation, and cardiac work. Furthermore, propofol only adversely deleteriously affected the myocardial oxygen supply- demand ratio. In contrast, s(+)-ketamine was associated with the best maintenance of cardiac function. Within the limits of the study – that is, the use of an ex vivo isolated organ model – the authors concluded that s(+)-ketamine may be an alternative to the comparably inert etomidate, the use of which is, however, limited due to its endocrine side effects.
Of course we should be cautious about extrapolating animal lab work to clinical practice, but this supports my position of vehement opposition to the injudicious use of propofol for RSI in critically ill patients!
Year in review 2009: Critical Care – shock
Critical Care 2010, 14:239 Full text
Sux vs Roc in ED RSI
Suxamethonium and rocuronium were compared in a database of prospectively recorded cases of RSI in the emergency department.
A total of 327 RSI were included in the final analyses. All patients received etomidate as the induction sedative and were successfully intubated. Of these, 113 and 214 intubations were performed using succinylcholine and rocuronium, respectively.
- The rate of first-attempt intubation success was similar between the succinylcholine and rocuronium groups (72.6% vs. 72.9%, p = 0.95).
- Median doses used for succinylcholine and rocuronium were 1.65 mg/kg (interquartile range [IQR] = 1.26–1.95 mg/kg) and 1.19 mg/kg (IQR = 1–1.45 mg/kg), respectively.
- The median dose of etomidate was 0.25 mg/kg in both groups.
In this study succinylcholine and rocuronium were equivalent with regard to first-attempt intubation success in the ED. This finding is consistent with previous investigations that used doses between 0.9 and 1.2 mg/kg and found similar intubating conditions to succinylcholine at these higher doses; subgroup analyses of studies using a lower rocuronium dose of 0.6 to 0.7 mg/kg had a relative risk favoring succinylcholine for excellent intubating conditions.
The low (in my view) rate of first-attempt intubation success in both groups was (72.6% vs. 72.9%), does make one wonder whether the intubating clinicians optimised their strategy for first-pass success.
Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department
Acad Emerg Med. 2011;18:11-14
Intubating spinal patients – the haemodynamics
Laryngoscopy and tracheal intubation transiently increase arterial pressure, heart rate (HR), and circulating catecholamines, in part attributed to reflex sympathetic discharge. In a complete spinal cord injury, the sympathetic nervous system and hence the cardiovascular responses to the intubation may be differentially affected according to the level of injury. Patients with acute quadriplegia often have a low resting arterial pressure due to inappropriate vasodilatation and loss of cardiac inotropy. Moreover, they frequently exhibit arrhythmias, reflex bradycardia, and cardiac arrest, especially during tracheal suction. In the days to weeks after injury, however, the reflex functioning of the lower cord recovers to maintain normal vascular tone. In the chronic stage, peripheral vascular changes and a loss of descending inhibitory control result in paroxysmal hypertension.
Korean investigators KY Yoo and colleagues1 aimed to determine the effect of the level (quadriplegia vs paraplegia) and duration of spinal cord injury on haemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with spinal cord injury. The outcome measures were the changes in systolic arterial pressure (SAP), HR, and catecholamine levels above awake baseline values after intubation.
Patients were divided into two groups: quadriplegia (above C7) and paraplegia (below T5). Each group was divided into six subgroups according to the time elapsed after the injury: <4 weeks (acute), 4 weeks– 1 yr, 1–5, 5–10, 10–20, and >20 yr. Twenty non-disabled patients undergoing surgery requiring tracheal intubation served as controls.
Patients with high-level paraplegia (T1–T4) were excluded because they were few in number and they had previously ‘shown different haemodynamic and catecholamine responses from the other groups‘ 2 which refers to work published by the same authors, in which high-paraplegic patients had a more pronounced increase in heart rate compared with other groups. Confusingly the ‘patients who were at increased risk of hyperkalemia after succinylcholine were excluded‘ although this statement appears only in the discussion, not the methods.
Anaesthesia was induced with sodium thiopental 5 mg/kg administered i.v. over 20 s, followed by succinylcholine 1 mg/kg for 5 s, and was followed by direct laryngoscopy and tracheal intubation.
Results were as follows:
The authors summarise: The pressor response was abolished in all quadriplegics regardless of the time elapsed after the injury. In contrast, the chronotropic and catecholamine responses differed over time. The chronotropic response was attenuated and the catecholamine response abolished in the acute quadriplegics. The chronotropic and catecholamine responses were improved in the quadriplegics after 4 weeks since the injury. In the paraplegic patients, cardiovascular responses did not change in the 10 yr after injury and the pressor response was enhanced at 10 yr or more after injury.
1.Altered cardiovascular responses to tracheal intubation in patients with complete spinal cord injury: relation to time course and affected level
Br J Anaesth. 2010 Dec;105(6):753-9
2. Hemodynamic and catecholamine responses to laryngoscopy and tracheal intubation in patients with complete spinal cord injuries.
Anesthesiolgy 2001; 95: 647–51
Paramedic RSI in Australia
A prospective, randomized, controlled trial compared paramedic rapid sequence intubation with hospital intubation in adults with severe traumatic brain injury in four cities in Victoria, Australia. The primary outcome was neurologic outcome at 6 months postinjury.
Training
Paramedics already experienced in ‘cold’ intubation (without drugs) undertook an additional 16-hour training program in the theory and practice of RSI, including class time (4 hours), practical intubating experience in the operating room under the supervision of an anesthesiologist (8 hours), and completion of a simulation-based examination (4 hours).
Methods
Patients included in the study were those assessed by paramedics on road ambulances as having all the following: evidence of head trauma, Glasgow Coma Score ≤9, age ≥15 years, and ‘intact airway reflexes’, although this is not defined or explained. Patients were excluded if any of the following applied: within 10 minutes of a designated trauma hospital, no intravenous access, allergy to any of the RSI drugs (as stated by relatives or a medical alert bracelet), or transport planned by medical helicopter. Drug therapy for intubation consisted of fentanyl (100μg), midazolam (0.1 mg/kg), and succinylcholine (1.5 mg/kg) administered in rapid succession. Atropine (1.2 mg) was administered for a heart rate <60/min. A minimum 500 mL fluid bolus (lactated Ringers Solution) was administered. A half dose of the sedative drugs was used in patients with hypotension (systolic blood pressure <100 mm Hg) or older age (>60 years).
Cricoid pressure was applied in all patients. After intubation and confirmation of the position of the endotracheal tube using the presence of the characteristic waveform on a capnograph, patients received a single dose of pancuronium (0.1 mg/kg), and an intravenous infusion of morphine and midazolam at 5 to 10 mg/h each. If intubation was not achieved at the first attempt, or the larynx was not visible, one further attempt at placement of the endotracheal tube over a plastic airway bougie was permitted. If this was unsuccessful, ventilation with oxygen using a bag/mask and an oral airway was commenced and continued until spontaneous respirations returned. Insertion of a laryngeal mask airway was indicated if bag/mask ventilation using an oral airway appeared to provide inadequate ventilation. Cricothyroidotomy was indicated if adequate ventilation could not be achieved with the above interventions. In all patients, a cervical collar was fitted, and hypotension (systolic blood pressure <100 mm Hg) was treated with a 20 mL/kg bolus of lactated Ringers Solution that could be repeated as indicated. Other injuries such as fractures were treated as required. In the hospital emergency department, patients who were not intubated underwent immediate RSI by a physician prior to chest x-ray and computed tomography head scan.
Follow up
At 6 months following injury, surviving patients or their next-of-kin were interviewed by telephone using a structured questionnaire and allocated a score from 1 (deceased) to 8 (normal) using the extended Glasgow Outcome Scale (GOSe). The interviewer was blinded to the treatment allocation.
Statistical power
A sample size of 312 patients was calculated to achieve 80% power at an alpha error of 0.05. Three hundred twenty-eight patients met the enrollment criteria. Three hundred twelve patients were randomly allocated to either paramedic intubation (160 patients) or hospital intubation (152 patients). A mean Injury Severity Score of 25 indicated that many patients had multiple injuries.
Success of intubation
Of the 157 patients administered RSI drugs, intubation was successful in 152 (97%) patients. The remaining 5 patients had esophageal placement of the endotracheal tube recognized immediately on capnography. The endotracheal tube was removed and the patients were managed with an oropharyngeal airway and bag/mask ventilation with oxygen and transported to hospital. There were no cases of unrecognised esophageal intubation on arrival at the emergency department during this study and no patient underwent cricothyroidotomy.
Outcome
After admission to hospital, both groups appeared to receive similar rates of neurosurgical interventions, including initial CT scan, urgent craniotomy (if indicated), and monitoring of intracranial pressure in the intensive care unit.
Favorable neurologic outcome was increased in the paramedic intubation patients (51%) compared with the hospital intubation patients (39%), just reaching statistical significance with P = 0.046. A limitation is that 13 of 312 patients were lost to follow-up and the majority of these were in the hospital intubation group. The authors do point out that the difference in outcomes would no longer be statistically significant whether one more patient had a positive outcome in the treatment group (P = 0.059) or one less in the control group (P = 0.061). The median GOSe was higher in the paramedic intubation group compared with hospital intubation (5 vs. 3), however, this did not reach statistical significance (P = 0.28).
More patients in the paramedic intubation group suffered prehospital cardiac arrest. There were 10 cardiac arrests prior to hospital arrival in the paramedic RSI group and 2 in the patients allocated to hospital intubation. Further detail on these patients is provided in the paper. The authors state that it is likely that the administration of sedative drugs followed by positive pressure ventilation had adverse hemodynamic consequences in patients with uncontrolled bleeding, and that it is possible that the doses of sedative drugs administered in this study to hemodynamically unstable patients were excessive and consideration should be given to a decreasing the dose of sedation.
Authors’ conclusions
The authors overall conclusion is that patients with severe TBI should undergo prehospital intubation using a rapid sequence approach to increase the proportion of patients with favorable neurologic outcome at 6 months postinjury. Further studies to determine the optimal protocol for paramedic rapid sequence intubation that minimize the risk of cardiac arrest should be undertaken.
Prehospital rapid sequence intubation improves functional outcome for patients with severe traumatic brain injury: a randomized controlled trial.
Ann Surg. 2010 Dec;252(6):959-65.
Victorian Ambulance Service protocols are available here, which include their current paramedic RSI protocol
Etomidate vs midazolam in sepsis
Given that single-dose etomidate can cause measurable adrenal suppression, its use in patients with sepsis is controversial. A prospective, double-blind, randomised study of patients with suspected sepsis who were intubated in the ED randomised patients to receive either etomidate or midazolam before intubation. The primary outcome measure was hospital length of stay, and no difference was demonstrated. The study was not powered to detect a mortality difference.
This study is interesting as a provider of fuel for the ‘etomidate debate’, but still irrelevant to those of us who have abandoned etomidate in favour of ketamine as an induction agent for haemodynamically unstable patients. Personally I remain unconvinced of the existence of patients who can’t be safely intubated using the limited choice of thiopentone or ketamine.
A Comparison of the Effects of Etomidate and Midazolam on Hospital Length of Stay in Patients With Suspected Sepsis: A Prospective, Randomized Study
Annals Emergency Medicine 2010;56(5):481-9
Rocuronium reusable after sugammadex
Sugammadex currently has no role in my own emergency / critical care practice. However a helpful paper informs us that patients whose rocuronium-induced neuromuscular blockade had been reversed by sugammadex may be effectively re-paralysed by a second high dose (1.2 mg/kg) of rocuronium. Onset was slower and duration shorter if the second dose of rocuronium was given within 25 minutes of the sugammadex.
The study was done with sixteen volunteers and the initial dose of roc was only 0.6 mg/kg – less than that used for rapid sequence intubation by many emergency & critical care docs.
When repeat dose roc was given five minutes after sugammadex (n=6), mean (SD) onset time maximal block was 3.06 (0.97) min; range, 1.92–4.72 min. For repeat dose time points ≥25 min after sugammadex (n=5), mean onset was faster (1.73 min) than for repeat doses <25 min (3.09 min) after sugammadex. The duration of block ranged from 17.7 min (rocuronium 5 min after sugammadex) to 46 min (repeat dose at 45 min) with mean durations of 24.8 min for repeat dosing <25 min vs 38.2 min for repeat doses ≥25 min.
Repeat dosing of rocuronium 1.2 mg kg−1 after reversal of neuromuscular block by sugammadex 4.0 mg kg−1 in anaesthetized healthy volunteers: a modelling-based pilot study
Br J Anaesth. 2010 Oct;105(4):487-92
Ketamine for HEMS intubation in Canada
Ketamine was used by clinical staff from the The Shock Trauma Air Rescue Society (STARS) in Alberta to facilitate intubation in both the pre-hospital & in-hospital setting (with a neuromuscular blocker in only three quarters of cases). Changes in vital signs were small despite the severity of illness in the study population.
A prospective review of the use of ketamine to facilitate endotracheal intubation in the helicopter emergency medical services (HEMS) setting
Emerg Med J. 2010 Oct 6. [Epub ahead of print]
Pre-hospital RSI by different specialties
This aim of the study was to evaluate the tracheal intubation success rate of doctors drawn from different clinical specialities performing rapid sequence intubation (RSI) in the pre-hospital environment operating on the Warwickshire and Northamptonshire Air Ambulance. Over a 5-year period, RSI was performed in 200 cases (3.1/month).
Failure to intubate was declared if >2 successive attempts were required to achieve intubation or an ETT could not be placed correctly necessitating the use of an alternate airway. Successful intubation occurred in 194 cases, giving a failure rate of 3% (6 cases, 95% CI 0.6 to 5.3%). While no difference in failure rate was observed between emergency department (ED) staff and anaesthetists (2.73% (3/110, 95% CI 0 to 5.7%) vs 0% (0/55, 95% CI 0 to 0%); p=0.55), a significant difference was found when non-ED, non- anaesthetic staff (GP and surgical) were compared to anaesthetists (10.34% (3/29, 95% CI 0 to 21.4%) vs 0%; p=0.04). There was no significant difference associated with seniority of practitioner (p=0.65). The authors conclude that non-anaesthetic practitioners have a higher tracheal intubation failure rate during pre-hospital RSI, which may reflect a lack of training opportunities.
The small numbers of ‘failure’ rates, combined with the definition of failure in this study, make it hard to draw generalisations. Of note is that the paper lists the outcomes of the six patients who met the failed intubation definition, all of whom appear to have had their airway satisfactorily maintained by the RSI practitioner, three by eventual tracheal intubation, one by LMA, and two by surgical airway. More data are needed before whole specialties are judged on the performance of a small group of doctors.
Should non-anaesthetists perform pre-hospital rapid sequence induction? an observational study
Emerg Med J. 2010 Jul 26. [Epub ahead of print]