[Rapid sequence anesthetic induction via prehospital tracheal intubation]

Emergency induction of anaesthesia in the prehospital setting: a review of the anaesthetic induction agents

The standard of prehospital care is improving in many trauma systems around the world. For patients surviving the primary injury, the optimal prehospital interven tions remain debatable. Current evidence suggests that patients with severe head injury may benefit from advanced airway management, most commonly per formed by rapid sequence induction of anaesthesia and orotracheal intubation. The ‘best choice’ induction agent remains unclear, and choice seems to depend on local preferences and the skill mix of the prehospital care team. In this review we look at the recent evidence for selected hypnotic agents.

[Should etomidate still be used?]

Etomidate blocks the cortisol synthesis by specifically inhibiting the activity of 11 beta-hydroxylase, resulting in a primary adrenal insufficiency. Therefore, a serum accumulation of 11 beta-deoxycortisol and a low secretion of serum cortisol must be required as diagnostic criteria to assign that adrenal impairment to the drug. These requirements have been rarely fulfilled in studies exploring the contribution of etomidate to the adrenal insufficiency despite numerous causes of adrenal derangement. In critically ill patients without sepsis, a single dose of etomidate results in a wide adrenal inhibition, reversible in 48 h after etomidate administration. Although there are still uncertainties as to whether etomidate directly affects mortality and morbidity, it seems preferable to avoid the use of etomidate in patients with severe sepsis and septic shock. In patients with severe traumatic brain injury, arterial hypotension is one of major factors of poor outcome and can be prevented with the use of etomidate for facilitating tracheal intubation. Substitutive opotherapy with low doses of hydrocortisone should be assessed after a single dose of etomidate for critically ill patients.

Prevention of awakening signs after rapid-sequence intubation: a randomized study

BACKGROUND

This study aimed to establish the incidence of signs of inadequate sedation after rapid-sequence intubation (RSI) and to determine whether a supplementary bolus of induction agent decreases these signs.

METHODS

A randomized, double-blind trial design was used. Patients were randomly assigned to 1 of 2 treatments: RSI plus etomidate bolus followed by continuous sedative infusion (ETO group) or RSI plus placebo followed by continuous sedative infusion (placebo group). The primary outcome measure was a composite sedation score measured 6 minutes after induction. The components of the score were the Ramsay sedation score, the presence of cough or pulling at endotracheal (ET) tube, jaw relaxation, motor activity, and eye opening. The total score (0-10) was the sum of the 5 components.

RESULTS

There were 21 patients in the ETO group and 20 patients in the placebo group. The percentage of patients presenting with at least 1 sign of awareness was 43% in the ETO group and 65% in the placebo group (P = .16) 6 minutes after induction. The sedation score was significantly higher at 6 minutes in the placebo group compared with the ETO group (2.4 +/- 2.9 vs 0.9 +/- 1.4; P < .05). The use of additional sedative drugs during the observation period was 43% (9/21) in the ETO group compared with 55% (11/20) in the placebo group (P = .44).

CONCLUSIONS

This study demonstrated that some patients have signs of inadequate sedation after RSI. These signs may be partially prevented by a supplementary dose of an induction agent but other supplementary sedation seems necessary.

Rapid sequence induction: a survey of practices in three French prehospital mobile emergency units

OBJECTIVES

This prospective study was conducted in three mobile emergency and intensive care units.

METHODS

The patients were over 15 years of age and were not in cardiac arrest. The study was to compare practices in the three units with the guidelines drawn up by the Commission of Experts so as to define the main parameters for quality assurance. All of the patients involved were considered to have full stomachs and required rapid sequence induction.

RESULTS

This procedure comply the guidelines only in 45% of cases; in the other cases succinylcholine should have been administered (mobile emergency and intensive care unit A) and the Sellick manoeuvre should have been used (mobile emergency and intensive care unit A and B). Notwithstanding, these two centres treated more traumatized patients than mobile emergency and intensive care unit C, and use of the Sellick manoeuvre in such circumstances is questionable.

CONCLUSIONS

More training and greater diffusion of the protocols are required, especially with regard to doctors who intervene intermittently.

Description d'un protocole de prise en charge préhospitalière du traumatisé crânien grave

OBJECTIVES

To analyze the frequency of systemic factors leading to secondary brain insults in victims of serious head trauma in a prehospital setting and to evaluate a protocol for the advanced prehospital emergency care by mobile intensive care unit (i.e., the French Samu-Smur system).

STUDY DESIGN

Prospective study, over a period of 24 months.

PATIENTS AND METHODS

This prospective study involved 60 victims of severe head injuries (with the exception of polytrauma patients). Tracheal intubation was performed on each patient under direct laryngoscopy and after induction of anaesthesia (fentanyl-etomidate-rocuronium). Controlled ventilation and vascular loading (objectives: SpO(2) >or= 97%, PETCO(2) between 30 and 35 mmHg, SAP >or= 90 mmHg) were administered.

RESULTS

Hypoxaemia was found to be the most frequent cause of secondary insults (57% of patients with SpO(2) < 97%). In the case involving an accident that occurred 17 km from the hospital (with extremes of 6-65 km), the speed of medical intervention was note-worthy: tracheal intubation was performed 50 min after the accident, and the patient was admitted into a trauma centre 101 min after impact (median). However, faster intervention could be obtained if the transmission of the alert was improved. The conditions under which the tracheal intubation was performed were found to be satisfactory (difficult intubation 1.6%) without deteriorating the haemodynamic status. This is probably related to the use of muscle relaxants and the choice of etomidate as the first line hypnotic in the prehospital emergency care.

Epidemiology of adverse effects of prehospital sedation analgesia

The aim of this study was to introduce a continuous monitoring of side effects related to sedation-analgesia in the field. A document was completed by physicians on board the ambulances for all prehospital interventions and checked daily by the medical staff. A total of 3605 interventions were evaluated over a 12-month period. Six hundred four patients undertook analgesia and/or sedation: group 1 (spontaneously breathing patients) n = 289 and group 2 (intubated-ventilated patients) n = 315. Sixty-four percent of patients received intravenous opioids in group 1. The anesthetic technique used for intubation was the rapid sequence induction in 70% of patients. Side effects were observed in 5.5% in group 1 (nausea: 2%, hypotension: 1%, hypoxemia: 1%) and 22% of patients in group 2 (hypotension-arrhythmia: 12%, cardiac arrest: 2%, difficult intubation: 5%, hypoxemia: 1%, pulmonary aspiration: 1%, laryngospasm/bronchospasm: 2%). No death was related to these medications. A close monitoring of side effects related to sedation-analgesia must be included in a quality program to improve patient safety in the field.

[Rapid sequence intubation in emergency: is there any place for fentanyl?]

OBJECTIVES

Rapid sequence intubation (RSI) with the association of etomidate and succinylcholine is the French "Gold standard" for urgent "full stomach" endotracheal intubations. The aim of this study is to assess the fentanyl as a co-induction agent to take over the sedation between the RSI and the keeping of sedation, which is a critical period in which harmful neuro-vegetatives events, and awakening signs are frequently seen.

STUDY DESIGN

Randomized, double blind controlled prospective study, after acceptation by the local ethical committee.

PATIENTS AND METHODS

Three groups of patients undergoing RSI in the intensive care unit and by the out-of-hospital medical team were compared: group A patients received fentanyl 3 micrograms kg-1 during RSI, before paralysis was induced. Group B patients received the same dose of fentanyl immediately after endotracheal intubation. Group C patients did not received fentanyl (control group). Outcome measures were awakening signs arrival (respiratory movements, eyes opening, spontaneous limb movements), Ramsay score assessment, and haemody namics. Attempt at intubation and vomiting incident were also measured. Discrete data were compared by chi-2 analysis, continuous data were compared with two-way analysis of variance. A p value < 0.05 was the significant threshold.

RESULTS

Thirty-six patients were enrolled and completed the study. All the included patients presented awakening signs. The use of fentanyl did not prevent the recourse of other sedative medications. Ten minutes after endotracheal intubation, significant differences has been noticed for the awakening signs arrival between fentanyl groups (A: 42% and B: 36%) and control group (C: 77%). The Ramsay score evolution follows the same variation. All the patients were intubated on the first attempt, there was no vomiting incident noticed.

CONCLUSION

The use of fentanyl, as a co-induction agent with etomidate and succinylcholine during RSI, allows a significant delay of the awakening signs arrival and attenuate the neurovegetative response during the minutes after endotracheal intubation after RSI, without deleterious haemodynamic effects.

New equipment and techniques for airway management in trauma

A patent, unobstructed airway is fundamental in the care of the trauma patient, and is most often obtained by placing a cuffed tube in the trachea. The presence of shock, respiratory distress, a full stomach, maxillofacial trauma, neck hematoma, laryngeal disruption, cervical spine instability, and head injury all combine to increase tracheal intubation difficulty in the trauma patient. Complications resulting from intubation difficulties include brain injury, aspiration, trauma to the airway, and death. The use of devices such as the gum-elastic bougie, McCoy laryngoscope, flexible and rigid fiberscopes, intubating laryngeal mask, light wand, and techniques such as rapid-sequence intubation, manual in-line axial stabilization, retrograde intubation, and cricothyroidotomy, enhance the ability to obtain a definitive airway safely. The management of the failed airway includes calling for assistance, optimal two-person bag-mask ventilation, and the use of the laryngeal mask airway, Combitube, or surgical airway. The simulation of airway management using realistic simulator tools (e.g. full-scale simulators, virtual reality airway simulators) is a promising modality for teaching physicians and advanced life support personnel emergency airway management skills.

[Prehospital management of patients with severe head injuries]

Advanced prehospital emergency medical care of patients with a severe head injury must essentially focus on the impact of secondary cerebral insults of systemic origin on the outcome. The first objective of prehospital care is to prevent hypoxaemia and hypercapnia. Therefore, all patients with a Glasgow Coma Scale score equal to or lower than 8 must be treated with endotracheal intubation and controlled ventilation under continuous monitoring of SpO2 and PETCO2. Treatment is similar in head-injured patients with significant deterioration of consciousness level, seizures, respiratory distress, or severe facial and thoracoabdominal injuries. The endotracheal tube is inserted by the orotracheal route under direct laryngoscopy, after a rapid induction sequence of anaesthesia and immobilization of the cervical spine in neutral position. For the induction of anaesthesia in these high-risk patients (full stomach, unknown medical history, deteriorated haemodynamic status), etomidate and suxamethonium are the preferred agents. Sedation is maintained with an hypnoticopioid association (fentanyl). Simultaneously, the main goal is the maintenance of an optimal cerebral perfusion pressure, as arterial hypotension severely worsens cerebral ischaemia. Volume loading is accomplished with 0.9% saline and hydroxyethyl starch.

[Management of severe head-injured patients in the first 24 hours. Resuscitation and initial diagnostic strategy]

Limitation of secondary insults after severe head injury is a permanent concern during the early phase of head trauma management. The objectives are to maintain mean arterial pressure between 80 and 100 mmHg, to avoid hypoxaemia, and to maintain arterial PCO2 near to 35 mmHg. Volume loading can be necessary to improve arterial pressure, and is carried out with isotonic critalloid (NaCl 9/1000) or colloids, with the exclusion of all hypotonic solutions (Ringer lactate or glucose). The use of catecholamines is reserved for patients with unstable haemodynamics despite an adequate volume loading. The rapid sequence induction is recommended for endotracheal intubation and is followed by continuous analgesia-sedation to keep patient-ventilator dysynchrony, but without compromising haemodynamic objectives. Mannitol is used in case of life-threatening intracranial hypertension. Conversely, specific treatment of intracranial hypertension, especially hypocapnia, is not recommended. Initial diagnostic procedures include cerebral tomodensitometry (TDM). However, TDM may be delayed in case of haemorrhage, which requires a rapid treatment. Intrahospital transport for additional explorations risks secondary insults, and thus requires close monitoring to detect and treat in due time all adverse events. This monitoring includes invasive arterial blood pressure assessment, use of continuous capnography and repeated arterial blood gas measurements. The usefulness of transcranial Doppler for initial management of head-trauma patients needs further evaluation.