The noxious stimulus of laryngoscopy & tracheal intubation can precipitate hypertension, tachycardia, and intracranial pressure elevation, risking exacerbation of brain injury or haemorrhage. Physicians from an English Helicopter Emergency Medical Service examined the response of heart rate and blood pressure to prehospital rapid sequence intubation (RSI). While a retrospective study, the haemodynamic data were prospectively recorded and documented using standard monitor printouts, and time of intubation could be accurately determined by the onset of capnography recordings. Their standardised system documents blood pressure recordings every three minutes. Etomidate and suxamethonium were used for RSI.
They report their findings:
A hypertensive response occurred in 79% (70/89) of patients. MAP exceeded the upper limit of estimated intact cerebral autoregulation (150 mmHg) in 18% (16/89) of cases and 9% (8/89) of patients had a greater than 100% increase in MAP and/or SBP. A single hypotensive response occurred. A tachycardic response occurred in 58% (64/110) of patients and bradycardia was induced in one.
Of note, 97 of the 115 patients had injuries that included head trauma.
The authors note that opioids are often co-administered during in-hospital RSI and that this may offset the haemodynamic stimulation, while possible increasing the complexity of the procedure in the prehospital environment. They have modified their pre-hospital anaesthesia standard operating procedure to include the use of an opioid and will report the associated outcomes and complication rates ‘in due course’.
This is interesting and important stuff, and something we should all be looking at in our respective prehospital critical care services.
The haemodynamic response to pre-hospital RSI in injured patients
Injury. 2013 May;44(5):618-23
BACKGROUND: Laryngoscopy and tracheal intubation provoke a marked sympathetic response, potentially harmful in patients with cerebral or cardiovascular pathology or haemorrhage. Standard pre-hospital rapid sequence induction of anaesthesia (RSI) does not incorporate agents that attenuate this response. It is not known if a clinically significant response occurs following pre-hospital RSI or what proportion of injured patients requiring the intervention are potentially at risk in this setting.
METHODS: We performed a retrospective analysis of 115 consecutive pre-hospital RSI’s performed on trauma patients in a physician-led Helicopter Emergency Medical Service. Primary outcome was the acute haemodynamic response to the procedure. A clinically significant response was defined as a greater than 20% change from baseline recordings during laryngoscopy and intubation.
RESULTS: Laryngoscopy and intubation provoked a hypertensive response in 79% of cases. Almost one-in-ten patients experienced a greater than 100% increase in mean arterial pressure (MAP) and/or systolic blood pressure (SBP). The mean (95% CI) increase in SBP was 41(31-51) mmHg and MAP was 30(23-37) mmHg. Conditions leaving the patient vulnerable to secondary injury from a hypertensive response were common.
CONCLUSIONS: Laryngoscopy and tracheal intubation, following a standard pre-hospital RSI, commonly induced a clinically significant hypertensive response in the trauma patients studied. We believe that, although this technique is effective in securing the pre-hospital trauma airway, it is poor at attenuating adverse physiological effects that may be detrimental in this patient group.
Comments Off on Make space for pre-hospital intubation
“Control your environment – don’t let it control you” is a reliable adage for pre-hospital providers, and its adherence can assist in in-hospital resuscitation too. Commanding control of ones space is a skill demonstrated by more seasoned paramedics compared with novices and the requirement, where possible, for 360 degrees of access around a patient is included in some Standard Operating Procedures for pre-hospital rapid sequence intubation.
Evidence for this approach is now further supported by a study demonstrating that limited surrounding space on scene was a significant risk factor for difficult pre-hospital intubation by European EMS physicians.
Other predisposing factors for difficult prehospital intubation included obesity and a short neck.
OBJECTIVES:For experienced personnel endotracheal intubation (ETI) is the gold standard to secure the airway in prehospital emergency medicine. Nevertheless, substantial procedural difficulties have been reported with a significant potential to compromise patients’ outcomes. Systematic evaluation of ETI in paramedic operated emergency medical systems (EMS) and in a mixed physician/anaesthetic nurse EMS showed divergent results. In our study we systematically assessed factors associated with difficult ETI in an EMS exclusively operating with physicians.
METHODS:Over a 1-year period we prospectively collected data on the specific conditions of all ETIs of two physician staffed EMS vehicles. Difficult ETI was defined by more than 3 attempts or a difficult visualisation of the larynx (Cormack and Lehane grade 3, or worse). For each patient ETI conditions, biophysical characteristics and factors of the surrounding scene were assessed. Additionally, physicians were asked whether they had expected difficult ETI in advance.
RESULTS:Out of 3979 treated patients 305 (7.7%) received ETI. For 276 patients complete data sets were available. The incidence of difficult ETI was 13.0%. In 4 cases (1.4%) ETI was impossible, but no patient was unable to be ventilated sufficiently. Predicting conditions for difficult intubation were limited surrounding space on scene (p<0.01), short neck (p<0.01), obesity (p<0.01), face and neck injuries (p<0.01), mouth opening<3cm (p<0.01) and known ankylosing spondylitis (p<0.01). ETI on the floor or with C-spine immobilisation in situ were of no significant influence. The incidence of unexpected difficult ETI was 5.0%.
CONCLUSIONS: In a physician staffed EMS difficult prehospital ETI occurred in 13% of cases. Predisposing factors were limited surrounding space on scene and certain biophysical conditions of the patient (short neck, obesity, face and neck injuries, and anatomical restrictions). Unexpected difficult ETI occurred in 5% of the cases.
Difficult prehospital endotracheal intubation – predisposing factors in a physician based EMS
Resuscitation. 2011 Dec;82(12):1519-24
A newly published study examines pre-hospital hypertonic saline during CPR. A randomised trial compared 7.2% hypertonic saline / hydroxyethyl starch with hydroxyethyl starch alone in over 200 adult patients with non-traumatic out-of-hospital cardiac arrest. The volume infused was 2 ml /kg over 10 mins. All patients were resuscitated by the physicians of the Emergency Medical System (EMS) in Bonn, Germany.
There were no differences in survival to admission or discharge. There was a barely statistically significant increase in those survivors with higher cerebral performance categories (1 or 2) in the hypertonic saline group, inviting further study. The study was conducted from 2001 to 2004 (according to the 2000 CPR-Guidelines), so took an interestingly long time to see print.
Randomised study of hypertonic saline infusion during resuscitation from out-of-hospital cardiac arrest
Resuscitation. 2011 Sep 19. [Epub ahead of print]
Aim of the study Animal models of hypertonic saline infusion during cardiopulmonary resuscitation (CPR) improve survival, as well as myocardial and cerebral perfusion during CPR. We studied the effect of hypertonic saline infusion during CPR (Guidelines 2000) on survival to hospital admission and hospital discharge, and neurological outcome on hospital discharge.
Methods The study was performed by the EMS of Bonn, Germany, with ethical committee approval. Study inclusion criteria were non-traumatic out-of-hospital cardiac arrest, aged 18–80 years, and given of adrenaline (epinephrine) during CPR. Patients were randomly infused 2 ml kg−1 HHS (7.2% NaCl with 6% hydroxyethyl starch 200,000/0.5 [HES]) or HES over 10 min.
Results 203 patients were randomised between May 2001 and June 2004. After HHS infusion, plasma sodium concentration increased significantly to 162 ± 36 mmol l−1 at 10 min after infusion and decreased to near normal (144 ± 6 mmol l−1) at hospital admission. Survival to hospital admission and hospital discharge was similar in both groups (50/100 HHS vs. 49/103 HES for hospital admission, 23/100 HHS vs. 22/103 HES for hospital discharge). There was a small improvement in neurological outcome in survivors on discharge (cerebral performance category 1 or 2) in the HHS group compared to the HES group (13/100 HHS vs. 5/100 HES, p < 0.05, odds-ratio 2.9, 95% confidence interval 1.004–8.5).
Conclusion Hypertonic saline infusion during CPR using Guidelines 2000 did not improve survival to hospital admission or hospital discharge. There was a small improvement with hypertonic saline in the secondary endpoint of neurological outcome on discharge in survivors. Further adequately powered studies using current guidelines are needed.
The tradition of transporting trauma patients to hospital in a supine position may not be the safest approach in obtunded patients with unprotected airways. The ‘solution’ of having them on an extrication board (backboard / long spine board) to enable rolling them to one side in the event of vomiting may not be practicable for limited crew numbers.
The Norwegians have been including the option of the lateral trauma position in their pre-hospital trauma life support training for some years now.
A questionnaire study demonstrates that this method has successfully been adopted by Norwegian EMS systems.
The method of application is described as:
- Check airways (look, listen, feel).
- Apply chin lift/jaw thrust, suction if needed.
- Apply stiff neck collar.
- If the patient is unresponsive, but has spontaneous respiration: Roll patient to lateral/recovery position while maintaining head/neck position.
- Roll to side that leaves the patient facing outwards in ambulance coupé.
- Transfer to ambulance stretcher (Scoop-stretcher, log-roll onto stretcher mattress, or use multiple helpers, lifting by patient’s clothing).
- Support head, secure with three belts (across legs, over hip, over shoulder)
- Manual support of head, supply oxygen, observation, suction, BVM (big valve mask) ventilation when needed.
Different options for supporting the head in the lateral position, according to questionnaire responders, include:
- putting padding under the head, such as a pillow or similar item (81%)
- a combination of padding and putting the head on the lower arm (7%)
- rest the head on the lower arm alone (10%)
- rest the head on the ground (<1%)
BACKGROUND: Trauma patients are customarily transported in the supine position to protect the spine. The Airway, Breathing, Circulation, Disability, and Exposure (ABCDE) principles clearly give priority to airways. In Norway, the lateral trauma position (LTP) was introduced in 2005. We investigated the implementation and current use of LTP in Norwegian Emergency Medical Services (EMS).
METHODS: All ground and air EMS bases in Norway were included. Interviews were performed with ground and air EMS supervisors. Questionnaires were distributed to ground EMS personnel.
RESULTS: Of 206 ground EMS supervisors, 201 answered; 75% reported that LTP is used. In services using LTP, written protocols were present in 67% and 73% had provided training in LTP use. Questionnaires were distributed to 3,025 ground EMS personnel. We received 1,395 (46%) valid questionnaires. LTP was known to 89% of respondents, but only 59% stated that they use it. Of the respondents using LTP, 77% reported access to written protocols. Flexing of the top knee was reported by 78%, 20% flexed the bottom knee, 81% used under head padding. Of 24 air EMS supervisors, 23 participated. LTP is used by 52% of the services, one of these has a written protocol and three arrange training.
CONCLUSIONS: LTP is implemented and used in the majority of Norwegian EMS, despite little evidence as to its possible benefits and harms. How the patient is positioned in the LTP differs. More research on LTP is needed to confirm that its use is based on evidence that it is safe and effective.
The lateral trauma position: What do we know about it and how do we use it? A cross-sectional survey of all Norwegian emergency medical services
Scand J Trauma Resusc Emerg Med. 2011 Aug 4;19:45
Open Access Full Text
The physician-staffed mobile intensive care units of SAMU (Service d’Aide Médicale Urgente) in France provided the location for this randomised controlled trial of CPAP for acute cardiogenic pulmonary oedema.
STUDY OBJECTIVE: The purpose of this randomized controlled trial was to determine the immediate and delayed effects of noninvasive ventilation for patients in acute cardiogenic pulmonary edema (ACPE) in addition to aggressive usual care in a medical prehospital setting.
METHODS: Out-of-hospital patients in severe ACPE were eligible for the study. Patients were randomized to receive either usual care, including conventional optimal treatment with furosemide, oxygen, and high-dose boluses of isosorbide dinitrate plus oxygen, or conventional medications plus out-of-hospital continuous positive airway pressure (CPAP). The primary outcome was the treatment success defined as all of respiratory rate less than 25 breaths per minute and oxygen saturation of greater than 90% at the end of 1-hour study. Secondary end points included death during 30 days after inclusion. Lengths of intensive care unit and hospital stays were also recorded.
RESULTS: In total, 124 patients were enrolled into the study. The 2 groups had similar baseline characteristics. For the primary outcome analysis, 22 (35.5%) of 62 patients were considered as experiencing a treatment success in the usual care group vs 19 (31.7%) of 60 in the CPAP group (P = .65). Seven patients died within 30 days in the usual care group vs 6 in the CPAP group (P = .52). There were no statistically significant differences between the treatment groups for length of stay either in hospital or in the intensive care unit.
CONCLUSION: In the prehospital setting, in spite of its potential advantages for patients in ACPE, CPAP may not be preferred to a strict optimal intravenous treatment.
Continuous positive airway pressure for cardiogenic pulmonary edema: a randomized study
Am J Emerg Med. 2011 Sep;29(7):775-81
The Executive Committee of Prehospital Trauma Life Support, comprised of surgeons, emergency physicians, and paramedics, has reviewed the literature and produced the following recommendations on Prehospital Spine Immobilisation for Penetrating Trauma:
- There are no data to support routine spine immobilization in patients with penetrating trauma to the neck or torso.
- There are no data to support routine spine immobilization in patients with isolated penetrating trauma to the cranium.
- Spine immobilization should never be done at the expense of accurate physical examination or identification and correction of life-threatening conditions in patients with penetrating trauma.
- Spinal immobilization may be performed after penetrating injury when a focal neurologic deficit is noted on physical examination although there is little evidence of benefit even in these cases.
Prehospital Spine Immobilization for Penetrating Trauma—Review and Recommendations From the Prehospital Trauma Life Support Executive Committee
Journal of Trauma-Injury Infection & Critical Care September 2011;71(3):763-770
The London Helicopter Emergency Medical Service provides a physician / paramedic team to victims of trauma. One of the interventions performed by their physicians is pre-hospital resuscitative thoracotomy to patients with cardiac arrest due to penetrating thoracic trauma. They have published the outcomes from this procedure over a 15 year period which show an 18% survival to discharge rate, with a high rate of neurologically intact survivors1.
The article was submitted for publication on February 1, 2010, and in the discussion mentions a further two survivors from the procedure performed after conducting the study. It is likely therefore in the year and a half since submission still more patients have been saved. It will be interesting to read future reports from this team as the numbers accumulate; penetrating trauma missions are sadly increasing in frequency.
Having worked for these guys and performed this procedure in the field a few times myself, I can attest to the training and governance surrounding this system. The technique of clamshell thoracotomy is well described 2 and one I would recommend for the non-surgeon.
BACKGROUND: Prehospital cardiac arrest associated with trauma almost always results in death. A case of survival after prehospital thoracotomy was published in 1994 and several others have followed. This article describes the result of prehospital thoracotomy in a physician-led system for patients with stab wounds to the chest who suffered cardiac arrest on scene.
METHODS: A 15-year retrospective prehospital trauma database review identified victims of stab wounds to the chest who suffered cardiac arrest on scene and had thoracotomy performed according to local standard operating procedures.
RESULTS: Overall, 71 patients met inclusion criteria. Thirteen patients (18%) survived to hospital discharge. Neurologic outcome was good in 11 patients and poor in 2. Presenting cardiac rhythm was asystole in four patients, pulseless electrical activity in five, and unrecorded in the remaining four. All survivors had cardiac tamponade. The medical team was present at the time of cardiac arrest for six survivors (good neurologic outcome): arrived in the first 5 minutes after arrest in three patients (all good neurologic outcome), arrived 5 minutes to 10 minutes after arrest in two patients (one poor neurologic outcome), and in one patient (poor neurologic outcome) the period was unknown. Of the survivors, seven thoracotomies were performed by emergency physicians and six by anesthesiologists.
CONCLUSIONS: Prehospital thoracotomy is a well-established procedure in this physician-led prehospital service. Results from this and other similar systems suggest that when performed for the subgroup of patients described, significant numbers of survivors with good neurologic outcome can be expected.
1. Thirteen Survivors of Prehospital Thoracotomy for Penetrating Trauma: A Prehospital Physician-Performed Resuscitation Procedure That Can Yield Good Results
J Trauma. 2011 May;70(5):E75-8
Comments Off on Exsanguinating cardiac arrest not always fatal
The British Military has developed a reputation for aggressive pre-hospital critical care including (but not limited to) the use of blood products and tourniquets, and coordinated field hospital trauma care. They now report the outcomes for patients with traumatic cardiac arrest, mainly from improvised explosive devices. Of 52 patients, 14 (27%) demonstrated return of spontaneous circulation (ROSC), of whom four (8%) survived to hospital discharge with a neurologically good recovery. Resuscitative thoracotomy (RT) was performed on 12 patients (8 in the ED), including all four survivors. RT enabled open-chest CPR, release of pericardial tamponade, lung resection and compression of the descending thoracic aorta for haemorrhage control.
No patients who arrested in the field survived, although one of the neurologically well-recovered survivors arrested during transport to hospital and was in cardiac arrest for 24 minutes. The authors propose this individual’s survival was in part due to ‘the high level of care that he received during retrieval, including haemorrhage control, tracheal intubation and transfusion of blood products‘.
Asystole was universally associated with death but agonal / bradycardic rhythms were not. In keeping with other studies, cardiac activity on ultrasound was associated with ROSC.
AIM: To determine the characteristics of military traumatic cardiorespiratory arrest (TCRA), and to identify factors associated with successful resuscitation.
METHODS: Data was collected prospectively for adult casualties suffering TCRA presenting to a military field hospital in Helmand Province, Afghanistan between 29 November 2009 and 13 June 2010.
RESULTS: Data was available for 52 patients meeting the inclusion criteria. The mean age (range) was 25 (18-36) years. The principal mechanism of injury was improvised explosive device (IED) explosion, the lower limbs were the most common sites of injury and exsanguination was the most common cause of arrest. Fourteen (27%) patients exhibited ROSC and four (8%) survived to discharge. All survivors achieved a good neurological recovery by Glasgow Outcome Scale. Three survivors had arrested due to exsanguination and one had arrested due to pericardial tamponade. All survivors had arrested after commencing transport to hospital and the longest duration of arrest associated with survival was 24min. All survivors demonstrated PEA rhythms on ECG during arrest. When performed, 6/24 patients had ultrasound evidence of cardiac activity during arrest; all six with cardiac activity subsequently exhibited ROSC and two survived to hospital discharge.
CONCLUSION: Overall rates of survival from military TCRA were similar to published civilian data, despite military TCRA victims presenting with high Injury Severity Scores and exsanguination due to blast and fragmentation injuries. Factors associated with successful resuscitation included arrest beginning after transport to hospital, the presence of electrical activity on ECG, and the presence of cardiac movement on ultrasound examination.
Outcomes following military traumatic cardiorespiratory arrest: A prospective observational study
Resuscitation. 2011 Sep;82(9):1194-7
Comments Off on Pre-hospital ECMO
Two cases are reported of the pre-hospital institution of venoarterial extracorporeal membrane oxygenation (ECMO) for patients in cardiac arrest. One was from France and the other from Germany – both countries with mature physician-staffed pre-hospital systems. The two cases were a 9 yr old drowning victim1 and a 48 year old marathon runner2. They each received BLS then ACLS then ECMO, and both went from asystole to sinus rhythm after the institution of ECMO. Sadly both failed to neurologically recover and died in hospital.
If irreversible anoxic encephalopathy could be detected in the field, patients could be better selected for this intervention. An editorialist3 states:
Until we have a hand held device which can measure neuronal integrity on a cellular level in the field we must use our best judgement, and in many cases give the patient the benefit of the doubt by cannulating them, cooling for 24 h and then making a neurological assessment and withdrawing ECLS if necessary.
Other issues to consider are:
- Can society afford this level of intervention?
- Could this intervention, when associated with brain death, result in sufficiently recovered organs for transplantation?
- How can the infrastructure be created to enable rapid institution of pre-hospital ECMO?
I suspect as the equipment becomes even more portable and self-maintaining, pre-hospital / retrieval physicians already expert in critical care interventions such as seldinger-guided vascular access will be the ones instituting this therapy. In the meantime, we await evidence of outcome benefit and some objective means of case selection.
1. Out-of-hospital extracorporeal life support for cardiac arrest—A case report
Resuscitation. 2011 Sep;82(9):1243-5
2. Out-of-hospital extra-corporeal life support implantation during refractory cardiac arrest in a half-marathon runner
Resuscitation. 2011 Sep;82(9):1239-42
3. Community extracorporeal life support for cardiac arrest – When should it be used?
Resuscitation. 2011 Sep;82(9):1117
My colleagues and I describe a tragic case in this month’s European Journal of Emergency Medicine1. Our physican-paramedic team was called to the home of a collapsed 38-week pregnant female who was in asystolic cardiac arrest. A peri-mortem caesarean delivery was performed by the physician in the patient’s home and the delivered newborn required intubation and chest compressions for bradycardia before resuming good colour and heart rate. Sadly there was ultimately a fatal outcome for both patients, but this case reminds us of the indications for this intervention and for emergency and pre-hospital physicians to be prepared to do it. A literature search yielded only one other reported prehospital case in recent medical literature2.
1.Prehospital resuscitative hysterotomy
Eur J Emerg Med. 2011 Aug;18(4):241-2
2.Out-of-hospital perimortem cesarean section
Prehosp Emerg Care. 1998 Jul-Sep;2(3):206-8