Measuring end-tidal carbon dioxide (ET CO2 ) is a practical non-invasive method for detecting pulmonary blood flow, reflecting cardiac output and thereby the quality of CPR. It has also been shown to rise before clinically detectable return of spontaneous circulation (ROSC).
Passive leg raising (PLR) increases venous return and may therefore augment cardiac output and in a cardiac arrest this may be reflected by an elevation in ETCO2.
A Swedish observational study of 126 patients with out of hospital cardiac arrest due to a likely cardiac aetiology underwent tracheal intubation with standardised ventilation and chest compressions (either manually or using the LUCAS device, as part of larger study of mechanical chest compressions according to a cluster design). Patients were stratified to receive either PLR to 20 degrees or no PLR. ETCO2 was measured during CPR, either for 15min, or until the detection of ROSC.
Hang on I think that's overdoing it a bit
During PLR, an increase in ETCO2 was found in all 44 patients who received PLR within 15s (p=0.003), 45s (p = 0.002) and 75 s (p = 0.0001). Survival to hospital discharge was 7% among patients with PLR and 1% among those without PLR (p = 0.12). Among patients experiencing ROSC (60 of 126), there was a marked increase in ETCO2 1 min before the detection of a palpable pulse. Passive leg raising during cardiopulmonary resuscitation in out-of-hospital cardiac arrest—Does it improve circulation and outcome? Resuscitation. 2010 Dec;81(12):1615-20
British trauma surgeon and pre-hospital pioneer Professor Keith Porter describes how to do a pre-hospital amputation in this months EMJ. Thankfully the procedure is only rarely necessary and often only requires cutting remaining skin bridges with scissors. The indications are:
An immediate and real risk to the patient’s life due to a scene safety emergency
A deteriorating patient physically trapped by a limb when they will almost certainly die during the time taken to secure extrication
A completely mutilated non-survivable limb retaining minimal attachment, which is delaying extrication and evacuation from the scene in a non-immediate life-threatening situation
The patient is dead and their limbs are blocking access to potentially live casualties
simple equipment for amputation
The recommended procedure is:
Ketamine anaesthesia
Apply an effective proximal tourniquet
Amputate as distally as possible
Perform a guillotine amputation
Apply haemostats to large blood vessels
Leave the tourniquet in situ
Apply a padded dressing and transport to hospital
Remember: the requirement for prehospital amputation other than cutting minimal soft tissue bridges is rare. However pre-hospital critical care physicians should be trained and equipped to amputate limbs in order to save life. Probably good to have a Gigli saw in your pack and to familiarise yourself with its use, as shown here:
A meta-analysis of pre-hospital airway control techniques evaluated alternative techniques to tracheal intubation. The outcome was placement success; there were no data on effectiveness of ventilation or other clinical outcomes. Although limited by poor quality studies, there are some interesting findings.
The pooled placement success rates for Combitube and LMA, were similar but unimpressive, with nonphysician placement success rates of 83.0% and 82.7%, respectively. The authors point out that while these devices might offer potential advantages over conventional tracheal intubation in terms of reduced training requirements, or perhaps fewer or less severe complications, they should not be expected to provide higher airway management success rates than conventional tracheal intubation.
Low success rates for this 'rescue procedure'. Just get your scalpel...
They identified only four studies reporting the success rates of needle cricothyroidotomy (NC). Regardless of patient circumstances or clinician credentials, the NC success rate was ubiquitously low, ranging from 25.0% to 76.9%. The pooled results for the 18 surgical cricothyroidotomy (SC) studies produced substantially higher success rates, although the success rate for all nonphysician clinicians was still only 90.4%. The authors state: “EMS systems that choose to incorporate a percutaneous airway procedure into their airway management protocols should recognize that the success rate of SC far exceeds that of NC”. A meta-analysis of prehospital airway control techniques part II: alternative airway devices and cricothyrotomy success rates Prehosp Emerg Care. 2010 Oct-Dec;14(4):515-30
An Australian randomised controlled trial of pre-hospital oxygen therapy in COPD patients compared titrated oxygen therapy with high flow oxygen. The primary outcome was prehospital and in-hospital mortality. Titrated oxygen treatment was delivered by nasal prongs to achieve arterial oxygen saturations between 88% and 92%, with concurrent bronchodilator treatment administered by a nebuliser driven by compressed air. High flow oxygen was 8-10 l/min administered by a non-rebreather face mask, with bronchodilators delivered by nebulisation with oxygen at flows of 6-8 l/min.
Titrated oxygen treatment significantly reduced mortality, hypercapnia, and respiratory acidosis compared with high flow oxygen in acute exacerbations of chronic obstructive pulmonary disease. The authors claim: ‘For high flow oxygen treatment in patients with confirmed chronic obstructive pulmonary disease in the prehospital setting, the number needed to harm was 14; that is, for every 14 patients who are given high flow oxygen, one will die.‘
The authors did not report data on the in-hospital management of the patients. Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial BMJ. 2010 Oct 18;341:c5462
A study of out-of-hospital paediatric arrests in Melbourne gives some useful outcome data: overall, paediatric victims of out-of-hospital cardiac arrest survived to leave hospital in 7.7% of cases, which is similar to adult survival in the same emergency system (8%). Survival was very rare (<1%) unless there was return of spontaneous circulation prior to hospital arrival. Sixteen of the 193 cases studied had trauma, but the survival in this subgroup was not specifically documented.
Epidemiology of paediatric out-of-hospital cardiac arrest in Melbourne, Australia Resuscitation. 2010 Sep;81(9):1095-100
A cadaveric study using a 3-dimensional electromagnetic tracking device to asses cervical motion compared the application of a scoop stretcher with two other manual transfer techniques, including log rolling onto an extrication (spine) board. The scoop method restricted cervical spine movement more than log rolling, although this was not statistically significant.
The authors conclude: the effectiveness of the scoop stretcher to limit spinal motion in the destabilized spine is comparable or better than manual techniques currently being used by primary responders. Are scoop stretchers suitable for use on spine-injured patients? Am J Emerg Med. 2010 Sep;28(7):751-6
An Australian randomised controlled trial assessed the effect of pre-hospital cooling (using 2 litres ice cold Hartmann’s) of post-cardiac arrest patients on functional status at hospital discharge. The intervention group were marginally cooler on arrival but did not have improved outcomes.
The authors conclude: In adults who have been resuscitated from out-of-hospital cardiac arrest with an initial cardiac rhythm of ventricular fibrillation, paramedic cooling with a rapid infusion of large-volume, ice-cold intravenous fluid decreased core temperature at hospital arrival but was not shown to improve outcome at hospital discharge compared with cooling commenced in the hospital. Induction of Therapeutic Hypothermia by Paramedics After Resuscitation From Out-of-Hospital Ventricular Fibrillation Cardiac Arrest Circulation. 2010 Aug 17;122(7):737-42 Free Full Text
One issue from this study was that relatively short urban pre-hospital transport times meant some patients did not get the full two litres, and some had already received room temperature fluids during the cardiac arrest resuscitation. The authors suggest further study should involved initiating cooling during the arrest. In fact a European study has done just that, using a device call a RhinoChill (a portable transnasal cooling device) to lower temperature during arrest in a randomised controlled trial. This trial showed pre-hospital intra-arrest transnasal cooling is safe and feasible and is associated with a significant improvement in the time intervals required to cool patients.
Intra-arrest transnasal evaporative cooling: a randomized, prehospital, multicenter study (PRINCE: Pre-ROSC IntraNasal Cooling Effectiveness) Circulation. 2010 Aug 17;122(7):729-36
Being human, I suffer from confirmation bias: I’ve become aware that I’m always on the look out for studies that show benefit from physician-provided pre-hospital care and therefore it’s possible I miss the ones that show no benefit. Of course, no ‘level 1’ evidence is out there yet. This study isn’t hugely impressive, but worth adding to the list. After adjusting for injury severity, trauma patients treated on scene by Dutch physicians had no difference in mortality compared with those that received standard care. In the subgroup analysis for patients with severe traumatic brain injury, the mortality rate with physician involvement was lower than that without, but was not statistically significant. On scene times averaged 2.7 minutes longer in the physician group although factors that might have contributed to this, such as entrapment or on scene interventions, were not recorded.
A Dutch Doctor
A major limitation in study design is that patients who died while under care at the scene or during transport were excluded from the analysis. The on scene time in these patients could have been prolonged by medical interventions in the field possibly contributing to the adverse outcome.
Take home message? More evidence needed. The Association of Mobile Medical Team Involvement on On-Scene Times and Mortality in Trauma Patients J Trauma. 2010 Sep;69(3):589-94
Okay – I admit to loving this paper, partly because it blows away the dogma of short scene times and ‘scoop & run’, and the oft-quoted but obnoxious assertion that the only pre-hospital fluid of benefit is gasoline.
A massive database of 3656 sick trauma patients (SBP < 90, 10>resp rate>29, GCS≤12, or advanced airway intervention), transported by 146 EMS agencies to 51 hospitals, was analysed to identify any association between mortality and emergency medical services (EMS) timings (activation, response, on-scene, transport, and total time). Overall mortality in this group was 22%.
There was no significant association between time and mortality for any EMS interval: activation (odds ratio [OR] 1.00; 95% confidence interval [CI] 0.95 to 1.05), response (OR 1.00; 95% CI 9.97 to 1.04), on-scene (OR 1.00; 95% CI 0.99 to 1.01), transport (OR 1.00; 95% CI 0.98 to 1.01), or total EMS time (OR 1.00; 95% CI 0.99 to 1.01).
The authors state: “In this study, we were unable to support the contention that shorter out-of-hospital times… improve survival among injured adults with field-based physiologic abnormality… Our findings are consistent with those of previous studies that similarly have failed to demonstrate a relationship between out-of-hospital time and outcome using different patient populations, trauma and EMS systems, regions, data sources, and confounders” Emergency Medical Services Intervals and Survival in Trauma: Assessment of the “Golden Hour” in a North American Prospective Cohort Ann Emerg Med. 2010 Mar;55(3):235-246
Data on patients with moderate to severe traumatic brain injury from the San Diego Trauma Registry were analysed using modified TRISS methodology to determine predicted survival, from which an observed-predicted survival differential (OPSD) was calculated. The mean OPSD was calculated as the primary outcome for the following comparisons: intubated versus nonintubated, air versus ground transport, eucapnia (PCO2 30–50 mm Hg) versus noneucapnia, and hypoxemia (PO<90 mm Hg) versus nonhypoxemia. Of note in this region is that ground EMS staff intubate without drugs, whereas air medical services use rapid sequence intubation with suxamethonium plus either etomidate or midazolam.
The rationale behind this methodology was to eliminate the possible selection bias present in previous studies linking pre-hospital intubation with mortality (sicker patients are able to be intubated without drugs).
A total of 9,018 TBI patients had complete data to allow calculation of probability of survival using TRISS. A total of 16.7% of patients were intubated in the field; 49.6% of these were transported by air medical providers. Patients undergoing prehospital intubation, transported by ground, with arrival eucapnia, and without arrival hypoxemia had higher mean OPSD values.
Intubated patients were more likely to be “unexpected survivors” and live to hospital discharge despite low predicted survival values; patients transported by air medical personnel had higher OPSD values and had a higher proportion of unexpected survivors. No statistically significant differences were observed between air- and ground-transported patients with regard to arrival PCO2 values arrival PO2 values.
Prehospital Airway and Ventilation Management: A Trauma Score and Injury Severity Score-Based Analysis J Trauma. 2010 Aug;69(2):294-301
