Category Archives: PHARM

Prehospital and Retrieval Medicine

All Updates, ICU, PHARM, Resus

Flying Docs and Airways

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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.

All Updates, PHARM, Resus

How to give cold saline in the field

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Pre-hospital therapeutic hypothermia might be a good thing, but there may be difficulties in achieving it if the 4 degrees C saline warms up during the infusion. What’s the optimal way of administering it? Czech investigators attempt to answer the question:
Background The cooling efficacy of intravenous administration of cold crystalloids can be enhanced by optimisation of the procedure. This study assessed the temperature stability of different application regimens of cold normal saline (NS) in simulated prehospital conditions.

Methods Twelve different application regimens of 4°C cold NS (volumes of 250, 500 and 1000 ml applied at infusion rates of 1000, 2000, 4000 and 6000 ml/h) were investigated for infusion temperature changes during administration to an artificial detention reservoir in simulated prehospital conditions.
Results An increase in infusion temperature was observed in all regimens, with an average of 8.163.38C (p<0.001). This was most intense during application of the residual 20% of the initial volume. The lowest rewarming was exhibited in regimens with 250 and 500 ml bags applied at an infusion rate of 6000 ml/h and 250 ml applied at 4000 ml/h. More intense, but clinically acceptable, rewarming presented in regimens with 500 and 1000 ml bags administered at 4000 ml/h, 1000 ml at 6000 ml/h and 250 ml applied at 2000 ml/h. Other regimens were burdened by excessive rewarming.
Conclusion Rewarming of cold NS during application in prehospital conditions is a typical occurrence. Considering that the use of 250 ml bags means the infusion must be exchanged too frequently during cooling, the use of 500 or 1000 ml NS bags applied at an infusion rate of $4000 ml/h and termination of the infusion when 80% of the infusion volume has been administered is regarded as optimal.
Prehospital cooling by cold infusion: searching for the optimal infusion regimen
Emerg Med J. 2010 Aug 23. [Epub ahead of print]

All Updates, PHARM, Resus, Trauma, Ultrasound

Inadequate pre-hospital needle thoracostomy

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The purpose of this study was to evaluate the frequency of inadequate needle chest thoracostomy in the prehospital setting in trauma patients suspected of having a pneumothorax (PTX) on the basis of physical examination.
This study took place at a level I trauma center. All trauma patients arriving via emergency medical services with a suspected PTX and a needle thoracostomy were evaluated for a PTX with bedside ultrasound. Patients too unstable for ultrasound evaluation before tube thoracostomy were excluded, and convenience sampling was used. All patients were scanned while supine. Examinations began at the midclavicular line and included the second through fifth ribs. If no sliding lung sign (SLS) was noted, a PTX was suspected, and the lung point was sought for definitive confirmation. When an SLS was noted throughout and a PTX was ruled out on ultrasound imaging, the thoracostomy catheter was removed. Descriptive statistics were calculated.

Image used with kind permission of Bret Nelson, MD, RDMS (click image for more great ultrasound images)

A total of 57 patients were evaluated over a 3-year period. All had at least 1 needle thoracostomy attempted; 1 patient underwent 3 attempts. Fifteen patients (26%) had a normal SLS on ultrasound examination and no PTX after the thoracostomy catheter was removed. None of the 15 patients were later discovered to have a PTX on subsequent computed tomography.
In this study, 26% of patients who received needle thoracostomy in the prehospital setting for a suspected PTX appeared not to have had a PTX originally, nor had 1 induced by the needle thoracostomy. It may be prudent to evaluate such patients with bedside ultrasound instead of automatically converting all needle thoracostomies to tube thoracostomies.
Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study
J Ultrasound Med. 2010 Sep;29(9):1285-9

All Updates, ICU, PHARM, Resus

End tidal CO2 in cardiac arrest

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Measuring end-tidal CO2 in cardiac arrest patients is helpful for

  1. confirming tracheal tube placement
  2. assessing the effectiveness of chest compressions
  3. predicting likelihood of return of spontaneous circulation (ROSC), in that a persistently low ETCO2 tends to predict death, whereas a high or rising ETCO2 is associated with a higher chance of ROSC.

It may be however that its predictive ability depends on the type of cardiac arrest, and how far into the resuscitation you’ve got when you measure the ETCO2. Consider this new study from Slovenian pre-hospital emergency physicians:
Methods: The study included two cohorts of patients: cardiac arrest due to asphyxia with initial rhythm asystole or pulseless electrical activity (PEA), and cardiac arrest due to arrhythmia with initial rhythm VF or pulseless VT. The causes of asphyxia were: asthma, severe acute respiratory failure, tumor of the airway, suicide by hanging, acute intoxication, pneumonia and a foreign body in the airway.PetCO2 was measured for both groups immediately after intubation and repeatedly every minute, both for patients with or without return of spontaneous circulation (ROSC). We compared the dynamic pattern of PetCO2 between groups. Resuscitation procedures were performed by an emergency medical team (emergency medical physician and two emergency medical technicians or registered nurses) in accordance with 2005 ERC Guideline
Results: Between June 2006 and June 2009 resuscitation was attempted in 325 patients and in this study we included 51 patients with asphyxial cardiac arrest and 63 patients with VF/VT cardiac arrest. The initial values of PetCO2 were significantly higher in the group with asphyxial cardiac arrest (6.74 ± 4.22 kilopascals (kPa) versus 4.51 ± 2.47 kPa; P = 0.004). In the group with asphyxial cardiac arrest, the initial values of PetCO2 did not show a significant difference when we compared patients with and without ROSC (6.96 ± 3.63 kPa versus 5.77 ± 4.64 kPa; P = 0.313). We confirmed significantly higher initial PetCO2 values for those with ROSC in the group with primary cardiac arrest (4.62 ± 2.46 kPa versus 3.29 ± 1.76 kPa; P = 0.041).

A significant difference in PetCO2 values for those with and without ROSC was achieved after five minutes of CPR in both groups (asphyxial arrest: 6.09 ± 2.63 kPa versus 4.47 ± 3.35 kPa; P = 0.006; primary arrest: 5.63 ± 2.01 kPa versus 4.26 ± 1.86; P = 0.015)
In mmHg, the PetCO2 values for those with and without ROSC after five minutes of CPR was: asphyxial arrest: 42.3 ± 20 mmHg versus 34 ± 25.5 mmHg; P = 0.006; primary arrest: 42.8 ± 15.3 mmHg versus 32.3 ± 14.1 mmHg; P = 0.015
Graphically, this difference in ROSC vs non-ROSC PetCO2 for both groups appeared to be even greater at ten minutes, with higher statistically significance (p<0.001), although the values of PetCO2 are not given in the paper.
In all patients with ROSC the initial PetCO2 was again higher than 1.33 kPa (10.1 mmHg).
Conclusions: The dynamic pattern of PetCO2 values during out-of-hospital CPR showed higher values of PetCO2 in the first two minutes of CPR in asphyxia, and a prognostic value of initial PetCO2 only in primary VF/VT cardiac arrest. A prognostic value of PetCO2 for ROSC was achieved after the fifth minute of CPR in both groups and remained present until final values. This difference seems to be a useful criterion in pre-hospital diagnostic procedures and attendance of cardiac arrest.
The authors summarise with the following key messages:

  • Initial values of PetCO2 are higher in asphyxial cardiac arrest than in primary cardiac arrest.
  • Initial values of PetCO2 in asphyxial cardiac arrest do not have a prognostic value for resuscitation outcome.
  • The prognostic value of PetCO2 for ROSC was achieved after the fifth minute of CPR in both groups and remained present until the final values.
  • The values of PetCO2 seem to be useful in differentiating the causes of cardiac arrest in a pre-hospital setting.

I think that last one’s a bit of a stretch. For me, this paper confirms that the longer you are into a cardiac arrest resuscitation, the worse news a low PetCO2 is. The lack of predictive value of initial PetCO2, particularly in the asphyxia group, is interesting but not surprising.
The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation: difference between asphyxial cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest
Critical Care 2011, 15:R13

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Pre-hospital therapeutic hypothermia

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A Czech study demonstrated effective pre-hospital therapeutic cooling of post-cardiac arrest patients using fairly modest amounts of intravenous saline at 4°C: the administration of 12.6 ± 6.4 mL/kg (1,032 ± 546 mL) of 4°C normal saline led to a tympanic temperature decrease of 1.4 ± 0.8°C (from 36.2 ± 1.5 to 34.7 ± 1.4°C; P < 0.001) in 42.8 ± 19.6 minutes. No ice packs were applied.

Before other emergency medical services adopt this, it should be noted that all these patients were managed in the field by emergency physicians who administered sedatives and neuromuscular blockers. It’s a European thing.
Pre-hospital cooling of patients following cardiac arrest is effective using even low volumes of cold saline
Critical Care 2010, 14:R231 Full text

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Better outcomes with conventional CPR

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A very large nationwide Japanese observational study examined outcomes in out-of-hospital cardiac arrest patients who received CPR from lay rescuers. They compared conventional CPR (with mouth-to-mouth and chest compressions) with compression-only CPR. Over 40 000 patients were included.
Conventional CPR was associated with better outcomes than chest compression only CPR, for both one month survival (adjusted odds ratio 1.17, 95% confidence interval 1.06 to 1.29) and neurologically favourable one month survival (1.17, 1.01 to 1.35). Neurologically favourable one month survival decreased with increasing age and with delays of up to 10 minutes in starting CPR for both conventional and chest compression only CPR. The benefit of conventional CPR over chest compression only CPR was significantly greater in younger people in non-cardiac cases (P=0.025) and with a delay in start of CPR after the event was witnessed in non-cardiac cases (P=0.015) and all cases combined (P=0.037).
The authors conclude that conventional CPR is associated with better outcomes than chest compression only CPR for selected patients with out of hospital cardiopulmonary arrest, such as those with arrests of non-cardiac origin and younger people, and people in whom there was delay in the start of CPR.
Outcomes of chest compression only CPR versus conventional CPR conducted by lay people in patients with out of hospital cardiopulmonary arrest witnessed by bystanders: nationwide population based observational study
BMJ 2011; 2011; 342:c7106 Full Text

All Updates, PHARM, Resus, Trauma

Helicopters and trauma: systematic review

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In the midst of reconfiguring its trauma systems, the United Kingdom’s National Health Service needed to evaluate the cost effectiveness of helicopter emergency medical services (HEMS). A systematic literature review was undertaken of all population-based studies evaluating the impact on mortality of helicopter transfer of trauma patients from the scene of injury. The authors also attempted to analyse whether it is the helicopter as a transport platform or the standard of the emergency medical service that accounts for any differences seen.
A search of the literature revealed 23 eligible studies. 14 of these studies demonstrated a significant improvement in trauma patient mortality when transported by helicopter from the scene. 5 of the 23 studies were of level II evidence with the remainder being of level III evidence.

Only one eligible study assessed HEMS in the UK. The other papers reported data from the USA, Italy, Australia, the Netherlands, Germany and South Africa.
The majority of studies show a mortality benefit with HEMS: fourteen studies reported results that demonstrated a significant mortality rate improvement with HEMS, four reported data that did not reach significance and five did not report whether results reached significance.
The authors suggest this variation may be a result of any of the following factors, and provide a thorough discussion of the literature pertaining to each of them:

  1. Transport of a physician to the scene
  2. Transport of advanced airway skills to the scene
  3. Transporting a team experienced in managing trauma patients
  4. Triage to the definitive treatment facility

The full text of the review is available at the link below.
Is it the H or the EMS in HEMS that has an impact on trauma patient mortality? A systematic review of the evidence
EMJ 2010;27(9):692-701 (Free Full Text)

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Paediatric airway gems

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Dr Rich Levitan has made an enormous contribution to the science and practice of emergency airway management, as his bibliography demonstrates. In a new article in Emergency Physicians Monthly entitled ‘Demystifying Pediatric Laryngoscopy’, Rich covers some great tips for optimising laryngoscopic view in kids.
Check this excerpt out for an example:
“During laryngoscopy in infants the epiglottis and uvula are often touching; the epiglottis may be located within an inch of the mouth. Often the epiglottis lies against the posterior pharynx, and it is critical to have a Yankauer to dab the posterior pharynx as the laryngoscope is advanced. Hyperextension of the head pushes the base of tongue and epiglottis backwards against the posterior pharyngeal wall, and makes epiglottis identification more difficult”
Gems like this come thick and fast when you hear or read what Rich has to say. Seven years ago I was left reeling after finishing his ‘Airway Cam Guide to Intubation and Practical Emergency Airway Management‘ which profoundly influenced the way I practice and teach emergency airway skills, including on the Critical Care for Emergency Physicians course.

I’ve finally gotten round to booking a place on one of his courses in March in Baltimore. I’ll let you know how it goes. In the mean time, I’d like to point you toward his training videos as a great educational resource, like this one that demonstrates for novice laryngoscopists the difference between the appearances of trachea and oesophagus, the former having recognisable, defined posterior cartilagenous structures:

Demystifying Pediatric Laryngoscopy
Emergency Physicians Monthly January 19, 2011

All Updates, PHARM, Trauma

A French FIRST in pre-hospital medicine

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A contribution has been made to the literature supporting physician intervention in some pre-hospital trauma patients, in the form of the FIRST study: French Intensive care Recorded in Severe Trauma. Not exactly the class 1 evidence we’d (well, I’d) like to see, but a prospective study from France comparing outcomes in patients treated by routine pre-hospital providers with those managed in the field by emergency physicians working for SMUR (Service Mobile d’Urgences et de Réanimation). Primary outcome was 30-day mortality. Only patients admitted to an ICU were included, and researchers were not blinded to which group (SMUR vs nonSMUR) patients belonged. A large group of SMUR patients (2513) was compared with a much smaller (190) nonSMUR group.
Patients were sicker in the SMUR group (lower GCS and SpO2, higher Injury Severity Score, higher frequency of abnormal pupils). Unadjusted mortality was not significantly different but when adjustment for ISS and physiological status was made (I don’t really understand how this was done), SMUR care was significantly associated with a reduced risk of 30-day mortality (OR: 0.55, 95% CI: 0.32-0.94, p = 0.03).

Lots of interesting points in this study, most of which ask more questions that they answer. The French pre-hospital physicians have an aggressive approach to trauma resuscitation, doing rapid sequence intubation in more than a half of their patients and even starting catecholamine infusions as a fluid-sparing strategy in shocked patients. The full text link is worth a read for those interested in this area of medicine.
Medical pre-hospital management reduces mortality in severe blunt trauma: a prospective epidemiological study
Critical Care 2011, 15:R34
Full text as provisional PDF

Acute Med, All Updates, PHARM, Resus

Improved survival with modified CPR

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A large randomised controlled trial1 on out-of-hospital cardiac arrest patients compared standard CPR with CPR augmented by two modifications:

  • active compression-decompression using a hand-held suction device to compress the chest. The device is attached to the chest of the patient during CPR and the rescuer actively lifts the chest upwards after each compression, which are done at a rate of 80/min

  • augmented negative intrathoracic pressure using an impedance threshold device, which is a valve that limits passive air entry into the lungs during chest compressions, thereby reducing intrathoracic pressure and increasing blood flow to vital organs

The primary study endpoint was survival to hospital discharge with favourable neurological function.
Funding issues resulted in premature cessation of the study. 47 (6%) of 813 controls survived to hospital discharge with favourable neurological function compared with 75 (9%) of 840 patients in the intervention group (odds ratio 1·58, 95% CI 1·07–2·36; p=0·019]. 74 (9%) of 840 patients survived to 1 year in the intervention group compared with 48 (6%) of 813 controls (p=0·03), with equivalent cognitive skills, disability ratings, and emotional-psychological statuses in both groups. The overall major adverse event rate did not differ between groups, but more patients had pulmonary oedema in the intervention group (94 [11%] of 840) than did controls (62 [7%] of 813; p=0·015).
An accompanying editorial2 points out that previous studies in animal models of cardiac arrest gave reassuring results for both devices individually and when used together, but results from clinical trials in patients have been mixed for each device when used individually:

  • For compression-decompression CPR, a systematic review pooled the existing data for such CPR versus standard CPR in 4162 patients and found no difference in short-term mortality (relative risk 0·98, 95% CI 0·94–1·03) or survival to hospital discharge (0·99, 0·98–1·01). The 2010 CPR guidelines for the USA and Europe do not recommend the use of compression–decompression CPR alone.
  • The most current systematic review for the impedance-threshold device showed a significantly improved early survival (relative risk 1·45, 1·16–1·80), and a short-term improved neurological outcome (2·35, 1·30–4·24); however, improved long- term survival did not reach conventional statistical significance (1·48, 0·91–2·41).

The Resuscitation Outcomes Consortium (ROC) PRIMED study3 showed no survival benefit in 8718 patients randomised to standard CPR with an active or sham impedance-threshold device (the Consortium includes the same investigators as the Lancet paper). This was published as an abstract in Circulation recently.
The editorialist has reservations regarding a change in clinical practice resulting from this new study, partly because the trial was stopped prematurely and enrolment of a larger cohort could have changed the findings, and partly because the open use of both devices might have unintentionally introduced bias into the study. Further validation is recommended.
1. Standard cardiopulmonary resuscitation versus active compression-decompression cardiopulmonary resuscitation with augmentation of negative intrathoracic pressure for out-of-hospital cardiac arrest: a randomised trial
 Lancet 2011;377:301-11
2. Augmented CPR: rescue after the ResQ trial
Lancet. 2011 Jan 22;377:276-7
3. The Resuscitation Outcomes Consortium ROC) PRIMED Impedance Threshold Device (ITD) Cardiac Arrest Trial: A Prospective, Randomized, Double-Blind, Controlled Clinical Trial
Circulation 2010; 122: 2215–26 (abstr)