Some pectus excavatum patients have a metal ‘Nuss bar’ inserted below the sternum which can make chest compressions more difficult. In those without one, standard compression depths compress the left ventricle more than in non-pectus subjects, and might lead to myocardial injury.
This has led to a recommendation in the journal Resuscitation:
“Until further studies are available, we recommend strong chest compressions, according to the current guidelines, in PE patients with a sternal Nuss bar and, to minimize the risk of myocardial injury, we suggest a reduced chest compression depth (approximately 3–4 cm) at the level of lower half of the sternum in PE patients who have not had corrective surgery.”
Cardiopulmonary resuscitation in pectus excavatum patients: Is it time to say more?
Resuscitation. 2014 Dec 10.[Epub ahead of print]
Category Archives: PHARM
Prehospital and Retrieval Medicine
Esmolol for refractory VF
Already well publicised on social media, the team at Hennepin County published a retrospective comparison between patients with refractory VF who received esmolol with those who did not(1). The results are impressive and I look forward to further studies on this.
I work in an ED in a hospital with no cath lab and no access to extracorporeal life support, limiting our options for patients who remain in shockable rhythms despite ACLS interventions. We now have esmolol available in our resus room. You might want to keep it in your list of options for ACLS-refractory VF, which might also include double sequential external defibrillation(2) and even stellate ganglion block.
The dose of esmolol used was: loading dose 500 mcg/kg, followed by infusions of 0, 50, or 100 mcg/kg/min
An important point to note in the esmolol study is that almost all patients received high-quality mechanical CPR with the combined use of an impedence threshold device to augment venous return and cardiac output. The authors “speculate that this additional hemodynamic support may be essential given the hypotensive effects of esmolol.”
1. Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation
Resuscitation. 2014 Oct;85(10):1337-41
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INTRODUCTION: We compare the outcomes for patients who received esmolol to those who did not receive esmolol during refractory ventricular fibrillation (RVF) in the emergency department (ED).
METHODS: A retrospective investigation in an urban academic ED of patients between January 2011 and January 2014 of patients with out-of-hospital or ED cardiac arrest (CA) with an initial rhythm of ventricular fibrillation (VF) or ventricular tachycardia (VT) who received at least three defibrillation attempts, 300mg of amiodarone, and 3mg of adrenaline, and who remained in CA upon ED arrival. Patients who received esmolol during CA were compared to those who did not.
RESULTS: 90 patients had CA with an initial rhythm of VF or VT; 65 patients were excluded, leaving 25 for analysis. Six patients received esmolol during cardiac arrest, and nineteen did not. All patients had ventricular dysrhythmias refractory to many defibrillation attempts, including defibrillation after administration of standard ACLS medications. Most received high doses of adrenaline, amiodarone, and sodium bicarbonate. Comparing the patients that received esmolol to those that did not: 67% and 42% had temporary return of spontaneous circulation (ROSC); 67% and 32% had sustained ROSC; 66% and 32% survived to intensive care unit admission; 50% and 16% survived to hospital discharge; and 50% and 11% survived to discharge with a favorable neurologic outcome, respectively.
CONCLUSION: Beta-blockade should be considered in patients with RVF in the ED prior to cessation of resuscitative efforts.
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2. Double Sequential External Defibrillation in Out-of-Hospital Refractory Ventricular Fibrillation: A Report of Ten Cases.
Prehosp Emerg Care. 2015 January-March;19(1):126-130
[EXPAND Abstract]
Background. Ventricular fibrillation (VF) is considered the out-of-hospital cardiac arrest (OOHCA) rhythm with the highest likelihood of neurologically intact survival. Unfortunately, there are occasions when VF does not respond to standard defibrillatory shocks. Current American Heart Association (AHA) guidelines acknowledge that the data are insufficient in determining the optimal pad placement, waveform, or energy level that produce the best conversion rates from OOHCA with VF.
Objective. To describe a technique of double sequential external defibrillation (DSED) for cases of refractory VF (RVF) during OOHCA resuscitation.
Methods. A retrospective case series was performed in an urban/suburban emergency medical services (EMS) system with advanced life support care and a population of 900,000. Included were all adult OOHCAs having RVF during resuscitation efforts by EMS providers. RVF was defined as persistent VF following at least 5 unsuccessful single shocks, epinephrine administration, and a dose of antiarrhythmic medication. Once the patient was in RVF, EMS personnel applied a second set of pads and utilized a second defibrillator for single defibrillation with the new monitor/pad placement. If VF continued, EMS personnel then utilized the original and second monitor/defibrillator charged to maximum energy, and shocks were delivered from both machines simultaneously. Data were collected from electronic dispatch and patient care reports for descriptive analysis.
Results. From 01/07/2008 to 12/31/2010, a total of 10 patients were treated with DSED. The median age was 76.5 (IQR: 65-82), with median resuscitation time of 51minutes (IQR: 45-62). The median number of single shocks was 6.5 (IQR: 6-11), with a median of 2 (IQR: 1-3) DSED shocks delivered. VF broke after DSED in 7 cases (70%). Only 3 patients (30%) had ROSC in the field, and none survived to discharge.
Conclusion. This case series demonstrates that DSED may be a feasible technique as part of an aggressive treatment plan for RVF in the out-of-hospital setting. In this series, RVF was terminated 70% of the time, but no patient survived to discharge. Further research is needed to better understand the characteristics of and treatment strategies for RVF.
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Difficult airways can't be reliably predicted
This paper1 proves what Rich Levitan has been saying (and writing) for years – that there is no method of prediction of difficult intubation that is both highly sensitive (the test wouldn’t miss many difficult airways) and highly specific (meaning those predicted to be difficult would indeed turn out to be difficult). Most importantly, this means one should always have a plan for failure to intubate and failure to mask-ventilate regardless of how ‘easy’ the airway may appear.
This study of a large prospectively collected database captured anaesthetists’ clinical assessment of likelihood of difficult intubation and difficult mask-ventilation, and compared them with actual findings. These studies are always difficult, due in part to the lack of standard definitions of difficult airways, but the take home was clear – the large majority of difficulties were unanticipated and not suspected from pre-operative clinical assessment.
This issue was brilliantly summed up by Yentis in a 2002 Editorial2:
“I dare to suggest that attempting to predict difficult intubation is unlikely to be useful – does that mean one shouldn’t do it at all? To this I say no, for there is another important benefit of this ritual: it forces the anaesthetist at least to think about the airway, and for this reason we should encourage our trainees (and ourselves) to continue doing it.”
1. Diagnostic accuracy of anaesthesiologists’ prediction of difficult airway management in daily clinical practice: a cohort study of 188 064 patients registered in the Danish Anaesthesia Database
Anaesthesia. 2014 Dec 16. doi: 10.1111/anae.12955. [Epub ahead of print]
[EXPAND Abstract]
Both the American Society of Anesthesiologists and the UK NAP4 project recommend that an unspecified pre-operative airway assessment be made. However, the choice of assessment is ultimately at the discretion of the individual anaesthesiologist. We retrieved a cohort of 188 064 cases from the Danish Anaesthesia Database, and investigated the diagnostic accuracy of the anaesthesiologists’ predictions of difficult tracheal intubation and difficult mask ventilation. Of 3391 difficult intubations, 3154 (93%) were unanticipated. When difficult intubation was anticipated, 229 of 929 (25%) had an actual difficult intubation. Likewise, difficult mask ventilation was unanticipated in 808 of 857 (94%) cases, and when anticipated (218 cases), difficult mask ventilation actually occurred in 49 (22%) cases. We present a previously unpublished estimate of the accuracy of anaesthesiologists’ prediction of airway management difficulties in daily routine practice. Prediction of airway difficulties remains a challenging task, and our results underline the importance of being constantly prepared for unexpected difficulties.
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2. Predicting difficult intubation–worthwhile exercise or pointless ritual?
Anaesthesia. 2002 Feb;57(2):105-9
High flow systems for apnoeic oxygenation
Apnoeic oxygenation during laryngoscopy via nasal prongs has really taken off in the last couple of years in emergency department RSI, and is associated with decreased desaturation rates in out-of-hospital RSI.
More effective oxygenation and a small amount of PEEP can be provided by high flow nasal cannulae with humidified oxygen (HFNC)
A logical step in the progression of this topic is to consider HFNC for apnoeic oxygenation, and Reuben Strayer wrote about this nearly three years ago.
In a Twitter conversation today, Dr Pete Sherren highlighted a new article describing its use in anaesthesia for patients with difficult airways. This is labelled Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE). A reply from Dr Neil Brain points out that when used in kids, the bulkiness of the apparatus may get in the way of bag-mask ventilation (if that becomes necessary).
But does HFNC apnoeic oxygenation confer any advantages over standard nasal cannulae?
In an apnoeic patient, 15l/min via standard cannulae should fill the pharyngeal space with 100% oxygen, and you can’t improve on 100%.
HFNC provide some continuous positive pressure, but this may be cancelled by the necessary mouth opening for laryngoscopy.
One issue with apnoea is of course a rise in carbon dioxide with consequent acidosis. The authors of the THRIVE paper (abstract below) point out that in previous apnoeic oxygenation studies, the rate of rise of carbon dioxide levels was between 0.35 and 0.45 kPa/min (2.7-3.4 mmHg/min), whereas with THRIVE the rise was 0.15 kPa/min (1.1 mmHg/min). They suggest that continuous insufflation with high flow oxygen facilitates oxygenation AND carbon dioxide clearance through gaseous mixing and flushing of the deadspace.
So should we switch from standard nasal cannula to high flow cannulae for apnoeic oxygenation? I think not routinely, but perhaps consider it in patients:
(1) with pressure-dependent oxygenation (eg. ARDS) although I’m not sure any CPAP effect would be sustained during laryngoscopy
and
(2) in patients with significant acidosis in whom a significant rise in carbon dioxide could be detrimental (eg. diabetic ketoacidosis).
I look forward to reading more studies on this, and to hearing from anyone with experience of this technique in the comments section.
Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE): a physiological method of increasing apnoea time in patients with difficult airways.
Anaesthesia. 2014 Nov 10. doi: 10.1111/anae.12923. [Epub ahead of print]
[EXPAND Abstract]
Emergency and difficult tracheal intubations are hazardous undertakings where successive laryngoscopy-hypoxaemia-re-oxygenation cycles can escalate to airway loss and the ‘can’t intubate, can’t ventilate’ scenario.
Between 2013 and 2014, we extended the apnoea times of 25 patients with difficult airways who were undergoing general anaesthesia for hypopharyngeal or laryngotracheal surgery. This was achieved through continuous delivery of transnasal high-flow humidified oxygen, initially to provide pre-oxygenation, and continuing as post-oxygenation during intravenous induction of anaesthesia and neuromuscular blockade until a definitive airway was secured. Apnoea time commenced at administration of neuromuscular blockade and ended with commencement of jet ventilation, positive-pressure ventilation or recommencement of spontaneous ventilation. During this time, upper airway patency was maintained with jaw-thrust.
Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) was used in 15 males and 10 females. Mean (SD [range]) age at treatment was 49 (15 [25-81]) years. The median (IQR [range]) Mallampati grade was 3 (2-3 [2-4]) and direct laryngoscopy grade was 3 (3-3 [2-4]). There were 12 obese patients and nine patients were stridulous. The median (IQR [range]) apnoea time was 14 (9-19 [5-65]) min. No patient experienced arterial desaturation < 90%. Mean (SD [range]) post-apnoea end-tidal (and in four patients, arterial) carbon dioxide level was 7.8 (2.4 [4.9-15.3]) kPa. The rate of increase in end-tidal carbon dioxide was 0.15 kPa.min(-1) .
We conclude that THRIVE combines the benefits of ‘classical’ apnoeic oxygenation with continuous positive airway pressure and gaseous exchange through flow-dependent deadspace flushing. It has the potential to transform the practice of anaesthesia by changing the nature of securing a definitive airway in emergency and difficult intubations from a pressured stop-start process to a smooth and unhurried undertaking.
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London Cardiac Arrest Symposium 2014
The focus of the entire day is cardiac arrest and this is the second day of the London Cardiac Arrest Symposium.
Professor Niklas Nielsen kicked off with a presentation of his Targeted Temperature Management trial. It seems that even now there is uncertainty in the interpretation of this latest study. I take heart from the knowledge that Prof Nielsen has changed the practice of his institution to reflect the findings of his study – I have certainly changed my practice. But we need to remain aware that there is more work to be done to answer the multiple questions that remain and the need for further RCTs is recognised.
The management of Cardiac arrest after avalanche is not a clinical scenario that I imagine I’ll ever find myself in. The management is well documented in the ICAR MEDCOM guidelines 2012. Dr Peter Paal reminded us that you’re not dead until you’re rewarmed and dead unless: with asystole, CPR may be terminated (or withheld) if a patient is lethally injured or completely frozen, the airway is blocked and duration of burial >35 min, serum potassium >12 mmol L(-1), risk to the rescuers is unacceptably high or a valid do-not-resuscitate order exists.
The age old question about prognostication after cardiac arrest was tackled by Prof Mauro Oddo. He covered the evidence for clinical examination, SSPE, EEG, and neurone specific enolase. Bottom line, all of these modalities are useful but none are specific enough to be used as a stand alone test so multiple modalities are required.
SAMU is leading the way with prehospital ECMO. They have mastered the art of cannulation (in the Louvre no less!) but there haven’t enough cases to demonstrate a mortality benefit. The commencement of ECMO prehospital reduces low flow time and theoretically should improve outcomes. This is begging for a RCT.
The experience of the Italians with in hospital ECMO shoes a better survival rate for in-hospital rather than out of hospital cardiac arrests, explained Dr Tomasso Mauri. They treat patients with a no flow time of <6min and low flow rate of <45min and had a 31% ICU survival rate. If you want to learn more about ED ECMO go to http://edecmo.org.
The Douglas Chamberlain lecture this year was Selective aortic arch perfusion presented by Prof James Manning. He spoke about the use of this technique in cardiac arrest and also in trauma (where it is known to you as Zone 1 REBOA).
In cardiac arrest the aim is to improve coronary perfusion, to preserve perfusion to the heart and the brain, offer a route of rapid temperature control and offer a direct route of administration of adrenaline. Coronary perfusion is seen to be supra normal after SAAP. And the suggested place for SAAP is prior to ECMO.
It’s more familiar ground talking about SAAP in trauma. This Zone 1 occlusion preserves cerebral and cardiac perfusion while blood loss is limited and rapid fluid resuscitation can occur.
You can hear Prof Manning on SAAP over at EMCrit (of course!).
It’s been another great conference. Put the dates for next year’s London Trauma & Cardiac Arrest Conferences in your diary: 8th-10th December 2015!
Happy Holidays & Keep Well
Louisa Chan
Bilateral fixed dilated pupils? Operate if extradural!
Almost two-thirds of patients with extradural haematoma and bilateral fixed dilated pupils survived after surgery, with over half having a good outcome
Neurosurgeon, HEMS doctor, and all round good egg Mark Wilson was on the RAGE podcast recently and mentioned favourable outcomes from neurosurgery in patients with extradural (=epidural) haematomas who present with bilateral fixed dilated pupils (BFDP). Here’s his paper that gives the figures – a systematic review and meta-analysis.
A total of 82 patients with BFDP who underwent surgical evacuation of either subdural or extradural haematoma were identified from five studies – 57 with subdural (SDH) and 25 with extradural haematomas (EDH).
In patients with EDH and BFDP mortality was 29.7% (95% CI 14.7% to 47.2%) and 54.3% had a favourable outcome (95% CI 36.3% to 71.8%).
Only 6.6% of patients with SDH and BFDP had a good functional outcome.
Clearly there is potential for selection bias and publication bias, but these data certainly suggest an aggressive surgical approach is appropriate in some patients with BFDP.
The authors comment on the pessimism that accompanies these cases, which potentially denies patients opportunities for recovery:
“We believe that 54% of patients with extradural haematoma with BFDPs having a good outcome is an underappreciated prognosis, and the perceived poor prognosis of BFDPs (from all causes) has influenced decision making deeming surgery inappropriately futile in some cases.”
Scotter J, Hendrickson S, Marcus HJ, Wilson MH.
Prognosis of patients with bilateral fixed dilated pupils secondary to traumatic extradural or subdural haematoma who undergo surgery: a systematic review and meta-analysis.
Emerg Med J 2014 e-pub ahead of print Nov 11;:1–7
[EXPAND Abstract]
Primary objective To review the prognosis of patients with bilateral fixed and dilated pupils secondary to traumatic extradural (epidural) or subdural haematoma who undergo surgery.
Methods A systematic review and meta-analysis was performed using random effects models. The Cochrane Central Register of Controlled Trials and PubMed databases were searched to identify relevant publications. Eligible studies were publications that featured patients with bilateral fixed and dilated pupils who underwent surgical evacuation of traumatic extra-axial haematoma, and reported on the rate of favourable outcome (Glasgow Outcome Score 4 or 5).
Results Five cohort studies met the inclusion criteria, collectively reporting the outcome of 82 patients. In patients with extradural haematoma, the mortality rate was 29.7% (95% CI 14.7% to 47.2%) with a favourable outcome seen in 54.3% (95% CI 36.3% to 71.8%). In patients with acute subdural haematoma, the mortality rate was 66.4% (95% CI 50.5% to 81.9%) with a favourable outcome seen in 6.6% (95% CI 1.8% to 14.1%).
Conclusions and implications of key findings Despite the poor overall prognosis of patients with closed head injury and bilateral fixed and dilated pupils, our findings suggest that a good recovery is possible if an aggressive surgical approach is taken in selected cases, particularly those with extradural haematoma.
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Non-ST-Elevation Acute Coronary Syndromes
The latest AHA/ACC guidelines on NSTEACS have been published ahead of print in Circulation.
Full text is available, and the Executive Summary is available here
Amsterdam EA, Wenger NK, Brindis RG, Casey DE, Ganiats TG, Holmes DR, et al.
2014 AHA/ACC Guideline for the Management of Patients With Non-ST-Elevation Acute Coronary Syndromes: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
Circulation. 2014 Sep 23. [Epub ahead of print]
Blunt traumatic arrest in kids
Traumatic cardiac arrest outcomes are not great, but they’re not so bad that resuscitation is futile – a subject I’ve ranted about before.
The largest study on blunt traumatic arrest in children to date has been published, showing that 340 / 7766 kids without signs of life in the field survived to hospital discharge. Neurological status at discharge was not documented. However, this represents 4.4%, or in other words for every 22 blunt traumatically arrested children who underwent prehospital resuscitation, one survived to discharge. The authors describe this survival as ‘dismal’. It’s not great, but my take on it is that survival is possible and in most cases resuscitation should be attempted.
The authors state:
“Based on these data, EMS providers should not be discouraged from resuscitating blunt pediatric trauma patients found in the field with no signs of life”
While the major focus should be on injury prevention, it is worthwhile considering whether more advanced resuscitation in the field could be provided to further increase the number of neurologically intact survivors.
Survival of pediatric blunt trauma patients presenting with no signs of life in the field
J Trauma Acute Care Surg. 2014 Sep;77(3):422-6
[EXPAND Abstract]
BACKGROUND: Prehospital traumatic cardiopulmonary arrest is associated with dismal prognosis, and patients rarely survive to hospital discharge. Recently established guidelines do not apply to the pediatric population because of paucity of data. The study objective was to determine the survival of pediatric patients presenting in the field with no signs of life after blunt trauma.
METHODS: We conducted a retrospective analysis of the National Trauma Data Bank research data set (2002-2010). All patients 18 years and younger with blunt traumatic injuries were identified (DRG International Classification of Diseases-9th Rev. codes 800-869). No signs of life (SOL) was defined on physical examination findings and included the following: pulse, 0; respiratory rate, 0; systolic blood pressure, 0; and no evidence of neurologic activity. These same criteria were reassessed on arrival at the emergency department (ED). Furthermore, we examined patients presenting to the ED who underwent resuscitative thoracotomy (Current Procedural Terminology code 34.02). Our primary outcome was survival to discharge from the hospital.
RESULTS: There were a total of 3,115,597 pediatric patients who were found in the field after experiencing blunt trauma. Of those, 7,766 (0.25%) had no SOL. Seventy percent of the patients with no SOL in the field were male. Survival to hospital discharge of all patients presenting with no SOL was 4.4% (n = 340). Twenty-five percent of the patients in the field with no SOL were successfully resuscitated in the field and regained SOL by the time they arrived to the ED (n = 1,913). Of those patients who regained SOL, 13.8% (n = 265) survived to hospital discharge. For patients in the field with no SOL, survival to discharge was significantly higher in patients who did not receive a resuscitative thoracotomy than in those who did.
CONCLUSION: Survival of pediatric blunt trauma patients in the field without SOL is dismal. Resuscitative thoracotomy poses a heightened risk of blood-borne pathogen exposure to involved health care workers and is associated with a significantly lower survival rate.
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When to Stop Resuscitation
My talk at the SmaccGOLD conference in March 2014
Cliff Reid – When Should Resuscitation Stop from Social Media and Critical Care on Vimeo.
Here are the slides:
Down with "down" time!
A man in his 40s has a witnessed collapse and CPR is immediately started. Paramedics are on scene within 5 minutes and initiate advanced cardiac life support. He has refractory ventricular fibrillation which degenerates to asystole. He arrives in an emergency department where, with good ongoing CPR, he appears reasonably well perfused and even demonstrates some spontaneous movements and reactive pupils. He is placed on a mechanical CPR device and activation of the cardiac cath lab is requested. The patient has been in cardiac arrest now for 32 minutes. The cardiology fellow appears and asks: ‘what’s the down time?’
What’s the right answer? Would you say ‘half an hour’? ’32 minutes’?
And does it matter? Why is the cardiology fellow asking? Does she have an arbitrary cut off in mind, over which emergency coronary reperfusion will be denied?
I think there are several problems with conversations like these.
The first, is what does ‘down time’ even mean?
The second, is how relevant is a cardiac arrest time interval to prognosis in an individual patient?
The third, is what is the significance of any time interval in a patient who at the time of assessment has some signs that CPR is providing some perfusion and there is some evidence of brain function?
Let’s take the first. The definition of ‘down time’ does not appear to be standardised:
In this publication it appears to refer to the time before resuscitation is commenced, where it is demonstrated to be prognostically important.
Similarly, in this medical dictionary, it is defined as the ‘temporal duration from cardiac arrest until beginning cardiopulmonary resuscitation or advanced cardiac life support.‘
However, a post in Life in the Fast Lane defines it as ‘time to return of spontaneous circulation‘
This appears to agree with The New South Wales Government’s Intensive Care Monitoring and Coordination Unit who define it as ‘the time from when a person’s heart stops beating to the time it starts beating again‘
Yet another definition is used in King County, Washington, where it is defined as ‘the time interval from collapse to call 911‘.
So the first thing is to clarify what we’re talking about: “This patient received immediate bystander CPR. He has had resuscitation for 32 minutes”.
My friend in the UK, nurse resuscitationist Fernando Candal Carballido, coined the term ‘Time of Supported Circulation‘, or TOSC. I quite like this and think it could catch on.
The next question is so what? What if it was 90 minutes? At what point do we declare futility? This is where I believe the game has changed. Multiple survivors of prolonged resuscitation are springing up in the news and in the literature. Particularly in the subgroup of patients with minimal comorbidity, early CPR, and who receive circulatory support via ECMO or mechanical CPR while they undergo coronary reperfusion.
For a great example of a prolonged CPR survivor, check out paramedic Wayne Schneider’s story,
…or listen to Steven Bernard describe amazing results from ECMO used in Melbourne in the CHEER study, which includes survivors of over two hours of CPR.
So, in summary:
- Be clear on your definitions when communicating with colleagues. ‘Down time’ does not appear to have a standard definition, so I would avoid its use.
- Some patients without comorbidities who have had early bystander CPR may survive despite long periods of CPR (or ‘TOSC’), provided the underlying cause can be treated or is reversible.
- ECMO and even more widely available mechanical CPR devices are extending the period in which these causes can be addressed.
- Bear in mind, that even if there is a period between collapse and initiation of CPR, the point that arrest occurred may not be known, and laypersons may overestimate time intervals in cardiac arrest.
Update 2016: I now use the terms ‘No Flow Time’ (time from arrest to first basic life support) and ‘Low Flow Time’ (time receiving CPR, which stops with ROSC). This is prognostically very important, with increasing numbers of reports of survivors who have had very long periods of low flow time.