Left Ventricular Assist Device for Cardiac Arrest?

October 7, 2014 by  
Filed under Acute Med, All Updates, ICU, Resus

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LVADguyiconAn interesting case report by Dr Heidlebaugh and colleagues from the Department of Emergency Medicine at the William Beaumont Hospital describes a 72 year old marathon runner who arrested during cardiac catheterisation. It suggests a possible novel alternative to ECMO for cardiac arrest.

The patient became bradycardic then asystolic during catheterisation of his right coronary artery. High quality CPR was initiated and an Impella LV assist device was placed. This restored cardiac output which was followed by episodes of venticular fibrillation and then ROSC. His initial low ejection fraction of 15% recovered after targeted temperature management on ICU to 50% and he fully recovered neurologically.

This patient already had femoral arterial access for introduction of the Impella, since he was in a cath lab. He also had immediate CPR on arresting, and was an abnormally fit 72 year old. It remains to be seen whether this procedure can be applied to other patients in cardiac arrest. The authors state:

..until ECLS is readily available, poor survival and neurological outcome after cardiac arrest might be avoided in many patients by the use of pLVAD to offload the LV and enhance perfusion. Furthermore, there may be a subset of patients, in whom the support that pLVAD offers is sufficient to optimize hemodynamic parameters and bridge to ROSC, thus reducing the need for ECLS.

This video by Dr. I-Wen Wang from the Barnes-Jewish Hospital explains how the Impella is inserted and how it works.

 

 

Full Neurologic Recovery and Return of Spontaneous Circulation Following Prolonged Cardiac Arrest Facilitated by Percutaneous Left Ventricular Assist Device
Ther Hypothermia Temp Manag. 2014 Sep 3. [Epub ahead of print]


Sudden cardiac arrest is associated with high early mortality, which is largely related to postcardiac arrest syndrome characterized by an acute but often transient decrease in left ventricular (LV) function. The stunned LV provides poor cardiac output, which compounds the initial global insult from hypoperfusion. If employed early, an LV assist device (LVAD) may improve survival and neurologic outcome; however, traditional methods of augmenting LV function have significant drawbacks, limiting their usefulness in the periarrest period. Full cardiac support with cardiopulmonary bypass is not always readily available but is increasingly being studied as a tool to intensify resuscitation. There have been no controlled trials studying the early use of percutaneous LVADs (pLVADs) in pericardiac arrest patients or intra-arrest as a bridge to return of spontaneous circulation. This article presents a case study and discussion of a patient who arrested while undergoing an elective coronary angioplasty and suffered prolonged cardiopulmonary resuscitation. During resuscitation, treatment included placement of a pLVAD and initiation of therapeutic hypothermia. The patient made a rapid and full recovery.
Image is of M. Joshua Morris, a happy LVAD recipient (not the patient in the described study) who kindly alerted me to this article. Used with permission.

ARISE study: EGDT no better than standard care

October 4, 2014 by  
Filed under Acute Med, All Updates, Guidelines, ICU, Resus

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periph-vasoactive-iconThe second of three major trials assessing early goal directed therapy (EGDT) in sepsis – the Australasian ARISE Trial – has been published.

ARISE tested the hypothesis that EGDT, as compared with usual care, would decrease 90-day all-cause mortality among patients presenting to the emergency department with early septic shock in diverse health care settings.

There was no difference in all-cause mortality at 90 days between EGDT and standard care, in keeping with the results from ProCESS.

Why are the results so different from Rivers’ original EGDT study? The authors explain:


“although our results differ from those in the original trial, they are consistent with previous studies showing that bias in small, single-center trials may lead to inflated effect sizes”

This cautions us all against making major practice changes based on one single centre study. In critical care we’ve learned this before with subjects like tight glycaemic control and Activated Protein C. However I do believe that the things we know to be of benefit – early recognition, source control, antibiotics, and fluids – are effective in making ‘standard’ care “as good as” EGDT because of heightened awareness of the condition and its treatment, and Rivers’ initial study and the subsequent Surviving Sepsis Campaign Guidelines have played a major role in raising that awareness.

The ARISE study is appraised by Wessex’s The Bottom Line and discussed on the one and only EMCrit podcast.

The ARISE Investigators and the ANZICS Clinical Trials Group.
Goal-Directed Resuscitation for Patients with Early Septic Shock
N Engl J Med. 2014 Oct;:141001063014008.Full Text


Background
Early goal-directed therapy (EGDT) has been endorsed in the guidelines of the Surviving Sepsis Campaign as a key strategy to decrease mortality among patients presenting to the emergency department with septic shock. However, its effectiveness is uncertain.

Methods In this trial conducted at 51 centers (mostly in Australia or New Zealand), we randomly assigned patients presenting to the emergency department with early septic shock to receive either EGDT or usual care. The primary outcome was all-cause mortality within 90 days after randomization.

Results Of the 1600 enrolled patients, 796 were assigned to the EGDT group and 804 to the usual-care group. Primary outcome data were available for more than 99% of the patients. Patients in the EGDT group received a larger mean (±SD) volume of intravenous fluids in the first 6 hours after randomization than did those in the usual-care group (1964±1415 ml vs. 1713±1401 ml) and were more likely to receive vasopressor infusions (66.6% vs. 57.8%), red-cell transfusions (13.6% vs. 7.0%), and dobutamine (15.4% vs. 2.6%) (P<0.001 for all comparisons). At 90 days after randomization, 147 deaths had occurred in the EGDT group and 150 had occurred in the usual-care group, for rates of death of 18.6% and 18.8%, respectively (absolute risk difference with EGDT vs. usual care, -0.3 percentage points; 95% confidence interval, -4.1 to 3.6; P=0.90). There was no significant difference in survival time, in-hospital mortality, duration of organ support, or length of hospital stay.

Conclusions In critically ill patients presenting to the emergency department with early septic shock, EGDT did not reduce all-cause mortality at 90 days.

Non-ST-Elevation Acute Coronary Syndromes

September 29, 2014 by  
Filed under Acute Med, All Updates, EMS, Guidelines, ICU, Resus

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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]

Profound hypothermia and no ECMO?

July 11, 2014 by  
Filed under Acute Med, All Updates, ICU, Kids, Resus

CPRsnow2sm

Patients in cardiac arrest due to severe hypothermia benefit from extracorporeal rewarming, and it is often recommended that they are treated at centres capable of providing cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO).

But what if they’re brought to a centre that doesn’t have those facilities?

If you work in such a centre do you have a plan, and are you familiar with what equipment you could use?

One option if you have an ICU is to provide extracorporeal warming using a haemofiltration machine used for renal replacement therapy(1). A double lumen haemofiltration catheter is inserted into a central vein and an ICU nurse can often do the rest, although some variables have to be set by the intensivist, often aided by a standard renal replacement therapy prescription chart. The machines are mobile and can be wheeled into the resus room (I have practiced this set up in resus). It might be worth discussing and practicing this option with your ICU.

Another extracorporeal option is to rig up a rapid infusion device such as a ‘Level 1′ to connect to arterial and venous catheters so that blood from the patient flows through and is warmed by the machine before being returned to the patient(2). Rapid rewarming has been achieved by this method but it requires some modification to the usual set up and so is much less likely to be a realistic option for most teams doing this on very rare occasions.

Less technical options are the traditionally taught warm saline lavage of body cavities such as the thorax and the peritoneal cavity. These can be achieved with readily available catheters and of course should be combined with ventilation with warmed gas and administration of warm intravenous fluid.

Thoracic lavage can be achieved with open thoracotomy or tube thoracostomy. One or two chest tubes can be placed on each side. One technique was described as:


Two 36 French chest tubes were placed in each hemithorax. One tube was placed in the fourth intercostal space in the mid-clavicular line. Another tube was placed into the sixth intercostal space in the mid-axillary line. Sterile saline at 39.0◦C was infused by gravity into each superior chest tube and allowed to drain passively through each inferior tube.(3)

Rapid rewarming at a rate of 6.8◦C per hour was achieved in an arrested hypothermic man using peritoneal lavage. It was done in the operating room with peritoneal lavage (saline 40◦C) with a rapid infusion system (Level 1) through two laparoscopic access sites. It was combined with external forced air rewarming and warm intravenous infusions(4).

Finally some devices manufactured for inducing hypothermia in post-cardiac arrest patients can also be used to rewarm patients, which might be endovascular devices, such as the Cool Line® catheter(5), or external, such as the Arctic Sun® Temperature Management System(6). It’s definitely worth finding out what your critical care services have as far as this equipment goes.

In summary, although the ‘exam answer’ for cardiac arrest due to profound hypothermia is often ECMO/cardiopulmonary bypass, in most centres that’s not an option. It’s helpful to remind ourselves that (1) other extracorporeal rewarming options exist and (2) non-extracorporeal techniques can provide rapid rewarming.

 

1. Spooner K, Hassani A. Extracorporeal rewarming in a severely hypothermic patient using venovenous haemofiltration in the accident and emergency department. J Accid Emerg Med. 2000 Nov;17(6):422–4. Full text

2. Gentilello LM, Cobean RA, Offner PJ, Soderberg RW, Jurkovich GJ. Continuous arteriovenous rewarming: rapid reversal of hypothermia in critically ill patients. The Journal of Trauma: Injury, Infection, and Critical Care. 1992 Mar;32(3):316–25 PubMed

3. Plaisier BR. Thoracic lavage in accidental hypothermia with cardiac arrest — report of a case and review of the literature. Resuscitation. 2005 Jul;66(1):99–104. PubMed

4. Gruber E, Beikircher W, Pizzinini R, Marsoner H, Pörnbacher M, Brugger H, et al. Non-extracorporeal rewarming at a rate of 6.8°C per hour in a deeply hypothermic arrested patient. Resuscitation. 2014 Aug;85(8):e119–20. PubMed

5. Kiridume K, Hifumi T, Kawakita K, Okazaki T, Hamaya H, Shinohara N, et al. Clinical experience with an active intravascular rewarming technique for near-severe hypothermia associated with traumatic injury. Journal of Intensive Care. BioMed Central Ltd; 2014;2(1):11. link to abstract

6. Cocchi MN, Giberson B, Donnino MW. Rapid rewarming of hypothermic patient using arctic sun device. Journal of Intensive Care Medicine. 2012 Mar;27(2):128–30. PubMed

When to Stop Resuscitation

July 9, 2014 by  
Filed under Acute Med, All Updates, EMS, Guidelines, ICU, Kids, Resus, Trauma

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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!

May 11, 2014 by  
Filed under Acute Med, All Updates, EMS, Resus

CPR-icon2A 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.

Blood pressure target in septic shock

April 1, 2014 by  
Filed under Acute Med, All Updates, ICU, Resus

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ABP-iconA study comparing mean arterial pressure (MAP) targets of 80 to 85 mm Hg (high-target group) with 65 to 70 mm Hg (low-target group) n 776 septic shock patients – the SEPSISPAM study – did not show a difference in the primary endpoint of 28 day mortality. Among patients with chronic hypertension, those in the high-target group required less renal-replacement therapy than did those in the low-target group. In my view this supports an approach that targets MAP based on the individual patient’s history rather than a blanket one-number-fits-all approach. The MAPs actually achieved in the low-target group were between 70-75 mm of Hg.

For a more thorough review check out the great PulmCCM blog.

High versus Low Blood-Pressure Target in Patients with Septic Shock.
N Engl J Med. 2014 Mar 18. [Epub ahead of print] Free Full Text


Background: The Surviving Sepsis Campaign recommends targeting a mean arterial pressure of at least 65 mm Hg during initial resuscitation of patients with septic shock. However, whether this blood-pressure target is more or less effective than a higher target is unknown.

Methods: In 31 emergency departments in the United States, we randomly assigned patients with septic shock to one of three groups for 6 hours of resuscitation: protocol-based EGDT; protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions; or usual care. The primary end point was 60-day in-hospital mortality. We tested sequentially whether protocol-based care (EGDT and standard-therapy groups combined) was superior to usual care and whether protocol-based EGDT was superior to protocol-based standard therapy. Secondary outcomes included longer-term mortality and the need for organ support.

Results: At 28 days, there was no significant between-group difference in mortality, with deaths reported in 142 of 388 patients in the high-target group (36.6%) and 132 of 388 patients in the low-target group (34.0%) (hazard ratio in the high-target group, 1.07; 95% confidence interval [CI], 0.84 to 1.38; P=0.57). There was also no significant difference in mortality at 90 days, with 170 deaths (43.8%) and 164 deaths (42.3%), respectively (hazard ratio, 1.04; 95% CI, 0.83 to 1.30; P=0.74). The occurrence of serious adverse events did not differ significantly between the two groups (74 events [19.1%] and 69 events [17.8%], respectively; P=0.64). However, the incidence of newly diagnosed atrial fibrillation was higher in the high-target group than in the low-target group. Among patients with chronic hypertension, those in the high-target group required less renal-replacement therapy than did those in the low-target group, but such therapy was not associated with a difference in mortality.

Conclusions: Targeting a mean arterial pressure of 80 to 85 mm Hg, as compared with 65 to 70 mm Hg, in patients with septic shock undergoing resuscitation did not result in significant differences in mortality at either 28 or 90 days.

No Benefit From Early Goal Directed Therapy

March 19, 2014 by  
Filed under Acute Med, All Updates, Guidelines, ICU, Resus

The first of three major trials assessing early goal directed therapy (EGDT) in sepsis – the American ProCESS Trial – has been published.

It showed what many of us thought – that the specific monitoring via a central line of central venous oxygen saturation – was not necessary for improved survival.

However the trial randomised 1341 patients to one of three arms:
(1) protocolised EGDT
(2) protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions
(3) ‘usual care’ which was not standardised.

There were no differences in any of the primary or secondary outcomes between the groups.

Interestingly, in the six hours of early care that the trial dictated, the volume of intravenous fluids administered differed significantly among the groups (2.8 litres in the protocol-based EGDT group, 3.3 litres in the protocol-based standard-therapy group, and 2.3 litres in the usual-care group).

There was also a difference in the amount of vasopressor given, with more patients in the two protocol-based groups receiving vasopressors (54.9% in the protocol-based EGDT group, 52.2% in the protocol-based standard-therapy group, 44.1% in the usual-care group).

The use of intravenous fluids, vasopressors, dobutamine, and blood transfusions between 6 and 72 hours did not differ significantly among the groups.

Overall 60 day mortality was in the region of 20% for all groups.

What are the take home points here? Firstly, overall sepsis outcomes have improved over recent years, and early recognition and antibiotic administration may be the most important components of care. In the early emergency department phase of care, protocolised fluid and vasopressor therapy may not be as important as we thought. Good clinical assessment and regular review seem to be as effective and perhaps more important than any specific monitoring modality or oxygen delivery-targeted drug and blood therapy.

We all await the ARISE and ProMISE studies which may shed more light on the most important components of early sepsis care.

A Randomized Trial of Protocol-Based Care for Early Septic Shock
NEJM Mar 18 2014 (Full Text Link)


Background: In a single-center study published more than a decade ago involving patients presenting to the emergency department with severe sepsis and septic shock, mortality was markedly lower among those who were treated according to a 6-hour protocol of early goal-directed therapy (EGDT), in which intravenous fluids, vasopressors, inotropes, and blood transfusions were adjusted to reach central hemodynamic targets, than among those receiving usual care. We conducted a trial to determine whether these findings were generalizable and whether all aspects of the protocol were necessary.

Methods: In 31 emergency departments in the United States, we randomly assigned patients with septic shock to one of three groups for 6 hours of resuscitation: protocol-based EGDT; protocol-based standard therapy that did not require the placement of a central venous catheter, administration of inotropes, or blood transfusions; or usual care. The primary end point was 60-day in-hospital mortality. We tested sequentially whether protocol-based care (EGDT and standard-therapy groups combined) was superior to usual care and whether protocol-based EGDT was superior to protocol-based standard therapy. Secondary outcomes included longer-term mortality and the need for organ support.

Results: We enrolled 1341 patients, of whom 439 were randomly assigned to protocol-based EGDT, 446 to protocol-based standard therapy, and 456 to usual care. Resuscitation strategies differed significantly with respect to the monitoring of central venous pressure and oxygen and the use of intravenous fluids, vasopressors, inotropes, and blood transfusions. By 60 days, there were 92 deaths in the protocol-based EGDT group (21.0%), 81 in the protocol-based standard-therapy group (18.2%), and 86 in the usual-care group (18.9%) (relative risk with protocol-based therapy vs. usual care, 1.04; 95% confidence interval [CI], 0.82 to 1.31; P=0.83; relative risk with protocol-based EGDT vs. protocol-based standard therapy, 1.15; 95% CI, 0.88 to 1.51; P=0.31). There were no significant differences in 90-day mortality, 1-year mortality, or the need for organ support.

Conclusions: In a multicenter trial conducted in the tertiary care setting, protocol-based resuscitation of patients in whom septic shock was diagnosed in the emergency department did not improve outcomes

Use a table for selecting PEEP in ARDS

March 13, 2014 by  
Filed under Acute Med, All Updates, ICU, Resus

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PEEPtable.001Selecting the right amount of PEEP to recruit collapsed alveoli in patients with ARDS is important but the best method isn’t proven. Using a table to select PEEP based on FiO2 was significantly but weakly associated with improved lung recruitability (on CT scan) when compare with other methods of selecting PEEP, and was the best method for avoiding higher PEEP in patients with lower recruitability.

This is a small study and the results do not necessarily translate to improved clinical outcomes, but they may be of interest to emergency and retrieval medicine physicians who require a simple and safe strategy when managing ARDS patients without the luxury of time or of access to highly sophisticated ICU ventilators.

Bedside selection of positive end-expiratory pressure in mild, moderate, and severe acute respiratory distress syndrome
Crit Care Med. 2014 Feb;42(2):252-64


OBJECTIVE: Positive end-expiratory pressure exerts its effects keeping open at end-expiration previously collapsed areas of the lung; consequently, higher positive end-expiratory pressure should be limited to patients with high recruitability. We aimed to determine which bedside method would provide positive end-expiratory pressure better related to lung recruitability.

DESIGN: Prospective study performed between 2008 and 2011.
SETTING: Two university hospitals (Italy and Germany).

PATIENTS: Fifty-one patients with acute respiratory distress syndrome.

INTERVENTIONS: Whole lung CT scans were taken in static conditions at 5 and 45 cm H2O during an end-expiratory/end-inspiratory pause to measure lung recruitability. To select individual positive end-expiratory pressure, we applied bedside methods based on lung mechanics (ExPress, stress index), esophageal pressure, and oxygenation (higher positive end-expiratory pressure table of lung open ventilation study).

MEASUREMENTS AND MAIN RESULTS: Patients were classified in mild, moderate and severe acute respiratory distress syndrome. Positive end-expiratory pressure levels selected by the ExPress, stress index, and absolute esophageal pressures methods were unrelated with lung recruitability, whereas positive end-expiratory pressure levels selected by the lung open ventilation method showed a weak relationship with lung recruitability (r = 0.29; p < 0.0001). When patients were classified according to the acute respiratory distress syndrome Berlin definition, the lung open ventilation method was the only one which gave lower positive end-expiratory pressure levels in mild and moderate acute respiratory distress syndrome compared with severe acute respiratory distress syndrome (8 ± 2 and 11 ± 3 cm H2O vs 15 ± 3 cm H2O; p < 0.05), whereas ExPress, stress index, and esophageal pressure methods gave similar positive end-expiratory pressure values in mild, moderate, and severe acute respiratory distress syndrome. The positive end-expiratory pressure selected by the different methods were unrelated to each other with the exception of the two methods based on lung mechanics (ExPress and stress index).

CONCLUSIONS: Bedside positive end-expiratory pressure selection methods based on lung mechanics or absolute esophageal pressures provide positive end-expiratory pressure levels unrelated to lung recruitability and similar in mild, moderate, and severe acute respiratory distress syndrome, whereas the oxygenation-based method provided positive end-expiratory pressure levels related with lung recruitability progressively increasing from mild to moderate and severe acute respiratory distress syndrome.

The ‘Magic Eye®’ method of rhythm assessment

February 9, 2014 by  
Filed under Acute Med, All Updates, EMS, ICU, Resus

Are you someone who tries to determine whether an ECG trace is ‘irregularly irregular’ by drawing little dots on a piece of paper level with the R waves to see if they are evenly spaced? I’d done that for years until I read this fantastic suggestion, which I’ve been following for over a year now.

In the 1990s there was a popular series of posters and books called ‘Magic Eye‘. These contained a ‘random dot autostereogram‘ which appeared as a mish-mash of coloured dots, but when you stared at it for a while the illusion of a 3D image would emerge. They looked a bit like this (although this one won’t work at such reduced resolution):

Image Credit: Wikimedia Commons

Image Credit: Wikimedia Commons

Dr Broughton and colleagues from Cambridge, UK, discovered that this technique, which involves forcing a divergent gaze to get repeating patterns to appear to overlap, can be applied to an ECG trace.

Stereoviewing an ECG trace causes successive QRS complexes to visually overlap and produce a new image. As Broughton and colleagues point out:

When achieved, this will lead to one of three outcomes. Entirely regular rhythms will ‘click’ into place as a new image at fixed depth. Rhythms with only mild irregularity may be stereoviewable, and if so, will appear to show successive QRS complexes at subtly varying depths. Rhythms with marked irregularity will not be stereoviewable, instead (in our experience) merely giving the viewer sore eyes after several failed viewing attempts.”

The authors assert that this can be applied to continuous ECG monitors, although unless you are really good at stereoviewing while moving your head/eyes horizontally, you should really freeze the trace on the screen first.

The ‘Magic Eye®’ method of rhythm assessment
Anaesthesia. 2012 Oct;67(10):1170-1

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