Technology Isn't Always Fail-Proof



Paul Werfel, NREMT-P | | Monday, August 18, 2008

Dear Paul,

I've noticed my most experienced partners seem to accept without question that technology is infallible. I'm a new paramedic. My instructor told us to take in all the data and make decisions. He also told us to prepare for the times the ECG didn't work or some other piece of electronics went south.

What's your opinion of this?


Charles M.

Dear Charles,

I like the way you think. To be sure, I'm writing this on a laptop while fielding messages on my Blackberry. However, I'm always aware that mistakes are still possible using electronics, and humans are capable of misinterpreting the machines' output. If we (and the patients) are lucky, the technology fails and the machine just doesn't work. Worse than this is the scenario in which technology suffers very subtle breakdowns. This may lead to catastrophic results. Want an eye-opener? The following are documented issues with current technology. Below I have highlighted some articles that discuss issues with AEDs, defibrillators, pulse oximeters, glucometers and the self-inflating bulb. They weren't difficult to find. Regardless, I guarantee many will still tout the wonders of electronics and technology.

AED issues

Problems with AEDs range from product recalls to problems with AED use in children.In 2004, Access CardioSystems, Inc. initiated a voluntary recall of all its Automated External Defibrillators (AEDs), andin March 2005, Medtronic issued a voluntary recall of nearly 2,000 LIFEPAK 500 AEDs because of the possibility that the devices continued to display a "connect electrodes" message and didn't accurately analyze a patient's ECG.

The study,"Problems with AED Use in Children," published in 2004 in the Journal of the Japan Pediatric Society found potential unintentional harmful effects on pediatric resuscitation if the BLS sequence for children is neglected while waiting for an AED.

Manual defibrillator problems

In the article"Advanced Life Support," published in 2000 in the British Journal of Sports Medicine, the author determines that the gain setting is too low on the monitor. This leads to missed interpretation of the ECG. "If the diagnosis is either asystole or electromechanical dissociation, outcome is generally less favorable unless a reversible cause can be found and treated. If the apparent diagnosis is asystole, it is vital to ensure that a shockable rhythm is not being missed because of lead disconnection, incorrect ECG gain setting, or equipment failure. When doubt exists, treatment is given as for VF."

Authors who published the article"Reliability of ECG monitoring with a gel pad/paddle combination after defibrillation" in 2000 in Resuscitation found unreliable electrodes and that the gel needs time to repolarize too.

Pulse oximetry gone wrong

There are several examples of prehospital providers using pulse oximetry and having problems, either from problems with the machines themselves or with humans misinterpreting the data output.

In the 1993 British Medical Journal article,"Upper airway obstruction ... and oxygen," the authors state that prehospital providers should never rely on the pulse oximeter as the sole monitor to detect esophageal intubation, cardiac arrest, breathing system disconnections, or failure of the oxygen supply.

"Although pulse oximitery may be the most significant technological advance ever made in the monitoring of the well-being and safety of patients during anaesthesia, recovery and critical care," they stated. The authors went on to say a normal reading of saturation in the presence of an increased inspired oxygen concentration gives no information about the adequacy of ventilation and that falls in saturation will occur late and are non-diagnostic.

Another view is that clinicians should be wary of taking pulse oximetry readings at face value, as stated by Patricia Carroll, RRT, RN, BC, CEN, MS in her 2003 RT for Decision Makers in Respiratory Care article "Pitfalls, Perils, and Pearls of Pulse Oximetry."

Pulse oximeter readings may not be accurate in several situations. According to the 1995 article "Pulse Oximetry" in Practical Procedures, they may result in an inadequate signal for analysis in patients with hypovolaemia, severe hypotension, cold, cardiac failure, some cardiac arrhythmias or peripheral vascular disease. In addition, nail polish and bright overhead lights in theatres may cause inaccurate signals. Finally, according to the 2007 article"Dark skin decreases the accuracy of pulse oximeters at low oxygen saturation: the effects of oximeter probe type and gender" published in a supplement to Anesthesia and analgesia, dark skin decreases the accuracy of pulse oximeters at low oxygen saturation.

Glucometer issues

According to the May 31, 2005 VA National Center for Patient Safety Alert, glucometers can provide inaccurate readings in several situations. In the article"Capillary versus venous bedside blood glucose estimations,"published in Emergency Medicine Journal in 2005, researchers found a small but significant difference in the blood glucose results from a glucometer when the samples are taken from capillary or venous sources.

Problems with using the self-inflating bulb to verify ETT placement

In the article "Accuracy and reliability of the self-inflating bulb to verify tracheal intubation in out-of-hospital cardiac arrest patients," published in 2000 in Anethesiology, researchers found false-negative results of the self-inflated bulb in out-of-hospital cardiac arrest patients.

So Charles, tell me if your partners still feel as secure with technology after reading this column as they did. We must all assess and treat our patients with the best of intentions. We can only do that when we have the most reliable information at our disposal. Knowing our equipment means knowing its limitations and the ramifications of trusting the technology.

Till next time,


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Related Topics: Cardiac and Circulation, Technology, Training

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