PrairiEDocs e-newsletter #7

Other archived PrairiEDocs e-newsletters

Surveying the land (and web) for news (and more)
for the emergency medicine practitioner…

Issue #7 "fasten your seat belt and adjust your headrest as this
electronic ed-venture continues" August 24, 2000

In this issue:

Special Edition-part one:
this entire e-newsletter begins a look at 
the just-released guidelines and recommendations 
for Advanced Cardiac Life Support 

Financial sponsorship statement & How to contact us

This report is based on final published ACLS changes reported in 
Circulation Supplement for August 22, 2000. All readers are 
encouraged to read the findings for themselves-this review is not 
meant to be comprehensive nor should it substitute for an ACLS 
provider's own inquiry into these subjects, issues and 
recommendations. This material in Circulation represents a process 
of intensive review and consensus begun well over 18 months ago. 
A "roll out" is scheduled for September 21-24 in San Diego where 
this information will be further explained and how it will be 
incorporated in future ACLS will be presented. This, then represents 
the content that the San Diego conference will be based upon..

Introduction

These most recently released guidelines for ACLS are--

Evidenced-based;

International (at least 40% non-US representation);

Guidelines are no longer simply "descriptive" but now are "prescriptive."

Note--the actual process of evidence evaluation used in this 2000 Conference 
will be published in Annals of Emergency Medicine soon.

Throughout the Guidelines, the following definitions of classes of 
recommendations are used:

Class I recommendations are always acceptable. They are proven 
safe and definitely useful, and they are supported by excellent 
evidence from at least one prospective, randomized controlled 
clinical trial

Class IIa recommendations are considered acceptable and useful 
with good to very good evidence providing support. The weight of 
evidence and expert opinions strongly favor these interventions.

Class IIb recommendations are considered acceptable and useful with 
weak or only fair evidence providing support. The weight of evidence 
and expert opinion are not strongly in favor of the intervention.

Class III refers to interventions that are unacceptable. These 
interventions lack any evidence of benefit, and often the evidence 
suggests or confirms harm.

Class Indeterminate refers to an intervention that is promising, but 
the evidence is insufficient in quantity and/or quality to support a 
definitive class of recommendation. The Indeterminate Class was 
added to indicate interventions that are considered safe and perhaps 
effective and are recommended by expert consensus. However, the 
available evidence supporting the recommendation is either too weak 
or too limited at present to make a definitive recommendation based 
on the published data.

Airway and oxygenation

AMI patients-recommend O2 4/lpm per nasal cannula for at least first 2-3 hours (IIa);

Adequate ventilation with a BVM---currently 10ml/kg (700-1000ml)—several studies suggest 6-7ml (approx. 500ml delivers adequate tidal volumes with BVM in unintubated patients (IIa);

Intubate only if trained and plenty of practice otherwise use LMA or ETC (both IIa);

COPA (cuffed oropharangeal airway) may be another device useful for those who cannot intubate;

Interrupt ventilations a maximum of 30 seconds for intubation, if unsuccessful   reventilate 15-30 seconds before trying again;

Inflate while auscultating during normal ventilation through ET tube---inflate to seal out audible air leak (usually 10ccs):

Correct initial and ongoing placement of the ET tube is an emphasized concern in the new guidelines;

Confirm tube placement with CO2 detectors or esophageal detection devices as well as with auscultation  over epigastrium, midaxillary, and anterior chest line right and left sides after placement (esophageal detection devices—use with caution with morbid obesity, late pregnancy and status asthmaticus---CO2 detectors use with caution with possible PE and with patients consuming carbonated beverages prior to arrest);

ATMs-automatic transport ventilators-time or volume cycled (not pressure-based)effective and  (even if patient is not intubated) seem appropriate;

Oxygen powered, manually triggered (“demand valve”) devices ‘are not recommended at this time” (Class Indeterminate)---need more studies. 

Defibrillation

Continued emphasis on the importance of early defibrillation--“All healthcare  providers with a duty to perform CPR should be trained, equipped, and encouraged to perform defibrillation (Class IIa). The Guidelines 2000 Conference recommends that early defibrillation be available throughout all hospital and outpatient medical facilities (Class IIa). The use of defibrillation now transcends both ACLS and BLS care.”

Continued support regarding biphasic wave forms;

No conclusive data to support fixed vs. escalating energy settings for the newer biphasic defibrillators; investigations continue on---effective waveform types as damped sinusoidal, truncated exponential, and rectilinear first pulse variants, and issues of transthoracic impedance (resistance) and current-based decisions (amperes vs. joules);

Quick –look paddles in initial rhythm identification (to avoid delays) are acceptable;

Cardioversion—atrial fibrillation 100-200J; atrial flutter and PSVT 50-100J; monomorphic VT 100J, polymorphic VT 200J (though energy settings for biphasic waveforms does not have enough data for recommendations to be made.

Assisting Circulation

Important to differentiate between what is appropriate for the lay public and what is appropriate for health care professionals--most of the following are relegated to specially trained individuals. Many of the following alternatives have shown some degree of success in short-term (improved blood flow, increased incidence of pulse return, etc.) but outcome improvement/increased survival data is lacking;

IAC-CPR-interposed abdominal compression-CPR-“recommended as an alternative to  conventional CPR whenever sufficient personnel are available and trained in this technique (Class IIb).” Safety not established for aortic aneuryism, pregnancy, or recent abdominal surgery. Randomized trials “have demonstrated improved outcome when IAC-CPR was compared with standard CPR for in-hospital resuscitation, but no survival benefit for out-of-hospital arrest has been shown.” Safety has been reviewed, no increase in emesis or aspiration.

High-frequency CPR-rates greater than 100 per minute-“shows some promise fpr improving CPR” but further study and outcomes research needed (Class Indeterminate).

ACD-CPR active compression decompression CPR (aka “plunger” CPR). Complications (eg., rib fractures) are “noteworthy  but not of major concern”…some have commented about possible rescuer fatigue. “ACD-CPR is considered an acceptable alternative to standard CPR when rescue personnel adequately trained in use of this device are available(Class IIb)…not proved effective in the out-of-hospital setting: acceptable but weak data supports in-hospital use.”

Vest CPR-“Vest CPR may be considered an alternative to standard CPR in-hospital or during ambulance transport…(Class IIb).” FDA permission to distribute and sell  has not yet been sought for this.

Mechanical CPR (eg., “Thumper”)-“The mechanical resuscitator is an acceptable alternative to standard manual CPR in circumstances that make chest compressions difficult, ie, cedrtain transport situations or lack of adequate personnel (Class IIb).”

SVC-CPR-simultaneous ventilation-compression CPR-…clinical studies have failed to identify any benefits of SVC-CPR…[it] is not currently available for clinical use.”

PTACD-CPR-phased thoracic-abdominal compression-decompression CPR-a hand-held device that combines IAC with ACD CPR. [article’s author note- appears to have been such a device that obtained recent approval by FDA—two years to marketplace?] As of this publishing, no clinical data available (Class Indeterminate).

Impedance threshold valve-(eg., ResQ Valve) adjunct used with intubated ACD patient (prevents inspiration during chest decompression with ACD) “…acceptable as an adjunct to be used with [ACD] device to augment hemodynamic parameters (Class IIb).”

Invasive-open chest CPR-“…can be considered under special circumstances but should not be done simply as a late last-ditch effort (Class IIb).”

Emergency cardiopulmonary bypass-(Class Indeterminate)…its success in special situations of drug overdoses and hypothermic arrest may be sufficient justification alone for its use in specific hospital settings.”

Pulse checks-results from pulse checks during CPR may be misleading—femoral pulse checks may reveal retrograde venous rather than arterial blood flow, and no studies exist that compare pulse findings during CPR with outcomes in terms of predictability;

Arterial blood gases can be useful in evaluating oxygenation but should not be used to assess the adequacy of  CPR

“End-tidal CO2 monitoring can be useful as a noninvasive indicator of cardiac output generated during CPR (Class IIa).”

CPR Plus-a metronome-like device placed on the chest (for rate and force of compressions information) has promising manikin performance results, but lacks in animal or human data (Class Indeterminate)