The 2015 AHA Guidelines Update isn’t a significant revision to the 2010 Guidelines. Rather, it uses advances in resuscitation research and the latest scientific evidence to further define, refine, clarify or otherwise alter the 2010 Guidelines.
In some areas, the lack of definitive research resulted in not recommending a certain procedure or leaving a guideline unchanged. This doesn’t mean that systems currently using a process, procedure or resuscitation device must stop using them if their medical leadership feels their resuscitation results have improved. There was simply insufficient evidence at this time for the committee to make a recommendation for change.
BLS, AEDS & CPR QUALITY
By Erin E. Brennan, MD
Although there aren’t significant changes in the 2015 AHA Guidelines Update relative to BLS practices and automated external defibrillator (AED) use, there are a few changes all EMS providers and educators need to be aware of.
- The guidelines continue to place significant emphasis on high-quality CPR given its association with improved survival.
- There’s a recommendation for coordinated team approach (i.e., pit crew approach) to resuscitation when multiple providers are available, enabling the coordinated and efficient provision of chest compressions, airway management, ventilations, and defibrillation if indicated.
The importance of a coordinated (“pit crew”) approach to resuscitation and close attention to limiting compression interruptions is heavily emphasized in the 2015 AHA Guidelines. Photo Courtney McCain
- For trained healthcare providers, pulse and breathing check can be performed simultaneously and should last no longer than 10 seconds.
- Evidence continues to support the C-A-B sequence (Class IIb), with a compression-to- ventilation ratio of 30:2 (Class IIa).
- For trained healthcare providers, it’s reasonable to tailor the sequence of rescue actions to the most likely cause of arrest
As in previous years, there’s an emphasis on providing high-quality chest compressions as a key component of effective CPR. Important characteristics of chest compressions outlined below are chest compression rate, depth, adequate recoil, and chest compression fraction.
- Depth: Compress to at least 2 in (5cm). It’s been found that injuries are more likely to occur with compressions > 2.4 in (6 cm), however, it’s important to recognize that the majority of rescuers are more likely to compress too shallowly and continue to emphasize “pushing hard” (Class I).
- Rate: An upper limit of 120 chest compressions per minute has been added, resulting in a recommendation of a compression rate between 100–120/minute (Class IIa).
- Recoil: Avoid leaning to allow full chest recoil (Class IIa).
- Fraction: Chest compression fraction is an indicator of how well the team is minimizing pauses in CPR. It’s calculated by dividing the amount of time compressions are delivered by the amount of time compressions are indicated. The goal is to have a fraction as high as possible, with a target of at least 60% (Class IIb).
Ventilation by either rescue breathing or bag-valve mask (BVM) continues to be an important skill for healthcare providers.
- Avoid excessive ventilation.
- In patients without an advanced airway, rescuers should deliver cycles of 30 compressions and 2 breaths (Class IIa).
- In patients with an advanced airway, rescuers should deliver 1 breath every 6 seconds (10 bpm) while continuous chest compressions are performed (Class IIb).
- Routine use of passive ventilation during CPR isn’t recommended, however, in EMS systems that use bundles of care involving continuous chest compressions, the use of passive ventilation may be considered (Class IIb).
In a patient with known or suspected opiate overdose who has a pulse but no normal breathing, in addition to standard BLS care, it’s reasonable for appropriately trained providers to administer intramuscular or intranasal naloxone (Class IIa).
- For witnessed adult cardiac arrest when an AED is immediately available, the defibrillator should be used as soon as possible (Class IIa).
- For unwitnessed arrest, or in cases where the AED isn’t immediately available, CPR should be initiated and the AED applied as soon as it is ready for use (Class IIa).
- There’s insufficient evidence to recommend the use of artifact-filtering algorithms for analysis of rhythm during CPR.
- It’s recommended to immediately return to chest compressions after shock delivery (Class IIb).
CPR Quality, Accountability & Healthcare Systems
- It’s reasonable to use audiovisual feedback devices during CPR for real-time optimization of performance (Class IIb).
- When resuscitation involves a team of caregivers, there should be a designated leader whose task it is to choreograph the team activities with an effort to minimize interruptions in CPR and ensure high-quality compressions and avoidance of excessive ventilation.
- CPR registry data continues to provide important information about the care and outcomes of patients and can be used to improve processes and systems of care.
ALTERNATIVE CPR TECHNIQUES & ADJUNCTS
By Steven C. Brooks, MD, MHSc, FRCPC
Conventional CPR consisting of manual chest compressions interspersed with rescue breathing is inherently inefficient with respect to generating significant cardiac output. A variety of alternatives and adjuncts to conventional CPR have been developed with the aim of enhancing perfusion during resuscitation from cardiac arrest, many of which can be used in the prehospital setting.
A number of clinical trials, many of them involving patients enrolled by prehospital providers, have resulted in new data on the effectiveness of these alternatives since the 2010 Guidelines were published.
Impedance Threshold Devices (ITDs)
There was new evidence to guide recommendations for the use of an ITD. One large multicenter randomized clinical trial from the Resuscitation Outcomes Consortium called ROC PRIMED failed to demonstrate any improvement associated with the use of an ITD (compared with a sham device) as an adjunct to conventional CPR. Therefore, the routine use of the ITD as an adjunct during conventional CPR is not recommended in the 2015 Guidelines Update (Class III, no benefit).
Combined Use of ACD-CPR & ITD
The use of active compression-decompression (ACD-CPR) in comparison with conventional CPR was reviewed for the 2010 Guidelines. Since then, new evidence is available regarding the use of ACD-CPR in combination with the ITD, and an ACD-CPR device has been FDA approved and is available on the market.
ACD-CPR is performed by using a handheld device with a suction cup applied over the midsternum of the chest. After chest compression, the device is used to lift up the anterior chest during decompressions. This enhances the negative intrathoracic pressure (vacuum) generated by chest recoil, thereby increasing venous return (preload) to the heart and cardiac output during the next chest compression.
Commercially available ACD-CPR devices have a gauge providing feedback on compression and decompression forces and a metronome to guide duty cycle and chest compression rate.
The new guidelines point out that ACDCPR is believed to act synergistically with the ITD to enhance venous return during chest decompression and improves blood flow to vital organs during CPR. Based on best available evidence, the guidelines state that the combination of ACD-CPR and ITD may be a reasonable alternative in settings with available equipment and properly trained personnel (Class IIb).
Extracorporeal Techniques & Invasive Perfusion Devices
The term “extracorporeal CPR” or “ECPR” is used to describe the initiation of extracorporeal circulation and oxygenation during the resuscitation of a patient in cardiac arrest. This is similar to heart-lung bypass used during some cardiac surgical procedures.
The goal of ECPR is to support patients in cardiac arrest while potentially reversible conditions are treated. ECPR is a complex process that requires a highly trained team, specialized equipment and multidisciplinary support within the local healthcare system.
The implementation of ECPR in the prehospital setting is currently being done in some areas of Europe, including Paris, France.
There have been no randomized trials studying ECPR. Published case series have restricted ECPR to patients aged 18 to 75 years with limited comorbidities, with arrest of cardiac origin, after conventional CPR for more than 10 minutes without return of spontaneous circulation (ROSC).
There’s currently insufficient evidence to recommend the routine use of ECPR for patients with cardiac arrest. However, in settings where it can be rapidly implemented, ECPR may be considered for select patients for whom the suspected etiology of the cardiac arrest is potentially reversible during a limited period of mechanical cardio-respiratory support (Class IIb). For example, ECPR could support a cardiac arrest patient while they undergo PCI to open an occluded coronary artery, could support patients with cardiotoxic drug overdoses while the poison is cleared from their system, or could support victims of cardiac arrest due to myocarditis while transplant options are explored.
Mechanical Chest Compression Devices
Three large randomized controlled trials studying patients suffering out-of-hospital cardiac arrest have been completed since the 2010 Guidelines: The CIRC study (Auto- Pulse), the LINC Study (LUCAS) and the PARAMEDIC Study (LUCAS).
None of these three studies demonstrated improved outcomes for patients with out-of-hospital cardiac arrest when treated with mechanical chest compression devices when compared with conventional manual CPR performed in a high-quality, consistent manner with limited compression interruptions.
The evidence doesn’t currently demonstrate a benefit with the use of mechanical devices (load-distributing band or mechanical piston) for chest compressions vs. manual chest compressions in patients with cardiac arrest. However, the 2015 Guidelines Update states that these devices may be a reasonable alternative to conventional CPR in specific settings where the delivery of high-quality manual compressions may be challenging or dangerous for the provider (e.g., limited rescuers available, prolonged CPR, CPR during hypothermic cardiac arrest, CPR in a moving ambulance, CPR in the angiography suite, CPR during preparation for ECPR) (Class IIb).
ADVANCED CARDIAC LIFE SUPPORT (ACLS)
By Mark S. Link, MD
Oxygen Dose During CPR
There were no adult human studies identified that directly compared maximal inspired oxygen with any other inspired oxygen concentration. However, one observational study of 145 OHCA patients evaluated arterial PO2 measured during CPR and cardiac arrest outcomes. When supplementary oxygen is available, it may be reasonable to use the maximal feasible inspired oxygen concentration during CPR (Class IIb).
Physiologic Monitoring to Guide CPR
Specific physiological monitoring parameters and values were specified in 2010. However, in 2015, although the committee did see the potential value of specific values, the exact targets were unclear and thus the specific targets weren’t specified.
- Although no clinical study has examined whether titrating resuscitative efforts to physiologic parameters during CPR improves outcome, it may be reasonable to use physiologic parameters (quantitative waveform capnography, arterial relaxation diastolic pressure, arterial pressure monitoring and central venous oxygen saturation) when feasible to monitor and optimize CPR quality, guide vasopressor therapy and detect ROSC (Class IIb).
Prognostication in Cardiac Arrest
There was evidence to guide the estimates of ROSC in patients undergoing CPR. If end-tidal carbon dioxide (EtCO2) didn’t improve in intubated patients with resuscitation, the odds of successful outcome was minimal.
- In intubated patients, failure to achieve an EtCO2 of greater than 10 mmHg by waveform capnography after 20 minutes of CPR may be considered as one component of a multimodal approach to decide when to end resuscitative efforts, but it should not be used in isolation (Class IIb).
- The above recommendation is made with respect to EtCO2 in patients who are endotracheally intubated.
- In nonintubated patients, a specific EtCO2 cutoff value at any time during CPR should not be used as an indication to end resuscitative efforts (Class III: Harm).
BVM vs. Advanced Airways
The majority of retrospective observational studies analyzed demonstrated slightly worse survival with the use of an advanced airway when compared with BVM ventilation. However, interpretation of these results is limited by significant concerns of selection bias. Two additional observational studies showed no difference in survival.
- Either a BVM device or an advanced airway may be used for oxygenation and ventilation during CPR in both the in-hospital and out-of-hospital setting (Class IIb).
- For providers trained in their use, either a supraglottic airway device or an endotracheal (ET) tube may be used as the initial advanced airway during CPR (Class IIb).
Clinical Assessment of Tube Placement
There was some evidence guiding clinical assessment of tracheal tube placement.
- Continuous waveform capnography is recommended in addition to clinical assessment as the most reliable method of confirming and monitoring correct placement of an ET tube (Class I).
- If continuous waveform capnometry isn’t available, a non-waveform CO2 detector, esophageal detector device or ultrasound used by an experienced operator is a reasonable alternative (Class IIa).
Ultrasound in Cardiac Arrest
The use of ultrasound in cardiac arrest was evaluated for the 2015 Guidelines Update. The studies were retrospective observational and thus limited, but ultrasonography during cardiac arrest was allowed.
- Ultrasound (cardiac or non-cardiac) may be considered during the management of cardiac arrest, although its usefulness hasn’t been well established (Class IIb).
- If a qualified sonographer is present and use of ultrasound doesn’t interfere with the standard cardiac arrest treatment protocol, then ultrasound may be considered as an adjunct to standard patient evaluation (Class IIb).
Vasopressors in Cardiac Arrest
There were a number of questions on vasopressors and it’s this section in the ACLS chapter that was most changed.
Timing of Epinephrine Administration
- It may be reasonable to administer epinephrine as soon as feasible after the onset of cardiac arrest due to an initial non-shockable rhythm (Class IIb).
- There’s insufficient evidence to make a treatment recommendation as to the optimal timing of epinephrine, particularly in relation to defibrillation, when cardiac arrest is due to a shockable rhythm, because optimal timing may vary based on patient factors and resuscitation conditions.
- Standard dose epinephrine (1 mg every 3–5 minutes) may be reasonable for patients in cardiac arrest (Class IIb).
- High dose epinephrine isn’t recommended for routine use in cardiac arrest (Class III: no benefit).
- Vasopressin offers no advantage as a substitute for epinephrine in cardiac arrest (Class IIb).
- Vasopressin in combination with epinephrine offers no advantage as a substitute for standard dose epinepherine in cardiac arrest (Class IIb).
Steroids in Cardiac Arrest
Steroid use in cardiac arrest was controversial based on two in-hospital arrest studies by the same institution. Importantly, these studies bundled steroids with vasopressin and epinephrine.
- There are no data to recommend for or against the routine use of steroids alone for in-hospital cardiac arrest patients.
- In in-hospital cardiac arrest, the combination of intra-arrest vasopressin, epinephrine and methylprednisolone and post-arrest hydrocortisone may be considered; however, further studies are needed before recommending the routine use of this therapeutic strategy (Class IIb).
- For patients with out-of-hospital cardiac arrest, use of steroids during CPR is of uncertain benefit (Class IIb).
Defibrillation strategies were evaluated extensively and the guidelines were updated, but there were no major changes.
- Based on their greater success in arrhythmia termination, defibrillators using biphasic waveforms are preferred to monophasic defibrillators for treatment of both atrial and ventricular arrhythmias (Class IIa).
- In the absence of conclusive evidence that one biphasic waveform is superior to another in termination of v fib, it’s reasonable to use the manufacturer’s recommended energy dose for the first shock. If this isn’t known, defibrillation at the maximal dose may be considered (Class IIb).
ACUTE CORONARY SYNDROMES
By Robert E. O’Connor, MD, MPH, FACEP
The 2015 AHA Guidelines Update continue to recognize that prompt diagnosis and treatment of acute coronary syndromes (ACS) offers the greatest potential benefit for myocardial salvage. EMS providers must recognize patients with potential ACS in order to initiate the evaluation, appropriate triage, and management as fast and early as possible because, in the case of ST elevation myocardial infarction (STEMI), this recognition allows for prompt notification of the receiving hospital and preparation for emergent reperfusion therapy.
Prehospital ECG & STEMI Alerts
Prehospital 12-lead ECGs expedite the diagnosis, shorten the time to reperfusion (fibrinolytics or primary percutaneous coronary intervention [PPCI]). The 2015 International Liaison Committee on Resuscitation (ILCOR) systematic review examined whether acquisition of a prehospital ECG with transmission of the ECG to the hospital, notification of the hospital of the need for fibrinolysis, or activation of the catheterization laboratory changes any major outcome. The 2015 Guidelines Update contains the following recommendations:
- Prehospital 12-lead ECG should be acquired early for patients with possible ACS (Class I).
- Prehospital notification of the receiving hospital (if fibrinolysis is the likely reperfusion strategy) and/or prehospital activation of the catheterization laboratory should occur for all patients with a recognized STEMI on prehospital ECG (Class I).
- Implementation of 12-lead ECG diagnostic programs with concurrent medically-directed qualityassurance is recommended (Class I).
- Prehospital personnel can accurately identify ST-segment elevation from the 12-lead ECG.
- If providers aren’t trained to interpret the 12-lead ECG, field transmission of the ECG or a computer report to the receiving hospital is recommended (Class I).
Non-Physician STEMI Interpretation
When physicians aren’t present or not available to interpret an ECG, other methods for interpretation must be used so that timely patient care is not adversely affected. The 2015 ILCOR systematic review examined whether non-physicians such as paramedics and nurses could identify STEMI on an ECG so that earlier identification of STEMI could be made with acceptable rates of either under-diagnosis (false-negative results) or over-diagnosis (false-positive results).
Although transmission of the prehospital ECG to the ED physician may improve positive predictive value and therapeutic decision-making regarding adult patients with suspected STEMI, if transmission isn’t performed, it may be reasonable for trained non-physician ECG interpretation to be used in making decisions, including activation of the catheterization laboratory, administration of fibrinolysis, and selection of destination hospital (Class IIa).
ADP Inhibition in Suspected STEMI
The 2015 ILCOR systematic review addressed the clinical impact of the timing of administration of adenosine diphosphate (ADP) inhibition in the treatment of patients with suspected STEMI.
The relative merit of early prehospital vs. hospital administration of ADP inhibition as a general treatment strategy was assessed. Differences between individual ADP inhibitors were not examined.
The preferred reperfusion strategy for STEMI patients is identification and restoration of normal flow in the infarct-related artery using percutaneous intervention. The use of potent dual antiplatelet therapy in STEMI patients undergoing PPCI is associated with improved clinical outcomes as well as lower rates of acute stent thrombosis.
Given the short time from first medical contact to balloon inflation, treatment with oral ADP inhibitors in a prehospital setting has the potential to enhance platelet inhibition and improve procedural and clinical outcomes after PPCI.
Three randomized controlled trials (RCTs) showed no additional benefit to the outcome of 30-day mortality and no additional benefit or harm with respect to major bleeding with prehospital administration compared with in-hospital administration of an ADP-receptor antagonist. Therefore, the 2015 AHA Guidelines Update recommends that in patients with suspected STEMI intending to undergo PPCI, initiation of ADP inhibition may be reasonable in either the prehospital or in-hospital setting (Class IIb).
Prehospital Anticoagulants inSTEMI
In patients with suspected STEMI, anticoagulation is standard treatment recommended by the American College of Cardiology Foundation/ AHA Guidelines. The 2015 ILCOR systematic review sought to determine if any important outcome measure was affected if an anticoagulant was administered prehospital compared with whether that same anticoagulant was administered in-hospital.
A single nonrandomized, case-control study found that while flow rates were higher in an infarct-related artery when heparin and aspirin were administered in the prehospital setting vs. the ED, there was no significant difference in death, PCI success rate, major bleeding, or stroke.
While there seems to be neither benefit nor harm to administering heparin to patients with suspected STEMI before their arrival at the hospital, prehospital administration of medication adds complexity to patient care. The 2015 AHA Guidelines Update recommends:
- That EMS systems that don’t currently administer heparin to suspected STEMI patients do not add this treatment, whereas those that do administer it may continue their current practice (Class IIb).
- In suspected STEMI patients for whom there is a planned PCI reperfusion strategy, administration of unfractionated heparin (UFH) can occur either in the prehospital or in-hospital setting (Class IIb).
The 2015 ILCOR systematic review also examined whether the prehospital administration of an anticoagulant such as bivalirudin, dalteparin, enoxaparin or fondaparinux instead of UFH, in suspected STEMI patients who are transferred for PPCI, changes any major outcome. After reviewing the evidence, the 2015 AHA Guidelines Update recommends:
- It may be reasonable to consider the prehospital administration of UFH in STEMI patients or the prehospital administration of bivalirudin in STEMI patients who are at increased risk of bleeding (Class IIb).
- In systems in which UFH is currently administered in the prehospital setting for patients with suspected STEMI who are being transferred for PPCI, it is reasonable to consider prehospital administration of enoxaparin as an alternative to UFH (Class IIa).
Prehospital Fibrinolysis & PCI Center Triage
Prehospital fibrinolysis requires a sophisticated system of provider expertise, well-established protocols, comprehensive training programs, medical oversight, and quality assurance. In many European systems, a physician provides prehospital fibrinolysis, but nonphysicians can also safely administer fibrinolytics.
The 2015 ILCOR systematic review evaluated whether prehospital fibrinolysis is preferred to reperfusion in-hospital where the prehospital fibrinolysis expertise, education, and system support exists. The following recommendations are included in the 2015 AHA Guidelines Update:
- Where prehospital fibrinolysis is available as part of a STEMI system of care, and in-hospital fibrinolysis is the alternative treatment strategy, it’s reasonable to administer prehospital fibrinolysis when transport times are more than 30 minutes (Class IIa).
- It’s strongly recommended that systems that administer fibrinolytics in the prehospital setting include the following features: protocols using fibrinolytic checklists, 12-lead ECG acquisition and interpretation, experience in advanced life support, communication with the receiving institution, medical director with training and experience in STEMI management, and continuous quality improvement (Class I).
- Where prehospital fibrinolysis is available as part of the STEMI system of care and direct transport to a PCI center is available, prehospital triage and transport directly to a PCI center may be preferred because of the small relative decrease in the incidence of intracranial hemorrhage without evidence of mortality benefit to either therapy (Class IIb).
- If PCI is the chosen method of reperfusion for the prehospital STEMI patient, it is reasonable to transport patients directly to the nearest PCI facility, bypassing closer EDs as necessary, in systems where time intervals between first medical contact and balloon times are (Class IIa).
Below is a summary of the 2015 AHA Guidelines Update recommendations for other interventions and treatments for ACS.
ACE Inhibitors: Although angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have been shown to reduce long-term risk of mortality in patients suffering an acute myocardial infarction (AMI), there’s insufficient evidence to support the routine initiation of ACE inhibitors and ARBs in the prehospital or ED setting (Class IIb).
Aspirin: In addition to the prehospital administration of aspirin, the 2015 Guidelines Update emphasizes that dispatch centers should play a key role in early ACS care by instructing patients with no history of aspirin allergy and without signs of active or recent gastrointestinal bleeding to chew an aspirin (160–325 mg) while awaiting the arrival of EMS (Class IIa).
Morphine: Although the efficacy of other analgesics is unknown, the recommendations for morphine use includes:
- Morphine is indicated in STEMI when chest discomfort is unresponsive to nitrates (Class I).
- Morphine should be used with caution in unstable angina/NSTEMI due to an association with increased mortality in a large registry (Class IIa).
Nitrates: Recommendations include:
- EMS providers should administer up to 3 nitroglycerin doses (tablets or spray) at intervals of 3–5 minutes until pain is relieved or low blood pressure limits its use. (Class I).
- Nitrates in all forms are contraindicated in patients with initial systolic blood pressure < 90 mm Hg or 30 mm Hg below baseline and in patients with right ventricular (RV) infarction.
- Caution is advised in patients with known inferior wall STEMI, and a right-sided ECG should be performed to evaluate RV infarction.
- Nitrates should be withheld in patients with inferior STEMI and suspected RV involvement because of the risk of a sudden drop in blood pressure.
- Because of the risk of hypotension, nitrates are contraindicated when patients have taken a phosphodiesterase-5 (PDE-5) inhibitor within 24 hours (48 hours for tadalafil).
Oxygen: There’s insufficient evidence to support the routine use of oxygen in uncomplicated ACS. However, if a patient is dyspneic, hypoxemic, or has obvious signs of heart failure, providers should titrate oxygen therapy, based on monitoring of oxyhemoglobin saturation, to 94% (Class I).
Ventricular Rhythm Disturbances
Treatment of ventricular arrhythmias during and after AMI has been a controversial topic for three decades. Primary v fib accounts for the majority of early deaths during AMI. The incidence of primary v fib is highest during the first 4 hours after onset of symptoms but remains an important contributor to mortality during the first 24 hours.
Secondary v fib occurring in the setting of CHF or cardiogenic shock can also contribute to death from AMI. V fib is a less common cause of death in the hospital setting with the use of fibrinolytics and percutaneous revascularization as early reperfusion strategies. The 2015 AHA Guidelines Update recommendations include:
- Although prophylaxis with lidocaine reduces the incidence of v fib, an analysis of data from ISIS-3 and a metaanalysis suggest that lidocaine increased all-cause mortality rates. Thus, the practice of prophylactic administration of lidocaine is not recommended (Class III).
- Sotalol has not been adequately studied (Class IIb).
- Amiodarone in a single RCT didn’t appear to improve survival in low doses and may increase mortality in high doses when used early in patients with suspected myocardial infarction (Class IIb).
- Prophylactic antiarrhythmics are not recommended for patients with suspected ACS or myocardial infarction in the prehospital or ED (Class III).
- Routine IV administration of beta-blockers to patients without hemodynamic or electric contraindications is associated with a reduced incidence of primary v fib (Class IIb).
- Low serum potassium, but not magnesium, has been associated with ventricular arrhythmias. It’s prudent clinical practice to maintain serum potassium > 4 mEq/L and magnesium > 2 mEq/L (Class IIB).
- Routine administration of magnesium to patients with MI has no significant clinical mortality benefit, particularly in patients receiving fibrinolytic therapy.
- Following an episode of v fib, there’s no conclusive data to support the use of lidocaine or any particular strategy for preventing v fib recurrence. Further management of ventricular rhythm disturbances is discussed in Part 7 of the Guidelines: Adult ACLS.
SPECIAL CONSIDERATIONS: PREGNANCY
By Eric Lavonas, MD & Farida Jeejeebhoy, MD
In 2015, not only did the AHA publish updated guidelines for the management of cardiac arrest during pregnancy, it also published an extensive scientific statement about preparation for and management of cardiac arrest in pregnancy, available at circ.ahajournals.org/content/early/2015/10/06/CIR.0000000000000300.
Figure 1: Manual left uterine displacement with one-handed technique (A) and two-handed technique used during resuscitation (B). Figure courtesy American Heart Association
- When a woman in the third trimester of pregnancy develops cardiac arrest, two patients are involved. Fortunately, best care for the mother and best care for the baby are almost always the same thing.
- Standard BLS (including high-quality, minimally-interrupted CPR) and ACLS are always the top priority. Do not delay CPR, shock or drug administration just because the patient is pregnant! The baby’s best chance comes from successful resuscitation of the mother.
- In addition, if the fundus is above the umbilicus, perform manual left uterine displacement. This simply involves pushing the uterus to the left to allow blood from the inferior vena cava to return to the heart. (See Figure 1.)
- Recognize that pregnant women may present a difficult airway. If you’re going to intubate or place a supraglottic airway, plan accordingly.
- Transport the pregnant woman quickly to a center capable of performing emergency cesarean delivery. If ROSC can’t be achieved by 4 minutes of resuscitative efforts, an emergency cesarean delivery may allow separate resuscitation of the infant; by decompressing the uterus, this may also improve the chances of maternal resuscitation.
- Emergency cesarean delivery isn’t a field procedure. Even if the cesarean could be performed successfully, resuscitation of the critically stressed, probably premature infant requires equipment and skills that aren’t available on the ambulance. Instead, continue highly effective CPR, transport promptly, and give the receiving hospital as much warning as possible so that they can assemble the specialized teams and equipment needed to resuscitate the mother and deliver and resuscitate the baby. A few minutes’ extra warning may make the difference.
SPECIAL CONSIDERATIONS: IV LIPID EMULSIONS
By Eric Lavonas, MD
Since the first animal studies were reported in 1998 and the first human case report in 2006, there’s been growing enthusiasm for the use of IV lipid emulsion (ILE) (sometimes known by the brand name, Intralipid) to treat severe poisoning.
This treatment was originally developed to treat a rare but feared complication of a nerve block, in which a bolus of the local anesthetic bupivacaine accidentally got into the bloodstream, causing seizures and cardiovascular collapse.
The concept has been termed, “lipid rescue.” The theory is that by giving a lot of IV fat very quickly, the fat-soluble drug will dissolve into fat globules in the bloodstream, taking it away from the heart cells. In addition, high-dose fatty acids provide extra energy for heart cells when they need it most.
All of this has coined a new term for accidental poisoning by bupivacaine, lidocaine, and similar drugs: local anesthetic systemic toxicity (LAST).
There’s little doubt that ILE works for LAST caused by bupivacaine, although there have been no human clinical trials, a large number of animal studies and human case reports consistently show a benefit.
The information isn’t so clear that ILE works for LAST from other local anesthetics, and is quite mixed for other drug poisoning. Certainly there are miraculous case reports of patients who were in cardiac arrest due to a drug overdose and who failed all other forms of resuscitation recovering suddenly after a bolus of ILE is given. However, animal studies are mixed, and case reports of failed resuscitation with ILE are also plentiful.
There’s also a big difference between most of the animal studies, in which the poison was given via IV, and most human overdoses, which involve pills. Some early studies suggest that ILE administration may increase absorption of fat-soluble medications from the intestinal tract, which could make the poisoning worse.
How this balances out for a patient who’s already critically ill isn’t known. Otherwise, ILE is quite safe, although it temporarily causes problems with some lab test results, and may cause pancreatitis and lung problems—minor concerns when the drug is used in life-threatening situations.
Lipid emulsion has been used for decades as part of IV feeding for people whose intestinal tracts don’t work, and they’re widely commercially available. Some animal studies show that ILE changes the body’s sensitivity to epinephrine and vasopressin, but as yet there are no data to show that changing from standard ACLS doses is necessary or beneficial.
The Bottom Line
ILE therapy can be life-saving for LAST due to bupivacaine toxicity, and should be considered part of first-line therapy for these conditions. However, EMS providers should rarely if ever encounter cases of LAST, and any surgery center that provides regional anesthesia probably has a protocol to give ILE.
Whether ILE helps with other forms of critical drug poisoning is much more questionable. The AHA believes that it may be reasonable to use ILE in patients with drug-induced cardiac arrest who are failing standard resuscitation measures. This group has little to lose.
Nobody knows the best dose of ILE. The most common approach is to use a 20% emulsion of long-chain triglycerides (e.g., Intralipid), giving 1.5 mL/kg of lean body mass IV over 1 minute. Repeat boluses may be given once or twice if needed for persistent cardiovascular collapse. If ROSC is achieved, an infusion of 0.25 mL/kg/min for 30–60 minutes may prevent recurrent toxicity. The same maximum dose isn’t known—10 mL/kg has been suggested.
PEDIATRIC BLS & CPR QUALITY
By Dianne L. Atkins, MD
The new recommendations in the Pediatric BLS guidelines are intended to improve the quality of CPR in children. The review was limited to specific elements of CPR for which there were new data to guide us.
The pediatric guidelines are intended for infants less than 1 year of age and pre-pubertal children. Puberty is defined in females as breast development and in males as the presence of axillary hair. Adult BLS guidelines apply after puberty. There are also new algorithms specific for 1- and 2-person CPR.
Asphyxial arrest occurs more commonly in children compared to primary cardiac arrest, making ventilations more important in children compared to adults. However, simulation studies demonstrate that the delay in starting ventilations is only 18 seconds when giving 30 compressions followed by two rescue breaths for a single rescuer and less for two rescuers.
A common algorithm for all ages decreases the complexity and provides consistency in teaching. Outcome data comparing CAB (i.e., chest compressions, airway, breathing) vs. ABC (i.e., airway, breathing, chest compressions) for infants and children aren’t available.
- Due to the limited amount and quality of the data, it may be reasonable to maintain the sequence from the 2010 Guidelines by initiating CPR with CAB over ABC (Class IIb, LOE E). Knowledge gaps exist and specific research will be required to examine best approach to initiating CPR in children.
Chest Compression Depth & Rate
Achieving a specific chest compression depth appears to improve resuscitation outcomes in children, similar to adult studies. Chest compression depth is often inadequate in children and a recent study has demonstrated that compression depth of > 51 mm (5.1 cm) in children older than 8 years was associated with improved 24-hour survival.
Since there was insufficient data to review compression rate in infants and children, the 2015 Guidelines Update recommends the adult compression rate.
- It’s reasonable that rescuers provide chest compressions in pediatric patients (1 month to the onset of puberty) that depress the chest at least 1/3 the anteriorposterior diameter of the chest. This equates to approximately 1.5 in. (4 cm) in infants to 2 in. (5 cm) in children. (Class IIa, LOE C). Once children have reached puberty, the recommended adult compression depth of at least 5 cm, but no more than 6 cm, should be used for the adolescent of average adult size.
- In order to maximize simplicity in CPR training, in the absence of sufficient pediatric evidence, the adult chest compression rate of 100–120 compressions per minute should be used for infants and children.
In a very large registry study of pediatric out-of-hospital cardiac arrest, the 30-day survival with good neurologic function was worse with compression-only CPR compared to conventional CPR. In a subset of children with presumed cardiac etiology, compression-only CPR was as effective as conventional CPR.
In patients with presumed asphyxial arrest, the outcomes with compression-only CPR were the same as patients who received no bystander CPR. In a second study, from the same registry, compression-only CPR was associated with worse 30-day outcomes compared to patients who received conventional CPR.
- Conventional CPR (i.e., rescue breathing and chest compressions) should be provided for pediatric cardiac arrests (Class I LOE B-NR). The asphyxial nature of the majority of pediatric cardiac arrests necessitates ventilation as part of effective CPR, however, as chest compression-only CPR is effective in patients with a primary cardiac event, if rescuers are unwilling or unable to deliver breaths, we recommend rescuers perform chest compressions only CPR for infants and children in cardiac arrest (Class I LOE B-NR).
By Allan de Caen, MD, FRCP
Effective ALS for children builds upon a foundation of excellent BLS, and CPR in particular. If good BLS isn’t provided, ALS interventions will be limited in their ability to improve patient outcomes. AHA pediatric ALS guidelines changes for 2015 relevant to the EMS practitioner can be broken down into pre-arrest, intra-arrest and post-arrest care recommendations.
- The use of early and rapid fluid resuscitation remains a cornerstone of therapy for shock states, but the specific role for bolus fluid therapy for some patients is controversial. Data suggests that when caring for febrile infants and children who are in shock in settings where there’s limited access to ventilatory or inotropic support, the use of bolus fluid therapy may be associated with increased patient mortality. Fluid therapy should still be administered by bolus to infants and children in shock, but with frequent reassessment of the patient during and following boluses to ensure excessive fluid isn’t administered.
- Atropine has historically been given as a routine component of pediatric rapid sequence intubation for critically ill infants and children. High-quality data supporting this indication is lacking. Recent observational data shows that its routine use pre-intubation for all critically ill infants and children is neither protective for bradycardia nor associated with reduced mortality. There may be subgroups of patients with a higher risk of bradycardia during intubation that may benefit from the prophylactic use of atropine (e.g., with the use of fentanyl or succinylcholine for intubation). New literature also suggests that if atropine is to be administered preintubation, there’s no lower limit to the dose (i.e., patients should receive 0.02 mg/kg, not a minimum dose of 0.1 mg).
- Pediatric observational data now exists that suggests that either lidocaine or amiodarone may be used for shock-refractory v fib or pulseless v tach.
- Despite an extensive review, there’s an absence of high-quality evidence supporting the use of a single factor during pediatric resuscitation to guide either termination or continuation of ongoing resuscitative measures. Practitioners must use multiple clinical factors during CPR to support these kinds of decisions.
- A recent study of infants and children remaining comatose after ROSC from out-of-hospital cardiac arrest compared the use of moderate hypothermia (32–34 degrees C) therapy for 2 days followed by 3 days of normothermia, to maintenance of normothermia (36–37.5 degrees C) for 5 days. No significant difference in survival or neurologic outcome was found. The application of either normothermia or moderate hypothermia are acceptable therapeutic alternatives for these children. Fever after ROSC has been associated with worsened outcomes and should be avoided. No data exists to support initiating cooling/avoidance of fever in the prehospital setting.
- Post-ROSC hypotension in survivors of pediatric cardiac arrest is common and associated with poor patient outcome. A systolic blood pressure above the 5th percentile for the child’s age should be maintained after ROSC by the use of fluid and/ or inotropes and vasopressors.
- Extremes (high and low) of patient PaCO2 and PaO2 post-ROSC are associated with worsened patient outcomes. Although the pediatric evidence is limited and contradictory, it’s suggested that rescuers target the patient’s pre-arrest norm for PaCO2, and oxygen saturations of between 94–99%.
By Marya L. Strand, MD, MS, FAAP &Henry C. Lee, MD, FAAP
For newly born infants or infants during the first few weeks after birth, the assessment of whether resuscitation is required depends on assessment of two vital signs: respirations (apnea or gasping) and heart rate (less than 100 beats per minute).
When either of those characteristics is abnormal, successful resuscitation depends on ventilation effective in expanding the lungs. Ventilation is most effective when using an appropriately sized mask, positioning the airway and making sure the airway is clear of obstruction. Key principles of achieving effective ventilation are shown in Table 1.
American Academy of Pediatrics and American Heart Association: Textbook of neonatal resuscitation, 6th ed. American Academy of Pediatrics: Elk Grove Village, Ill., p. 95, 2011. Used with permission.
Initial ventilation for term infants is provided with 21% oxygen. Preterm infants can also be ventilated using 21% oxygen and should be started at no more than 30%. The oxygen concentration should be increased to 100% when chest compressions are needed. Oxygen delivery should be guided by pulse oximetry, and newborns can take up to 10 minutes to reach saturations of 85%. (See Table 2, p. 35.) With the recognition that the most sensitive indicator of a successful response to resuscitation is heart rate, a new recommendation is the use of 3-lead ECG when possible to monitor heart rate. This is due to the relative inaccuracy of auscultation or palpation of the umbilical pulse. However, even when ECG is used, pulse oximetry is also required in order to guide oxygen use.
American Academy of Pediatrics and American Heart Association: Textbook of neonatal resuscitation, 6th ed. American Academy of Pediatrics: Elk Grove Village, Ill., p. 54, 2011. Used with permission.
Maintaining normothermia is important in neonatal resuscitation. Methods to keep babies warm, particularly preterm infants less than 32 weeks gestational age, include using a hat, wrapping in food-grade plastic, warm blankets, increasing environmental temperature, using a chemical warming mattress, and placing the infant skin-to-skin with his or her mother.
Most neonatal events are due to respiratory failure, as opposed to older children who likely have cardiac failure. Because of this difference, neonatal CPR uses 3 compressions to 1 breath. This cycle is completed in a 2-second interval, resulting in 90 compressions and 30 breaths each minute. Compressions should be delivered using the 2-thumb technique with both hands encircling the thorax and the thumbs on the lower 1/3 of the sternum. The 2-finger technique is no longer recommended. Unlike resuscitation for older patients, compressions and ventilations should be coordinated to avoid simultaneous delivery.
Drugs are rarely needed for neonatal resuscitation. However, if a heart rate less than 60 persists despite adequate ventilation with 100% oxygen and CPR, epinephrine (0.1 to 0.3 mL/kg of 1:10,000 epinephrine) or normal saline (10 mL/kg) may be given by IV. For a newborn infant, the umbilical vein or intraosseous route may be the quickest way to achieve access.
Although previous iterations of guidelines have recommended intratracheal suctioning of infants born through meconium-stained amniotic fluid, routine suctioning of such patients is no longer suggested. Instead, appropriate interventions to support ventilation and oxygenation, such as ventilation with bag and mask, should be initiated. Intubation and suctioning with a meconium aspirator can be attempted if the airway appears to be obstructed.
As neonatal resuscitation requires teamwork and may be an infrequent occurrence for emergency providers, we encourage teams to practice both technical skills as well as behavioral and communication skills through simulation and debriefing.