Controversial issues in cardiopulmonary resuscitation

Use of the impedance threshold device in cardiopulmonary resuscitation

Although approximately one million sudden cardiac deaths occur yearly in the US and Europe, cardiac arrest (CA) remains a clinical condition still characterized by a poor prognosis. In an effort to improve the cardiopulmonary resuscitation (CPR) technique, the 2005 American Heart Association (AHA) Guidelines for CPR gave the impedance threshold device (ITD) a Class IIa recommendation. The AHA recommendation means that there is strong evidence to demonstrate that ITD enhances circulation, improves hemodynamics and increases the likelihood of resuscitation in patients in CA. During standard CPR, venous blood return to the heart relies on the natural elastic recoil of the chest which creates a transient decrease in intrathoracic pressure. The ITD further decreases intrathoracic pressure by preventing respiratory gases from entering the lungs during the decompression phase of CPR. Thus, although ITD is placed into the respiratory circuit it works as a circulatory enhancer device that provides its therapeutic benefit with each chest decompression. The ease of use of this device, its ability to be incorporated into a mask and other airway devices, the absence of device-related adverse effects and few requirements in additional training, suggest that ITD may be a favorable new device for improving CPR efficiency. Since the literature is short of studies with clinically meaningful outcomes such as neurological outcome and long term survival, further evidence is still needed.

Reverse CPR: a pilot study of CPR in the prone position

BACKGROUND

Cardiopulmonary resuscitation (CPR), as described in 1960, remains the cornerstone of therapy for cardiopulmonary arrest. Recent case reports have described CPR in the prone position. We hypothesized rhythmic back pressure on a patient in the prone position with sternal counter-pressure (termed reverse CPR here) would increase intra-thoracic pressure and in turn systolic blood pressure (SBP) during cardiac arrest versus standard CPR.

METHODS AND RESULTS

Six patients from Columbia Presbyterian Medical Center's Cardiac and Medical Intensive Care Units (CICU and MICU) were enrolled. Eligible patients had suffered circulatory arrest and failed standard CPR for at least 30 min. After enrollment the patients received 15 additional min of standard CPR and then reverse CPR for 15 min. The study's primary endpoint, mean SBP, significantly improved from 48 mmHg during standard CPR to 72 mmHg during reverse CPR (mean improvement=23+/-14 mmHg). Mean calculated mean arterial pressure (MAP) was also improved significantly from 32 mmHg during standard CPR to 46 mmHg during reverse CPR (mean improvement=14+/-11 mmHg). The mean diastolic blood pressure (DBP) improved from 24 mmHg during standard to 34 mmHg during reverse CPR (mean improvement=10+/-12 mmHg). This difference did not meet statistical significance. No patients had return of spontaneous circulation.

CONCLUSIONS

Reverse CPR generates higher mean SBP and higher mean MAP during circulatory arrest than standard CPR. These novel findings justify further research into this technique.

Pediatric resuscitation in the operating room

The resuscitation of pediatric patients undergoing anesthesia involves appropriate administration of fluid and blood products and stabilization of vital signs. Crystalloid is first-line therapy for fluid resuscitation, and should be given with awareness of its potential dilution of the child's hematocrit. Many alternatives to homologous blood transfusions now exist, however, when necessary for increasing oxygen-carrying capacity or treating coagulopathy benefits likely outweight the risks. The risks for such transfusion include infectious, hemolytic, metabolic, and immunologic effects. When fluid and blood administration does not stabilize the patient, the differential diagnosis of hypotension, arrest, or arrhythmias must include medication errors, anesthetic overdose, electrolyte disturbances, hypoxemia, ventilatory problems, and surgical insults, including medications given in the operative field. Resuscitation should include treatment of hypocalcemia and hyperkalemia, chest compressions, and the administration of epinephrine when necessary.

Alternative methods of mechanical cardiopulmonary resuscitation

Due to the relative ineffectiveness of standard resuscitation techniques, alternative methods have been explored for many years. The aim of new methods is to improve haemodynamics and increase survival rates. In spite of some encouraging haemodynamic results, all but one study failed to show an increase in long-term survival rates with an alternative method in a convincingly large group of patients (hospital discharge without neurological damage, and 1-year survival). In this study active compression-decompression resuscitation (ACD-CPR) increased long-term survival compared to standard-CPR. The results from certain individual studies, which showed a significant increase in short-term survival rate, could not be reproduced in other trials. This may be attributed in part to the fact that the alternative methods are not significantly superior, but also due to logistical and statistical problems in the conduct of the studies and differences in application within and between the study sites. ACD-CPR has been the most studied method amongst the alternatives and can be recommended for patients with asystole in centres with special training and where outcome quality is regularly verified and evaluated.

Management and emergency intervention during anesthesia

Proper management and monitoring during anesthesia minimizes the need for emergency intervention. Monitoring of circulation, ventilation, and oxygenation allows for early recognition of problems such as airway obstruction, hypotension, acid-base disturbances, or cardiac arrest, and is discussed. Appropriate therapies are instituted early for best success and are described in this article.

Intraoperative cardiopulmonary resuscitation in the prone position

Cardiopulmonary resuscitation (CPR) occasionally is necessary in the operating-room setting. In such instances, it may be difficult to perform CPR if the patient is in the prone position. Although the supine position is optimal for CPR, it may not be feasible because of the risks of damage to craniospinal structures. The authors present the case of a 12-year-old boy who had cardiac arrest during spinal fusion. Successful CPR was performed with the patient in the prone position, with the use of "reversed precordial compressions," and the patient was resuscitated despite 7 minutes of asystole. Effective cardiac output was maintained and was confirmed by systolic blood pressure readings of 80 to 90 mm Hg on both the arterial catheter waveform and the noninvasive blood pressure cuff, by a waveform and the reading on the pulse oximeter, and by the presence of end-tidal carbon dioxide.

Pharmacologic controversies in CPR

Since the 1985 Emergency Cardiac Care Conference, numerous controversies about the pharmacology of CPR have arisen (eg, questions about the pharmacokinetics and pharmacodynamics of drugs during CPR, the optimal vehicle for delivery of medications, and the dose of atropine in brady-asystolic cardiac arrest). This article has three objectives: 1) to critically explore these controversies, 2) to provide recommendations for clinical practice, and 3) to identify areas for future study. The ideal route is one which combines rapid access with quick delivery of drug to the central circulation. Because of hemodynamic changes during CPR, administration of drugs into the central circulation is preferable when compared with peripheral venous injection. Whenever drugs are administered from a peripheral i.v. site, the extremity should be elevated, and a 20-mL bolus of i.v. fluid should be given to facilitate access of the agent to the central circulation. If there is a delay in obtaining venous access, epinephrine, lidocaine, and atropine may be administered through the endotracheal tube at 2.5 times the i.v. dose. When administering these drugs through the endotracheal tube, dilute the drug in 10 mL of saline or water and inject it through a long catheter beyond the tip of the endotracheal tube. Dextrose 5% water is the primary vehicle for drug delivery during CPR. However, the administration of glucose during CPR is controversial because of the potentially detrimental effects of hyperglycemia on neuronal function during periods of ischemia. Data are inconclusive regarding the effects of glucose levels on neurologic outcome following resuscitation. Hyperglycemia may be a marker for prolonged resuscitation with subsequent impairment in insulin release.(ABSTRACT TRUNCATED AT 250 WORDS)

Right atrial-jugular venous pressure gradients during CPR in children

OBJECTIVE

This study measured the internal jugular vein and right atrium pressures during pediatric CPR to detect and quantify venous pressure gradients across the thoracic inlet.

DESIGN

Ten children from 2 months to 15 years old who underwent CPR had simultaneous pressure measurements recorded from the right atrium and jugular vein.

RESULTS

The right atrium-jugular vein peak compression-phase gradient was 18.3 +/- 4.7 mm Hg (mean +/- SD), and the end-relaxation gradient was 0.7 +/- 0.6. Jugular vein pressure exceeded the right atrium only in the early-relaxation phase (right atrium-jugular vein = -2.1 +/- 1.2). Thoracic inlet venous valving persisted throughout the duration of CPR.

CONCLUSION

There is a large venous gradient across the thoracic inlet during chest compressions in children, facilitating cerebral blood flow. This gradient reversed only in the early-relaxation phase. The data suggest that jugular venous return occurs only in the early-relaxation phase, whereas cerebral venous drainage persists throughout the CPR cycle.