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Background: Hyperventilation during cardiopulmonary resuscitation (CPR) is harmful., Methods: We tested the hypotheses that, during CPR, 2 breaths/min would result in higher cerebral perfusion pressure and brain-tissue oxygen tension than 10 breaths/min, and an impedance threshold device (known to increase circulation) would further enhance cerebral perfusion and brain-tissue oxygen tension, especially with 2 breaths/min., Results: Female pigs (30.4 +/- 1.3 kg) anesthetized with propofol were subjected to 6 min of untreated ventricular fibrillation, followed by 5 min of CPR (100 compressions/min, compression depth of 25% of the anterior-posterior chest diameter), and ventilated with either 10 breaths/min or 2 breaths/min, while receiving 100% oxygen and a tidal volume of 12 mL/kg. Brain-tissue oxygen tension was measured with a probe in the parietal lobe. The impedance threshold device was then used during an 5 additional min of CPR. During CPR the mean +/- SD calculated coronary and cerebral perfusion pressures with 10 breaths/min versus 2 breaths/min, respectively, were 17.6 +/- 9.3 mm Hg versus 14.3 +/- 6.5 mm Hg (p = 0.20) and 16.0 +/- 9.5 mm Hg versus 9.3 +/- 12.5 mm Hg (p = 0.25). Carotid artery blood flow, which was prospectively designated as the primary end point, was 65.0 +/- 49.6 mL/min in the 10-breaths/min group, versus 34.0 +/- 17.1 mL/min in the 2-breaths/min group (p = 0.037). Brain-tissue oxygen tension was 3.0 +/- 3.3 mm Hg in the 10-breaths/min group, versus 0.5 +/- 0.5 mm Hg in the 2-breaths/min group (p = 0.036). After 5 min of CPR there were no significant differences in arterial pH, PO2, or PCO2 between the groups. During CPR with the impedance threshold device, the mean carotid blood flow and brain-tissue oxygen tension in the 10-breaths/min group and the 2-breaths/min group, respectively, were 102.5 +/- 67.9 mm Hg versus 38.8 +/- 23.7 mm Hg (p = 0.006) and 4.5 +/- 6.0 mm Hg versus 0.7 +/- 0.7 mm Hg (p = 0.032)., Conclusions: Contrary to our initial hypothesis, during the first 5 min of CPR, 2 breaths/min resulted in significantly lower carotid blood flow and brain-tissue oxygen tension than did 10 breaths/min. Subsequent addition of an impedance threshold device significantly enhanced carotid flow and brain-tissue oxygen tension, especially in the 10-breaths/min group.

Background: Positive-pressure ventilation of patients with unprotected airways during cardiopulmonary resuscitation can cause gastric dilation., Objective: Determine if there is a significant difference in volume delivered to lungs and stomach while using an adult 1,000-mL disposable bag-valve-mask (BVM) device and the oxygen-powered, flow-limited Oxylator EMX resuscitator., Methods: We used a bench model to simulate a patient with an unprotected airway, consisting of an intubation manikin, lung analog, and simulated lower esophageal sphincter set at an opening pressure of 20 cm H2O. The BVM and the Oxylator were used to provide mask ventilation at a verbally prompted rate of 12 breaths/min., Results: The volumes delivered with the BVM and the Oxylator to the lungs and stomach were not significantly different: 262 + 112 mL versus 297 + 99 mL and 227 + 199 mL versus 159 + 73 mL, respectively., Conclusion: Our study found no significant difference between the Oxylator and BVM when comparing tidal volume delivered to lungs and stomach during ventilation of a simulated unconscious nonintubated patient. More research on BVM use and the Oxylator should be done to validate the American Heart Association's guideline recommendations for ventilating unconscious patients with unprotected airways. Research on gastric dilation during cardiopulmonary resuscitation needs to be done with bench models using manikins that simulate chest excursion, bidirectional airway flow, lung impedance, and gastric compliance.

Objective: Assess a prototype inspiratory impedance threshold valve (ITV) designed to enhance vital organ circulation during standard and active compression/decompression cardiopulmonary resuscitation (CPR)., Background: The ITV attaches to commonly used airway assist devices and decreases intrathoracic pressure during the decompression (chest recoil) phase of CPR by creating a vacuum within the thorax, which increases venous blood flow to the heart and thus increases coronary perfusion pressure and blood flow to the brain., Methods: The evaluation included laboratory bench testing, according to American Society for Testing and Materials (ASTM) and International Standards Organization (ISO) guidelines, and performance testing with pigs in cardiac arrest. A vacuum pull test was developed to determine the inspiratory impedance under various inspiratory flow conditions., Results: The valve passed all minimum ASTM and ISO performance tests. During cardiac arrest in pigs the ITV decreased intrathoracic pressures by 6-8 mm Hg during the decompression phase. The vacuum pull test demonstrated that the prototype ITV functioned as intended., Conclusions: The prototype ITV passed all performance testing recommended by international guidelines and functioned effectively as intended for use. The animal study results, when combined with recent clinical data, suggest that an ITV inspiratory cracking pressure of 12 cm H(2)O should be sufficient to decrease intrathoracic pressure during the decompression phase of standard CPR. Clinical studies are now underway.

The development of the AHA Guidelines for CPR and ECC and the AARC RACH Clinical Practice Guideline should both be instrumental in improving the performance of RCPs on in-hospital resuscitation teams. The AARC and AHA are assuming important leadership roles in this movement by publishing CPGs for CPR and ECC. RCPs with ACLS training are in a prime position to assume more responsibility on resuscitation teams within acute care facilities. They should be prominent members of the resuscitation team--committed to the entire team's performance--and be actively involved in ACLS training. The first step in that process is to study the current levels of RCP competence in ACLS. Further, RCPs and health-care providers should define the goals of resuscitation in terms of long-term survival, quality of life, and years of useful life after CPR. The cost of inadequate attention to which patients should have DNR orders is a drain on the entire health-care system. Research on the impact of disease categories on CPR outcome should be used to educate physicians, nurses, and RCPs so they can help patients better understand their chances of regaining their pre-CPR quality of life. Successful CPR outcome should be carefully defined using the patient's disease category. Each patient should be individually evaluated for DNR orders. As suggested by Schwenzer, "Patients' perception of their quality of life before and after CPR should guide their and our decisions." However, we must all accept the responsibility for defining the limitations of medical technology and try to determine when CPR is futile.

Emergency ventilation techniques used during CPR have been refined over the last 40 years. The methods and equipment for emergency ventilation all have their advantages and disadvantages (Table 5), and the appropriate technique varies with the training and experience of the rescuer. Problems encountered during CPR with victims who have unsecured airways remain unresolved at this time and more work needs to be done. Respiratory care practitioners because of their special training and experience with resuscitation are in an excellent position to make contributions to our knowledge by implementing and publishing relevant clinical studies.