Incomplete chest wall decompression: a clinical evaluation of CPR performance by trained laypersons and an assessment of alternative manual chest compression-decompression techniques.

BACKGROUND: Complete chest wall recoil improves hemodynamics during CPR by generating relatively negative intrathoracic pressure, which draws venous blood back to the heart, providing cardiac preload prior to the next chest compression. OBJECTIVE: This study was designed to assess the quality of CPR delivered by trained laypersons and to determine if a change in CPR technique or hand position would improve complete chest wall recoil, while maintaining adequate duty cycle, compression depth, and proper hand position placement. Standard manual CPR and three alternative manual CPR approaches were assessed. METHODS: This randomized prospective trial was performed on an electronic test manikin. Thirty laypersons (mean age of 40.6 years (range 28-55)), who were trained in CPR within the last 24 months, signed an informed consent and participated in the trial. Subjects performed 3 min of CPR on a Laerdal Skill Reportertrade mark CPR manikin using the Standard Hand Position followed by 3 min of CPR (in random order) using three alternative CPR techniques: (1) Two-Finger Fulcrum Technique - lifting the heel of the hand slightly but completely off the chest during the decompression phase of CPR using the thumb and little finger as a fulcrum; (2) Five-Finger Fulcrum Technique - lifting the heel of the hand slightly but completely off the chest during the decompression phase of CPR using all five fingers as a fulcrum; (3) Hands-Off Technique - lifting the heel and all fingers of the hand slightly but completely off the chest during the decompression phase of CPR. The participants did not know the purpose of the study prior to, or during this investigation. RESULTS: Adequate compression depth was poor for all hand positions tested and ranged only from 18.6 to 35.7% of all compressions. When compared with the Standard Hand Position, the Hands-Off Technique decreased the mean compression duty cycle from 39.0 +/- 1.0 to 33.5 +/- 1.0%, (P < 0.0001) but achieved the highest rate of complete chest wall recoil (92.5% versus 24.1%, P < 0.0001) and was 46.3 times more likely to provide complete chest wall recoil (OR: 46.3; CI: 16.4-130.3). There were no significant differences in accuracy of hand placement, adequate depth of compression, or perceived discomfort with its use compared with the Standard Hand Position. CONCLUSIONS: The Hands-Off Technique decreased compression duty cycle but was 46.3 times more likely to provide complete chest wall recoil (OR: 46.3; CI: 16.4-130.3) compared to the Standard Hand Position without differences in accuracy of hand placement, adequate depth of compression, or perceived discomfort with its use. All forms of manual CPR tested (including the Standard Hand Position) in trained laypersons produced an inadequate depth of compression for two-thirds of the time. These data support development and testing of more effective layperson CPR training programmes and more effective means to deliver manual as well as mechanical CPR.

Incomplete chest wall decompression: a clinical evaluation of CPR performance by EMS personnel and assessment of alternative manual chest compression-decompression techniques.

BACKGROUND: Complete chest wall recoil improves hemodynamics during cardiopulmonary resuscitation (CPR) by generating relatively negative intrathoracic pressure and thus draws venous blood back to the heart, providing cardiac preload prior to the next chest compression phase. OBJECTIVE: Phase I was an observational case series to evaluate the quality of chest wall recoil during CPR performed by emergency medical services (EMS) personnel on patients with an out-of-hospital cardiac arrest. Phase II was designed to assess the quality of CPR delivered by EMS personnel using an electronic test manikin. The goal was to determine if a change in CPR technique or hand position would improve complete chest wall recoil, while maintaining adequate duty cycle, compression depth, and correct hand position placement. Standard manual CPR and three alternative manual CPR approaches were assessed. METHODS AND RESULTS: Phase I--The clinical observational study was performed by an independent observer noting incomplete chest wall decompression and correlating that observation with electronically measured airway pressures during CPR in adult patients with out-of-hospital cardiac arrest. Rescuers were observed to maintain some residual and continuous pressure on the chest wall during the decompression phase of CPR, preventing full chest wall recoil, at some time during resuscitative efforts in 6 (46%) of 13 consecutive adults (average +/- S.D. age 63 +/-5.8 years). Airway pressures were consistently positive during the decompression phase (>0 mmHg) during those observations. Phase II: This randomized prospective trial was performed on an electronic test manikin. Thirty EMS providers (14 EMT-Basics, 5 EMT-Intermediates, and 11 EMT-Paramedics), with an average age +/- S.D. of 32 +/- 8 years and 6.5 +/- 4.2 years of EMS experience, performed 3 min of CPR on a Laerdal Skill Reporter CPR manikin using the Standard Hand Position followed by 3 min of CPR (in random order) using three alternative CPR techniques: (1) Two-Finger Fulcrum Technique--lifting the heel of the hand slightly but completely off the chest during the decompression phase of CPR using the thumb and little finger as a fulcrum; (2) Five-Finger Fulcrum Technique--lifting the heel of the hand slightly but completely off the chest during the decompression phase of CPR using all five fingers as a fulcrum; and (3) Hands-Off Technique--lifting the heel and all fingers of the hand slightly but completely off the chest during the decompression phase of CPR. These EMS personnel did not know the purpose of the studies prior to or during this investigation. Adequate compression depth was poor for all hand positions tested and ranged only from 29.9 to 48.5% of all compressions. When compared with the Standard Hand Position, the Hands-Off Technique decreased mean compression duty cycle from 46.9 +/- 6.4% to 33.3 +/- 4.6%, (P < 0.0001) but achieved the highest rate of complete chest wall recoil (95.0% versus 16.3%, P < 0.0001) and was 129 times more likely to provide complete chest wall recoil (OR: 129.0; CI: 43.4-382.0). There were no significant differences in accuracy of hand placement, depth of compression, or reported increase in fatigue or discomfort with its use compared with the Standard Hand Position. CONCLUSIONS: Incomplete chest wall decompression was observed at some time during resuscitative efforts in 6 (46%) of 13 consecutive adult out-of-hospital cardiac arrests. The Hands-Off Technique decreased compression duty cycle but was 129 times more likely to provide complete chest wall recoil (OR: 129.0; CI: 43.4-382.0) compared to the Standard Hand Position without differences in accuracy of hand placement, depth of compression, or reported increase in fatigue or discomfort with its use. All forms of manual CPR tested (including the Standard Hand Position) in professional EMS rescuers using a recording manikin produced an inadequate depth of compression more than half the time. These data support development and testing of more effective means to deliver manual as well as mechanical CPR.

Hyperventilation-induced hypotension during cardiopulmonary resuscitation.

BACKGROUND: A clinical observational study revealed that rescuers consistently hyperventilated patients during out-of-hospital cardiopulmonary resuscitation (CPR). The objective of this study was to quantify the degree of excessive ventilation in humans and determine if comparable excessive ventilation rates during CPR in animals significantly decrease coronary perfusion pressure and survival. METHODS AND RESULTS: In humans, ventilation rate and duration during CPR was electronically recorded by professional rescuers. In 13 consecutive adults (average age, 63+/-5.8 years) receiving CPR (7 men), average ventilation rate was 30+/-3.2 per minute (range, 15 to 49). Average duration per breath was 1.0+/-0.07 per second. No patient survived. Hemodynamics were studied in 9 pigs in cardiac arrest ventilated in random order with 12, 20, or 30 breaths per minute. Survival rates were then studied in 3 groups of 7 pigs in cardiac arrest that were ventilated at 12 breaths per minute (100% O2), 30 breaths per minute (100% O2), or 30 breaths per minute (5% CO2/95% O2). In animals treated with 12, 20, and 30 breaths per minute, the mean intrathoracic pressure (mm Hg/min) and coronary perfusion pressure (mm Hg) were 7.1+/-0.7, 11.6+/-0.7, 17.5+/-1.0 (P<0.0001), and 23.4+/-1.0, 19.5+/-1.8, and 16.9+/-1.8 (P=0.03), respectively. Survival rates were 6/7, 1/7, and 1/7 with 12, 30, and 30+ CO2 breaths per minute, respectively (P=0.006). CONCLUSIONS: Professional rescuers were observed to excessively ventilate patients during out-of-hospital CPR. Subsequent animal studies demonstrated that similar excessive ventilation rates resulted in significantly increased intrathoracic pressure and markedly decreased coronary perfusion pressures and survival rates.