title: Hyperventilation-induced hypotension during cardiopulmonary resuscitation.
abstract: 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.
  
  
  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.
authors.affiliation: Department of Emergency Medicine, Medical College of Wisconsin, Milwaukee, USA.
authors.forename: Tom P
authors.initials: TP
authors.lastname: Aufderheide
authors.forename: Gardar
authors.initials: G
authors.lastname: Sigurdsson
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Pirrallo
authors.forename: Demetris
authors.initials: D
authors.lastname: Yannopoulos
authors.forename: Scott
authors.initials: S
authors.lastname: McKnite
authors.forename: Chris
authors.initials: C
authors.lastname: von Briesen
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Sparks
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Conrad
authors.forename: Terry A
authors.initials: TA
authors.lastname: Provo
authors.forename: Keith G
authors.initials: KG
authors.lastname: Lurie
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001794:Blood Pressure; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects* / Q000401:mortality; D003331:Coronary Vessels / Q000502:physiology; D005260:Female; D006323:Heart Arrest / Q000628:therapy; D006439:Hemodynamics; D006801:Humans; D006985:Hyperventilation / Q000150:complications* / Q000209:etiology; D007022:Hypotension / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012123:Pulmonary Ventilation; D016019:Survival Analysis