BACKGROUND: A study was performed to demonstrate that slower respiratory rates (RRs) of positive-pressure ventilation can preserve adequate oxygenation and acid-base status in hemorrhagic states, whereas "normal" or higher RRs worsen hemodynamics. METHODS: Eight swine (ventilated with 12 mL/kg tidal volume, 0.28 Fio(2); RR of 12 breaths/min) were hemorrhaged to < 65 mm Hg systolic arterial blood pressure (SABP). RRs were then sequentially changed every 10 minutes to 6, 20, 30, and 6 breaths/min. RESULTS: With RRs at 6 breaths/min, the animals maintained pH > 7.25/Sao(2) > 99%, but increased mean SABP (from 65 to 84 mm Hg; p < 0.05), time-averaged coronary perfusion pressure (CPP) (from 50 +/- 2 to 60 +/- 4 mm Hg; p < 0.05), and cardiac output (Qt) (from 2.4 to 2.8 L/min; p < 0.05). With RRs of 20 and 30 breaths/min, SABP (73 and 66 mm Hg), CPP (47 +/- 3 and 42 +/- 4 mm Hg), and Qt (2.5 and 2.4 L/min) decreased, as did Pao(2) and Paco(2) (< 30 mm Hg), with p < 0.05 for each comparison, respectively. When RR returned to 6 breaths/min, SABP (95 mm Hg), CPP (71 +/- 6 mm Hg), and Qt (3.0 L/min) improved significantly (p < 0.05). CONCLUSION: After even moderate levels of hemorrhage in animals, positive-pressure ventilation with "normal" or higher RRs can impair hemodynamics. Hemodynamics can be improved with lower RRs while still maintaining adequate oxygenation and ventilation.
BACKGROUND: A study was performed to demonstrate that slower respiratory rates (RRs) of positive-pressure ventilation can preserve adequate oxygenation and acid-base status in hemorrhagic states, whereas "normal" or higher RRs worsen hemodynamics. METHODS: Eight swine (ventilated with 12 mL/kg tidal volume, 0.28 Fio(2); RR of 12 breaths/min) were hemorrhaged to < 65 mm Hg systolic arterial blood pressure (SABP). RRs were then sequentially changed every 10 minutes to 6, 20, 30, and 6 breaths/min. RESULTS: With RRs at 6 breaths/min, the animals maintained pH > 7.25/Sao(2) > 99%, but increased mean SABP (from 65 to 84 mm Hg; p < 0.05), time-averaged coronary perfusion pressure (CPP) (from 50 +/- 2 to 60 +/- 4 mm Hg; p < 0.05), and cardiac output (Qt) (from 2.4 to 2.8 L/min; p < 0.05). With RRs of 20 and 30 breaths/min, SABP (73 and 66 mm Hg), CPP (47 +/- 3 and 42 +/- 4 mm Hg), and Qt (2.5 and 2.4 L/min) decreased, as did Pao(2) and Paco(2) (< 30 mm Hg), with p < 0.05 for each comparison, respectively. When RR returned to 6 breaths/min, SABP (95 mm Hg), CPP (71 +/- 6 mm Hg), and Qt (3.0 L/min) improved significantly (p < 0.05). CONCLUSION: After even moderate levels of hemorrhage in animals, positive-pressure ventilation with "normal" or higher RRs can impair hemodynamics. Hemodynamics can be improved with lower RRs while still maintaining adequate oxygenation and ventilation.
Authors: Daniel P Davis; Kent M Koprowicz; Craig D Newgard; Mohamud Daya; Eileen M Bulger; Ian Stiell; Graham Nichol; Shannon Stephens; Jonathan Dreyer; Joseph Minei; Jeffrey D Kerby Journal: Prehosp Emerg Care Date: 2011-02-10 Impact factor: 3.077
Authors: Paula Ferrada; Rachael A Callcut; David J Skarupa; Therese M Duane; Alberto Garcia; Kenji Inaba; Desmond Khor; Vincent Anto; Jason Sperry; David Turay; Rachel M Nygaard; Martin A Schreiber; Toby Enniss; Michelle McNutt; Herb Phelan; Kira Smith; Forrest O Moore; Irene Tabas; Joseph Dubose Journal: World J Emerg Surg Date: 2018-02-05 Impact factor: 5.469