The hemodynamic and respiratory effects of cuirass ventilation in healthy volunteers: Part 1.
OBJECTIVE
Negative-pressure ventilation (NPV) by external cuirass (RTX; Deminax Medical Instruments Limited, London, UK) in intubated patients after cardiac surgery improves hemodynamics measured by pulmonary artery catheter (PAC)-based methods, with an increased cardiac output (CO) and stroke volume (SV), without changing the heart rate (HR). The less-invasive pressure recording analytical method (PRAM) (Mostcare; Vytech Health srl, Padova, Italy) allows radial artery-based monitoring of the CO, SV, SV variation, and cardiac cycle efficiency (CCE). The authors investigated the hypothesis that NPV improves PRAM-based hemodynamics and arterial blood gas analysis in spontaneously breathing subjects.


METHODS
A clinical investigation.


METHODS
A teaching hospital.


METHODS
Ten healthy volunteers.


METHODS
Subjects underwent 5 consecutive experimental ventilation modalities lasting 5 minutes: (1) baseline (no cuirass ventilation), (2) mode 1: cuirass ventilation with a continuous negative pressure of -20 cmH(2)O, (3) first rest period (no cuirass ventilation), (4) mode 2: cuirass ventilation in control mode of 12 breaths/min at -20 cmH(2)O, and (5) second rest period.


RESULTS
PRAM parameters were analyzed throughout the final minute of each experimental modality, which concluded with arterial blood gas sampling. Both NPV modes significantly reduced HR without changing CO or systemic vascular resistance. Mode 1 significantly increased CCE and decreased SVV. PO(2) decreased in both rest modes compared with baseline. This was prevented by NPV. In 5 smokers, PO(2) significantly increased in the control mode compared with first rest period. The control mode NPV improved oxygenation with a reduced PCO(2) and reciprocally increased pH.


CONCLUSIONS
Five minutes of NPV improves hemodynamics and oxygenation in healthy subjects.
Department of Cardiac Anaesthesia, Royal Victoria Hospital, Belfast, UK. williamthomasmcb@doctors.org.uk
William T
WT
McBride
Giulia
G
Ranaldi
Mark J
MJ
Dougherty
Tommaso
T
Siciliano
Brian
B
Trethowan
Peter
P
Elliott
Claire
C
Rice
Sabino
S
Scolletta
Pierpaolo
P
Giomarelli
Salvatore Mario
SM
Romano
David M
DM
Linton
D000328:Adult; D001784:Blood Gas Analysis / Q000379:methods; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D016896:Treatment Outcome; D015919:Ventilators, Negative-Pressure