Spontaneous breathing trial in T-tube negatively impact on autonomic modulation of heart rate compared with pressure support in critically ill patients.
BACKGROUND
Spontaneous breathing with a conventional T-piece (TT) connected to the tracheal tube orotraqueal has been frequently used in clinical setting to weaning of mechanical ventilation (MV), when compared with pressure support ventilation (PSV). However, the acute effects of spontaneous breathing with TT versus PSV on autonomic function assessed through heart rate variability (HRV) have not been fully elucidated.


OBJECTIVE
The purpose of this study was to examine the acute effects of spontaneous breathing in TT vs PSV in critically ill patients.


METHODS
Twenty-one patients who had received MV for ≥ 48 h and who met the study inclusion criteria for weaning were assessed. Eligible patients were randomized to TT and PSV. Cardiorespiratory responses (respiratory rate -ƒ, tidal volume-VT, mean blood pressure (MBP) and diastolic blood pressure (DBP), end tidal dioxide carbone (PETCO2), peripheral oxygen saturation (SpO2) and HRV indices in frequency domain (low-LF, high frequency (HF) and LF/HF ratio were evaluated.


RESULTS
TT increased ƒ (20 ± 5 vs 25 ± 4 breaths/min, P<0.05), MBP (90 ± 14 vs 94 ± 18 mmHg, P<0.05), HR (90 ± 17 vs 96 ± 12 beats/min, P<0.05), PETCO2(33 ± 8 vs 48 ± 10 mmHg, P<0.05) and reduced SpO2(98 ± 1.6 vs 96 ± 1.6%, P<0.05). In addition, LF increased (47 ± 18 vs 38 ± 12 nu, P<0.05) and HF reduced (29 ± 13 vs 32 ± 16 nu, P<0.05), resulting in higher LF/HF ratio (1.62 ± 2 vs 1.18 ± 1, P<0.05) during TT. Conversely, VTincreased with PSV (0.58 ± 0.16 vs 0.50 ± 0.15 L, P<0.05) compared with TT.


CONCLUSIONS
Acute effects of TT mode may be closely linked to cardiorespiratory mismatches and cardiac autonomic imbalance in critically ill patients.
Intensive Medicine Service, Hospital de Clinicas de Porto Alegre, Brazil.
Adriana M
AM
Güntzel Chiappa
Exercise Pathophysiology Research Laboratory and Cardiology Division, Hospital de Clinicas de Porto Alegre, Brazil.
Gaspar R
GR
Chiappa
Faculty of Ceilandia, University of Brasilia, Brazil.
Gerson
G
Cipriano
Department of Medicine, Faculty of Medicine, Federal University of Rio Grande Sul, Brazil.
Ruy S
RS
Moraes
Biomedical Engineering, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil.
Elton L
EL
Ferlin
Cardiopulmonary Physiotherapy Laboratory, Federal University of Sao Carlos, São Carlos, SP, Brazil.
Audrey
A
Borghi-Silva
Intensive Medicine Service, Hospital de Clinicas de Porto Alegre, Brazil.
Silvia R
SR
Vieira
D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D016638:Critical Illness / Q000628:therapy*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D026741:Physical Therapy Modalities / Q000592:standards; D011175:Positive-Pressure Respiration / Q000295:instrumentation / Q000379:methods; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods*; D013990:Tidal Volume / Q000502:physiology; D015300:Ventilator Weaning / Q000009:adverse effects* / Q000379:methods / Q000592:standards
intensive care unit; mechanical ventilation; non-invasive ventilation; physical therapy