Performance of Advanced Ambu Bag System among Adult Patients with Mechanical Ventilation: A Mixed-Effects Analysis

We conducted the study at the Department of Stroke Care of the Can Tho Central General Hospital, Vietnam. There are eight intensive care beds for critical illness. The study was performed according to the Helsinki Declaration and approved by the Can Tho Central General Hospital ethics committee. All patients gave written informed consent by a legal surrogate. We enrolled patients with mechanical ventilation between November 2022 and September 2023. The inclusion criteria were: (1) patients aged 16 years and older, (2) pulse rate less than 120 times per minute, (3) systolic blood pressure from 110 to 160 mmHg, (4) peripheral oxygen saturation (SpO2) greater than 90%, (5) spontaneous breathing rate less than 28 times per minute, (6) end-tidal carbon dioxide (EtCO2) from 20 to 45 mmHg, (7) secretion required suction less than one time per hour, (8) positive end-expiratory pressure less than or equal to 5 cmH2O, (9) fraction of inspired oxygen less than or equal to 60%, (10) minute ventilation less than 15 liters per minute, (11) diameter of a tracheal or tracheostomy tube greater than or equal to 7.0 mm, (12) no usage of sedation, (13) normal ST wave in the electrocardiogram. Patients were excluded from the trial if they had one of the following conditions: (1) acute myocardial infarction, (2) acute pulmonary embolism, or (3) new dangerous arrhythmias appeared in this episode (multiform ventricular ectopy, bigeminy or trigeminy ventricular ectopy, coupled ventricular ectopy, R-on-T ventricular ectopy, high-grade atrioventricular heart block, supraventricular tachycardia, atrial fibrillation, atrial flutter, ventricular tachycardia, ventricular fibrillation), (4) using vasopressors or inotropic agents. Patients could withdraw from the study at any time without giving any reason. Besides, the patient stopped the trial of the advanced Ambu bag system immediately when one of the signs appeared, such as (1) the peripheral oxygen saturation lower than 90% prolonging more than 1 minute, (2) the end-tidal carbon dioxide greater than 45 mmHg or less than 15 mmHg prolonging more than 10 minutes, (3) pulse rate greater than 120 times per minute or less than 60 times per minute prolonging more than 10 minutes, (4) systolic blood pressure greater than 170 mmHg prolonging more than 10 minutes, (5) appearing dangerous arrhythmias, (6) progressive cognitive impairment (based on Grady coma scale), or (7) any abnormal sign that the physician evaluated the patient required respiratory support immediately with conventional mechanical ventilation.

            The following is the meaning of the variables in the study:

age: Age of study participants.

gender: Gender of study participants (0: Woman, 1: Man).

day1: Day of admission to the hospital

day2: Intervention day.

dia1: Major disease.

dia2: Cause of respiratory failure.

nihss1: National Institute of Health Stroke Scale on admission

hsg: Severity of cerebral hemorrhage (0: No hemorrhagic stroke, hi1: Scattered small petechiae, no mass effect, hi2: Confluent petechiae, no mass effect, ph1: Hematoma within infarcted tissue, occupying <30%, no substantive mass effect, ph2: Hematoma occupying 30% or more of the infarcted tissue, with obvious mass effect, 3a: Parenchymal hematoma remote from infarcted brain tissue, 3b: Intraventricular hemorrhage, 3c: Subarachnoid hemorrhage, 3d: Subdural hemorrhage)

aspects1: Alberta stroke program early CT score of anterior circulation on CTscan

aspect2: Alberta stroke program early CT score of anterior circulation on DWI- Diffusion-weighted Imaging.

aspects3: Alberta stroke program early CT score of posterior circulation on CTscan

aspects4: Alberta stroke program early CT score of posterior circulation on DWI- Diffusion-weighted Imaging.

nihss2: National Institute of Health Stroke Scale before intervention

grady: Grady coma scale before intervention

rtpa: Use alteplase (0: No, 1: Yes)

thromb: Thrombectomy (0: No, 1: Yes)

crani: Craniectomy (0: No, 1: Yes).

coil: Endovascular coiling (0: No, 1: Yes)

mode: Ventilation mode

mv: Mechanical ventilation (L/min)

fio2: Fraction of inspired oxygen (%)

peep: Positive end-expiratory pressure (cmH2O)

sc: Static compliance (mL/cmH2O)

alv: Pulmonary consolidation (0: No, 1: ¼ lung, 2: ½ lung, 3: ¾ lung, 4: Complete lung)

sf: spo2/fio2 ratio.

p13a: Number of pulse beats at time -13 (conventional mechanical ventilation stage)

s13a: Systolic blood pressure at time -13 (conventional mechanical ventilation stage)

d13a: Diastolic blood pressure at time -13 (conventional mechanical ventilation stage)

sp13a: SpO2 at time -13 (conventional mechanical ventilation stage)

e13a: EtCO2 at time -13 (conventional mechanical ventilation stage)

p12a: Number of pulse beats at time -12 (conventional mechanical ventilation stage)

s12a: Systolic blood pressure at time -12 (conventional mechanical ventilation stage)

d12a: Diastolic blood pressure at time -12 (conventional mechanical ventilation stage)

sp12a: SpO2 at time -12 (conventional mechanical ventilation stage)

e12a: EtCO2 at time -12 (conventional mechanical ventilation stage)

p11a: Number of pulse beats at time -11 (conventional mechanical ventilation stage)

s11a: Systolic blood pressure at time -11 (conventional mechanical ventilation stage)

d11a: Diastolic blood pressure at time -11 (conventional mechanical ventilation stage)

sp11a: SpO2 at time -11 (conventional mechanical ventilation stage)

e11a: EtCO2 at time -11 (conventional mechanical ventilation stage)

p10a: Number of pulse beats at time -10 (conventional mechanical ventilation stage)

s10a: Systolic blood pressure at time -10 (conventional mechanical ventilation stage)

d10a: Diastolic blood pressure at time -10 (conventional mechanical ventilation stage)

sp10a: SpO2 at time -10 (conventional mechanical ventilation stage)

e10a: EtCO2 at time -10 (conventional mechanical ventilation stage)

p9a: Number of pulse beats at time -9 (conventional mechanical ventilation stage)

s9a: Systolic blood pressure at time -9 (conventional mechanical ventilation stage)

d9a: Diastolic blood pressure at time -9 (conventional mechanical ventilation stage)

sp9a: SpO2 at time -9 (conventional mechanical ventilation stage)

e9a: EtCO2 at time -9 (conventional mechanical ventilation stage)

p8a: Number of pulse beats at time -8 (conventional mechanical ventilation stage)

s8a: Systolic blood pressure at time -8 (conventional mechanical ventilation stage)

d8a: Diastolic blood pressure at time -8 (conventional mechanical ventilation stage)

sp8a: SpO2 at time -8 (conventional mechanical ventilation stage)

e8a: EtCO2 at time -8 (conventional mechanical ventilation stage)

p7a: Number of pulse beats at time -7 (conventional mechanical ventilation stage)

s7a: Systolic blood pressure at time -7 (conventional mechanical ventilation stage)

d7a: Diastolic blood pressure at time -7 (conventional mechanical ventilation stage)

sp7a: SpO2 at time -7 (conventional mechanical ventilation stage)

e7a: EtCO2 at time -7 (conventional mechanical ventilation stage)

p6a: Number of pulse beats at time -6 (conventional mechanical ventilation stage)

s6a: Systolic blood pressure at time -6 (conventional mechanical ventilation stage)

d6a: Diastolic blood pressure at time -6 (conventional mechanical ventilation stage)

sp6a: SpO2 at time -6 (conventional mechanical ventilation stage)

e6a: EtCO2 at time -6 (conventional mechanical ventilation stage)

p5a: Number of pulse beats at time -5 (conventional mechanical ventilation stage)

s5a: Systolic blood pressure at time -5 (conventional mechanical ventilation stage)

d5a: Diastolic blood pressure at time -5 (conventional mechanical ventilation stage)

sp5a: SpO2 at time -5 (conventional mechanical ventilation stage)

e5a: EtCO2 at time -5 (conventional mechanical ventilation stage)

p4a: Number of pulse beats at time -4 (conventional mechanical ventilation stage)

s4a: Systolic blood pressure at time -4 (conventional mechanical ventilation stage)

d4a: Diastolic blood pressure at time -4 (conventional mechanical ventilation stage)

sp4a: SpO2 at time -4 (conventional mechanical ventilation stage)

e4a: EtCO2 at time -4 (conventional mechanical ventilation stage)

p3a: Number of pulse beats at time -3 (conventional mechanical ventilation stage)

s3a: Systolic blood pressure at time -3 (conventional mechanical ventilation stage)

d3a: Diastolic blood pressure at time -3 (conventional mechanical ventilation stage)

sp3a: SpO2 at time -3 (conventional mechanical ventilation stage)

e3a: EtCO2 at time -3 (conventional mechanical ventilation stage)

p2a: Number of pulse beats at time -2 (conventional mechanical ventilation stage)

s2a: Systolic blood pressure at time -2 (conventional mechanical ventilation stage)

d2a: Diastolic blood pressure at time -2 (conventional mechanical ventilation stage)

sp2a: SpO2 at time -2 (conventional mechanical ventilation stage)

e2a: EtCO2 at time -2 (conventional mechanical ventilation stage)

p1a: Number of pulse beats at time -1 (conventional mechanical ventilation stage)

s1a: Systolic blood pressure at time -1 (conventional mechanical ventilation stage)

d1a: Diastolic blood pressure at time -1 (conventional mechanical ventilation stage)

sp1a: SpO2 at time -1 (conventional mechanical ventilation stage)

e1a: EtCO2 at time -1 (conventional mechanical ventilation stage)

p0a: Number of pulse beats at time 0 (conventional mechanical ventilation stage)

s0a: Systolic blood pressure at time 0 (conventional mechanical ventilation stage)

d0a: Diastolic blood pressure at time 0 (conventional mechanical ventilation stage)

sp0a: SpO2 at time 0 (conventional mechanical ventilation stage)

e0a: EtCO2 at time 0 (conventional mechanical ventilation stage)

p1b: Number of pulse beats at time +1 (advanced Ambu bag system stage)

s1b: Systolic blood pressure at time +1 (advanced Ambu bag system stage)

d1b: Diastolic blood pressure at time +1 (advanced Ambu bag system stage)

sp1b: SpO2 at time +1 (advanced Ambu bag system stage)

e1b: EtCO2 at time +1 (advanced Ambu bag system stage)

p2b: Number of pulse beats at time +2 (advanced Ambu bag system stage)

s2b: Systolic blood pressure at time +2 (advanced Ambu bag system stage)

d2b: Diastolic blood pressure at time +2 (advanced Ambu bag system stage)

sp2b: SpO2 at time +2 (advanced Ambu bag system stage)

e2b: EtCO2 at time +2 (advanced Ambu bag system stage)

p3b: Number of pulse beats at time +3 (advanced Ambu bag system stage)

s3b: Systolic blood pressure at time +3 (advanced Ambu bag system stage)

d3b: Diastolic blood pressure at time +3 (advanced Ambu bag system stage)

sp3b: SpO2 at time +3 (advanced Ambu bag system stage)

e3b: EtCO2 at time +3 (advanced Ambu bag system stage)

p4b: Number of pulse beats at time +4 (advanced Ambu bag system stage)

s4b: Systolic blood pressure at time +4 (advanced Ambu bag system stage)

d4b: Diastolic blood pressure at time +4 (advanced Ambu bag system stage)

sp4b: SpO2 at time +4 (advanced Ambu bag system stage)

e4b: EtCO2 at time +4 (advanced Ambu bag system stage)

p5b: Number of pulse beats at time +5 (advanced Ambu bag system stage)

s5b: Systolic blood pressure at time +5 (advanced Ambu bag system stage)

d5b: Diastolic blood pressure at time +5 (advanced Ambu bag system stage)

sp5b: SpO2 at time +5 (advanced Ambu bag system stage)

e5b: EtCO2 at time +5 (advanced Ambu bag system stage)

p6b: Number of pulse beats at time +6 (advanced Ambu bag system stage)

s6b: Systolic blood pressure at time +6 (advanced Ambu bag system stage)

d6b: Diastolic blood pressure at time +6 (advanced Ambu bag system stage)

sp6b: SpO2 at time +6 (advanced Ambu bag system stage)

e6b: EtCO2 at time +6 (advanced Ambu bag system stage)

p7b: Number of pulse beats at time +7 (advanced Ambu bag system stage)

s7b: Systolic blood pressure at time +7 (advanced Ambu bag system stage)

d7b: Diastolic blood pressure at time +7 (advanced Ambu bag system stage)

sp7b: SpO2 at time +7 (advanced Ambu bag system stage)

e7b: EtCO2 at time +7 (advanced Ambu bag system stage)

p8b: Number of pulse beats at time +8 (advanced Ambu bag system stage)

s8b: Systolic blood pressure at time +8 (advanced Ambu bag system stage)

d8b: Diastolic blood pressure at time +8 (advanced Ambu bag system stage)

sp8b: SpO2 at time +8 (advanced Ambu bag system stage)

e8b: EtCO2 at time +8 (advanced Ambu bag system stage)

p9b: Number of pulse beats at time +9 (advanced Ambu bag system stage)

s9b: Systolic blood pressure at time +9 (advanced Ambu bag system stage)

d9b: Diastolic blood pressure at time +9 (advanced Ambu bag system stage)

sp9b: SpO2 at time +9 (advanced Ambu bag system stage)

e9b: EtCO2 at time +9 (advanced Ambu bag system stage)

p10b: Number of pulse beats at time +10 (advanced Ambu bag system stage)

s10b: Systolic blood pressure at time +10 (advanced Ambu bag system stage)

d10b: Diastolic blood pressure at time +10 (advanced Ambu bag system stage)

sp10b: SpO2 at time +10 (advanced Ambu bag system stage)

e10b: EtCO2 at time +10 (advanced Ambu bag system stage)

p11b: Number of pulse beats at time +11 (advanced Ambu bag system stage)

s11b: Systolic blood pressure at time +11 (advanced Ambu bag system stage)

d11b: Diastolic blood pressure at time +11 (advanced Ambu bag system stage)

sp11b: SpO2 at time +11 (advanced Ambu bag system stage)

e11b: EtCO2 at time +11 (advanced Ambu bag system stage)

p12b: Number of pulse beats at time +12 (advanced Ambu bag system stage)

s12b: Systolic blood pressure at time +12 (advanced Ambu bag system stage)

d12b: Diastolic blood pressure at time +12 (advanced Ambu bag system stage)

sp12b: SpO2 at time +12 (advanced Ambu bag system stage)

e12b: EtCO2 at time +12 (advanced Ambu bag system stage)

p13b: Number of pulse beats at time +13 (advanced Ambu bag system stage)

s13b: Systolic blood pressure at time +13 (advanced Ambu bag system stage)

d13b: Diastolic blood pressure at time +13 (advanced Ambu bag system stage)

sp13b: SpO2 at time +13 (advanced Ambu bag system stage)

e13b: EtCO2 at time +13 (advanced Ambu bag system stage)

p14b: Number of pulse beats at time +14 (advanced Ambu bag system stage)

s14b: Systolic blood pressure at time +14 (advanced Ambu bag system stage)

d14b: Diastolic blood pressure at time +14 (advanced Ambu bag system stage)

sp14b: SpO2 at time +14 (advanced Ambu bag system stage)

e14b: EtCO2 at time +14 (advanced Ambu bag system stage)