A Prospective Comparison of IMV and T-Piece Weaning from Mechanical Ventilation: Results

Two hundred (200) patients were initially enrolled in the study. The mean age was 53 years (range, 18 to 87) with 134 males and 66 females. Of the 200 patients, 133 were ventilated following surgery or trauma and 67 patients were ventilated for medical diseases (Table 2). There was no difference in age between patients in the IMV and T-piece groups. One hundred sixty-five (165) (82 percent) of the patients were maintained in the study until the weaning phase was initiated, and 155 of the 165 (93 percent) were weaned successfully by protocol. Of the 35 patients withdrawn from the study before the weaning phase was initiated, 20 were ventilated by AMV and 15 by IMV Twenty-four of the 35 (69 percent) patients were withdrawn from protocol because of attending physician preference; four patients were withdrawn because of procedural problems, four because of death, and three because of self-extubation. Twenty-seven of the 35 (77 percent) were surgical patients. In three patients withdrawn due to attending preference, the stabilization mode was changed from AMV to IMV because of respiratory alkalosis. However, in each instance, the change in ventilatory mode did not correct the alkalemia. All surgical patients were weaned on 5 cm HzO PEEP, while all medical patients were weaned on 0 PEEP.

Table 3 lists the variables that were analyzed in the three groups and in all 200 patients. Group C (three-day wean) was combined with group B (7-h wean) for statistical purposes since only five patients required an attempt on the three-day wean. There was no difference in total ventilation time (TVT) or weaning time (WT) between the IMV or T-piece groups comparing the total, 2-h weans or combined 7-h and three-day weans.
One hundred fifty-five (93 percent) of the 165 patients were weaned successfully by protocol (Table 4). One hundred thirty-six (136) of 155 (88 percent) weaned on the first attempt, while 19 (12 percent) patients required more than one trial to wean successfully. One hundred twenty-three (123) of the 155 (79 percent) successful weans by protocol were in patients who required less than 72 h of mechanical ventilation. Eighty-three (83) of 128 (65 percent) patients who weaned successfully in group A (mechanical ventilation <72 h) were surgical patients, while 27 of the 32 (84 percent) patients that were weaned in groups B (mechanical ventilation ^72 h) or C were medical patients. http://cheap-asthma-inhalers.com/

Ten patients did not wean by protocol; six were weaned by T-piece and four by IMV Two of the nine patients were extubated immediately despite unacceptable weaning parameters, and both required reintubation within 2 h. Four had acceptable weaning parameters and failed a 2-h wean (one hypercapnia, one tachypnea, one hypotension, and one hypoxemia); all were weaned successfully over the following 4 to 16 h on a higher FIo2 (0.5 to 0.6). The remaining three patients were weaned by IMV, although their initial weaning parameters had been unacceptable. Only one patient failed to wean after completing all steps of the protocol; he weighed 200 kg, had a history of asthma and sleep apnea syndrome, and was intubated with a 7.5-mm endotracheal tube. He developed acute hypercapnia during both weaning modes.
Of 160 patients who satisfied weaning criteria, 159 (99 percent) weaned either on the first trial (136), second trial (11), third trial (5), or three-day wean (3), or off protocol (4). Of the five of the 165 patients who did not satisfy weaning criteria, two failed and had to be reintubated and ventilated for several more days; while three patients weaned and were extubated by the attending physician. To summarize the weaning data: (1) 165 patients entered the weaning phase; (2) 160 satisfied weaning criteria; (3) 155 weaned by protocol; (4) 136 weaned on the first trial; (5) 19 weaned on sequential trials; and (6) ten did not wean by protocol.

Table 2—Indications for Mechanical Ventilation (n = 200)

Surgical (n = 133) Medical (n = 67)
CABG 73 Sepsis 24
Valve replacement 19 Cardiopulmonary arrest 14
Trauma/general surgery 17 Cerebrovascular accident 12
Neurosurgery 14 Pulmonary edema 10
Thoracic surgery 10 COPD 6
Near-drowning 1

Table 3— Tbtal Ventilation Time and Weaning Time in IMV and T-Piece Weaning

Total Group
(2-h) (7 h and 3-day)
IMV wean
No. of patients 98 83 15
Medical 39 27 12
Surgical 59 56 3
Age, yr 52.4 ± 1.5ft 52.7 ±1.8$ 52.3 ±4.7$
TVT, h 115.5 ±48.4$ 29.3 ±2.5$ 436.3 ± 284.4$
WT, h 5.3 ±1.2$ 2.8 ±0.2$ 15.9 ±5.9$
T-Piece wean
No. of patients 102 85 17
Medical 28 13 15
Surgical 74 72 2
Age, yr 54.7±1.5 55.2±2.0 51.0±3.6
TVT, h 67.4 ±9.9 34.2 ±5.5 204.5 ±31.6
WT, h 5.9±1.4 2.8±0.2 18.3 ±6.3

Table 4—Results cf’Weaning

Patients entered into weaning phase 165
Patients weaned successfully by protocol 155
On first trial (136)
On subsequent trial (19)
Patients not weaned by protocol 10
Failed initial 2 h wean (weaned on 2nd trial with Flo*) (4)
Wfeaned by IMV, initial weaning parameters did not satisfy protocol (3)
Extubated despite not satisfying weaning parameters; required reintubation by 2 h (2)
Failed to wean after completing all steps of protocol (1)


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