News about Medicine - Part 8

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

The majority of patients removed from protocol were weaned by IMV with a longer total ventilation time and weaning time. There was a significant difference in TVT between patients in the IMV and T-piece groups who were withdrawn from protocol because two patients (arbitrarily assigned to the IMV group) required longer stabilization, and the number of patients was small. In general, the patients on the medical service required longer mechanical ventilation (stabilization) because of preexisting lung disease and multiorgan system failure. Read the rest of this entry »

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

A Prospective Comparison of IMV and T-Piece Weaning from Mechanical Ventilation: DiscussionThis study showed that both medical and surgical patients assigned randomly to either an IMV or T-piece mode could be weaned from mechanical ventilation over the same period. Two-thirds of the patients who were weaned in 2 h were postsurgical patients who were ventilated for <72 h. The majority of these patients had undergone uncomplicated coronary artery bypass grafting (CABG) and usually were weaned as soon as they awoke from anesthesia. This represents a group of patients that usually present minimal problems in weaning from mechanical ventilation rapidly and may represent a bias to the hypothesis. Ideally, the use of a similar protocol with a large group of long-term ventilator patients might uncover differences in success between the two modes of weaning. Read the rest of this entry »

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 Of the 35 patients withdrawn from the study before the weaning phase was initiated, 20 were ventilated by AMV and 15 by IMV Twenty-four of the 35 (69 percent) patients were withdrawn from protocol because of attending physician preference; four patients were withdrawn because of procedural problems, four because of death, and three because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. Read the rest of this entry »

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

A Prospective Comparison of IMV and T-Piece Weaning from Mechanical Ventilation: Group AGroup A (Mechanical Ventilation <72 h): 2-H Wean
IMV: The IMV rate was progressively decreased over 2 h. This consisted of 30 minutes of an IMV rate of 6, 30 minutes of an IMV rate of 4, and 1 h of an IMV rate of 0. Blood gas levels were measured 30 minutes after each ventilator change, and the patient was changed to the next step in the protocol if clinically stable while blood gas results were pending.
T-Piece: A 30-minute T-piece trial was followed by 30 minutes on the original ventilator settings, and then with a 1-h T-piece trial (total, 2 h). At the end of each T-piece trial, a blood gas analysis was obtained. Read the rest of this entry »

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

Weaning parameters (spontaneous ventilatory measurements) were obtained by the respiratory therapist at the beginning of each 8-h shift. Acceptable weaning parameters included: (1) minute ventilation (Ve) <12 L/min, and two of the following four parameters: (2) maximum voluntary ventilation (MW) > two times Ve; (3) tidal volume (Vt) >5 ml/kg body weight; (4) forced vital capacity (FVC) >10 ml/kg body weight; and (5) negative inspiratory force (NIF) ^ — 20 cm HfO. When weaning parameters were satisfied, the patient was randomized immediately, according to hospital number, into either an IMV (even) or T-piece weaning mode (odd). The time from having acceptable weaning parameters to completion of a successful wean was recorded as weaning time (WT). Total ventilation time (TVT) was defined as the time from initiation of mechanical ventilation to completion of a successful wean. A successful wean was defined as discontinuation of mechanical ventilation for more than 48 h. The decision to extubate the patient was made by the attending physicians. Read the rest of this entry »

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

A Prospective Comparison of IMV and T-Piece Weaning from Mechanical VentilationSince the advent of positive pressure ventilation, various methods for elective withdrawal of ventilatory support (weaning) have been proposed. The introduction of intermittent mandatory ventilation (IMV) as a method of weaning has initiated a controversy concerning the optimum weaning mode. Several studies have examined the attributes of T-piece and IMV weaning with inconclusive results. Criticism of these studies has included machine variability in relation to the work of breathing, improper application of the two weaning methods, and the lack of a heterogeneous study population. We report the results of a prospective, randomized trial of medical and surgical patients who were weaned from mechanical ventilation by either T-piece or IMV. To test the hypothesis that patients satisfying specific ventilatory and gas transfer criteria can wean rapidly by either IMV or T-piece, a protocol was developed to ensure equal weaning time for all successful weaning attempts. Read the rest of this entry »

Timing of Tracheostomy in the Critically III Patient: Conclusions

To further examine the major determinants for tracheostomy in each of these 6 diagnostic subgroups, we looked at the relationships between the underlying diagnosis, the use of invasive monitoring, and the time during which mechanical ventilation was required (Table 5, Fig 1). In addition, we noted whether tracheostomy was discontinued at hospital dismissal or continued. Our bias led us to believe that the major positive determinants would be (1) time of needed intubation (>7-10 days) and (2) anticipation of future need for tracheostomy, whereas the major negative determinants would be (3) anticipation of imminent death (not wishing to add unnecessary charges to the patient bill), or (4) anticipa tion of imminent recovery and easy extubation. This is borne out by our findings. Read the rest of this entry »

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