Tracheostomy in the intensive care unit. Part 2: Complications

Errors in tracheal pressure recording in patients with a tracheostomy tube--a model study

The recording of intratracheal pressure in patients breathing through a tracheostomy tube is marred by methodological problems. In model experiments it has been shown that the introduction of a recording catheter into the tracheostomy tube alters the recorded pressure by as much as 20-40%. To avoid such inaccuracy, a specially designed tracheostomy tube is proposed with an externally placed channel for introduction of the recording catheter. In in vivo measurements, recordings can be made at a distance of up to about 20 mm below the end of tube. Pressure recordings from this part of a model trachea are compared with results obtained from a reference pressure port 100 mm below the tube ending. The results show that it is possible to record expiratory pressure with good accuracy but that inspiratory pressure is still overestimated by 9-16%.

Clinical predictors of prolonged translaryngeal intubation in patients with the adult respiratory distress syndrome

This study was designed to determine if clinical features apparent after seven days of mechanical ventilation predict long-term intubation beyond 14 days and subsequent need for tracheotomy in patients with ARDS. Twenty-four patients were entered into the study. Group 1 patients were successfully extubated in less than or equal to 14 days after onset of ARDS and group 2 patients remained intubated greater than 14 days. On day 7 of ARDS, group 1 had a higher PaO2/PAO2 ratio, a lower PEEP requirement, less severe chest radiographic abnormalities and a greater likelihood of an improved radiograph from the baseline study. None of group 1 and 11 group 2 patients eventually underwent tracheotomy. Clinical features apparent after seven days of mechanical ventilation in patients with ARDS suggest the likelihood of prolonged intubation beyond 14 days and eventual tracheotomy. Recognition of these features may allow more timely conversion of endotracheal intubation to tracheotomy.

Ventilatory muscle support in respiratory failure with nasal positive pressure ventilation

Long-term intermittent mechanical ventilation results in improvements in ventilatory performance and clinical status between ventilation sessions in patients with chronic respiratory failure. The application of intermittent positive pressure ventilation through a nasal mask (NPPV) is a simple, noninvasive method for the provision of chronic intermittent ventilatory support. We investigated the effects of NPPV on inspiratory muscle activity in three normal subjects and nine patients with acute or chronic ventilatory failure due to restrictive (four subjects) or obstructive (five subjects) respiratory disorders. NPPV resulted in reductions of phasic diaphragm electromyogram amplitude to 6.7 +/- 0.7 percent (mean +/- SEM) of values obtained during spontaneous breathing in the normal subjects, 6.4 +/- 3.2 percent in the restrictive group, and 8.3 +/- 5.1 percent in the obstructive group. Simultaneous decreases in activity of accessory respiratory muscles were observed. The reductions in inspiratory muscle activity were confirmed by the finding of positive intrathoracic pressure swings on inspiration in all subjects. With NPPV, oxygen saturation and PCO2 remained stable or improved as compared with values obtained during spontaneous breathing. These results indicate that NPPV can noninvasively provide ventilatory support while reducing inspiratory muscle energy expenditure in acute and chronic respiratory failure of diverse etiology. Long-term assisted ventilation with NPPV may be useful in improving ventilatory performance by resting the inspiratory muscles.

Timing of tracheostomy in the critically ill patient

The decision for timing of tracheostomy remains controversial. The relative complication rates in two retrospective series, in which 79 and 150 critically ill patients were examined, respectively, showed increased incidence of late complications with tracheostomy and led Petty's group to conclude "The value of tracheotomy when an artificial airway is required for periods as long as 3 weeks is not supported by data obtained in this study."

Bedside percutaneous tracheostomy: experience with 55 elective procedures

Over a 24-month period, tracheostomy was performed in 55 patients using a percutaneous, wire-guided, dilatational technique. All such procedures were undertaken at the patient's bedside in the intensive care unit, with the patient under local anesthesia and mechanically ventilated through an oral endotracheal tube. A variety of wire-guides, dilators, and tracheal tubes were used as experience and proficiency were gained with the approach, and eventually, a simple modification of a standard low-pressure cuffed endotracheal tube was found to facilitate the procedure. The percutaneous method was found to be rapid and simple, to leave almost no cosmetic deformity, and to be almost totally free from infectious complications. This technique should be considered for routine use in critically ill, ventilator-dependent patients.

Assisting ventilation in respiratory failure by negative pressure ventilation and by rocking bed

The present study was undertaken to evaluate the effectiveness of acute ventilation by rocking bed (RB) and by negative-pressure ventilator (NPV) on arterial oxygenation and carbon dioxide tension in seven patients in whom respiratory failure (PaCO2 [+/- SD], 64 +/- 4 mm Hg; PaO2, 54 +/- 10 mm Hg) was consequent on nonobstructive ventilatory impairment. The increase in SaO2 (percent above baseline, 5 percent RB and 6 percent NPV) was similar for both methods, but a greater fall in PCO2 (percentage change in PCO2, 3 percent RB; 15 percent NPV; p less than 0.05) was observed during NPV. Diaphragmatic and accessory muscle electrical activity was markedly reduced during NPV but remained unchanged or increased on RB. Asynchronous breathing was frequently observed with RB but only rarely with NPV. These preliminary results suggest that effective mechanical ventilatory support could be achieved with either RB or NPV. However, their long-term effects as compared with those of positive-pressure ventilation remain to be explored.