Effects of regional perfusion block in healthy and injured lungs.

BACKGROUND: Severe hypoperfusion can cause lung damage. We studied the effects of regional perfusion block in normal lungs and in the lungs that had been conditioned by lavage with 500 ml saline and high V T (20 ml kg-1) ventilation. METHODS: Nineteen pigs (61.2 ± 2.5 kg) were randomized to five groups: controls (n = 3), the right lower lobe block alone (n = 3), lavage and high V T (n = 4), lung lavage, and high V T plus perfusion block of the right (n = 5) or left (n = 4) lower lobe. Gas exchange, respiratory mechanics, and hemodynamics were measured hourly. After an 8-h observation period, CT scans were obtained at 0 and 15 cmH2O airway pressure. RESULTS: Perfusion block did not damage healthy lungs. In conditioned lungs, the left perfusion block caused more edema in the contralateral lung (777 ± 62 g right lung vs 484 ± 204 g left; p < 0.05) than the right perfusion block did (581 ± 103 g right lung vs 484 ± 204 g left; p n.s.). The gas/tissue ratio, however, was similar (0.5 ± 0.3 and 0.8 ± 0.5; p n.s.). The lobes with perfusion block were not affected (gas/tissue ratio right 1.6 ± 0.9; left 1.7 ± 0.5, respectively). Pulmonary artery pressure, PaO2/FiO2, dead space, and lung mechanics were more markedly affected in animals with left perfusion block, while the gas/tissue ratios were similar in the non-occluded lobes. CONCLUSIONS: The right and left perfusion blocks caused the same "intensity" of edema in conditioned lungs. The total amount of edema in the two lungs differed because of differences in lung size. If capillary permeability is altered, increased blood flow may induce or increase edema.

Incidence of difficult intubation in intensive care patients: analysis of contributing factors.

Difficulties in endotracheal intubation increase morbidity and mortality in intensive care patients. We studied the problem in surgical intensive care patients with the aim of risk reduction. Patients intubated in the intensive care unit were evaluated. The intubations were performed or supervised by anaesthetists following the algorithm valid at the time of the study. Fifty percent of the 198 intubations were performed by specialist anaesthetists, 41.5% by anaesthesia trainees and 8.5% by surgical trainees. The initial attempt was by direct laryngoscopy (n=173), flexible fibrescope (n=8) or blind nasal technique (n=17). When direct laryngoscopy failed (n=7), intubation was accomplished with an intubating laryngeal mask airway (n=5), Frova stylet (n=1) or fibrescope (n=1). Thirty percent were rated as easy, 47% as moderately easy and 23% as difficult. Difficult intubations were associated with a higher incidence of anatomic anomalies, difficult bag-mask ventilation and severe oxygen desaturation. Every intubation in the ICU setting should be considered potentially difficult. The existing algorithm should be modified to incorporate the American Society of Anesthesiologists difficult airway algorithm adapted to the needs of the intensive care unit. A training program for alternative methods of airway management for difficult intubations should be established.