Non-invasive positive pressure ventilation versus invasive pressure support ventilation for post extubation respiratory distress in patients recovered from respiratory failure

Respiratory failure after a planned extubation is reported to be a common event, leading to reintubation and can occur in as many as 3-20% of extubated patients. It is crucial to identify the right time to extubate a patient, since re-intubation after pre-term extubation is associated with an increased risk for nosocomial pneumonia, prolonged intensive care unit [ICU] stay and death, and also accounts for substantially increased costs. This study was planned to assess the effectiveness of non-invasive pressure support ventilation [NIPPV] as a weaning technique in patients who develop respiratory distress after discontinuation of mechanical ventilation and extubation in comparison with conventional weaning through invasive pressure support ventilation. This is a randomized controlled study, sixty patients with either type I or II respiratory failure who developed post extubation respiratory failure were enrolled; they were randomly divided into two groups to receive either NIPPV or invasive pressure support ventilation. The primary outcome measure was the technique outcone; secondary outcome measures were incidence of complications, hemodynamic parameters, arterial blood gas parameters, ventilator parameters and length of ICU stay. Despite a longer time to failure observed with invasive pressure support ventilation, no statistically significant differences were observed in success rate, hemodynamic, and arterial blood gas parameters, although incidence of complications differs greatly according to the technique used. In a heterogonous group of patients; NIPPV is not superior to invasive pressure support ventilation in patients who developed post-extubation respiratory distress after successful weaning

Mechanical ventilation with traditional large tidal volume versus lower tidal volune in patients with acute lung injury: pulmonary and hemodynamic study

This study was carried out in the ICU of Assuit University Hospital. A total of 30 patients who fulfilled the criteria of acute lung injury [AL1] and ARDS with lung injury score of 2.5 were enrolled in the study. The patients were randomly classified into 2 groups namely traditional tidal volume group which was managed with TV of 10- 12 ml/kg, and lower tidal volume group which was managed with TV of 6 ml/kg. The patients were mechanically ventilated using SIMV mode. In the traditional group of patients, the plateau pressure was kept >/= 40 cm H2O, respiratory rate was adjusted to maintain PaCO2 of 35-45 mmHg. PEEP level was >/= 5cmH2O. in the lower tidal volume group, the PaCO2 was allowed to increase [permissive hypercarbia], unless the pH was severely affected 7.2, to allow lowering of the plateau pressure to 25-30 cmH2O. PEEP was used according to the calculation of optimal PEEP. In both groups of patients, the FiO2 was adjusted to maintain PaO2 60 mmHg, and arterial oxygen saturation >/= 90%. Traditional or protective mechanical ventilation was maintained until the patient was extubated or died. The following parameters were studied for 17 days including: hemodynamics [HR. MAP, CVP, MPAP, PCWP, and CI], arterial blood gases and oxygenation parameters [pH, PaCO2, HCO3, PaO2, PvO2, QS/QT, PaO2/Fi02]; lung mechanics [PP, PIP, CST]. The present results demonstrated that the mean value of HR was mildly decreased in the traditional tidal volume group while it was increased in the lower tidal volume group throughout all days of the study. An initial decrease in MAP, which was followed by an increase, was found in the traditional tidal e group. But lower tidal volume group demonstrated a continuous rise in MAP. Both groups of patients demonstrated an increase in CVP, MPAP and PCWP levels in most of investigated days especially in lower tidal volume group. Reasonable values of CI were observed in both groups. The mean value of PaCO2 was found to be increased in the lower tidal volume group in the early period of the study resulting in a lower PH. The greater rise in HCO3 found in later period resulting in methiogation of the increase in pH. In the conventional TV group of patients, the PH, PaCO2 and HCO3 were within its normal limits. The conventional tidal volume group revealed more elevation in PaO2 levels than lower tidal volume group in the earlier period of the study. Later on, the PaO2 levels in the lower tidal volume group were increased to greater levels than traditional tidal volume group. Similar effects were obtained concernbg PaO2/FiO2 levels in both groups. The shunt fraction was mildly improved in both studied groups especially in lower TV group, but still it did not achieve its normal levels. In both groups there was an increase in the levels of the PvO2 during most investigated days of mechanics ventilation Better respiratory mechanics were found in lower tidal volume group The plateau pressure was less, the peak inspiratory pressure was also less, and static compliance was greater in this group as compared with traditional tidal volume group. In conclusion, the consequences of application of this lung protective strategy resulted in modest effects regarding the investigated hemodynamics due to modest increments in PaCO2. Lower tidal volume group of patients demonstrated better oxygenation parameters and better improvement in lung mechanics. Further studies may be needed to investigate the combined use of other ventilatory strategies, for example: prone positioning in addition to the one applied in this work to obtain better results regarding the studied oxygenation

Protective ventilatory lung strategy and inflammatory mediators

After approval by the local ethics committee and informed consent was obtained from each patient or the patient's relatives a 24 patients who were intubated and receiving mechanical ventilation [SIMV mode] and who fulfilled the criteria of ALI and ARDS with lung injury score /= 60 mmHg and SaO[2] >/= 90%], Bronchoalveolar lavage [BAL] samples were taken at the first, fifth, tenth and seventeenth day of study. Samples were processed immediately for biochechemical studying in order to estimate the: total protein and the albumin content, Interleukin-6 [IL-6 Interleukin-8 [IL-8] and Tumor Necrosis Factor- alpha [TNF- alpha]: by an immunoenzymometric assay. The results of this study revealed that the BAL total proteins, albumin, IL-6, TNF- alpha were generally significantly lowered in the lower tidal volume group than the conventional tidal volume group of patients. Minimal rise in the IL-8 levels was found in lower tidal volume group, but this rise was statistically insignificant. On the contrary the conventional tidal volume group of patients demonstrated progressive significant increase in levels of IL-8. These laboratory findings may denote the presence of more intense inflammatory response initiated by the applied large tidal volume. Large tidal volume ventilatory strategy with its associated high airway pressure, through its effects on the healthy alveoli by over distending them, or through its effects on the inflammatory response by increasing the inflammatory process through the more stretch of the alveolar capillary membrane, it may lead to additional injury to the alveolar capillary membrane. On the contrary the lower tidal volume ventilatory stragegy may either did not add more injury to the alveolar capillary membrane, or it may gave the alveoli the adequate period for spontaneous resolution of the pathological process and so it may did not add more injurious mechanical stretch as indicated by less rise in the investigated cytokines in the bronchoalveolar lavage fluid. On the basis of these results, high priority should be given to preventing excessive lung stretch during institution of mechanical ventilation, and lower-tidal-volume strategy should be used in patients with acute lung injury and the acute respiratory distress syndrome