We investigated the early changes of respiratory mechanics in mechanically ventilated patients with acute respiratory failure (ARF): 8 patients after acute exacerbation of chronic airway obstruction (CAO), 8 patients with cardiogenic pulmonary edema (CPE), and 8 patients with adult respiratory distress syndrome (ARDS). The patients were studied within the first day from the onset of mechanical ventilation. Flow, changes in lung volume, and airway pressure were measured using the 900C Servo Ventilator. End-inspiratory and end-expiratory occlusions of the airway were performed to obtain respiratory compliance and resistance. We found that: (1) acute exacerbation of CAO was characterized by high respiratory resistance (reflecting in part time-constant inequalities within the lung) and severe pulmonary hyperinflation, with "intrinsic" PEEP (PEEPi) up to 22 cm H2O (mean [SD], 13.5 [6.7] cm H2O); (2) PEEPi, even if not high, was present in almost all patients with pulmonary edema, averaging 3.8 and 3.0 cm H2O in ARDS and CPE, respectively; (3) respiratory resistance was increased in patients with CPE and ARDS who had no history of airway disease; (4) patients with ARDS were characterized also by low compliance (mean [SD], 0.035 [0.005] L/cm H2O) and high resistance, the latter also reflecting a substantial component caused by time-constant inequalities; (5) in all 24 patients, static respiratory compliance (and its reciprocal, elastance) was significantly correlated with the pulmonary oxygenation index, i.e., the PaO2/PAO2 ratio. We conclude that early assessment of respiratory mechanics in mechanically ventilated patients with ARF can provide better understanding of the patients' conditions as well as guidelines for therapeutic approach and weaning attempts.
In ten mechanically ventilated patients, six with chronic obstructive pulmonary disease (COPD) and four with pulmonary edema, we have partitioned the total respiratory system mechanics into the lung (l) and chest wall (w) mechanics using the esophageal balloon technique together with the airway occlusion technique during constant-flow inflation (J. Appl. Physiol. 58: 1840-1848, 1985). Intrinsic positive end-expiratory pressure (PEEPi) was present in eight patients (range 1.1-9.8 cmH2O) and was due mainly to PEEPi,L (80%), with a minor contribution from PEEPi,w (20%), on the average. The increase in respiratory elastance and resistance was determined mainly by abnormalities in lung elastance and resistance. Chest wall elastance was slightly abnormal (7.3 +/- 2.2 cmH2O/l), and chest wall resistance contributed only 10%, on the average, to the total. The work performed by the ventilator to inflate the lung (WL) averaged 2.04 +/- 0.59 and 1.25 +/- 0.21 J/l in COPD and pulmonary edema patients, respectively, whereas Ww was approximately 0.4 J/l in both groups, i.e., close to normal values. We conclude that, in mechanically ventilated patients, abnormalities in total respiratory system mechanics essentially reflect alterations in lung mechanics. However, abnormalities in chest wall mechanics can be relevant in some COPD patients with a high degree of pulmonary hyperinflation.
Fulminant hepatic failure is a rare, but often fatal complication of acute viral hepatitis. This condition, in absence of orthotopic liver transplantation (OLTx) surgery, is associated with a high mortality rate, despite the improvement of general intensive care. Plasma-exchange (PEx) therapy has been long used to treat FHF, in particular by removing toxic substances and correcting the severe coagulopathy. In this study we describe our experience with PEx treatment of FHF, beginning in 1982. Seventy patients affected with FHF due to various causes (HBV=40; cryptogenic/non-A, non-E=15; Amanita phalloides=8; other=7) were treated with PEx (altogether 348 sessions). Overall survival rate, comprising patients undergoing OLTx, was 51%, a little higher than what we observed in patients (N=49) treated solely by PEx, i.e., 41%. The best outcome predictor was FHF aetiology, owing to the good survival rate in patients with Amanita phalloides intoxication and the very poor prognosis of patients suffering from cryptogenic/non-A, non-E FHF. Moreover, the marked increase in prothrombin time and alpha-fetoprotein levels after 48 hours from admission was associated with a good prognosis, whereas the patient's age and coma grade were not clearly predictive of survival. Additionally, lymphocyte subpopulation, resulting in a CD4/CD8 ratio lower than 1.0 along with CD8 activation with HLA-DR strong expression, were associated with a high rate of mortality and morbidity. Our data indicate that PEx therapy can improve survival in patients with sufficient residual capacity of liver regeneration. Moreover, the identification of certain prognostic factors may be useful for the rational planning of therapeutic strategy in FHF.
The abdominal compartment syndrome (ACS) is a clinical condition characterized by an increase of abdominal pressure which needs prompt i~ abdominal decompression. The surgery of large abdominal hernias can present similar problems with an increased abdominal pressure at peritoneal closure which needs a prosthetic tension-free abdominal closure to correct ~ the increased respiratory work-load. We undertook a study in order to com-~:i' il pare the respiratory mechanical work-load changes during the surgery of large abdominal incisional hernias and the ACS. We measured the static compliance of the entire respiratory system (Crs), and its components -lung (CL) and chest-wall (Ccw) -during the acute phase of increased abdominal pressure and after decompressive treatment. In ACS the baseline measurements i:~ of Crs, CL, Ccw were 0.034, 0.049 and o.115 L/cmH20 respectively; after decompression treatment we observed a great increase of Ccw (o.167 L/cmHzO) !~i whereas C1 remained the same (o.o49L/cmHzO); Crs varied from 0.034 to i I 0.038 L/cmH20. In the surgery of large laparoceles, the Crs changed from i~i:i 0.048 to 0.046 and the Ccw from o.15o to o.18o, with an unchanged C1. We .... conclude that the abdominal compartment syndrome is characterized by a i!~il well-defined alteration of respiratory work-load (decrease of chest-wall corn-:i~; pliance), and that from a mechanical point of view there is only a quantitative difference if compared to large ventral hernia repair. The decrease of chestwall compliance in the latter is less severe and statistically different ~!~ (p = o.oo~).~;
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