Search PubMed⌕ Search

Biomedical subjects

L Gattinoni

Publications and source records attributed to L Gattinoni.

At least 109 records · Page 6Linked to original sources
PubMed1985

Mean airway pressure vs. positive end-expiratory pressure during mechanical ventilation.

To investigate the effects of both positive end-expiratory pressure (PEEP) and mean airway pressure (Paw) on gas exchange, we used lung lavage to induce severe respiratory insufficiency in six lambs. The animals were then mechanically ventilated at constant tidal volume, respiratory rate, and inspired O2 fraction. PEEP levels were varied -5, +5 and +10 cm H2O around the pressure (Pflex) corresponding to a major change in slope of the inspiratory limb of the respiratory volume-pressure curve. In each animal the effects of the three PEEP levels were studied at two Paw levels, differing by 5 cm H2O. Increasing Paw significantly improved PaO2 and reduced venous admixture. A 5-cm H2O PEEP increase from +5 to +10 did not affect oxygenation; however, oxygenation was significantly better when PEEP was greater than Pflex. Both PaCO2 and anatomic dead space were higher at higher PEEP, and decreased with increasing Paw. Hence, Paw was a major determinant of oxygenation, although a PEEP greater than Pflex appeared necessary to optimize oxygenation at a constant Paw.

Analysis of Variance↗
PubMed1985

Studies of complement activation in ARDS patients treated by long-term extracorporeal CO2 removal.

To investigate the role of complement activation in the adult respiratory distress syndrome (ARDS) and in the complications of extracorporeal circulation (ECC), several parameters (CH50, C3 split products, C3a, C5a, PMN aggregating activity, carboxypeptidase activity) of the complement profiles of 23 ARDS patients were measured. Twenty patients were treated by long-term extracorporeal support. Before connection to ECC, marked leukocytosis (18,250 +/- 5,950) and significantly high plasma C3a levels (p less than 0.005) were observed. After connection, C3a levels increased further, up to values eight times higher than the basal ones. The WBC count transiently decreased to 41% of prebypass levels after 15 minutes of ECC. At the same time C3 split products appeared and PMN aggregating activity was shown in 52% of the patients. C5a levels remained normal during bypass, even in two samples in which PMN aggregating activity was detected. Later decreases in CH50 titers (p less than 0.001) and carboxypeptidase activity (p less than 0.005) were observed. Complement activation was no longer evident after the 24th hour of bypass. We conclude that there is a low-degree complement activation in ARDS, and ECC is a further strong stimulus for complement activation. This phenomenon appears, however, to be self-limited.

Adolescent↗
PubMed1984

The main determinants of nitrogen balance during total parenteral nutrition in critically ill injured patients.

Factors influencing nitrogen balance during total parenteral nutrition have been investigated in 34 critically ill injured patients studied during the first 6 days after trauma. Basal nitrogen balance was severely negative (-0.26 +/- 0.12 (SD) g X kg-1), but improved consistently during treatment. Nitrogen intake proved to be the major determinant of a positive, or less negative, nitrogen balance, only secondarily followed by total energy intake corrected to predicted basal energy expenditure, according to multiple regression analysis. The amount of non-protein calories and the non-protein calorie to nitrogen ratio appeared to have little significance on nitrogen balance, when corrected for the two former variables.

Adolescent↗
PubMed1984

The role of total static lung compliance in the management of severe ARDS unresponsive to conventional treatment.

A group of 36 patients with severe adult respiratory distress syndrome (ARDS) meeting previously established blood gas criteria (mortality rate 90%) became candidates for possible extracorporeal respiratory support [low frequency positive pressure ventilation with extracorporeal CO2 removal (LFPPV-ECCO2R)]. Before connecting the patients to bypass we first switched the patients from conventional mechanical ventilation with positive end expiratory pressure (PEEP) to pressure controlled inverted ratio ventilation (PC-IRV), and then when feasible, to spontaneous breathing with continuous positive airways pressure (CPAP). Forty eight hours after the patients had entered the treatment protocol, only 19 out of the 36 patients in fact required LFPPV-ECCO2R, while 5 were still on PC-IRV, and 12 were on CPAP. The overall mortality rate of the entire population was 23%. The only predictive value of success or failure of a particular treatment mode was total static lung compliance (TSLC). No patients with a TSLC lower than 25 ml (cm H2O)-1 tolerated either PC-IRV or CPAP, while all patients with a TSLC higher than 30 ml (cm H2O)-1 were successfully treated with CPAP. Borderline patients (TSLC between 25 and 30 ml (cm H2O)-1) had to be treated with PC-IRV for more than 48 h, or were then placed on LFPPV-ECCO2R if Paco2 rose prohibitively. We conclude that TSLC is a most useful measurement in deciding on the best management of patients with severe ARDS, unresponsive to conventional treatment.

Adolescent↗
PubMed1983

Venous admixture (Qva/Q) and true shunt (Qs/Qt) in ARF patients: effects of PEEP at constant FIO2.

Venous admixture (Qva/Q) in ARF patients is due to both true right to left shunt (Qs/Qt: perfusion of truly unventilated areas) and to maldistribution [Qva-Qs)/Qt: effects of unevenness of ventilation/perfusion ratio). Using the retention rate of sulphur hexafluoride we determined the effects of PEEP on Qs/Qt and (Qva-Qs)/Qt at a constant FIO2 for each patient (0.57 +/- 0.19 SD, range 0.4-0.95). Eleven patients with ARF (treated either by CPPV or CPAP) were studied on 16 occasions. Each measurement was repeated at two levels of PEEP, 5 cm H2O below and 5 cm H2O above the patient's clinically determined PEEP level. The increase in PEEP resulted in: - a decrease in Qva/Q (from 0.37 +/- 0.13 to 0.27 +/- 0.12, p less than 0.01); - a parallel decrease in Qs/Qt (from 0.29 +/- 0.16 to 0.22 +/- 0.14, p less than 0.01); there was a positive correlation between Qva/Q and Qs/Qt changes (r = 0.53, p less than 0.05). No significant variation was demonstrated in (Qva-Qs)/Qt (from 0.074 +/- 0.045 to 0.054 +/- 0.048). On the other hand there was a negative correlation between the fraction of Qva/Q due to the maldistribution and FIO2: (Qva-Qs)/Qva = 0.75-0.86 FIO2 (r = 0.74, p less than 0.01). We conclude that: PEEP decreased Qva/Q mainly through changes in Qs/Qt but did not have a definite effect on (Qva-Qs)/Qt. Maldistribution was responsible for a significant portion of Qva/Q in those ARF patients tolerating a relatively low FIO2 (0.4-0.6).

Acute Disease↗
PubMed1982

Protein sparing and protein replacement in acutely injured patients during TPN with and without amino acid supply.

The metabolic effects of TPN were studied in a selected group of trauma patients. Nineteen patients were randomly divided into two groups: the first was treated with glucose and insulin, the second with glucose, insulin and amino acids. Each patient in both groups received TPN isocaloric with respect to daily energy output and the treatment lasted five days. Each group was further divided into two subsets (severe or moderate catabolism) according to fasting energy output with respect to the expected energy expenditure. During the acute flow phase, both in moderate as well as in severe catabolism, glucose and insulin were effective for protein sparing; the maximum protein sparing effect was reached when giving a caloric intake equal to 130% of daily energy output. Glucose, insulin and amino acids were effective in replacement of nitrogen losses. In moderately catabolic patients nitrogen balance was significantly better than in severely catabolic patients. This study shows that early and short-term TPN is effective in controlling the flow phase of trauma. Glucose and insulin appear to be the determinants of the protein sparing effect when given in amounts equal to those needed; amino acids provided protein replacement when given in amounts equal to about 20% of energy output. Energy supply higher than 120-130% of daily energy output does not increase protein sparing and protein replacement, the only effect being a further increase in metabolism, which is possibly dangerous in critically ill patients.

Adolescent↗
PubMed1982

Simple estimate of the true right to left shunt (Qs/Qt) at maintenance F1O2 by sulphur hexafluoride retention.

Differentiating Qs/Qt over Qva/Q (as measured by the standard O2 content formula) appears to be of great interest in applying and evaluating different therapeutic approaches. The estimation of Qs/Qt by 100% O2 breathing may alter "per se" the lung condition and is unsatisfactory. We used Sulphur Hexafluoride (SF6; lambda = 6.10(-3) ml ml-1 760 mmHg-1) to identify the true shunt (VA/Q less than 0.05) at maintenance F1O2. A simple and rapid determination of SF6 retention is performed by ECD gas chromatography from contemporaneous arterial and mixed venous blood samples, taken during i.v. infusion of an SF6 containing solution. QS/Qt estimate is then given by the ratio: PaSF6/PvSF6. It is not necessary to know the absolute gas partial pressures or concentration, hence absolute gas calibrations are not required. This method is suggested as feasible and satisfactory for clinical use, allowing the determination of QS/Qt at the maintenance F1O2.

Fluorides↗
PubMed1981

Effect of PGI2 infusion during long term extracorporeal circulation with membrane lung in sheep.

PGI2 plus very low dose of heparin was infused in 6 lambs connected for long term extracorporeal circulation with a membrane lung. Hemodynamic and hemostasis parameters were compared to those of a control group treated only with standard doses of heparin. PGI2 efficacy in inhibiting platelet aggregation and platelet fall was confirmed. A small platelet release, measured as antiheparin activity, was observed during all the by-pass, but did not influence platelet capacity of recovering when PGI2 effect dissolved. Heparin needed resulted less than a quarter of the quantity used for the control group. In our experimental conditions the hemodynamic changes were mainly limited to a decrease in diastolic blood pressure.

Animals↗