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H Proquitté

Publications and source records attributed to H Proquitté.

6 recordsLinked to original sources
PubMed2006

The effect of changing ventilator settings on indices of ventilation inhomogeneity in small ventilated lungs.

BACKGROUND: In ventilated newborns the use of multiple breath washout (MBW) techniques for measuring both lung volume and ventilation inhomogeneity (VI) is hampered by the comparatively high dead space fraction. We studied how changes in ventilator settings affected VI indices in this particular population. METHODS: Using a computer simulation of a uniformly ventilated volume the interaction between VI indices (lung clearance index (LCI), moment ratios (M1/M0, M2/M0, AMDN1, AMDN2) of the washout curve) and tidal volume (VT), dead space (VD) and functional residual capacity (FRC) were calculated. The theoretical results were compared with measurements in 15 ventilated piglets (age <12 h, median weight 1135 g) by increasing the peak inspiratory pressure (PIP). FRC and VI indices were measured by MBW using 0.8% heptafluoropropane as tracer gas. RESULTS: The computer simulation showed that the sensitivity of most VI indices to changes in VD/VT and VT/FRC increase, in particular for VD/VT > 0.5. In piglets, the raised PIP caused a significant increase of VT from 15.4 +/- 9.5 to 21.9 +/- 14.7 (p = 0.003) and of the FRC from 31.6 +/- 14.7 mL to 35.0 +/- 15.9 mL (p = 0.006), whereas LCI (9.15 +/- 0.75 to 8.55 +/- 0.74, p = 0.019) and the moment ratios M1/M0, M2/M0 (p < 0.02) decreased significantly. No significant changes were seen in AMDN1 and AMDN2. The within-subject variability of the VI indices (coefficient of variation in brackets) was distinctly higher (LCI (9.8%), M1/M0 (6.6%), M2/M0 (14.6%), AMDN1 (9.1%), AMDN2 (16.3%)) compared to FRC measurements (5.6%). Computer simulations showed that significant changes in VI indices were exclusively caused by changes in VT and FRC and not by an improvement of the homogeneity of alveolar ventilation. CONCLUSION: In small ventilated lungs with a high dead space fraction, indices of VI may be misinterpreted if the changes in ventilator settings are not considered. Computer simulations can help to prevent this misinterpretation.

Animals↗
PubMed2003

Breathing gas perfluorocarbon measurements using an absorber filled with zeolites.

BACKGROUND: Perfluorocarbon (PFC) has been widely used in the treatment of respiratory diseases; however, PFC content of the breathing gases remains unknown. Therefore, we developed an absorber using PFC selective zeolites for PFC measurement in gases and investigated its accuracy. METHODS: To generate a breathing gas with different PFC contents a heated flask was rinsed with a constant air flow of 4 litre x min(-1) and 1, 5, 10, and 20 ml of PFC were infused over 20 min using an infusor. The absorber was placed on an electronic scale and the total PFC volume was calculated from the weight gain. RESULTS: Steady-state increase in weight was achieved 3.5 min after stopping the infusion. The calculated PFC volume was slightly underestimated but the measuring error did not exceed -1% for PFC less than 1 ml. The measurement error decreased with increasing PFC volume. CONCLUSIONS: This zeolite absorber is an accurate method to quantitatively determine PFC in breathing gases and can be used as a reference method to validate other PFC sensors.

Absorption↗
PubMed2001

Deadspace free ventilatory measurements in newborns during mechanical ventilation.

OBJECTIVE: To improve the accuracy of ventilatory measurements in ventilated newborns by means of a numerical correction when a deadspace free differential measuring method using two pneumotachographs (PNTs) is applied and to investigate the clinical usefulness of this correction procedure. DESIGN: In vitro study and prospective animal study. SETTING: Research laboratory of the Clinic of Neonatology and the Animal Research Laboratory, Charité Hospital Berlin. SUBJECTS: Ten newborn piglets, weighing 610-1340 g (median, 930 g), age <12 hrs. INTERVENTIONS: The accuracy of both the deadspace free method and the endotracheal flow measurements (conventional method) was investigated using mechanical lung models. A correction procedure for the deadspace free method was developed considering signal delay time and tube compliance between both PNTs. This method was applied to the piglets measured during partial liquid ventilation (PLV). Measurements were done before and after lung lavage and during 30 and 120 mins of PLV (30 mL/kg body weight perfluorocarbon). MEASUREMENTS AND MAIN RESULTS: In vitro measurements showed volume differences between both methods of 8%, 12%, 16%, and 17%, respectively, depending on the distance between the PNTs of 10, 60, 120, and 180 cm. After applying the correction algorithm, the differences decreased to 3%, 0%, -2%, and -8%, respectively. The piglets were measured with 120-cm tube length between the PNTs. The correction algorithm reduced the measured tidal volume before lavage by 7%, after lavage by 14%, 30-min PLV by 12%, and 120-min PLV by 10%, corresponding to the changes in respiratory compliance of 1.2, 0.6, 1.0, and 1.1 mL/cm H2O. CONCLUSIONS: The deadspace free method can be advantageously used for continuous measurements in newborns despite much higher technical expense. The correcting procedure improved the accuracy of the volume measurement remarkably, especially for lower respiratory compliance.

Algorithms↗
PubMed2000

Effect of lung water content, manipulated by intratracheal furosemide, surfactant, or a mixture of both, on compliance and viscoelastic tissue forces in lung-lavaged newborn piglets.

OBJECTIVE: To study the impact of lung water content and its reduction by a topically applied diuretic on respiratory and lung tissue mechanics in comparison with surfactant administration in surfactant-deficient newborn piglets with lavage-induced lung injury. DESIGN: Controlled, randomized study. SETTING: Animal research facility. SUBJECTS: Newborn piglets. TREATMENT Piglets were surfactant depleted by lung lavage and, after a pretreatment period, randomly treated with intratracheal furosemide, furosemide and surfactant, or with surfactant alone. MEASUREMENTS AND MAIN RESULTS: Dynamic compliance (C(DYN)), static compliance (C(ST)), stress-adaptation pressures (P(DIFF)) and post mortem lung water content were determined. Static compliance in the furosemide-surfactant group was not significantly higher than in the surfactant group. At the end of the study, C(ST) did not differ between the three groups because C(ST) in the furosemide group had increased to values similar to those of the surfactant-containing treatment groups: C(ST) F+S: 0.73 +/- 0.2 mL/cm H2O/kg body weight (BW); C(ST) S: 0.61 +/- 0.11 mL/cm H2O/kg BW; and C(ST) F: 0.60 +/- 0.19 mL/cm H2O/kg BW). Compliance was inversely and P(DIFF) was directly correlated to lung water (LW) content (C(ST) vs. LW: r2 = .59, p = .001; C(DYN) vs. LW: r2 = .49, p = .006; P(DIFF) vs. LW: r2 = .37, p = .059), independent of the type of treatment. Changes in C(ST) and C(DYN) were inversely related to changes in P(DIFF). Intrapulmonary furosemide was more rapidly absorbed when administered to the surfactant-depleted lung alone compared with the mixture with surfactant, and intrapulmonary furosemide had a rapid systemic effect. CONCLUSION: Although the combination of surfactant with a diuretic failed to increase respiratory compliance to a significantly larger extent than surfactant alone, furosemide at the end of the study increased respiratory compliance to a level similar to surfactant-containing treatments. Lung water content and, to a lesser extent, the absence or presence of surfactant appeared to determine lung mechanics, and its impact on lung mechanics was similar to surfactant administration.

Animals↗
PubMedDate not supplied

[Case example: malignant infantile osteopetrosis--pathogenesis and therapeutic options].

Malignant infantile osteopetrosis is a rare disease but can be clinically unequivocally diagnosed. Normal bone formation in the presence of decreased bone breakdown leads to the typical symptoms. The only proven curative approach, bone marrow transplantation, can reverse most of the symptoms and prevent progression to irreversible nerve damage when done early in infancy. Therefore, early diagnosis is decisive. We present a case report of an infant with osteopetrosis and discuss pathogenesis and therapeutical options.

Bone Marrow Transplantation↗