This study presents a methodology for applying the forced-oscillation technique in total liquid ventilation. It mainly consists of applying sinusoidal volumetric excitation to the respiratory system, and determining the transfer function between the delivered flow rate and resulting airway pressure. The investigated frequency range was f ∈ [0.05, 4] Hz at a constant flow amplitude of 7.5 mL/s. The five parameters of a fractional order lung model, the existing "5-parameter constant-phase model," were identified based on measured impedance spectra. The identification method was validated in silico on computer-generated datasets and the overall process was validated in vitro on a simplified single-compartment mechanical lung model. In vivo data on ten newborn lambs suggested the appropriateness of a fractional-order compliance term to the mechanical impedance to describe the low-frequency behavior of the lung, but did not demonstrate the relevance of a fractional-order inertance term. Typical respiratory system frequency response is presented together with statistical data of the measured in vivo impedance model parameters. This information will be useful for both the design of a robust pressure controller for total liquid ventilators and the monitoring of the patient's respiratory parameters during total liquid ventilation treatment.
The accuracy of the Radiometer OSM3 oxymeter for measurement of fetal haemoglobin (HbF) in infants was investigated, and compared to one of the standard reference methods using alkali electrophoresis of haemoglobin. Blood samples of 37 infants with different gestational (27-41 weeks) and postnatal (1-198 days) ages were analysed. The two methods gave very close results but a significant mean difference (range -4.5-16.5%). However, agreement between the two methods was judged clinically acceptable (95% limits of agreement -7.5-15.5%). A rapid determination of HbF percentage, using OSM3, is an important determinant for correct assessment of oxygen saturation in newborn infants in intensive care units.
Total liquid ventilation is an innovative experimental method of mechanical assisted ventilation in which lungs are totally filled and then ventilated with a tidal volume of perfluorochemical liquid (PFC) by using a dedicated liquid ventilator. The positive end-inspiratory and end-expiratory pressures (PEIP and PEEP) are static pressure measurements that are critic to the safe and efficient control of the ventilation. However, their measurement is impeded by large oscillations of pressure caused by the propagation of pressure waves along the flexible tubes carrying the PFC to the patient. The aim of this paper is to describe a method to accurately estimate the PEEP and the PEIP from noisy data hindered by flexible tubing resonance during short respiratory pauses. The method developped makes use of the least squares technique to estimate the steady state pressure. Preliminary in vivo validation of the algorithm shows that the method gives accurate estimations with respiratory pauses as short as 0.3 second. I. INTRODUCTIONIn the last decade, a vast array of preclinical studies have shown the efficacy and safety of total liquid ventilation (TLV) in pediatric and adult animal models [1]. In TLV, the lungs are totally filled with a breathable perfluorocarbon (PFC) liquid and then ventilated with a tidal volume of PFC controlled by a dedicated liquid ventilator [2]. TLV offers many advantages over conventional mechanical ventilation (CMV). By eliminating the air-liquid interface, it allows the recruitment of collapsed lung regions ensuring more homogeneous alveolar ventilation [1], an efficient lung lavaging effect [3] and the capability to induce ultra-fast mild therapeutic hypothermia [4].The liquid ventilator Inolivent-5 ( Figure 1) includes different control modes found on conventional ventilators [5], [6]. The use of a volume controlled ventilation during inspiration and of a pressure controlled ventilation during expiration to avoid airway collapsus [7] greatly improves the efficiency and the safety of the ventilator for clinical use [8]. The positive end-inspiratory pressure (PEIP) and the positive endexpiratory pressure (PEEP) are critical parameters for the control of the ventilation. They are static pressure measurements reflecting the alveolar pressure and are related to the endinspiratory (EI) and end-expiratory (EE) lung volume. Usually,
The diagnosis of hyperimmunoglobulinemia E (hyper IgE) or Job’s syndrome was made in a five-month-old girl with chronic staphylococcal mastitis, elevated serum IgE and abnormal neutrophil chemotaxis. After multiple hospitalizations for severe skin in functions, right upper lobe bullae were found and treated by lobectomy when the patient was three years of age. Thereafter, the patient was repeatedly hospitalized for pneumonia while on cloxacillin prophylaxis and receiving regular chest physiotherapy. When she was 12 years old, pulmonary deterioration (increased frequency of pulmonary infections, hemoptysis, radiological destruction or the right middle lobe) led 10 a right middle lobectomy. Since this intervention, the patient has had an improved quality nf life, takes part in regular sports activities, without recurrence of severe pulmonary infections, and has had near normal pulmonary function studies. A concerted medicosurgical therapeutic regimen can control severe pulmonary complications in patients with this rare syndrome.
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