Wim P.J. Holland

Aerosol delivery from spacers in wheezy infants: a daily life study

The aims of this study were to assess and compare dose delivery and dose variability of pressurized metered dose inhalers (pMDI)/spacers in wheezy infants in daily life and to investigate factors influencing aerosol delivery. In an open randomized crossover study in 25 wheezy infants aged 5-26 months, a metal spacer (Nebuchamber), a detergent coated (DC) and a non-detergent coated (nonDC) plastic spacer (Babyhaler) were tested at home for 7 days each. Budesonide (200 microg b.i.d) was administered via a Nebuchamber or fluticasone (125 microg b.i.d) via a Babyhaler. Aerosol was trapped in filters, positioned between the spacer and face mask. Cooperation was scored on diary cards. Electrostatic charge (ESC) of the spacers was measured. Evaluations of the administration technique were made from video recordings. Median (range) dose delivery of the filters expressed as per cent (%) of nominal dose, was 34% (3-59), 23% (1-49), and 41% (12-55) for the Nebuchamber, nonDC-Babyhaler, and DC-Babyhaler respectively. Considerable dose variability was found, median (range) within-subject dose variability, expressed as coefficient of variation, for the Nebuchamber (49% (15-249)) was significantly higher when compared with both nonDC- (36% (12-325)) and DC-Babyhalers (27% (10-122)), for which dose variabilities were similar. Detergent coating was effective to reduce electrostatic charge, and to increase dose delivery, but had no effect on dose variability. Bad cooperation was an important cause for high dose variability for all spacers (r=0.5-0.6, p<0.02). Many mistakes were made during the administration procedure.

Measurement of sacroiliac joint stiffness in peripartum pelvic pain patients with Doppler imaging of vibrations (DIV)

OBJECTIVES The research question of the present study was: are sacroiliac joint stiffness levels of peripartum pelvic pain patients different from those of healthy subjects? STUDY DESIGN A cross-sectional comparative sacroiliac joint stiffness analysis of peripartum pelvic pain patients with healthy subjects. In previous studies we introduced a new technique, Doppler imaging of vibrations (DIV), to assess sacroiliac joint stiffness using colour Doppler imaging and vibrations. The measurements were performed on a group of peripartum pelvic pain patients (n=56) and on a control group (n=52). The differences in sacroiliac joint stiffness between the patient group and the control group were tested statistically by means of the Wilcoxons two sample test, the chi-square test and Students t-tests. RESULTS Both patients and controls displayed stiff as well as unstiff joints with no significant difference. There was a significant difference between the groups with regard to the relative difference of sacroiliac joint stiffness between left and right. CONCLUSIONS A diagnostic tool which can possibly be developed in the future could demonstrate an objective finding among women with peripartum pelvic pain. DIV is easy to apply and non-invasive. Asymmetric stiffness of the sacroiliac joints seems to be more directly related to low back pain and pelvic pain, not the stiffness level of a single sacroiliac joint.

The measurements of sacroiliac joint stiffness with colour Doppler imaging: a study on healthy subjects

RATIONALE AND OBJECTIVES Primary peripartum pelvic and low back pain is a common complaint of females. The etiologic relation between pain and pelvic stability has been shown in previous studies, but at present there is no objective clinical testing method to evaluate pelvic stability. METHODS In this study, a dynamic measurement method using sonoelasticity to assess the sacroiliac joint (SI) stiffness was tested in vivo in 14 healthy female volunteers. With the subjects in supine position vibrations were unilaterally applied to the anterior iliac spine. The vibrations were registered by a Colour Doppler Imaging (CDI) transducer over the ipsilateral SI joint. Since the threshold level of the apparatus has a direct relation with the power of the vibrations, the intensity of the vibrations (sonoelasticity) on the sacrum and ilium was measured indirectly in threshold units. The differences between the threshold values were accepted as the power loss of vibrations through the SI joint. One-way analysis of variance-test and T-test for paired samples were applied on the measurement results (P < 0.05). RESULTS Statistically, the results showed a satisfactory intraindividual reproducibility and inter-individual variability. There was no significant difference between the data derived from the left SI joint and right SI joint. CONCLUSIONS Based on the promising results on healthy female volunteers, this method will be specifically used in future studies on patients with peripartum pelvic pain.

Exhaled nitric oxide measurements with dynamic flow restriction in children aged 4-8 yrs

Fractional exhaled nitric oxide concentration (FEno) depends on exhalation flow; however, children often are unable to perform controlled flow procedures. Therefore, a device was developed for off-line FEno sampling, with dynamic flow restriction (DFR). The authors compared off-line with on-line FEno, assessed feasibility, and obtained normal values for FEno in children aged 4–8 yrs. Subjects inhaled nitric oxide (NO)-free air and exhaled into the device, where DFR kept exhalation flow constant at 50 mL·s−1. Dead space air was discarded. Exhaled air was collected in a 150 mL mylar balloon. On-line measurements were performed and values compared with off-line FEno in 19 adult volunteers. Seventy-nine children performed off-line sampling. All samples were analysed with a chemiluminescence NO-analyser. Normal values were obtained in 34 healthy children. There was an excellent correlation between on- and off-line values. Bland and Altman plots showed good agreement between on- and off-line FEno. Seventy-four out of 79 children were able to perform a correct off-line procedure. Geometric mean±sem FEno in healthy children was 4.9±1.2 parts per billion (ppb) for male children and 7.6±1.1 ppb for female children. It can be concluded that off-line fraction of exhaled nitric oxide measurements with dynamic flow restriction are feasible in young children and correspond to on-line values.

A novel method of evaluation of three heat-moisture exchangers in six different ventilator settings

Objective: The purpose of this study was to assess and compare the humidification, heating, and resistance properties of three commercially available heat-moisture exchangers (HMEs). To mimic clinical conditions, a previously validated, new, realistic experimental setup and measurement protocol was used.Design: Prospective, comparative experimental study.Setting: Surgical Intensive Care Unit, University Hospital of Rotterdam.Materials: An experimental set-up consisting of a patient model, measurement systems, and ventilator and three different HME types.Interventions: The air flow, pressure in the ventilation circuit, pressure difference over the HME, and partial water vapour pressure and temperature at each side of the HMEs were measured. Measurements were repeated every 30 min during the first 2 h and every hour up to 24 h for each HME at six different ventilator settings. The mean inspiratory and maximum expiratory resistance, flow-weighted mean absolute humidity and temperature outputs, and humidification and heating efficiencies of HMEs were calculated.Measurements and results: The Dar Hygroster had the highest humidity output, temperature output, humidification efficiency, and heating efficiency values throughout the study (32.8 ± 21. mg/l, 32.2 ± 0.8 °C, 86.3 ± 2.3 %, and 0.9 ± 0.01 %, respectively) in comparison to the Humid-Vent Filter (25.3 ± 3.2 mg/l, 31.9 ± 0.8 °C, 72.2 ± 5.3%, 0.9 ± 0.02 %, respectively) and the Pall Ultipor BB100 breathing circuit filter (23.4 ± 3 mg/l, 28.3 ± 0.7 °C, 68.8 ± 5.9 %, 0.8 ± 0.02 %, respectively). The inspiratory and expiratory resistance of the HMEs remained below clinically acceptable maximum values (2.60 ± 0.04 and 2.45 ± 0.05 cmH2O/l per s, respectively). Conclusion: The Dar Hygroster filter was found to have the highest humidity and temperature output of all three HMEs, the Humid-Vent filter had a satisfactory humidity output only at low tidal volume flow rate and minute volume settings, whereas the Pall Ultipore BB100 never achieved a sufficient humidity and temperature output.

THE USE OF COLOR DOPPLER IMAGING FOR THE ASSESSMENT OF SACROILIAC JOINT STIFFNESS: A STUDY ON EMBALMED HUMAN PELVISES

PURPOSE The validity and reproducibility of an instrumented dynamic examination method to measure sacroiliac (SI) joint stiffness was tested in vitro. METHODS Four embalmed human female pelvises were excitated by a pelvic vibrator. A color Doppler imaging (CDI) scanner was used to image the amplitude of vibrations at different sites of the pelvis. Vibrations were applied to the anterior superior iliac spines unilaterally and were received by CDI all over the ipsilateral SI region. Three different stability conditions were created in the SI joints: no intervention, screwed and ligaments cut. Test results were quantified by taking the minimum threshold levels of the bones. The relative difference of vibration intensity between ipsilateral ilium and sacrum at each stability condition is accepted as the stiffness level for the SI joint. RESULTS Statistics showed high reproducibility and significant differences between the stability conditions. Dynamic testing based on the use of vibrations provides visible and quantifiable intra- and inter-individual differences between SI joint stiffnesses. CONCLUSIONS This new method is objective and reproducible. Future in vivo application is promising since there are no technical and safety restrictions.

Measurement of tendon excursion velocity with colour Doppler imaging: a preliminary study on flexor pollicis longus muscle

PURPOSE To study the use of colour Doppler imaging (CDI) for the measurement of maximum and mean tendon velocity. Recent studies showed that CDI, normally used for blood flow examinations, can be used for the imaging of tendons at the hand and wrist region. Although other modalities are available for imaging of the muscle-skeletal system, in vivo measurements of the velocity of tendon excursion are not possible. METHODS The flexor pollicis longus (FPL) tendon of 16 healthy volunteers was measured bilaterally at two levels (wrist and thenar). A splint from the fingers along the proximal lower arm was applied. The thumb was fixed to the splint from the the first phalanx to allow flexion of the interphalangeal (IP) joint only. Pulsed CDI was used for the measurements. The maximum and mean velocities of the FPL tendon were measured at spectrum display mode during continuous voluntary contractions. At least 10 sequential Doppler peaks (cm/s) were recorded at every trial. The measurements were repeated three times. Paired t-test and correlation coefficients were calculated between levels on the same side and the opposite side. RESULTS No significant differences were found between two levels of the same hand and of the opposite hand. As expected, the data revealed variations in the inter-individual tendon velocities. CONCLUSIONS The velocity of the excursion of the FPL tendon can be measured with CDI with good reproducibility. It is expected that velocity measurements can be used in the future for the assessment of other tendons affected by various disorders.

Tendon excursion measurements with colour doppler imaging. A calibration study on an embalmed human specimen

We assessed the applicability of tendon excursion measurement by means of Colour Doppler Imaging (CDI) on human specimens, and also assessed the correlation between values measured by Doppler and by displacement meters. Muscles were separately connected to a mass of 1 kg with a steel wire running over a pulley. This weight moved the telescopic end of a digital displacement meter up and down during passive extension and flexion of the fingers. Excursion was measured with a pulsed multi-channel CDI scanner on the same arm. Assessment of finger tendon excursion with CDI correlated well with the mechanical micro displacement meter, the latter being considered the most accurate method in cadaver studies.

Laser speckle imaging identification of increases in cortical microcirculatory blood flow induced by motor activity during awake craniotomy

OBJECT The goal of awake neurosurgery is to maximize resection of brain lesions with minimal injury to functional brain areas. Laser speckle imaging (LSI) is a noninvasive macroscopic technique with high spatial and temporal resolution used to monitor changes in capillary perfusion. In this study, the authors hypothesized that LSI can be useful as a noncontact method of functional brain mapping during awake craniotomy for tumor removal. Such a modality would be an advance in this type of neurosurgery since current practice involves the application of invasive intraoperative single-point electrocortical (electrode) stimulation and measurements. METHODS After opening the dura mater, patients were woken up, and LSI was set up to image the exposed brain area. Patients were instructed to follow a rest-activation-rest protocol in which activation consisted of the hand-clenching motor task. Subsequently, exposed brain areas were mapped for functional motor areas by using standard electrocortical stimulation (ECS). Changes in the LSI signal were analyzed offline and compared with the results of ECS. RESULTS In functional motor areas of the hand mapped with ECS, cortical blood flow measured using LSI significantly increased from 2052 ± 818 AU to 2471 ± 675 AU during hand clenching, whereas capillary blood flow did not change in the control regions (areas mapped using ECS with no functional activity). CONCLUSIONS The main finding of this study was that changes in laser speckle perfusion as a measure of cortical microvascular blood flow when performing a motor task with the hand relate well to the ECS map. The authors have shown the feasibility of using LSI for direct visualization of cortical microcirculatory blood flow changes during neurosurgery.

Design and validation of an automatic metabolic monitor

A self-calibrating fully automatic instrument for the measurement of oxygen consumption, carbon dioxide production and the respiratory quotient of mechanically ventilated patients has been developed. The instrument is based on commercially available conventional oxygen and carbon dioxide gas analysers and a domestic natural gas volumetric flow meter. The distribution of the different gas flows, i.e. calibration gases, the inspiratory mixture sample and the expiratory mixture sample, are controlled by in inexpensive microprocessor, which also performs the necessary calculations. The accuracy of the instrument has been validated by bench tests. The present prototype has been in use for over 3000 h without major failures.