Statistical considerations in the design and analysis of community intervention trials.

Community intervention trials are often characterized by the allocation of intact social units to different intervention groups. The assessment of adequate sample size for such trials must take into account the statistical dependencies among responses observed within an allocated unit. However, the small numbers of units typically involved in such trials imply that many methods of analysis that have been proposed for analyzing correlated data, particularly in the case of a dichotomous outcome variable, are not applicable to such designs.

Testing the homogeneity of kappa statistics.

Procedures are compared for testing the homogeneity of k > or = 2 independent kappa statistics in the case of two raters and a dichotomous outcome. One of the procedures is based on the estimated large sample variance derived under a model frequently adopted for inferences concerning interobserver agreement. The other is based on a goodness-of-fit approach to this model.

High frequency ventilation techniques in ARDS.

High frequency ventilation techniques are not applied as routine measures but are still regarded as lastditch efforts in treating patients with severe ARDS or with extensive bronchoplural fistula when conventional mechanical ventilation is not capable in providing sufficient gas exchange. High frequency ventilation techniques can be used in patients with septicemia or recent cerebral bleeding, which is a contraindication for ECMO, or in patients with increased ICP. We believe that high frequency ventilation techniques provide an important therapeutic tool in the treatment of pulmonary insufficiency since the hardware requirement is minimal and, after a brief explanation, the application is easy.

Application of SHFJV for surgical procedures.

Using SHFJV in combination with the jet laryngoscope it is possible to ventilate patients for laryngeal surgery with out the necessity for any kind of endotracheal tube or catheters. This technique can also safely be applied in patients with underlying pulmonary or cardiac disease or in obese patients. Patients with laryngeal stenosis can be ventilated from above the stenosis eliminating the danger of barotrauma.

[Superimposed high-frequency jet ventilation (SHFJV) in the administration of NO. Technical basis and early clinical results with ARDS].

The mortality of patients with acute respiratory distress syndrome (ARDS) is still above 50% despite continuous progress in intensive care medicine. Recent therapy regimens such as the extra corporeal life support (ECLS), permissive hypercarbia, high-frequency ventilation techniques and inhaled nitric oxide (NO) are being applied. All of the above techniques are aimed at different parts of the problems caused by ARDS.

Optimal intravenous dosing strategies for sedatives and analgesics in the intensive care unit.

Achieving and maintaining adequate levels of analgesia and sedation in critically ill patients is a fundamental part of ICU care. Understanding the clinical pharmacology of commonly used sedative agents (e.g.

[Flow pattern of respiratory gases in superimposed high-frequency jet ventilation (SHFJV) with the jet laryngoscope].

High-frequency ventilation techniques have been applied for a number of years for laryngeal surgery in order to ventilate patients without endotracheal tubes or catheters. A further development of high-frequency jet ventilation (HFJV) is the technique of superimposed HFJV (SHFJV), which was achieved by combining low- and high-frequency jet streams. Although good clinical results were observed, which have been published in the past, the clinical details of development of SHFJV have not been previously published.

[Behavior of cerebral blood flow velocity in conventional ventilation and superimposed high frequency jet ventilation].

Objective: Patients with increased intracranial pressure or vasospasm after subarachnoidal haemorrhage with decreased cerebral perfusion present a special problem on developing respiratory insufficiency, since kinetic therapy or extracorporal life support are contraindicated. Superimposed High Frequency Jet Ventilation (SHFJV) has been shown to be of benefit in ventilating patients with pulmonary insufficiency. The aim of this study was to evaluate if SHFJV could be safely applied in patients with critical cerebral blood flow; if so, SHFJV might be beneficial when pulmonary insufficiency occurs concomitantly.

Cluster randomization trials in tropical medicine: a case study.

Field trials in tropical medicine are often designed so that intact social units (e.g., families, schools, communities) rather than independent individuals are randomized to an intervention group.

[Preliminary experiences with superimpoposed high-frequence jet ventilation in intensive care].

The study aimed to evaluate whether superimposed high-frequency jet ventilation (SHFJV) is a useful tool in intensive care medicine to ventilate patients with pulmonary insufficiency. METHODS. SHFJV is the simultaneous application of low- and high-frequency jet ventilation performed using a specially designed ventilator.

[Ventilation during tracheotomy in extensive, 90% laryngeal stenosis using superimposed high frequency jet ventilation via the jet laryngoscope].

In a 35-year old male patient with laryngeal carcinoma an acute respiratory insufficiency with early hypoxaemia developed due to massive laryngeal stenosis. An endotracheal intubation was not possible since the available lumen was too small. Tracheotomy using local anaesthesia was not possible since spontaneous respiration with a Venturi mask applying 100% oxygen was not sufficient and the patient was becoming restless and agitated due to the hypoxaemia.

[Laryngeal surgery with a 3-D technique. Early results with the jet-laryngoscope in superimposed high-frequency jet ventilation].

Surgery by three-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported as being used in microlaryngeal surgery. METHODS. We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the laryngoscope as well as intrapulmonary pressures while applying superimposed high-frequency jet ventilation.

Statistical methodology for estimating twin similarity with respect to a dichotomous trait.

Statistical methodology is presented for the estimation of twin similarity with respect to a dichotomous trait. The methodology focuses on the intraclass correlation as the parameter of interest and is analogous to methodology commonly applied to continuous outcome data. For inference problems involving a single sample, confidence interval construction and significance testing are discussed.

Evaluation of a palliative care service: problems and pitfalls.

Objective: To evaluate a palliative care home support team based on an inpatient unit.

Design: Randomised controlled trial with waiting list. Patients in the study group received the service immediately, those in the control group received it after one month.

Methods for comparing event rates in intervention studies when the unit of allocation is a cluster.

The aim of many research investigations is to compare the proportion of individuals in each of several groups that have a certain characteristic. The unit of allocation for such investigations is often an intact social unit, as in randomizing families, medical practices, schools, or entire communities, to different intervention groups. Standard statistical methods are not appropriate for these designs, since they do not take into account the dependencies among individuals within the same cluster.

[Anesthesia in acute respiratory tract obstructions caused by high degree laryngeal and tracheobronchial stenoses].

Unlabelled: Stenotic process of the laryngeal and/or tracheobronchial system may lead to dyspnoea which can become life threatening.

Objective: The object of our study was to determine whether sufficient gas exchange can be ensured in patients with a massive stenosis of the respiratory tract applying the Superimposed High-Frequency-Jet-Ventilation (SHFJV) via the jet laryngoscope. Further, it was to be determined whether SHFJV can be applied for insertion of endoluminal stents into the tracheo-bronchial system.

[3-D endoscopy for laryngeal interventions in tubeless superimposed high frequency jet ventilation. A clinical trial].

Unlabelled: Surgery by 3-dimensional (3D) endoscopy is being used routinely in abdominal surgery and, in special cases, in thoracic surgery; however, it has not been reported to be used in laryngeal surgery.

Methods: We inserted a 3-D endoscope into a jet laryngoscope and studied the pressure properties at the tip of the jet laryngoscope as well as the intrapulmonary pressures while applying SHFJV. The studies were conducted initially using a lung simulator, and then in 6 patients undergoing endoscopic laryngeal surgery.

[Tubeless superimposed high frequency jet ventilation in high grade laryngeal stenoses].

Unlabelled: Massive stenosis of the larynx may present a potentially life-threatening situation for the patient, requiring immediate measures to ensure a patient's airway. The aim of this prospective study was to evaluate potential benefits of Superimposed High Frequency Jet Ventilation (SHFJV) in patients requiring microlaryngeal surgery due to massive stenosis of the larynx.

Patients And Methods: 23 patients (age range 1.

A comparison of methods for testing homogeneity of proportions in teratologic studies.

We consider teratologic studies in which the aim is to compare the survival rate of animals in a treatment group to the corresponding rate in a control group. The design of such studies often involves the allocation of intact litters of animals to treatment, invalidating the application of standard statistical methods. We review the strengths and weaknesses of several approaches for dealing with this problem including methodology recently developed for the analysis of clustered binary data.

Statistical implications of the choice between a dichotomous or continuous trait in studies of interobserver agreement.

A frequently occurring question in the planning of studies is whether to measure the trait of interest on a continuous or dichotomous scale. An issue potentially relevant to this question centers around the resulting reliability of the measure. Assuming the continuous trait has a normal distribution, we quantify the effect of this decision on the overall number of subjects required to test whether a population reliability coefficient equals a specified criterion value.

[Jet ventilation superimposed on a special jet laryngoscope for endoluminal stent insertion in the tracheobronchial system].

Background: Stenotic processes of the tracheobronchial system may lead to dyspnoea that can become lift-threatening. To restore sufficient function of the blocked airway, a silicone stent can be inserted. The anaesthesia techniques used for this intervention so far have been complicated.

[Ventilation in laryngeal laser-surgical interventions using superimposed high frequency jet ventilation (SHFJV)--a further revision of jet ventilation technique for laryngeal interventions].

In laser surgery of the larynx the surgeon and the anaesthesist have to compete for the limited space available. The surgeon requiring good visibility and an undisturbed operating area whereas the anesthetist has to ensure sufficient ventilation of the patient. Further, complications of anaesthesia and laser must be avoided.

Biochemical characterization of binding of multiple HIV-1 Rev monomeric proteins to the Rev responsive element.

Recombinant HIV-1 Rev protein was overexpressed in Escherichia coli using translational coupling to the beta-glucuronidase gene and demonstrated to interact with high affinity and specificity with the Rev responsive element (RRE). A complex Rev-dependent binding pattern was observed using the gel shift assay which could be simplified to one or two primary bands in the presence of stoichiometric concentrations of RRE. Competition of these bands with a series of homopolymer RNA species demonstrated that Rev is essentially a poly-G binding protein, although poly-I was also shown to compete for specific RRE binding.

Confidence interval construction for effect measures arising from cluster randomization trials.

Methods of confidence interval construction are provided for summary measures of treatment effect arising from designs randomizing clusters to one of two treatment groups. Three basic designs are considered for the case of continuous and dichotomous variables: completely randomized, pair-matched and stratified.