Positive end-expiratory pressure and the damaged right ventricle. An experimental open versus closed chest study

Hemodynamic changes after isolated impairment of right ventricular function (produced by increasing afterload by temporary banding of the pulmonary artery) were studied in 22 ventilated pigs during increased levels of positive end-expiratory pressure (4, 8, 12, and 16 cm H2O). In the open chest group, application of positive end-expiratory pressure produced only a slight decrease of cardiac index. After right ventricular damage a decrease of cardiac index of more than 25% occurred only when higher levels of positive end-expiratory pressure were applied. In contrast to the open chest group, the closed chest group showed more distinct cardiovascular responses after positive end-expiratory pressure. In the damaged right ventricle with a positive end-expiratory pressure of 16 cm H2O, right ventricular end-diastolic pressure increased more than 100%. With positive end-expiratory pressure, cardiac index decreased 34% before and 47% after right ventricular damage. We conclude that positive end-expiratory pressure induces a more pronounced decrease in cardiac index if right ventricular function is impaired. During open chest conditions with lower levels of positive end-expiratory pressure, these changes are only small, however, and probably irrelevant. During closed chest conditions, the hemodynamic changes are much more pronounced. High right ventricular end-diastolic pressures resulting from impaired right ventricular contractility as well as from high levels of positive end-expiratory pressure may have an impact on biventricular function and right ventricular coronary driving pressure.     

The development of a research human milk bank.

Although there are well-established clinical human milk banks in the United States, there are no milk banks specifically intended to foster research on human milk. The authors' goal was to establish a milk bank with a core data set to support exploratory and hypothesis-driven studies on human milk. Donations to the Cincinnati Children's Research Human Milk Bank are accepted within the context of ongoing, hypothesis-driven research or on an ad hoc basis. Donors must give informed consent, and scientists wishing to use the samples must have Institutional review board approval for their use. Development of more research human milk banks can potentially provide resources for multidisciplinary collaboration and advance the study of human milk and lactation.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Ethik in der Intensivmedizin

In more than 30 years of development of intensive care medicine (ICM), our speciality has acquired moral and ethical standpoints, although not without public pressure and discussions. Special commissions dealing, e.g., with brain death, terminal care, ethics of foregoing life-sustaining treatment in the critically ill, withholding or withdrawing mechanical ventilation, and other issues have meen formed in a number of medical societies. International consensus conferences have helped to clarify some of the issues. With increasing experience, a multitude of ethical problems have arisen in ICM that have to be dealt with, such as the issue of quality of life. What is an unworthy life? Are we allowed to make judgments for our patients? What is cost-effectiveness in ICM? Other restrictions include bed and equipment shortages in the intensive care unit (ICU), the necessity for triage – undisputed in catastrophe medicine – and how one should proceed in managing elective patients? In situations of limited ICU bed availability, sicker patients will be admitted, sparing out patients who are less ill for observation and those with poor quality of life and poor prognosis. For the future, it will likely be necessary to define the patients who should be admitted to an ICU more than those who should not be admitted. An ICU treatment entitlement index would be directly proportional to the probability of successful outcome and the quality of the remaining life, and would be inversely related to costs for achieving success. The ICU outcome with survival, hospital mortality, and follow-up of ICU patients is considered. DNR (do not resuscitate), the dying patient, terminal care, terminal weaning – DNT (do not treat) – active and passive euthanasia, living wills, quality of life, and cost-effectiveness for ICU patients are defined. Their application in the ICU will be discussed and problems pointed out. Outcome predictions using scores (APACHE III, SAPS II, MPM) have been developed based on previous experience, but should only be applied to patient groups and for quality assurance in ICUs. The most frequent and difficult problem in the ICU is the vegetative state, which requires an exact diagnosis. The differential diagnosis from other comatose states such as coma, brain death, and locked-in-syndrome is depicted. The ethics of interrupting life-sustaining treatment in critically ill patients have been worked out by a Task Force on Ethics of the Society of Critical Care Medicine (1990). A consensus was found that the patient may judge to forego therapy; ethically it is then appropriate to withhold or withdraw therapy. According to the consensus, withdrawing an already initiated treatment should not necessarily be regarded as more problematic than a decision not to initiate treatment. In my mind, however, there is a great difference between withdrawing or withholding, e.g., ventilation. A dissentive opinion by some members of the Task Force stated that hydration and nutrition other than high-technology or parenteral nutrition are key components of patient care, and should not be equated with medical intervention. The ethical problems associated with active euthanasia (physician-assisted suicide or death) as practised in the Netherlands are also discussed. In most countries this practice seems unacceptable. From 30 years experience in ICM, there are many more ethical questions and case reports without clear solutions. Care decisions for single patients in unacceptable situations should be made after medical evaluation by the intensivist with the medical team and, if possible, by the patient and/or his or her surrogate. Legislation and solutions cannot be expected for single patients, but ethics committees could be helpful in decision-making.     

Segmental intestinal muscular thinning: a possible cause of intestinal obstruction in the newborn

Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.