Pressure-controlled versus volume-controlled one-lung ventilation for MIDCAB.

One-lung ventilation is limited by hypoventilation and hypoxemia because of increasing airway pressure and intrapulmonary shunt. Previous clinical studies compared pressure-controlled versus volume-controlled ventilation during one-lung ventilation in patients with pre-existing pulmonary disease. We studied 50 patients undergoing thoracotomy and one-lung ventilation because of cardiovascular disease. After two-lung ventilation with volume-controlled ventilation, patients were divided randomly into two groups. In one group, ventilation was switched to pressure-controlled ventilation after starting one-lung ventilation. In the other group, volume-controlled ventilation was continued. Parameters of ventilation, pulmonary function and systemic and pulmonary hemodynamics were recorded. We observed, that peak airway pressure, dead space ventilation and arterial carbon dioxide partial pressure were significantly higher during volume-controlled ventilation. After one-lung ventilation patients with pressure controlled ventilation had lower alveolar-arterial oxygen tension difference and a higher arterial oxygen partial pressure with significant differences for those patients in the intensive care unit. We conclude that pressure-controlled ventilation may be useful to improve gas exchange and alveolar recruitment during one lung ventilation.

Effects of gender and region on proton MRS of normal human brain.

Localized, in vivo 1H magnetic resonance spectroscopy has been performed in a number of brain regions of neuropsychiatric interest in male and female control subjects to determine if gender and region affect the measured metabolite ratios. In contrast to some previous reports, no significant differences were seen in any region for any metabolite ratio between males and females. As expected, significant variations with brain region were seen for metabolite ratios for the total group of subjects.

Regional proton magnetic resonance spectroscopy in schizophrenia and exploration of drug effect.

Schizophrenia is a disorder with an unclear pathophysiology, despite numerous attempts to elucidate its etiology. We have employed proton magnetic resonance spectroscopy in vivo to explore the neurochemistry of several brain regions (left frontal and temporal cortices, left basal ganglia, and left and right thalamus) in patients with schizophrenia and in normal control subjects. We have also examined patients in different medication states. A trend toward a decreased level of inositol/creatine was found in the left temporal lobe of patients with schizophrenia, as was a trend toward a reduced level of N-acetylaspartate/creatine in the left thalamus of patients. In schizophrenic patients treated with atypical antipsychotics, decreased levels of choline were found in the left basal ganglia, while increased levels of N-acetylaspartate were found in the left frontal cortex. These results suggest altered metabolism in patients with schizophrenia, and imply that further study is needed to clarify the effects of the more recently available antipsychotics.

Post-traumatic stress disorder and serotonin: new directions for research and treatment.

The overlap in clinical phenomenology and morbidity between post-traumatic stress disorder (PTSD) and such conditions as major depression, anxiety disorders and aggression, in which a serotonin dysfunction is implicated, suggests a role for serotonin in the pathophysiology of PTSD. In this paper, we review current knowledge concerning the role of serotonergic mechanisms and interventions in PTSD. Since there is no clearly effective pharmacologic intervention for this disorder, the underlying neurochemical dysfunction needs to be carefully defined so that more effective treatment can be developed. Preclinical and clinical studies of the serotonergic mechanisms in the pathophysiology of PTSD and treatment trials involving serotonergic agents are limited, but indicate considerable promise. Further investigation of a serotonergic dysfunction in PTSD and of its treatment with serotonergic agents is warranted.

Risperidone-associated burning paraesthesia.

This report notes the incidence and quality of paraesthesiae related to treatment with risperidone, as well as potential implications for treatment. Possible pathophysiologic explanations are offered.

Gender differences in the clinical expression of schizophrenia.

Gender differences have been reported for a variety of clinical measures in patients with schizophrenia. Clinical characterization may be helpful in identifying symptom clusters which can then be linked to underlying brain function. In this study 74 men and 33 women meeting DSM-IIIR criteria for schizophrenia were studied off medication and rated on measures of symptom type and severity, as well as premorbid and current function. Men were more severely impaired in ratings of negative symptoms, while positive symptoms were not significantly different. There were also differences in premorbid and current functioning, with women manifesting better social functioning than men.

Facial emotion discrimination: II. Behavioral findings in depression.

The facial discrimination tasks described in part I (Erwin et al., 1992) were administered to a sample of 14 patients with depression and 14 normal controls matched for sex (12 women, 2 men) and balanced for age and sociodemographic characteristics. Patients performed more poorly on measures of sensitivity for happy discrimination and specificity for sad discrimination, and had a higher negative bias across tasks. Severity of negative affect was correlated with poorer performance for patients. The results suggest that depression is associated with an impaired ability to recognize facial displays of emotion.

Facial emotion discrimination: III. Behavioral findings in schizophrenia.

Emotional discrimination was studied in patients with schizophrenia (n = 20) and matched controls. Performance of the emotion-discrimination tasks in the schizophrenic patients was impaired, relative to their performance of an age-discrimination task. Performance patterns in the patient group could also be reliably distinguished from those of normal controls. The impairment was associated with the severity of both emotional and nonemotional symptoms specific to schizophrenia, but not with the severity of nonspecific symptoms. The deficit associated with schizophrenia is more marked than that reported for depression (Gur et al., 1992), particularly for the emotion-discrimination tasks, and showed no difference between "happy" discrimination and "sad" discrimination. The main difficulty in patients with schizophrenia is the assignment of emotional valence to neutral faces. The magnitude of the deficit underscores the salience of emotional impairment in schizophrenia, and its relation to cognitive dysfunction in this disorder merits further scrutiny.

Phenomenology and functioning in first-episode schizophrenia.

One current view of schizophrenia is that its clinical and functional features show a deteriorating course, particularly for negative symptoms. However, this is difficult to study in chronic patients who have been exposed to pharmacologic treatment and institutionalization. Examining first-episode (FE) patients can help clarify which symptoms are present initially and how the symptom pattern is linked to functioning. We evaluated a sample of 37 FE patients with schizophrenia and compared them to 70 other schizophrenia (OS) patients on standard clinical scales, measures of premorbid functioning, and quality of life. FE patients showed a symptom profile similar to OS patients; in particular, there was no evidence that negative symptoms are less severe in the FE group. Analysis of the clinical data led us to the conclusion that the symptom profile of schizophrenia exists at the outset, that negative symptoms are associated with poor premorbid and current functioning, but that the role of positive symptoms is more complex and may vary in subtypes.

Volunteers for biomedical research. Recruitment and screening of normal controls.

We examined the process of accruing healthy control subjects for biomedical research on brain function. Of 1670 responders to newspaper advertising, 23.1% were uninterested when learning more about the studies, and 50.9% of those remaining were found by structured telephone screening to meet exclusionary criteria for having a history of psychiatric, neurologic, or medical disease that might affect brain function. Of 312 volunteers passing the telephone screening who came to an in-person evaluation by a physician and agreed to participate, 49.7% were found to meet exclusionary criteria, and only 157 were admitted to the study. This underscores the importance of attending to the issue of screening and assessment of "normal volunteers." Alternative strategies should be considered for enriching the pool.