No abstract

The purposes of this study were to conduct afactor analysis of Baldwin and Bell's African Self-Consciousness (ASC) Scale, evaluate the effect of demographic variables on one's African self-consciousness, and relate the ASC Scale scores to criterion behaviors in a non-Southern and noncollege population. The scale was administered to 147AfricanAmericans residing in three Southern California cities. The ASC Scale's reliability, factor structure, and construct validity were examined. The scale had a Cronbach's alpha of .78. Principal axesfactoranalysis foundfourfactors, and it is suggested that 32 out of 42 items be retained to formulate the revised subscale dimensions identified as Personal Identification With the Group, Self-ReinforcementAgainstRacism, Racial and Cultural Awareness, and Value for African Culture. The ASC Scale appears to be a viable instrument for use in research investigating African Americans.

SummaryTo assess the potential for atmospheric nitrogen to enter the nonventilated lung following the initiation of single-lung ventilation, the nonventilated lung of 10 patients undergoing videoassisted thoracoscopy was connected to the air in a water-filled spirometer, and gas movement outof and back into the lung was measured. Airway pressure from both lungs and pleural pressure from the nonventilated side were also measured. With each breath of positive-pressure ventilation to the ventilated lung prior to the thoracic cavity being opened to the atmosphere, the pressure transmitted to the opposite hemithorax generated a mean (range) tidal movement of gas in the nonventilated lung of 134 (65-265) ml. In addition, ongoing gas exchange resulted in a progressive influx of gas from the spirometer over the 110-120 s measurement period of a mean (range) volume of155 (70-320) ml. This easily preventable influx of atmospheric nitrogen could, in theory, predispose to arterial desaturation and to delayed lung collapse after the parietal pleura is opened.

SummaryAn ambient pressure oxygen reservoir bag apparatus for connecting to the nonventilated lung as soon as single-lung ventilation is initiated is described. The theoretical benefits are the facilitation of collapse of the lung on the side of surgery and a reduced likelihood of arterial desaturation. Although these main benefits are yet to be proven, the authors believe that the weight of theoretical argument and practical observation serves to justify the use of the apparatus while the outcome of suitably designed clinical trials is awaited. It can be used for all one-lung anaesthetics and is especially recommended for thoracoscopic surgery, where temporary re-expansion of the nonventilated lung is either counter-productive or contraindicated, and where there is a possibility that lung collapse may be delayed.

SummaryA study of 10 anaesthetised patients placed in the lateral position for thoracoscopic surgery assessed whether transient increases in pleural pressure on the side of the non-ventilated lung might increase the speed at which gas vents from that lung. The transient increases in pleural pressure were generated by the mediastinal displacement that occurs with each inspiratory phase of positive pressure ventilation of the dependent lung. When combined with a unidirectional valve allowing gas to flow out of the non-ventilated lung, and a second valve allowing ambient airflow into, but not out of, the thoracic cavity via an initial thoracoscopy access site, this mediastinal displacement could conceivably serve to`pump' gas out of the non-ventilated lung. Using the four different combinations of valve inclusion or omission, the volume of gas that vented from the non-ventilated lung into a measuring spirometer was recorded during a 120-s measurement sequence. It was found that the speed of venting was not increased by the transient increases in pleural pressure, and that in all but one of a total of 34 measurement sequences, venting had ceased by the end of the sequence. Gas venting was a mean (SD) of 85.5 (11.9)% complete in 25 s (five breaths), and 96.6 (6.1)% complete in 60 s. This prompt partial lung collapse very likely reflected the passive elastic recoil of the lung, while the failure of transient increases in pleural pressure to result in ongoing venting of gas was probably a consequence of airways closure as the lung collapsed. It is concluded that techniques that aim to speed lung collapse by increasing pleural pressure are unlikely to be effective. Many thoracoscopic operations are facilitated by prompt collapse of the non-ventilated lung on the side of surgery. One method that has been used to speed lung collapse is CO 2 insufflation into the pleural space on the side of surgery [1, 2], a practice that has also been recommended as a means of improving surgical access during thoracoscopic internal mammary artery harvesting for coronary artery bypass grafting [3]. However, whilst the latter indication when performed as described [3] may well achieve the specific desired result, the practice of CO 2 insufflation as a means of expediting and maintaining lung collapse has yet to be shown to be effective. As well as possibly not achieving a faster rate of lung collapse, CO 2 insufflation has been associated with several reports of marked adverse cardiovascular effects [4,5] that have been likened to those seen in tension pneumothorax.The present study was undertaken to assess whether an alternative method of increasing the pleural pressure that does not at the same time create a situation similar to a tension pneumothorax might serve to increase the speed of lung collapse during thoracoscopy.