The Single Logon Application: an enabler for access to disparate systems in a patient-focused care environment.

The presence of separate, independent systems for patient results is a common problem in many institutions. The Single Logon Application (SLA) was developed to mitigate the problems presented by these disparate systems, and its use was a key component in a Patient-Focused Care (PFC) implementation.

Factors associated with rectal injury in spontaneous deliveries.

Rectal injury during childbirth is a complication with potentially debilitating long-term consequences. Several factors have been suggested as influencing the risk of rectal injury. Among these are parity, infant birth weight, and various procedures performed by the birth attendant, including episiotomy. Whether episiotomies protect against or provoke laceration of the rectal sphincter and rectal mucosa is particularly controversial. Logistic analysis was used in an observational study of 2706 spontaneous cephalic deliveries to determine the risk of rectal injury for each of six explanatory factors, simultaneously controlling for the other factors. The adjusted risk for rectal injury was significantly increased for midline episiotomy (8.9 versus no episiotomy), nulliparity (3.3 versus parous), delivery by a physician (2.4 versus midwife), fetal macrosomia (2.4 versus normal weight), and delivery in a delivery room (2.0 versus labor bed). Compared with the risk for whites, significantly increased risk was found for Hispanic (1.9), Filipino (3.7), and Chinese (2.9) women. The practice of prophylactic midline episiotomy is questioned, and suggestions are offered for the design of experimental studies to resolve the questions raised.

Zone 2 and zone 3 pulmonary blood flow.

In the West model of zonal distribution of pulmonary blood flow, increases in flow down zone 2 are attributed to an increase in driving pressure and a decrease in resistance resulting from recruitment and distension. The increase in flow down zone 3 is attributed to a decrease in resistance only. Recent studies indicate that, besides the pressure required to maintain flow through a vessel, there is an added pressure cost that must be overcome in order to initiate flow. These additional pressure costs are designated critical pressures (Pcrit). Because Pcrit exceed alveolar pressure, the distinction between zones in the West model becomes less secure, and the explanation for the increase in flow even in West zone 3 requires reexamination. We used two methods to test the hypothesis that the Pcrit is the pertinent backpressure to flow even in zone 3, when the pulmonary venous pressure (Ppv) exceeds alveolar pressure (PA) but is less than Pcrit in the isolated canine left caudal lobe. First, PA was maintained at 5 cmH2O, and pressure flow (P-Q) characteristics were obtained in zone 2 and zone 3. Next, with PA still at 5 cmH2O, we maintained a constant flow and measured the change in pulmonary arterial pressure as Ppv was varied. Both techniques indicated that the pertinent backpressure to flow was the greater of either Pcrit or Ppv and that PA was never the pertinent backpressure to flow. Also, our results indicate no significant change in the geometry of the flow channels between zone 2 and zone 3. These findings refine the zonal model of the pulmonary circulation.

Relationship of arterial wedge pressure to closing pressure in the pulmonary circulation.

We studied the relationship between the pulmonary artery wedge pressure (Pw) and pulmonary venous pressure (Ppv) at 2 alveolar pressures (PA) in 7 isolated perfused dog lobes. If PA were the critical pressure in the pulmonary circulation, one would expect Pw to equal Ppv for all Ppv greater than PA. Relative to the hilum, the average critical pressure in these lobes was 15.07 +/- 0.40 cmH2O at PA = 5 cmH2O and increased significantly to 17.23 +/- 0.82 cmH2O at PA = 7 cmH2O. Because the critical pressure in fact exceeded PA, Pw was found to be relatively constant and independent of Ppv even when Ppv exceeded PA by 5 cmH2O or more. For example, at PA = 5.13 +/- 0.04 cmH2O and Ppv = 9.64 +/- 0.28, the mean value for Pw was 13.30 +/- 0.59 cmH2O. Pw is equal neither to the average critical pressure nor to PA, but instead lies between these two values. It is determined by the spectrum of closing pressures in the pulmonary circulation, and the time-constants for drainage of beds downstream from the occluded pulmonary arterial branch.

Computerized body plethysmography: an algorithm for minimizing drift and hysteresis.

The use of linear regression for on-line data processing of airway resistance measurements in the body plethysmograph may be difficult. When airflow (V) is plotted against plethysmographic pressure (Pbox), the resulting loop exhibits hysteresis and may drift along the PBox axis. Although the slope of the V-PBox loop can be estimated visually, computer calculations of the slope are difficult if baseline drift is present. Taking the derivatives of V and PBox eliminates the effect of drift and reduces the loops to a series of essentially parallel lines from which the slope can be readily calculated using linear regression. The identical technique can be employed when mouth pressure is plotted against plethysmographic pressure, enabling on-line calculation of thoracic gas volume.

Intensity and motion responses of giant vertical neurons of the fly eye.

There are nine "giant vertical" neurons in the lobula plate of the fly optic lobe. Intracellular recordings were obtained from the three most peripheral of these cells. These cells respond to a light flash with graded changes in the membrane potential. The response consists of an "on" transient, a sustained depolarization, an increase in membrane potential fluctuations, and an "off" transient. Signal averaging showed that only the "on" and "off" transients are correlated to the stimulus. A pattern of horizontally oriented stripes moving in the vertical direction evokes a response larger than the response to a stationary pattern. The response is most sensitive to vertical movement; motion in the downward direction evokes a net membrane potential depolarization, and upward motion results in a net hyperpolarization. We conclude that the giant vertical cells function primarily as vertical motion detectors and that the direction of the motion is encoded in the polarity of the shift in the membrane potential.