Autonomic hyperreflexia in a pregnant paraplegic patient. Case report.

BACKGROUND AND OBJECTIVES: Pregnant patients with spinal cord injuries are predisposed to autonomic hyperreflexia, which if unrecognized or untreated can lead to death. Hypertension occurring in laboring patients at risk for autonomic hyperreflexia must be managed aggressively. METHODS: Epidural anesthesia can safely control autonomic hyperreflexia during labor and delivery, but because spinal cord impaired patients lack sensory and motor function below the level of injury, it is difficult to determine the dermatomal spread of epidural anesthesia by the usual methods. This difficulty is highlighted by the following case, reporting an epidural that failed during labor, with the subsequent development of autonomic hyperreflexia. RESULTS: Previously, autonomic hyperreflexia occurring in pregnant patients (undergoing surgical procedures) was treated with intravenous antihypertensive agents. During labor, however, titrating these agents to coincide with uterine contractions is difficult. In this case, epidural anesthesia was repeated and the autonomic hyperreflexia resolved. CONCLUSIONS: Autonomic hyperreflexia can develop in unanesthetized laboring paraplegic patients (failed epidural) but it can be successfully managed with adequate epidural anesthesia.

Effect of oxygenator type and bypass flow pattern on the P(a-ET)CO2 gradient.

Changes in pre-bypass and post-bypass P(a-ET)CO2 gradients were evaluated regarding the type of bypass flow (pulsatile or nonpulsatile) and oxygenator (membrane or bubble). Duration of bypass and hemodynamic changes were analyzed also to determine their possible influence on PaCO2, PETCO2, and P(a-ET)CO2. A total of 36 adult patients undergoing cardiopulmonary bypass were anesthetized using a sufentanil-pancuronium-oxygen technique. Patients were divided into three groups based on the type of oxygenator and pump flow: group 1 (control group) consisted of a bubble oxygenator with nonpulsatile flow (BN), group 2 consisted of a bubble oxygenator with pulsatile flow (BP), and group 3 consisted of a membrane oxygenator with nonpulsatile flow (MN). Cardiac parameters (MAP, CI, SVR, and PVR) PaCO2, PETCO2, and P(a-ET)CO2 were determined pre-bypass and post-bypass following steady-state conditions. For the entire group there was a trend for the P(a-ET)CO2 gradient to increase in the post-bypass period (pre-bypass = 3.5 +/- 0.5 mm Hg, post-bypass = 4.3 +/- 0.5 mm Hg.). However, this increase was not statistically significant. Pulsatile flow (group 2) demonstrated a significant correlation with the change in P(a-ET)CO2 gradients from the pre-bypass to the post-bypass period (r = 0.85) when compared with the other two groups (group 1: r = -0.09 and group 3: r = 0.37). Thus, the P(a-ET)CO2 gradient tended to remain constant from the pre-bypass to the post-bypass period in group 2, whereas it increased in groups 1 and 3. Changes in MAP, CI, SVR, and PVR and the duration of CPB did not influence the P(a-ET)CO2 gradient.

Transorally obtained oxygen tension as an indicator of arterial oxygen tension.

Transcutaneous oxygen electrodes have been used with success in neonates as indicators of arterial oxygenation, but with less success in adults because of differences in skin thickness and vascularity. In this study, a prototype transoral oxygen electrode was evaluated to determine if a heated mucous membrane would yield arterialized values of oxygen tension in adults. Using a miniaturized Clark electrode, we measured transoral oxygen tension (PtoO2) in 29 subjects at steady-state conditions. Simultaneously a sample was anaerobically obtained from a radial artery for measurement of arterial oxygen tension (PaO2). Data were analyzed using linear regression analysis, Student's t test, and analysis of variance. There was no statistically significant difference between nonwhite and white subjects or male and female subjects. There was a highly significant difference (P less than 0.001) between the pooled, matched values for PtoO2 versus PaO2, and the regression between the PtoO2 and the PaO2 was linear (slope 0.92, y-intercept -8.37, r = 0.62, P less than 0.003). The calculated ratio of PtoO2 to PaO2 was 0.83 +/- 0.03 (standard error). We concluded that the PtoO2 was linearly related to the PaO2, although its accuracy in reflecting PaO2 was low. This finding correlates with previously published data that suggested that the PtoO2 reflects tissue oxygen tension rather than arterialized oxygen tension. Gender and race appeared not to affect the function of the electrode in our study.