Steep Trendelenburg position during robotic sacrocolpopexy and heart rate variability.

OBJECTIVES: The objective of this study was to evaluate heart rate variability and hemodynamic parameters following steep Trendelenburg positioning during robotic sacrocolpopexy. STUDY DESIGN: For 19 women, median age 57 (range: 45-72), blood pressure and ECG were recorded during surgery. From the ECG signals interbeat intervals were used to assess heart rate variability, analyzed in time and frequency domains using the Fast Fourier transform. The low frequency and high frequency spectral bands were used to assess sympathetic and parasympathetic pathways respectively. RESULTS: All women underwent robotic supracervical hysterectomy and sacrocolpopexy. A statistically significant decrease in the mean values of the low-frequency and high-frequency spectral bands, representing sympathetic and parasympathetic activity, respectively were demonstrated 5min following Trendelenburg positioning of the patients (from 3.6±1.4 to 2.9±0.8ms(2)/Hz, and from 3.5±1.4 to 2.9±1ms(2)/Hz, P<0.05). These changes correlated with a mean 20% decrease in heart rate, which lasted for 30min, and with a second drop in sympathetic and parasympathetic activity and heart rate, commencing 2h from the start of surgery, and lasting until the end of the operation. CONCLUSIONS: Steep Tredelenburg positioning during robotic urogynecology surgery results in significant changes in the autonomic nervous system modulation of heart rate variability and in other hemodynamic parameters.

Combined spinal and general anesthesia vs general anesthesia for robotic sacrocervicopexy: a randomized controlled trial.

INTRODUCTION AND HYPOTHESIS: Gynecologic laparoscopic surgery is frequently accompanied by early postoperative pain. This study assessed the effect of combined general and spinal anesthesia on postoperative pain score, analgesic use, and patient satisfaction following robotic surgeries. METHODS: This was a randomized controlled trial. Thirty-eight consecutive women who underwent robotic surgeries for pelvic organ prolapse (sacrocolpopexy with or without subtotal hysterectomy) were randomly assigned to receive general anesthesia (control group, n = 20) or combined general with spinal anesthesia (study group, n = 18). Pain scores were assessed at rest and while coughing using a visual analog scale (VAS) 0-10. Dosage of analgesic medication consumption was retrieved from patients' charts. RESULTS: There were no statistically significant differences between the two groups with respect to demographic data and intraoperative hemodynamic parameters. In the postanesthesia care unit (PACU) mean total IV morphine and meperidine dosages were significantly lower for the study than the control group (0.33 vs 7.59 mg, 1.39 vs 27.89 mg, respectively, P < 0.003, <0.001, respectively). In addition, a significantly lower percentage of patients belonging to the study group demanded analgesic medications while in the PACU (33 vs 53 %, P = 0.042). Pain scores in the PACU and during postoperative day 1 were significantly lower in the study group than in the control group (delta VAS 1.9 vs 3.0, P = 0.04). Satisfaction with pain treatment among both patients and nurses was significantly higher in the study group. CONCLUSIONS: Reported levels of pain and analgesic use during the first 24 h following robotic gynecologic surgery were significantly lower following general and spinal anesthesia compared to general anesthesia alone.

Predicting difficult airways using the intubation difficulty scale: a study comparing obese and non-obese patients.

STUDY OBJECTIVE: To compare intubation difficulty in obese and non-obese patients by intubation difficulty scale (IDS), intubation duration measurement, and oxygen saturation (SaO(2)) levels. DESIGN: Prospective, controlled study. SETTING: Operating room of a tertiary-care hospital. PATIENTS: 204 ASA physical status I, II, and III adult patients who underwent elective surgery with endotracheal intubation. INTERVENTIONS AND MEASUREMENTS: Preoperative airway parameters, intubation duration, IDS scores, and lowest SaO(2) during intubation were recorded. MAIN RESULTS: IDS scores were higher in the obese group than the non-obese (2.29 +/- 0.45 and 1.26 +/- 0.2, respectively, P = 0.03). Intubation duration was 45.1 +/- 6 sec for obese versus 36.8 +/- 2.6 sec for the non-obese group (P = 0.20). The lowest SaO(2) recorded was 97%, with no difference noted between groups. Mallampati class >or=3 was found to positively predict intubation difficulty scores greater than 5. CONCLUSIONS: Difficult intubation was more prevalent among obese than non-obese patients, but intubation duration and lowest SaO(2) levels during intubation were not. Moreover, the modified Mallampati test was found to be a moderately good (60%) predictor of difficult intubation among obese patients.

A role for ZnT-1 in regulating cellular cation influx.

The ZnTs are a growing family of proteins involved in lowering or sequestration of cellular zinc. Using fluorescent measurements of zinc transport we have addressed the mechanism of action of the most ubiquitously expressed member of this family, ZnT-1. This protein has been shown to lower levels of intracellular zinc though the mechanism has remained elusive. The rate of zinc efflux in HEK293 cells expressing ZnT-1 was not accelerated in comparison to control cells, suggesting that ZnT-1 may be involved in regulating influx rather than efflux of zinc. Co-expression of the L-type calcium channel, a major route for zinc influx, and ZnT-1 resulted in a 3-fold reduction in the rate of zinc influx in HEK293 and PC-12 cells, indicating that ZnT-1 modulates zinc permeation through this channel. Immunoblot analysis indicates that ZnT-1 expression does not modulate LTCC expression. Our findings therefore indicate that ZnT-1 modulates the permeation of cations through LTCC, thereby, regulating cation homeostasis through this pathway. Furthermore, ZnT-1 may play a role in cellular ion homeostasis and thereby confer protection against pathophysiological events linked to cellular Ca(2+) or Zn(2+) permeation and cell death.

A sodium zinc exchange mechanism is mediating extrusion of zinc in mammalian cells.

Zinc influx, driven by a steep inward electrochemical gradient, plays a fundamental role in zinc signaling and in pathophysiologies linked to intracellular accumulation of toxic zinc. Yet, the cellular transport mechanisms that actively generate or maintain the transmembrane gradients are not well understood. We monitored Na+-dependent Zn2+ transport in HEK293 cells and cortical neurons, using fluorescent imaging. Treatment of the HEK293 cells with CaPO4 precipitates induced Na+-dependent Zn2+ extrusion, against a 500-fold transmembrane zinc gradient, or zinc influx upon reversal of Na+ gradient, thus indicating that Na+/Zn2+ exchange is catalyzing active Zn2+ transport. Depletion of intracellular ATP did not inhibit the Na+-dependent Zn2+ extrusion, consistent with a mechanism involving a secondary active transporter. Inhibitors of the Na+/Ca2+ exchanger failed to inhibit Na+-dependent Zn2+ efflux. In addition, zinc transport was unchanged in HEK293 cells heterologously expressing functional cardiac or neuronal Na+/Ca2+ exchangers, thus indicating that the Na+/Zn2+ exchange activity is not mediated by the Na+/Ca2+ exchanger. Sodium-dependent zinc exchange, facilitating the removal of intracellular zinc, was also monitored in neurons. To our knowledge, the Na+/Zn2+ exchanger described here is the first example of a mammalian transport mechanism capable of Na+-dependent active extrusion of zinc. Such mechanism is likely to play an important role, not only in generating the transmembrane zinc gradients, but also in protecting cells from the potentially toxic effects of permeation of this ion.