Anesthesia and analgesia
-
Anesthesia and analgesia · Oct 2003
Comparative StudyA laboratory evaluation of the level 1 rapid infuser (H1025) and the Belmont instrument fluid management system (FMS 2000) for rapid transfusion.
In this investigation I compared the heating capabilities, infusion rates, and air management system of the new FMS 2000 and the Level 1 infusion systems. A rollerhead pump was placed at the position of the IV bag spikes on the Level 1 disposable set and used to match the flow of the rollerhead pump of the FMS 2000. Infusate temperature was measured at 250 and 500 mL/min by using packed red blood cells (PRBC) at the infusate supply and distal end of the disposable tubing. Tubing lengths were equal for both systems. Devices were set at maximum flow while temperatures were measured as described previously. Flow was measured with a graduated cylinder and stopwatch. Air management was evaluated with a 10-mL air bolus injected proximal to the heat exchanger at maximum flow. Air passing through the system was collected and measured. At 250 mL/min, both devices provided infusate at >or=37 degrees C. At 500 mL/min, only the FMS 2000 provided PRBC at >or=37 degrees C. PRBC infusate temperature decreased over time with the Level 1 device. The FMS 2000 delivered PRBC at its maximum flow rate of 500 mL/min. The Level 1 attained a maximum flow of 575 mL/min of PRBC with a temperature of 32 degrees C. Air (10 mL) was recovered from the distal tubing of the Level 1. No air was recovered from the tubing of the FMS 2000. In this laboratory investigation, the FMS 2000 performance was superior with respect to providing PRBC at physiologic temperatures (at 500 mL/min) and with respect to air detection and elimination compared with current widely used pressure-infuser technology. ⋯ The FMS 2000 and Level 1 H1025 warming capabilities were similar at metered flows of 500 mL/min. At more rapid flow rates, which are achieved by the H1025, fluid warming decreases dramatically. The air-detection and -elimination system of the FMS 2000 is superior to that of the H1025.
-
Anesthesia and analgesia · Oct 2003
Analgesic synergy between topical morphine and butamben in mice.
Studies have revealed that lidocaine is an effective analgesic when applied topically to the tail of a mouse in the radiant heat tail-flick assay. In addition, the topical combination of lidocaine with morphine revealed synergistic interactions between the two drugs. In the current studies, we demonstrate that topical butamben, benzocaine, and bupivacaine are active in the radiant heat tail-flick assay. In this assay, topical lidocaine has a ceiling effect and displays a biphasic curve, with large doses markedly decreasing the responses almost to baseline levels. In contrast, butamben has an S-shape dose-dependent response in the assay and did not display a biphasic curve as seen with lidocaine, suggesting that topical butamben may have advantages over lidocaine. Both benzocaine and bupivacaine also showed dose-dependent analgesic activity in this model. Like lidocaine, butamben/morphine combinations displayed synergistic interactions. Indeed, the synergy appeared more prominent with a butamben/morphine combination. We also observed synergy between topical benzocaine and morphine. Although the bupivacaine/morphine combination was suggestive of synergy on isobolographic analysis, it did not achieve statistical significance. These studies indicate that a series of local anesthetics are all active topically in the radiant heat tail-flick assay in mice and that several interact synergistically with morphine. Of the local anesthetics tested, butamben seemed to have several pharmacological characteristics, alone and in combination with morphine, which suggest that it may be superior to the other local anesthetics. Together, these observations suggest that topical combinations of opioids and local anesthetics may prove clinically valuable. ⋯ Topical administration of the opioid micro -agonist morphine and the sodium channel inhibitors butamben and benzocaine results in a synergistic interaction for antinociception in radiant heat tail-flick assay in mice, suggesting that the combination of these drugs will enhance rather than detract from the analgesia of either alone.
-
Anesthesia and analgesia · Oct 2003
Use of operating room information system data to predict the impact of reducing turnover times on staffing costs.
Potential benefits to reducing turnover times are both quantitative (e.g., complete more cases and reduce staffing costs) and qualitative (e.g., improve professional satisfaction). Analyses have shown the quantitative arguments to be unsound except for reducing staffing costs. We describe a methodology by which each surgical suite can use its own numbers to calculate its individual potential reduction in staffing costs from reducing its turnover times. Calculations estimate optimal allocated operating room (OR) time (based on maximizing OR efficiency) before and after reducing the maximum and average turnover times. At four academic tertiary hospitals, reductions in average turnover times of 3 to 9 min would result in 0.8% to 1.8% reductions in staffing cost. Reductions in average turnover times of 10 to 19 min would result in 2.5% to 4.0% reductions in staffing costs. These reductions in staffing cost are achieved predominantly by reducing allocated OR time, not by reducing the hours that staff work late. Heads of anesthesiology groups often serve on OR committees that are fixated on turnover times. Rather than having to argue based on scientific studies, this methodology provides the ability to show the specific quantitative effects (small decreases in staffing costs and allocated OR time) of reducing turnover time using a surgical suite's own data. ⋯ Many anesthesiologists work at hospitals where surgeons and/or operating room (OR) committees focus repeatedly on turnover time reduction. We developed a methodology by which the reductions in staffing cost as a result of turnover time reduction can be calculated for each facility using its own data. Staffing cost reductions are generally very small and would be achieved predominantly by reducing allocated OR time to the surgeons.
-
Anesthesia and analgesia · Oct 2003
The hemodynamic and metabolic effects of shivering during acute normovolemic hemodilution.
To assess the hemodynamic and metabolic effects of shivering during extreme normovolemic hemodilution, we anesthetized 16 pigs with fentanyl-midazolam-pancuronium. Mild hypothermia (36.5 degrees +/- 0.1 degrees C) was induced by surface cooling, and the animals were randomized to either a control group (hemoglobin 118 +/- 3 g/L) or a hemodilution group (hemoglobin 52 +/- 2 g/L). In the latter group, blood was replaced with an isotonic Ringer's acetate/dextran 70 solution. Shivering was allowed to occur by a controlled decrease in the infusion rate of pancuronium. Shivering increased oxygen consumption (VO(2)) in both groups (P < 0.001). Initially, this was predominantly compensated for by an increased oxygen extraction ratio (ER), but when VO(2) was 2.3 +/- 0.2 times baseline, critical levels of mixed venous oxygenation (SVO(2) = 18% +/- 2%; PVO(2) = 22.5 +/- 1.5 mm Hg) and ER (82% +/- 3%) were recorded in anemic animals. Control animals did not reach critical levels until VO(2) was maximal (3.7 +/- 0.3 times baseline). Maximal attained VO(2) was less (2.9 +/- 0.1 times baseline) in the anemic animals (P = 0.01), and at this stage two of these pigs had myocardial lactate production, one of which died in ventricular fibrillation. Coronary perfusion pressure was significantly less (P < 0.001) in the anemic animals. We conclude that in this experimental model, maximal shivering as measured by VO(2) was limited in hemodiluted animals, and left ventricular oxygen balance was marginal, as evidenced by a decreased lactate uptake and extraction. ⋯ The effect of acute increases in oxygen consumption (shivering) on severely anemic individuals has not been evaluated. In this experimental model, left ventricular oxygen balance was marginal, as evidenced by decreased lactate extraction.
-
Anesthesia and analgesia · Oct 2003
Early identification of bacteria leading to central venous catheter contamination.
Catheter-related bloodstream infections (CRBSI) are a common problem in patients after central venous catheterization. Using DNA analysis we compared bacteria found on the tip of central venous catheters removed because of clinical signs of CRBSI with bacteria found on needle, dilator, and guidewire used for insertion of these catheters. In five of seven central venous catheters removed because of clinical signs of CRBSI, bacteria on the catheter tip were genetically identical to bacteria found on the insertion device, proving that catheter contamination in these cases was caused by contacting bacteria during the initial puncture. These findings may be important for antibiotic prophylaxis or therapy in patients at risk for CRBSI. ⋯ In five of seven central venous catheters removed because of clinical signs of catheter-related blood infections, DNA analysis showed bacteria found on the catheter tip to be identical with bacteria found on the puncture kits used for insertion of these catheters.