Anesthesia and analgesia
-
Anesthesia and analgesia · Mar 2004
The effects of a polymerized bovine-derived hemoglobin solution in a rabbit model of arterial thrombosis and bleeding.
Hemoglobin-based oxygen carriers (HBOCs) have been developed primarily for their oxygenating function and possible use as an alternative to red blood cells during surgery or after major trauma. However, their effect on hemostasis has not been studied extensively. We compared the effects on hemostasis of bovine-derived hemoglobin solution (HBOC-201) with gelatin solution and saline infusion in an experimental model of arterial thrombosis and bleeding. After anesthesia, the Folts model was constructed in 30 rabbits. The common carotid artery was exposed, and a 60% stenosis was induced. A compression injury of the artery was then produced, which triggered a series of cyclic episodes of thrombosis (cyclic flow reductions [CFRs]). After the number of baseline CFRs was counted, animals were assigned randomly to one of three groups (n = 10 each): saline (control), gelatin, or HBOC-201 solution. The effect of studied solutions was observed by recording the number of CFRs during another period and was compared with that of saline. Ear immersion bleeding time was recorded after each CFR period. Gelatin and HBOC-201 had similar effects, manifested by significantly decreased CFRs (from median of 7 to 1 and 6 to 1, respectively) and significantly lengthened bleeding time (from 88 to 98 s and 81 to 102 s, respectively; P < 0.05). Saline infusion had no significant effect on CFRs or bleeding time. HBOC-201 and gelatin had similar effects marked by a reduction in the arterial thrombosis rate and increased bleeding time in rabbits. ⋯ In a rabbit thrombosis and hemorrhagic model, a polymerized bovine-derived hemoglobin solution and a gelatin solution infusion decreased arterial thrombosis and lengthened bleeding time.
-
Anesthesia and analgesia · Mar 2004
Case ReportsTransesophageal echocardiographic diagnosis of a liver laceration accompanied by hemodynamic instability.
Transesophageal echocardiography (TEE) is a useful adjunct in the evaluation of trauma patients, particularly in the area of aortic injury and cardiac tamponade. Little has been written on the use of this modality in the evaluation of extra-cardiac injury. We present a case of a trauma patient in whom TEE was used to evaluate hemodynamic instability; during the course of the examination a previously undiagnosed liver laceration was identified. We report the diagnosis of a liver laceration in a trauma patient by novel use of the transesophageal echocardiographic imaging modality.
-
Anesthesia and analgesia · Mar 2004
Functional residual capacity and respiratory mechanics as indicators of aeration and collapse in experimental lung injury.
Increased functional residual capacity (FRC) and compliance are two desirable, but seldom measured, effects of positive end-expiratory pressure (PEEP) in mechanically ventilated patients. To assess how these variables reflect the morphological lung perturbations during the evolution of acute lung injury and the morphological changes from altered PEEP, we correlated measurements of FRC and respiratory system mechanics to the degree of lung aeration and consolidation on computed tomography (CT). We used a porcine oleic acid model with FRC determinations by sulfur hexafluoride washin-washout and respiratory system mechanics measured during an inspiratory hold maneuver. Within the first hour, during constant volume-controlled ventilation with PEEP 5 cm H(2)O, FRC decreased by 45% +/- 15% (P = 0.005) and compliance decreased by 35% +/- 12% (P = 0.005). Resistance increased by 60% +/- 62% (P = 0.005). Only the FRC changes correlated significantly to the decreased aeration (R(2) = 0.56; P = 0.01) and the increased consolidation (R(2) = 0.43; P = 0.04) on CT. When the PEEP was changed to either 10 or 0 cm H(2)O, there were larger changes in FRC than in compliance. We conclude that, in our model, FRC was a more sensitive indicator of PEEP-induced aeration and recruitment of lung tissue and that FRC may be a useful adjunct to PaO(2) monitoring. ⋯ Lung injury was quantified on computed tomography and related to monitored values of functional residual capacity and mechanical properties of the respiratory system. We found the functional residual capacity to be a more sensitive marker of the lung perturbations than the compliance. It might be of value to include functional residual capacity in the monitoring of acute lung injury.
-
Anesthesia and analgesia · Mar 2004
Clinical TrialAnalgesia after total knee arthroplasty: is continuous sciatic blockade needed in addition to continuous femoral blockade?
Continuous femoral "3-in-1" nerve blocks are commonly used for analgesia after total knee arthroplasty (TKA). There are conflicting data as to whether additional sciatic blockade is needed. Our routine use of both continuous femoral (CFI) and sciatic (CSI) peripheral nerve blocks was changed because of concerns that sciatic blockade, and its motor consequences in particular, might obscure diagnosis of perioperative sciatic nerve injury. ⋯ Within 1 h of a 5-10 mL CSI bolus of 0.2% ropivacaine and beginning an infusion of the same drug at 5 mL/h, patients' median pain by verbal analog scale decreased from 7.5 to 2.0 (mean scores from 7.3 to 2.4). It was possible to maintain this level of analgesia until the third postoperative day when catheters were discontinued. Our experience suggests that, in most patients, adequate analgesia after TKA cannot be achieved with CFI alone and that the addition of CSI renders a significant improvement in analgesia.
-
Anesthesia and analgesia · Mar 2004
Attenuation of gap-junction-mediated signaling facilitated anesthetic effect of sevoflurane in the central nervous system of rats.
Accumulating evidence suggests that reduction of intrinsic excitability or synaptic excitation and/or an enhancement of synaptic inhibition underlie the general anesthetic condition. Besides chemical synapse, neurons could communicate with each other by electrical coupling via gap-junctions. We hypothesized that inhibition of cell-to-cell signaling through gap-junction in the central nervous system (CNS) is involved in the anesthetic mechanism of volatile anesthetics. The minimum alveolar concentration (MAC) of sevoflurane was measured after the intracerebroventricular (ICV) or intrathecal (IT) administration of carbenoxolone (CBX), a gap-junction inhibitor, in vivo. The spontaneous oscillation in membrane currents of locus coeruleus neurons that results from electrical coupling between neurons was also recorded from young rat pontine slices by the patch clamp method, and the effect of sevoflurane on this oscillation was examined in vitro. The ICV administration of CBX (125 and 250 micro g/rat) significantly reduced the MAC of sevoflurane dose-dependently, whereas IT injection failed to inhibit the MAC. Sevoflurane at clinically relevant concentrations (0.1-0.5 mM) suppressed the spontaneous oscillation in membrane current concentration-dependently. These suppressions were significant at 0.5 mM with both amplitude and frequency. We suggest that suppression of gap-junction-mediated signaling in the CNS is involved in the anesthetic-induced immobilization by sevoflurane. ⋯ The intracerebroventricular administration of the gap-junction inhibitor, carbenoxolone, reduced the MAC of sevoflurane, and sevoflurane suppressed the signaling through gap-junctions in the central nervous system. The inhibition of gap-junctions may be one of the mechanisms and the site of action of sevoflurane.