Three-in-one blocks with ropivacaine: evaluation of sensory onset time and quality of sensory block.

UNLABELLED: The purpose of this prospective, randomized, double-blinded study was to evaluate the sensory onset time and the quality of sensory block of ropivacaine, a new long-acting local anesthetic, compared with bupivacaine, for 3-in-1 blocks. Fifty ASA physical status I-III patients undergoing hip surgery after trauma were randomly assigned to two study groups of 25 patients each. The two study groups received a 3-in-1 block with either 20 mL of ropivacaine 0.5% or 20 mL of bupivacaine 0.5%. Blocks in both groups were performed using a nerve stimulator. The sensory onset time and the quality of sensory block was assessed by pinprick test in the central sensory region of each of the three nerves and compared with the same stimulation in the contralateral leg. We used a scale from 100% (normal sensation) to 0% (no sensory sensation). We did not find significant differences in sensory onset times between the ropivacaine group and the bupivacaine group (30+/-11 vs 32+/-10 min). The quality of sensory blocks was also comparable between the study groups (19%+/-20% vs 21%+/-15%). We conclude that the sensory onset time and quality of sensory block during 3-in-1 blocks performed with ropivacaine are comparable to those with bupivacaine. Ropivacaine is described as being less potent than bupivacaine, making this local anesthetic promising for 3-in-1 blocks because of its reportedly lower incidence of cardiovascular and central nervous system complications. IMPLICATIONS: Ropivacaine 0.5% has a sensory onset time and quality of sensory block during 3-in-1 blocks similar to that of bupivacaine 0.5%. Ropivacaine is described as being less potent than bupivacaine, making it a promising local anesthetic for 3-in-1 blocks because of its reportedly lower cardiovascular and central nervous system toxicity.

Controlled airway pressure therapy, nitric oxide inhalation, prone position, and extracorporeal membrane oxygenation (ECMO) as components of an integrated approach to ARDS.

BACKGROUND: Recent years have seen the introduction of innovative additive therapies for acute respiratory distress syndrome. However, because there are no reliable predictors of response to a particular therapy, potential responders to a specific therapeutic intervention may be lost. Therefore, the authors evaluated the effect of a combined therapeutic approach on the survival of patients with acute respiratory distress syndrome, when treated according to a strict algorithm. METHODS: During a 2.5-yr period, 84 patients with acute respiratory distress syndrome were assigned to a standardized treatment protocol. Data analysis was performed by retrospective review of patient charts. Patients were treated using a stepwise treatment algorithm of pressure-controlled ventilation (peak airway pressure < 35 cm H2O), positive end-expiratory pressure (PEEP; 12-15 cm H2O), permissive hypercapnia, inhaled nitric oxide (5-20 ppm), and prone positioning. These interventions were termed "conventional therapy." Response to treatment was defined as a more than 20% increase in arterial oxygen tension (PaO2). Nonresponders were triaged to extracorporeal membrane oxygenation. RESULTS: The overall survival rate was 80%. All patients received conventional therapy up to 96 h; 71 responded to conventional therapy and 59 survived (83%). Thirteen patients (15%) did not respond to conventional therapy and underwent extracorporeal membrane oxygenation; 8 of these patients (62%) survived. For the group, the mean admission lung injury score was 3.3+/-0.5, the PaO2/fractional inspired oxygen tension (F(I)O2) ratio was 96+/-45, and the Acute Physiology and Chronic Health Evaluation (APACHE) II score was 18+/-6. CONCLUSIONS: The 80% overall survival rate achieved in this group of patients with severe acute respiratory distress syndrome may in part reflect the additive beneficial effects of combined treatment methods, such as airway pressure control, nitric oxide inhalation, prone position, and early triage of nonresponders to extracorporeal membrane oxygenation.

Cardiovascular effects of 6% hetastarch and lactated Ringer's solution during spinal anesthesia.

BACKGROUND AND OBJECTIVES: The purpose of this prospective, randomized, double-blinded study was to compare the hemodynamic effects of 6% hetastarch with lactated Ringer's solution and to determine the main reasons for hemodynamic impairment following spinal anesthesia in elderly patients undergoing emergent hip surgery. METHODS: After receiving institutional approval and informed consent, we enrolled 24 ASA physical status III patients for this study. Hemodynamics were recorded with pulmonary artery and arterial catheters and an electrocardiogram. Following fluid administration with either 500 mL 6% hetastarch (group H) or 1500 mL lactated Ringer's solution (group R), spinal anesthesia was administered with 3.0 mL 0.5% bupivacaine (isobaric). Hemodynamic measurements were recorded prior to fluid administration, before spinal anesthesia, and 10, 20, and 30 minutes following spinal anesthesia and reported as relative changes relating to baseline. RESULTS: Although the hemodynamic measurements after spinal anesthesia remained stable in group H throughout the observation period, blood pressure, central venous pressure, pulmonary artery (PA) wedge pressure and systemic vascular resistance decreased significantly in group R (blood pressure: -7 +/- 10 vs - 14 +/- 8% 30 minutes after spinal anesthesia, P < .05 to group R; central venous pressure: 51 +/- 106 vs -26 +/- 27% 10 minutes, 63 +/- 89 vs -36 +/- 30% 20 minutes and 73 +/- 112 vs -33 +/- 29% 30 minutes after spinal anesthesia, P < .01 to group R; PA wedge pressure: 40 +/- 37 vs -5 +/- 40% 10 minutes, 40 +/- 35 vs -23 +/- 32% 20 minutes and 38 +/- 36 vs -23 +/- 32% 30 minutes after spinal anesthesia, P < .01 to group R; systemic vascular resistance: -10 +/- 16 vs -18 +/- 7% 20 minutes and -10 +/- 15 vs - 19 +/- 12% 30 minutes after spinal anesthesia, P < .05 to group R). CONCLUSIONS: Six percent hetastarch minimizes the hemodynamic responses during spinal anesthesia in elderly patients undergoing emergent hip surgery. In this study population, spinal anesthesia-induced hemodynamic impairment is caused by decreases in cardiac filling pressures and systemic vascular resistance.

Additive effect of nitric oxide inhalation on the oxygenation benefit of the prone position in the adult respiratory distress syndrome.

BACKGROUND: The response to inhaled nitric oxide and prone positioning was investigated in 47 patients with adult respiratory distress syndrome to test the hypothesis that inhalation of nitric oxide when in the prone position would result in additive improvement in oxygenation. METHODS: The authors prospectively studied patients of both genders who were 15 to 75 yr old and had adult respiratory distress syndrome confirmed by computed tomography (lung injury score, 3.1+/-1). RESULTS: Compared with baseline values in the supine position (T1), inhalation of 10 ppm nitric oxide for 1 h (T2) decreased the mean pulmonary artery pressure from 33+/-9 mmHg to 28+/-6 mmHg (P < 0.05; T2 vs. T1) and increased the ratio of the partial pressure of oxygen in arterial blood (PaO2) to inspired oxygen concentration (FiO2) from 115 (median first quartile [Q1] 97, median third quartile [Q3] 137) to 148 (Q1 132, Q3 196) (P < 0.05; T2 vs. T1). Cessation of nitric oxide brought the values back to baseline (T3). Two hours of prone positioning (T4) significantly increased the PaO2:FiO2 ratio (T4 vs. T3). However, after an additional hour of nitric oxide inhalation in the prone position (T5), a significant decrease of the venous admixture (from 33+/-6% to 25+/-6%; P < 0.05) and an increase of the PaO2:FiO2 ratio (from 165 [Q1 129, Q3 216] to 199 [Q1 178, Q3 316] [P < 0.05; T5 vs. T4]) were observed. CONCLUSIONS: In patients with isolated severe adult respiratory distress syndrome, inhalation of nitric oxide in the prone position significantly improved oxygenation compared with nitric oxide inhalation in the supine position or in the prone position without nitric oxide. The combination of the prone position with nitric oxide inhalation in the treatment of severe adult respiratory distress syndrome should be considered.

Clonidine: an adjunct in isoflurane N2O/O2 relaxant anaesthesia. Effects on EEG power spectra, somatosensory and auditory evoked potentials.

We investigated the effect of clonidine in 19 patients having lumbar disc surgery under nitrous oxide/isoflurane/relaxant anaesthesia. The EEG, spinal and cortical somatosensory evoked potentials, and the brainstem auditory evoked potentials were recorded. After equilibration of the general anaesthetic, two successive infusions of clonidine (5 micrograms.kg-1) were given. After the second infusion of clonidine, the plasma concentration increased from 0.2(SEM 0.05) to 6.4(SEM 0.06) ng.ml-1 (p < 0.05). In the EEG, delta-activity was maintained, but the beta-fraction, and the 95% and 50% spectral frequencies were reduced. Total EEG power progressively decreased from 296(152-397) microV2 to 108(51-240) microV2. The somatosensory evoked spinal potential (N13) decreased in amplitude, (1.77(SEM 0.35) microV to 1.59(SEM 0.35) microV, p < 0.05) and increased in latency (14.37(SEM 0.29) ms to 14.69(SEM 0.31) ms, p < 0.05). The central conduction time increased from 6.47(SEM 0.16) ms to 6.92(SEM 0.25) ms, ns. There was no effect on the cortical somatosensory potentials, or the brainstem auditory evoked potentials. According to the EEG spectral indices, anaesthesia appeared to deepen despite a reduction in the end expiratory isoflurane concentration from 0.53(SEM 0.07) to 0.28(SEM 0.06) vol%, which indicated a reduction in anaesthetic requirements following clonidine.

Forced-air warming maintains intraoperative normothermia better than circulating-water mattresses.

The hypothesis that forced-air warming preserves core temperature better than circulating-water mattresses was tested in: (a) 16 adults undergoing major maxillofacial surgery, including radical node resection and flap reconstruction; (b) 53 adults undergoing hip arthroplasty, having approximately 25% of their body surface area available for warming; (c) 20 infants undergoing minor maxillofacial surgery; and (d) 10 young children undergoing pelvic or femoral osteotomies. Patients having each type of surgery were randomly assigned to forced-air warming (approximately 40 degrees C) or conductive warming using a full-length circulating-water mattress at 40 degrees C. Forced-air warming was applied to the legs of the adults undergoing maxillofacial surgery and to one arm, the shoulders, and the neck in the adults undergoing hip arthroplasty; a U-shaped, tubular forced-air cover was positioned around the pediatric patients. Core temperatures increased in all patients given forced-air warming and decreased or remained constant in those without active warming. Furthermore, we needed to decrease the temperature of the warmer from high to medium (approximately 37 degrees C) in most patients assigned to forced-air warming to prevent hyperthermia. After 15 h of anesthesia, rectal temperatures in the adults undergoing maxillofacial surgery were 3.4 degrees C higher in the forced-air group (P < 0.01). After 4 h of anesthesia, esophageal temperatures had increased 0.8 +/- 0.5 degrees C in the patients warmed with forced-air and decreased 0.8 +/- 0.3 degrees C in those warmed by circulating-water mattresses (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)