SummaryWe performed a randomised, blinded, controlled study with adult patients scheduled for primary total knee arthroplasty under spinal anaesthesia. The aim was to investigate the analgesic effects of adductor canal block using catheter‐based repeated boluses, either through a new suture‐method catheter or a standard perineural catheter, compared with a single‐injection technique. All patients received an adductor canal block after surgery with an initial bolus of 20 ml ropivacaine 0.75%, followed by 20 ml of ropivacaine 0.2% every 8 h in the standard and suture‐method catheter groups, and sham boluses for the single‐injection group. The primary outcome measure was total opioid consumption (intravenous morphine equivalents) from the end of surgery until 12:00 on postoperative day 2. Secondary outcomes were pain, muscle strength and ambulation. We randomly assigned (1:1:1) and analysed 153 patients. Total opioid consumption was median (IQR [range]) 24 (11–37 [0–148]) mg in the suture‐method group, 38 (17–51 [0–123]) mg in the standard catheter group and 37 (14–57 [0–158]) mg in the single‐injection group (p = 0.049). Differences were not statistically significant after Bonferroni correction (α = 0.05/3). There were no differences between groups on postoperative day 1. On postoperative day 2, there were no differences between catheter groups, but muscle strength and ambulation were improved compared with the single‐injection group. We conclude that providing repeated boluses via a catheter did not decrease opioid consumption or pain compared with a single injection, but improved muscle strength and ambulation on postoperative day 2. The two types of catheters were similar.
Running induces characteristic fluctuations in blood pressure (BP) of unknown consequence for organ blood flow. We hypothesized that running-induced BP oscillations are transferred to the cerebral vasculature. In 15 healthy volunteers, transcranial Doppler-determined middle cerebral artery (MCA) blood flow velocity, photoplethysmographic finger BP, and step frequency were measured continuously during three consecutive 5-min intervals of treadmill running at increasing running intensities. Data were analysed in the time and frequency domains. BP data for seven subjects and MCA velocity data for eight subjects, respectively, were excluded from analysis because of insufficient signal quality. Running increased mean arterial pressure and mean MCA velocity and induced rhythmic oscillations in BP and in MCA velocity corresponding to the difference between step rate and heart rate (HR) frequencies. During running, rhythmic oscillations in arterial BP induced by interference between HR and step frequency impact on cerebral blood velocity. For the exercise as a whole, average MCA velocity becomes elevated. These results suggest that running not only induces an increase in regional cerebral blood flow but also challenges cerebral autoregulation.
Background: Good quality basic life support (BLS) improves outcome following cardiac arrest. As BLS performance deteriorates over time we performed a parallel group, superiority study to investigate the effect of feedback on quality of chest compression with the hypothesis that feedback delays deterioration of quality of compressions. Methods: Participants attending a national one-day conference on cardiac arrest and CPR in Denmark were randomized to perform single-rescuer BLS with (n = 26) or without verbal and visual feedback (n = 28) on a manikin using a ZOLL AED plus. Data were analyzed using Rescuenet Code Review. Blinding of participants was not possible, but allocation concealment was performed. Primary outcome was the proportion of delivered compressions within target depth compared over a 2-minute period within the groups and between the groups. Secondary outcome was the proportion of delivered compressions within target rate compared over a 2-minute period within the groups and between the groups. Performance variables for 30-second intervals were analyzed and compared.
The sitting beach-chair position is regularly used for shoulder surgery and anesthesia may be induced in that position. We tested the hypothesis that the cardiovascular challenge induced by induction of anesthesia is attenuated if the patient is placed in a reclining beach-chair position. Anesthesia was induced with propofol in the sitting beach-chair (n = 15) or with the beach-chair tilted backwards to a reclining beach-chair position (n = 15). The last group was stepwise tilted to the sitting beach-chair position prior to surgery. Hypotension was treated with ephedrine. Continuous hemodynamic variables were recorded by photoplethysmography and frontal cerebral oxygenation (ScO2) by near infrared spectroscopy. Significant differences were only observed immediately after the induction when patients induced in a reclining beach-chair position had higher mean arterial pressure (MAP) (35 ± 12 vs. 45 ± 15 % reduction from baseline, p = 0.04) and ScO2 (7 ± 6 vs. 1 ± 8% increase from baseline, p = 0.02) and received less ephedrine (mean: 4 vs. 13 mg, p = 0.048). The higher blood pressure and lower need of vasopressor following induction of anesthesia in the reclining compared to the sitting beach-chair position indicate more stable hemodynamics with the clinical implication that anesthesia should not be induced with the patient in the sitting position.
BackgroundThe intraosseous (IO) access is an alternative route for vascular access when peripheral intravascular catheterization cannot be obtained. In Denmark the IO access is reported as infrequently trained and used. The aim of this pilot study was to investigate if medical students can obtain competencies in IO access when taught by a modified Walker and Peyton’s four-step approach.MethodsNineteen students attended a human cadaver course in emergency procedures. A lecture was followed by a workshop. Fifteen students were presented with a case where IO access was indicated and their performance was evaluated by an objective structured clinical examination (OSCE) and rated using a weighted checklist. To evaluate the validity of the checklist, three raters rated performance and Cohen’s kappa was performed to assess inter-rater reliability (IRR). To examine the strength of the overall IRR, Randolph’s free-marginal multi rater kappa was used.ResultsA maximum score of 15 points was obtained by nine (60%) of the participants and two participants (13%) scored 13 points with all three raters. Only one participant failed more than one item on the checklist. The expert rater rated lower with a mean score of 14.2 versus the non-expert raters with mean 14.6 and 14.3. The overall IRR calculated with Randolph’s free-marginal multi rater kappa was 0.71.ConclusionThe essentials of the IO access procedure can be taught to medical students using a modified version of the Walker and Peyton’s four-step approach and the checklist used was found reliable.
We performed a randomised double-blind pilot study in 16 healthy volunteers to investigate the success rate for placing a new suture-method catheter for sciatic nerve block. A catheter was inserted into both legs of volunteers and each was randomly allocated to receive 15 ml lidocaine 2% through the catheter in one leg and 15 ml saline in the other leg. Successful placement of the catheter was defined as a 20% decrease in maximum voluntary isometric contraction for dorsiflexion of the ankle. Secondary outcomes were maximum voluntary isometric contraction for plantar flexion at the ankle, surface electromyography and cold sensation. After return of motor and sensory function, volunteers performed standardised physical exercises; injection of the same study medication was repeated in the same leg and followed by motor and sensory assessments. Fifteen of 16 (94%; 95%CI 72-99%) initial catheter placements were successful. The reduction in maximum voluntary isometric contraction and surface electromyography affected the peroneal nerve more often than the tibial nerve. Eleven of 15 (73%; 95%CI 54-96%) catheters remained functional with motor and sensory block after physical exercise, and the maximal displacement was 5 mm. Catheters with secondary block failure were displaced between 6 and 10 mm. One catheter was displaced 1.8 mm that resulted in a decrease in maximum voluntary isometric contraction of less than 20%. After repeat test injection, 14 of the 16 volunteers had loss of cold sensation. Neither motor nor sensory functions were affected in the legs injected with placebo. We conclude that the suture-method catheter can be placed with a high success rate, but that physical exercise may cause displacement.
BackgroundWe performed a randomised blinded pilot study in 16 healthy volunteers to assess whether placing a suture‐method catheter in the adductor canal is feasible with two different insertion techniques.MethodsEach volunteer had a suture‐method catheter placed approximately halfway between the superior anterior iliac spine and base of the patella in both legs. Catheters were placed using a parallel technique in one leg and a perpendicular technique in the other leg, according to randomisation. 15 mL lidocaine 1% was injected in each catheter. Successful placement was defined as loss of cold sensation in the saphenous area 30 min after injection. Volunteers were sent home and returned the following day and another dose of lidocaine (15 mL, 1%) was injected through the catheters. Catheter displacement distance was assessed by ultrasound and cold sensation was assessed. In case of preserved cold sensation, we attempted to reposition the catheter with a subsequent injection of lidocaine and reassessment of cold sensation.ResultsAll primary placements were successful using the perpendicular approach (100%; 95% CI 81%‐100%) whereas one placement failed using the parallel approach (94%; 95% CI 72%‐99%). Three catheters placed using the perpendicular approach were displaced on day 2, compared to one catheter placed with the parallel approach. Displacement distance was highly variable. All catheters, except one, could be repositioned. Three volunteers reported transient sensory deficits lasting approximately 6‐8 weeks.ConclusionThe suture‐method catheter can be placed in the adductor canal with high success rates for initial placement with both techniques.
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