Skin temperature measured by infrared thermography after ultrasound-guided blockade of the sciatic nerve.

BACKGROUND: In the present study, we assessed the relationship between subgluteal sciatic nerve blocking and skin temperature by infrared thermography in the lower extremity. We hypothesized that blocking the sciatic nerve will lead to an increase in temperature, and that this will correlate with existing sensory block tests. METHODS: We studied 18 healthy individuals undergoing orthopaedic surgery of the foot under ultrasound-guided subgluteal blockade of the sciatic nerve with 30 ml ropivacaine 7.5 mg/ml. Skin temperature was measured on the toes, the dorsal and plantar side of the foot, the malleoli, and the lateral side of the lower leg, just before sciatic nerve blockade and at 10-min intervals thereafter. RESULTS: Baseline skin temperatures showed a significant distal-to-proximal gradient. After sciatic block, temperatures on the blocked side increased significantly in the toes and foot. When comparing pinprick to skin temperature in a receiver operating curve, there was an AUC of 85.9% (95% confidence interval = 83.7-88.2%, P < 0.001). The medial malleolus (not being innervated by the sciatic nerve) showed no significant difference to the lateral. CONCLUSIONS: After sciatic nerve block, temperatures of the foot increased significantly. There was a good correlation between pinprick testing and infrared temperature measurement. This makes infrared skin temperature measuring a good test in determining block success when sensory testing is impossible.

The effect of addition of pregabalin and s-ketamine to local infiltration analgesia on the knee function outcome after total knee arthroplasty.

Pain reduction is important for early mobilization after total knee arthroplasy. Recent studies show that local infiltration analgesia and addition of anti-hyperalgesic drugs (pregabalin and s-ketamine) may improve postoperative analgesia and mobilization. This pilot study was meant to evaluate if this new method of analgesia might improve patients' ability to exercise in the first postoperative days. The secondary goal was to determine what side effects could be expected by using this drug combination. A pilot study showed that patients achieved knee flexion of 88.5 degrees (SD 9.6) already on the second postoperative day. The side effects were mild and mostly self-limiting.

Train-of-four ratio recovery often precedes twitch recovery when neuromuscular block is reversed by sugammadex.

BACKGROUND: Sugammadex reverses rocuronium-induced neuromuscular block (NMB). In all published studies investigating sugammadex, the primary outcome parameter was a train-of-four (TOF) ratio of 0.9. The recovery time of T1 was not described. This retrospective investigation describes the recovery of T1 vs. TOF ratio after the reversal of NMB with sugammadex. METHODS: Two studies were analyzed. In study A, a phase II dose-finding study, ASA I-II patients received an intravenous (IV) dose of rocuronium 1.2 mg/kg, followed by an IV dose of sugammadex (2.0, 4.0, 8.0, 12.0 or 16.0 mg/kg) or placebo (0.9% saline) after 5 min. In study B, a phase III trial comparing patients with renal failure and healthy controls, rocuronium 0.6 mg/kg was used to induce NMB; sugammadex 2.0 mg/kg was administered at reappearance of T2. Neuromuscular monitoring was performed by acceleromyography and TOF nerve stimulation. The primary efficacy variable was time from the administration of sugammadex to recovery of the TOF ratio to 0.9. Retrospectively, the time to recovery of T1 to 90% was calculated. RESULTS: After the reversal of rocuronium-induced NMB with an optimal dose of sugammadex [16 mg/kg (A) or 2 mg/kg (B)], the TOF ratio recovered to 0.9 significantly faster than T1 recovered to 90%. Clinical signs of residual paralysis were not observed. CONCLUSION: After the reversal of NMB by sugammadex, full recovery of the TOF ratio is possible when T1 is still depressed. The TOF ratio as the only measurement for the adequate reversal of NMB by sugammadex may not always be reliable. Further investigations for clinical implications are needed.

Reduced clearance of rocuronium and sugammadex in patients with severe to end-stage renal failure: a pharmacokinetic study.

BACKGROUND: Sugammadex is a selective relaxant binding agent designed to encapsulate the neuromuscular blocking agent, rocuronium. The sugammadex-rocuronium complex is eliminated by the kidneys. This trial investigated the pharmacokinetics (PKs) of sugammadex and rocuronium in patients with renal failure and healthy controls. METHODS: Fifteen ASA class II-III renal patients [creatinine clearance (CL(CR)) <30 ml min(-1)] and 15 ASA I-II controls (CL(CR) > or =80 ml min(-1)) were included. After induction of anaesthesia, a single i.v. dose of rocuronium 0.6 mg kg(-1) was given, followed by a single i.v. dose of sugammadex 2.0 mg kg(-1) at reappearance of the second twitch of the train-of-four response. Plasma concentrations of rocuronium and sugammadex were estimated and PK variables determined using non-compartmental analyses. Percentages of sugammadex and rocuronium excreted in the urine were measured. RESULTS: PK data were obtained from 26 patients. Mean total plasma clearance (CL) of sugammadex was 5.5 ml min(-1) in renal patients and 95.2 ml min(-1) in controls (P<0.05). Rocuronium CL was 41.8 ml min(-1) in renal patients and 167 ml min(-1) in controls (P<0.05). The median amount of sugammadex and rocuronium excreted in the urine over 72 h in renal patients was 29% and 4%, respectively, and 73% and 42% over 24 h in controls. CONCLUSIONS: Large differences in the PKs of sugammadex and rocuronium between patients with renal failure and healthy controls were observed. The effect of renal impairment on the PK variables of rocuronium was less than with sugammadex. Urinary excretion of both drugs was reduced in renal patients.

The relation between skin temperature increase and sensory block height in spinal anaesthesia using infrared thermography.

BACKGROUND AND OBJECTIVES: To evaluate the feasibility of determining the extent of sympathetic blockade by skin temperature measurement with infrared thermography and relate the cranial extent of the temperature increase to that of the sensory block after spinal anaesthesia. METHODS: Before and 5, 10 and 20 min after the administration of spinal anaesthesia, skin temperatures were measured with infrared thermography at the dermatomes T2-L3, in 12 male patients scheduled for lower limb surgery. The most cephalad dermatome at which sensory blockade occurred was related to the dermatome at which the largest temperature jump (corrected for baseline temperature) occurred. RESULTS: The baseline temperatures showed considerable variation across the dermatomes, being lower below T12 than at the thoracic dermatomes. The mean difference between the level of the cephalad skin temperature elevation front (mean 1.03 °C, SD 0.8 °C) and cranial sensory block height was 0.10 dermatomes (SD 1.16), correlation coefficient (0.88, P<0.001). CONCLUSION: The varying baseline temperatures across the trunk, the limited sympathetic block-induced increase in skin temperature at the trunk and the difficult control of influences from the surroundings partly obscured the extent of the skin temperature increase and its correlation to sensory block height. These factors have to be controlled to improve the use of infrared cameras as an easy bedside tool for predicting the cranial extent of (sympathetic blockade during) spinal anaesthesia.

An unexpected outcome of cervical near-hanging injury. A case report.

Cervical near-hanging injuries are most frequent in the young adult population. However, the literature gives little guidance regarding diagnostic evaluation of these patients, although it is well known that their initial clinical presentation has limited prognostic value. This case report presents a patient who actually survived a suicidal near-hanging attempt and was later able to walk and talk to his physician. He died the next day due to carotid dissection and cerebral ischemia. In this case report we emphasize the importance of thorough radiological investigation in the accurate assessment of these patients. Early imaging should be performed routinely after near-hanging injury, in order to establish the correct diagnosis and allow appropriate treatment to be started.

A new approach to anesthesia management in myasthenia gravis: reversal of neuromuscular blockade by sugammadex.

A neuromuscular blocking drug (NMBD) induced neuromuscular blockade (NMB) in patients with myasthenia gravis usually dissipates either spontaneously or by administration of neostigmine. We administered sugammadex to a patient with myasthenia gravis to reverse a rocuronium-induced profound NMB. NMBDs predispose such patients to severe postoperative residual paralysis and respiratory complications. Sugammadex binds steroidal NMBDs and, therefore reverses a rocuronium or vecuronium-induced NMB, without interfering with cholinergic transmission. A rapid and complete recovery from profound NMB was achieved and no adverse events were observed. This case suggests that sugammadex is a safe and effective antagonist of a rocuronium induced NMB blockade in patients with myasthenia gravis.

Continuous femoral nerve block after total knee arthroplasty?

BACKGROUND: A continuous femoral nerve block is frequently used as an adjunct therapy after total knee arthroplasty (TKA). However, there is still debate on its benefits. METHODS: In this prospective, randomized study, patients received a basic analgesic regimen of paracetamol and dicloflenac for the first 48 h postoperatively. In addition, the study group received a continuous femoral nerve block. A morphine patient-controlled analgesia pump was also available as a rescue analgesic to all the patients. Patients' numeric rating scores for pain, the amount of morphine consumed and its side effects during the first 48 h were recorded. Knee flexion angles achieved during the first week were registered. Three months postoperatively, patients completed Western Ontario and McMaster Universities Osteoarthritis Index and Knee Society Score. RESULTS: The study group (n=27) had less pain (P=0.0016) during the first 48 h, was more satisfied with the analgesia (P<0.001) and used less morphine (P=0.007) compared with the control group (n=26). Fewer patients were nauseated, vomited or were drowsy in the study group (P=0.001). Also, the study group achieved better knee flexion in the first 6 days after surgery (P=0.001), with more patients reaching 90 degrees flexion than the control group. However, after 3 months, there were no significant functional differences between the groups. CONCLUSION: A continuous femoral nerve block leads to better analgesia, less morphine consumption and less morphine-related side effects after TKA. Early functional recovery is improved, resulting in more patients reaching 90 degrees knee flexion after 6 days. However, after 3 months, no significant functional benefits were found.

In vivo animal studies with sugammadex.

A review is presented of animal studies of the selective steroidal neuromuscular blocking drug binding agent sugammadex. These studies demonstrate that sugammadex is faster in onset than the currently used acetylcholinesterase inhibitors, has no muscarinic effects, and is characterised by lack of adverse effects on other organs. These results offer support for the further development of sugammadex for clinical use in humans.

The effect of neuromuscular blockade on oxygen consumption in sedated and mechanically ventilated pediatric patients after cardiac surgery.

OBJECTIVE: To measure the effect of intense neuromuscular blockade (NMB) on oxygen consumption (VO(2)) in deeply sedated and mechanically ventilated children on the first day after complex congenital cardiac surgery. DESIGN: Prospective clinical interventional study. SETTING: Pediatric intensive care unit of an university medical centre. MEASUREMENTS AND RESULTS: Nine mechanically ventilated and sedated children (weight 2.8-8.7 kg) were included. All children were treated with vasoactive drugs. The level of sedation was quantified using the comfort score, Ramsay score and bispectral index (BIS). The intensity of NMB was quantified using acceleromyography and VO(2) was measured using indirect calorimetry. Analgo-sedation using various intravenous agents was targeted at a deep level (comfort score < 18, BIS < 60 and Ramsay score > 4). NMB was achieved by intravenous administration of rocuronium. All measurements were conducted before, during and after recovery from a period of intense NMB. Baseline values were VO(2) 6.1 ml/(kg min) (SD 1.3), comfort score 13 (SD 0.7), BIS 42.5 (SD 14.2), mean blood pressure 54.0 mmHg (SD 10.5), mean heart rate 129.9 bpm (SD 28.9) and mean core temperature 36.7 degrees C (SD 0.5). There were no significant differences in VO(2) or other parameters between baseline, during NMB and the recovery phase. CONCLUSION: Neuromuscular blocking agents do not reduce oxygen consumption in deeply sedated and mechanically ventilated children after congenital cardiac surgery.

Multicentre, parallel-group, comparative trial evaluating the efficacy and safety of sugammadex in patients with end-stage renal failure or normal renal function.

BACKGROUND: Sugammadex, a modified gamma-cyclodextrin, is the first selective relaxant binding agent that specifically encapsulates the steroidal neuromuscular blocking agent, rocuronium. The action of rocuronium is prolonged in patients with renal failure. As sugammadex is primarily cleared renally, this phase III trial investigated the efficacy and safety of sugammadex for reversal of rocuronium-induced neuromuscular block (NMB) in patients with end-stage renal failure. METHODS: Thirty adult patients were studied: 15 renally impaired [creatinine clearance (CL(CR)) <30 ml min(-1)] and 15 controls (CL(CR)>80 ml min(-1)). Anaesthesia was induced and maintained using i.v. opiates and propofol. Neuromuscular monitoring was performed by acceleromyography and train-of-four (TOF) nerve stimulation. Rocuronium (0.6 mg kg(-1)) was given, followed by a single i.v. dose of sugammadex (2.0 mg kg(-1)) at reappearance of the second twitch of the TOF. The primary efficacy variable was time from administration of sugammadex to recovery of the TOF ratio to 0.9. Safety variables included clinical evidence of reoccurrence of NMB. RESULTS: After sugammadex administration, the mean (sd) time to recovery of the TOF ratio to 0.9 was 2.0 (0.72) min in renal patients and 1.65 (0.63) min in controls (NS). Recurrence of NMB was not observed in any patient. No sugammadex-related serious adverse events were reported. CONCLUSIONS: Sugammadex administered at reappearance of T(2) rapidly and effectively reverses NMB induced by rocuronium in renal failure and healthy patients. Sugammadex was well tolerated by all patients. Further safety studies on sugammadex in patients with severe renal impairment are warranted.

Depth of the thoracic epidural space in children.

Thoracic epidural anaesthesia in anaesthetized children requires a meticulous technique and may have an increased success rate when the distance between skin and epidural space is known. The objective of this observational study was to measure the skin to epidural distance (SED) during thoracic epidural puncture in 61 children. The epidural puncture was performed using the loss of resistance technique with saline 0.9%. The distance from the needle tip to the point where the needle emerged from the skin was measured. The post-operative analgesia parameters were also measured. Skin to epidural distance correlated significantly with the age and weight of the children. The equation for the relation between SED (cm) and age was 2.15 + (0.01 x months) and for SED vs weight was 1.95 + (0.045 x kg). Despite considerable variability among individuals, the observed correlation of SED with both age and weight shows that this parameter may be helpful to guide thoracic epidural puncture in anaesthetized children.

Decreased plasma albumin concentration results in increased volume of distribution and decreased elimination of midazolam in intensive care patients.

The pharmacokinetic parameters of 16 patients in the intensive care unit, sedated with midazolam, were evaluated. A large variation was observed in the plasma concentration of midazolam and between the plasma concentration of midazolam and its metabolite 1-hydroxymethylmidazolam glucuronide. The plasma albumin concentration governs the volume of distribution of midazolam. Decreased plasma albumin concentration (25 gm/L) results in an increased volume of distribution and a decreased elimination rate of midazolam. The observed plasma concentration ratio between the parent drug and its metabolite 1-hydroxymethylmidazolam glucuronide is governed by the variables of protein binding, the metabolic rate of midazolam, and the renal clearance of the glucuronide metabolite itself (which can be considered as a measure of the kidney function of the patient).

Epidural administration of morphine for control of cancer pain: long-term efficacy and complications.

The long-term analgesic effects and the complications of epidural narcotic analgesia (ENA) were investigated in 40 cancer patients in whom systemic narcotic therapy failed to relieve pain or caused unacceptable side effects. In 32 patients, an externally fixated polyamide epidural catheter was used ("external group"), and in 8 patients, a polyurethane epidural catheter was tunneled and connected to a subcutaneous access port ("internal group"). The average duration of catheter treatment was 80.9 days (range 9-533 days). Twenty-five patients were treated as outpatients, and 15 remained hospitalized. Initially, all patients had significant or complete pain relief from 10 mg morphine/day, but the daily epidural morphine requirement showed a threefold increase during the first 3 weeks. During ENA, other methods of pain relief (radiotherapy, chemotherapy, surgery, epidural administration of local anesthetics, and nerve blocks) were necessary in 14 patients. Pharmacological side effects were of minor importance, with transient pruritus being the main subjective complaint. In the "external" group, 31 catheter replacements were necessary, mostly due to backflow of injected morphine outside the catheter. In two patients of the internal group, neurological complications occurred, but these disappeared spontaneously after removal of the system. They were presumably due to epidural fibrosis with compression of the spinal cord. Further technical improvements are necessary for the easier use and higher safety of the catheter technique.

Effect of some benzodiazepines on peripheral neuromuscular function in the rat in-vitro hemidiaphragm preparation.

The effect of equimolar cumulative concentrations of 11 different benzodiazepines on the indirectly evoked twitch contraction was investigated in the rat in-vitro phrenic nerve-hemidiaphragm preparation. Depending on the pattern of the concentration-response curves two groups of benzodiazepines can be distinguished: (i) a first group with a biphasic action, e.g. potentiation of twitch tension in low concentrations and depression of twitch tension in high concentrations, and (ii) a second group with primary depression of twitch tension with increasing concentrations. All of the tested compounds ultimately caused a 100% depression of twitch tension at concentrations ranging from 0.175 to 0.35 mmol litre-1. Although this peripheral effect of benzodiazepines on neuromuscular function is not the main site of action of these compounds, there are enough arguments to state that it is not a simple toxic effect. There is some evidence from this study that the peripheral component of the benzodiazepine effect on muscle relaxation may involve a multi- rather than one single receptor system.

Pharmacokinetics of diazepam and four 3-hydroxy-benzodiazepines in the cat.

Biotransformation and elimination of diazepam and four 3-hydroxy-benzodiazepines after i.v. injection in anaesthetized cats were investigated. Decay of plasma concentration of 3-hydroxy-benzodiazepines was slow and plasma concentrations of their glucuronides were lower than of unchanged parent compounds. In the urine, very low excretion rates of all investigated benzodiazepines were found during the first eight hours. It is concluded that cats poorly glucuronidate 3-dydroxy-benzodiazepines.

The effects of acute changes in renal function on the pharmacokinetics of midazolam during long-term infusion in ICU patients.

This study investigated the pharmacokinetics of midazolam and its main metabolite, 1-hydroxymethylmidazolam glucoronide, during long-term i.v. infusion in 39 mechanically ventilated ICU patients of whom 6 were in acute renal failure (ARF). The mean infusion rate of midazolam was similar (9.4 vs 8.7 mg/h) in the control patients and those with ARF. The renal clearance of 1-hydroxymethylmidazolam glucuronide was much lower in the ARF group than in the control group (3.9 vs 136 ml/min). Consequently, its plasma elimination half-life after discontinuation was also greatly prolonged, but this shouldn't cause very prolonged sedative effects since this metabolite is much less active than the parent drug. However, the half-life of midazolam itself was also significantly longer in patients with ARF than in the control group (13.2 vs 7.6 h). Apparently, this was caused by a combination of a slightly lower total clearance and a higher volume of distribution. Therefore, regular reassessment of the degree of sedation and appropriate adaptation of the infusion rate of midazolam are recommended in ICU patients with ARF.

Bilateral ulnar nerve injury after high abdominal surgery.

We report a case of bilateral injury to the ulnar nerve above the level of the elbow due to a particular retractor used for high abdominal surgery. Possible mechanisms of pathogenesis and predestinating conditions are discussed.

Epidural anesthesia with plain bupivacaine 0.75% for elective caesarean section.

The clinical effects of epidural anesthesia with bupivacaine 0.75% for elective caesarean section were investigated in 20 healthy pregnant women. The mean total dose of bupivacaine which offers sufficient sensory and motor block, provided the epidural catheter is properly placed, was 137.5 mg. Maternal hypotension occurred in 4 patients in spite of prehydratation and left uterine displacement. No maternal systemic toxicity or local neurotoxicity was found. The results of the Apgar scoring and the neonatal acid-base studies showed that there is no clinically important neonatal depression with this technique.