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.

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.

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.

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.

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.

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.

Time course of action of sugammadex (Org 25969) on rocuronium-induced block in the Rhesus monkey, using a simple model of equilibration of complex formation.

BACKGROUND: Reversal of neuromuscular block can be accomplished by chemical encapsulation of rocuronium by sugammadex (Org 25969), a synthetic gamma-cyclodextrin derivative. The present study determined the time course of the reversal action of sugammadex on rocuronium-induced block in the anaesthetized Rhesus monkey using train-of-four stimulation. METHODS: A bolus injection of rocuronium 100 microg kg(-1) (about 1xED(90)) was given to determine the degree of neuromuscular block reached by this dose. After complete spontaneous recovery, a rapid bolus injection of sugammadex, 1 mg kg(-1), was given and at different time intervals (15, 30 or 60 min, in three different experiments) the effect of another rocuronium bolus injection of 100 microg kg(-1) was determined. RESULTS: Injection of the first dose of rocuronium resulted in a mean neuromuscular block (depression of first twitch) of 93 (SEM=1.6)%. Fifteen minutes after injection of sugammadex the same rocuronium dose resulted in 17% (SEM=5.6) block. After 30 and 60 min these maximum blocks amounted to 49% (SEM=7.6) and 79% (SEM=4.2), respectively. The estimated half-life of sugammadex in Rhesus monkey is 30 (SEM=4.9) min. CONCLUSIONS: The half-life of sugammadex (Org 25969), a new fast and efficient reversal agent for rocuronium-induced block, is relatively short in the Rhesus monkey, implying the possibility to perform neuromuscular block by rocuronium shortly after reversal of a prior block. In translation to the human situation differences in rocuronium sensitivity and kinetics should be taken into account.

Anesthetic management in a child with Arnold-Chiari malformation and bilateral vocal cord paralysis.

We report a case of a child who was scheduled for an emergency ventriculoperitoneal shunt procedure. The patient had a type II Arnold-Chiari malformation (ACM) and associated hydrocephalus and presented with near complete respiratory obstruction from bilateral abductor vocal cord palsy. Early diagnosis and management of airway abnormalities associated with ACM may be lifesaving. Chiari malformations and anesthesia management are discussed.

Pharmacodynamics of rocuronium 0.3 mg kg(-1) in adult patients with and without renal failure.

BACKGROUND AND AIM: The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg(-1) under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg(-1) rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients. METHODS: With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg(-1) was given intravenously after induction of anaesthesia with propofol 1-2 mg kg(-1) and fentanyl 2 microg kg(-1). Propofol 6-12 mg kg(-1) h(-1) was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant. RESULTS: No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block. CONCLUSIONS: Rocuronium 0.3 mg kg(-1) is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.

Pharmacokinetics and pharmacodynamics of rocuronium in patients with and without renal failure.

BACKGROUND AND OBJECTIVE: This study clarifies the relationship between the neuromuscular blocking effects of rocuronium 0.6 mg kg(-1) and its pharmacokinetics in patients with renal failure. METHODS: Seventeen healthy patients and 17 patients with renal failure were studied under propofol anaesthesia in this prospective open label study. Rocuronium 0.6 mg kg(-1) was given after induction of anaesthesia. The train-of-four mechano-myographic response of the thumb to supramaximal stimulation of the ulnar nerve at 2 Hz every 12 s was measured. Venous blood samples (4 mL) were obtained at 0, 2, 4, 7, 10, 15, 20, 30, 60, 120, 180, 240 and 360 min after relaxant administration. Samples were centrifuged, separated and stored at -20 degrees C until plasma levels of rocuronium and its metabolites were measured. Two- and three-exponential equations were used to describe the pharmacokinetic data in each group and these were compared to each other using the Wilcoxon signed rank sum test as was the pharmacodynamic data. P < 0.05 was significant. RESULTS: Onset of block was similar in both groups. Clinical duration and the time to recovery of the train-of-four to 70% were prolonged in the renal failure group compared to control; 49 vs. 32 min (P < 0.004, 95% confidential, interval 17, difference 5-28) and 88 vs. 55 min (P < 0.001, 95% confidential interval 33, difference 17-50), respectively. Clearance of rocuronium was reduced by 39% in the renal failure patients compared to control, with an 84% increase in the mean residence time. The volume of distribution was unaffected by renal failure. CONCLUSIONS: The duration of action of a bolus dose of 0.6 mg kg(-1) rocuronium is increased significantly in patients with end-stage renal failure compared to healthy controls. This increase may be due to a decreased clearance of rocuronium, the disease process causing the renal failure and/or the medication which patients with renal failure need in their treatment.

Acceleromyography in neonates and small infants: baseline calibration and recovery of the responses after neuromuscular blockade with rocuronium.

BACKGROUND: We have evaluated the use of the TOF-Guard (TOF, train-of-four) acceleromyographic thumb responses to ulnar nerve stimulation in neonates and infants and the return of the responses after neuromuscular blockade. METHODS: Baseline acceleromyographic recording of thumb adduction to ulnar nerve stimulation during volatile anaesthesia was performed in 22 babies aged less than 30 weeks. At the start of stimulation the automatic set-up procedure of the TOF-Guard was used to see if a 100% control twitch height could be achieved. Irrespective of the ability to achieve a 100% control twitch height, TOF stimulation was used thereafter. When no automatic 100% control twitch could be reached, the transducer signal gain factor was set manually to obtain a 100% value. In 14 of the 22 children the recovery after neuromuscular blockade with rocuronium 0.3 mg kg(-1) was recorded. RESULTS: In nine of 22 patients a 100% baseline twitch height was obtained with the automatic set-up. In the other 13 babies the TOF-Guard display indicated that the transducer signal was too low. The mean time to recovery of control twitch to 75% of baseline after rocuronium 0.3 mg kg(-1) was 51 min (SD = 21) and the time to recovery of the TOF ratio to 70% was 49 min (SD = 19). The mean final twitch height and TOF after recovery from rocuronium blockade were 101% (SD = 15) and 92% (SD = 12), respectively. CONCLUSION: The recovery of the responses after neuromuscular blockade to near baseline values shows that acceleromyography can be used to measure neuromuscular block and recovery in neonates and infants.

Suxamethonium administration prolongs the duration of action of subsequent rocuronium.

BACKGROUND AND AIM: Rocuronium may be given to patients for intubation and also after they have received suxamethonium for intubation. The neuromuscular profile of rocuronium given after recovery from suxamethonium may not be identical to that when rocuronium has been given alone. The neuromuscular effects of suxamethonium and rocuronium, and their effects on intraocular pressure (IOP), heart rate (HR) and arterial pressure were also recorded. METHODS: Thirty patients were randomly allocated to receive either 0.6mg kg(-1) rocuronium (n = 15) or 1 mg kg(-1) suxamethonium (n = 15) for intubation. Anaesthesia was first induced using propofol 2.5 mg kg(-1) and fentanyl 2 microg kg(-1) and maintained with propofol 6-12 mg kg(-1) h(-1). The response of the thumb to supramaximal train-of-four (TOF) ulnar nerve stimulation at the wrist was measured using a mechanomyograph. In the suxamethonium group, when the first twitch of the TOF had recovered to 90%, rocuronium 0.6 mg kg(-1) was administered. Before administration of relaxant, baseline readings of HR, arterial pressure and IOP were measured until stable, then the appropriate relaxant administered. Thereafter, all readings were repeated at 30, 90, 150, 210 and 270 s. Tracheal intubation was performed 300 s after the intubating dose and all recordings repeated 30 s later. Mechanomyographic monitoring was continued until 70% TOF recovery. RESULTS: Suxamethonium had a more rapid onset than rocuronium (49s vs. 74s, P < 0.0001). The onset time of rocuronium after suxamethonium was significantly reduced (56 s) and the time to recover to a TOF of 70% following rocuronium was increased by previous suxamethonium administration (47 vs. 58 min, P < 0.05). Suxamethonium caused a marked rise in IOP (>30%) and HR (>10%) while rocuronium had little effect on either. CONCLUSION: Previous suxamethonium administration decreases the onset time and increases the duration of action of rocuronium. Unlike suxamethonium, rocuronium has few cardiovascular effects and causes little change in IOP.

Severe myocardial ischaemia during mask induction of anaesthesia in an infant with unknown critical supravalvular aortic stenosis.

Congenital supravalvular aortic stenosis is an uncommon type of aortic obstruction. When critical, it represents an extreme variant of outflow tract obstruction with increased risk of cardiovascular instability during exercise or anaesthesia. We present a case of severe myocardial ischaemia during induction of anaesthesia with sevoflurane in a 3-month baby with a presumed diagnosis of valvular aortic stenosis for which a percutaneous balloon dilatation of the aortic valve was scheduled.