Inadequate Anesthesia Research Articles

A Complication Associated with the Use of a Drug Injection Catheter through a Fiberscope

Fiberoptic intubation is a very useful technique for patients whose tracheas are difficult to intubate using conventional methods. However, insertion of a fiberscope and insertion of an endotracheal tube over the fiberscope into the trachea are two major difficulties.1We encountered an unusual difficulty during removal of the fiberscope after successful tracheal intubation. Our search revealed no such difficulty reported in the literature.A 30-yr-old man with atlanto-axial dislocation came for trans-oral decompression and posterior fixation. An awake intubation was planned. After adequate oral and intravenous sedation, bilateral superior laryngeal nerve blocks, and topical anesthesia to the airway, a bite block was inserted.Endotracheal tube (8.5, polyvinyl chloride) was loaded over the fiberscope (Fujinon F B 120-p, Fujinon Corporation, Saitoma, Japan). A long catheter (drug spray cannula) was inserted through forceps port of the fiberscope for the administration of local anesthesia in the event of inadequate anesthesia. This catheter comes with a fiberscope set.The fiberscope and enodotracheal tube were inserted through the mouth. Excellent local anesthesia was observed while introducing the fiberscope and the tube into the trachea, which was performed within 30–40 s. The patient remained comfortable during and after intubation of the endotracheal tube without any sign of distress. Administration of local anesthesia was not required. With successful intubation, we tried to remove the fiberscope. Initially we felt some resistance. After applying slight force, the fiberscope came out but the injection catheter remained inside the tube. We were unable to remove the catheter with moderate force. To determine the reason, we reinserted the fiberscope into the trachea over the catheter. We noticed that the catheter had gone beyond the tip of the endotracheal tube, making a U shape over the edge of it. We removed the tube along with the fiberscope and the catheter. The catheter was not used during the second attempt of awake fiberoptic intubation, which was accomplished without difficulty. Subsequent endoscopic examination of the distal trachea and major bronchi revealed normal anatomy.We hypothesized that during advancement of the endotracheal tube over the fiberscope, the injecting catheter migrated beyond the tip of the fiberscope. With further advancement, it became U shaped over the edge of the tube, and one arm of it got trapped between the tube and the trachea, which caused it to be stalked within the tube (figure 1).Inadvertent advancement of the tip of the fiberscope through a side hole (Murphy eye) of an endotracheal tube, causing difficulty in intubation has been reported.2To eliminate this kind of problem with the use of an injection catheter, we suggest a simple measure. The catheter should be fixed with adhesive tape or a rubber band at the inlet of the forceps port so that it will not protrude from the tip of fiberscope in situ .*Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India. mihirpandia@yahoo.co.in

A Measure of Gold

Since its founding in 1954, the Society of Anaesthetists of Hong Kong has set fundamental aims to assure professionalism of the specialty, uphold the honor and status of anesthetists, provide appropriate anesthetic training, establish close liaison with professional partners worldwide and educate the lay public about anesthesia.

Early Reversal of Profound Rocuronium-induced Neuromuscular Blockade by Sugammadex in a Randomized Multicenter Study: Efficacy, Safety, and Pharmacokinetics

Sugammadex reverses the neuromuscular blocking effects of rocuronium by chemical encapsulation. The efficacy, safety, and pharmacokinetics of sugammadex for reversal of profound rocuronium-induced neuromuscular blockade were evaluated. Ninety-eight male adult patients were randomly assigned to receive sugammadex (1, 2, 4, 6, or 8 mg/kg) or placebo at 3, 5, or 15 min after 0.6 mg/kg rocuronium. Patients were anesthetized with propofol and fentanyl. The primary endpoint of the study was the time to achieve a recovery of train-of-four ratio to 0.9. Neuromuscular blockade was measured using acceleromyography. Concentrations of rocuronium and sugammadex were determined in venous blood and urine samples. A population pharmacokinetic model using NONMEM (GloboMax LLC, Hanover, MD) was applied. The mean time to recovery of the train-of-four ratio to 0.9 after dosing at 3, 5, and 15 min decreased from 52.1, 51.7, and 35.6 min, respectively, after administration of placebo to 1.8, 1.5, and 1.4 min, respectively, after 8 mg/kg sugammadex. Sugammadex was safe and well tolerated. However, 20.4% of patients showed signs of inadequate anesthesia after its administration. The median cumulative excretion of rocuronium in the urine over 24 h was 26% in the placebo group and increased to 58-74% after 4-8 mg/kg sugammadex. The mean plasma clearances of sugammadex and rocuronium were 0.084 and 0.26 l/min, respectively. In male subjects, sugammadex safely reversed profound neuromuscular blockade induced by 0.6 mg/kg rocuronium in a dose-dependent manner. Sugammadex enhanced the renal excretion of rocuronium, and its clearance is approximately one third that of rocuronium.

This Month in Anesthesiology

This Month in Anesthesiology

Use of CobraPLA with total intravenous anesthesia and constant BIS level in elective, non-obese orthopedic patients

Inadequate anesthesia may cause inability to ventilate the patient with a supraglottic airway device. We assessed the insertion characteristics and adequacy of positive pressure ventilation with the CobraPLA in patients anesthetized at a constant bispectral index (BIS) level. The airways of 40 ASA I-II patients who underwent elective orthopedic surgery were managed with CobraPLA, using positive pressure ventilation without muscle relaxation. Anesthesia was induced and maintained with propofol and fentanyl at a constant BIS level of 40-50. We measured ease and time of insertion, sealing pressure, peak inspiratory pressure, gastric insufflation, oxygen saturation, end-tidal carbon dioxide, mean arterial pressure, heart rate and the BIS. Postoperative complications were recorded. Ninety percent were inserted at first attempt within 32±10 sec. Sealing pressure was 27±5 cmH2O. Mean BIS during CobraPLA insertion was 40 ± 4. One patient had a mild postoperative pneumonia. It is concluded that under constant BIS levels, the CobraPLA is easily inserted and enables effective positive pressure ventilation.

The Effects of Electromyographic Activity on the Bispectral Index During Combined Anesthesia

To the Editor: Liu et al. (1) addressed an interesting topic in their article concerning the influence of a muscle relaxant bolus on the Bispectral Index (BIS) and Datex-Ohmeda entropy during induction of anesthesia. We would like to add a similar observation about the effect of electromyographic activity (EMG) on the accuracy of the BIS. After obtaining IRB approval and written informed consent from each patient, we enrolled 60 patients in a study designed to investigate the effects of different concentrations of epidurally administered ropivacaine on the desflurane requirement under the combination of thoracic epidural analgesia and general anesthesia. After inserting a midthoracic epidural catheter, followed by induction of general anesthesia, we gave patients 10 mL ropivacaine 0.3% and 10 μg sufentanil epidurally every 60 min. We maintained anesthesia with 1.5%–2.0% desflurane and 65% N2O. We continuously recorded the output of the BIS® XP monitor and the Narcotrend™ (MonitorTechnik, version 2.0 AF). In six patients EMG activity increased to more than 35 dB during surgery as indicated by the BIS® XP module’s EMG signal. This was accompanied by an increase in BIS from 40–55 to 70–80, indicating inadequate anesthetic depth. There was no change in the Narcotrend, nor was there any clinical evidence of inadequate anesthesia. In the other 54 patients, EMG remained less than 35 dB during surgery. In the six patients with EMG activity, the end-tidal concentration of desflurane was set to an age-adapted 1 MAC, and patients received additional remifentanil, as mandated by the study protocol. These interventions did not alter the BIS values. On the basis of the findings of Bruhn et al. (2), we then gave these six patients a bolus of 10 mg atracurium. The BIS declined within 2 min to a value between 40 and 50, and the EMG value decreased to 25–30 dB. We analyzed the BIS and Narcotrend data for these six patients and found a significant correlation between the BIS and the EMG more than 35 dB. Narcotrend values did not correlate significantly with the EMG (Figure 1).Figure 1.: Scatterplot of BIS and Narcotrend values vs. EMG in six patients with EMG activity above 35 dB. In these six patients the increased EMG was significantly correlated with increasing BIS. There was no correlation between EMG and Narcotrend.Similar to the findings of Liu et al., we found that the BIS XP is clearly affected by high levels of EMG activity. Periklis Panousis, MD Thea Koch, MD, PhD Axel R. Heller, MD, PhD, DEAA Department of Anesthesiology and Intensive Care Therapy University Hospital Carl-Gustav-Carus Technical University Dresden Dresden, Germany [email protected]

Incidence of obesity in parturients scheduled for caesarean section, intra-operative complications, management and outcome

To determine the incidence of obesity in parturients scheduled for Caesarean section, identify intra-operative complications, management and outcome. A prospective observational study. University of Benin Teaching Hospital, a university-affiliated tertiary centre. Parturients scheduled for Caesarean section excluding patients in American Society of Anaesthesiologists (ASA) health status 4 and 5. Three hundred patients were recruited in the study. One hundred and forty eight (49.3%) were non-obese (BMI < 30kgm2) while 152 (50.7%) were obese (BMI >30kgm(-2)). The incidence of obesity was extremely significant P<0.0001, t = 19.721 and 95% C.I. = 11.998 - -9.820. Twenty four percent of the obese and 6% of the non-obese parturients had intercurrent medical diseases. 40.5% of the non-obese parturients had general anaesthesia while 13.1% of the obese parturients were offered general anaesthesia. The incidence of intra-operative complications was higher in the obese group. P<0.0001; extremely significant. Odds ratio = 3.647; 95% C.I. of 2.0007 - 6.626. The most common complications were hypotension (n = 14), shivering (n = 12) and inadequate anaesthesia (n = 8). There is a high incidence of obesity in parturients. This group of patients constitutes a high risk group in obstetric anaesthesia. The incidence of complications was higher in the obese than in the non-obese.

Cerebral state index response to incision: a clinical study in day‐surgical patients

Inadequate anaesthesia, with somatic/autonomic response or awareness, is often revealed at intubation and surgical incision. Anaesthetic depth monitors should be able to prevent this risk. This explorative study examined the ability of the cerebral state monitor to predict autonomic/somatic responses to incision. Forty-two ASA I-II day-surgical patients [19 men and 23 females; mean age 52 (29-79) years, mean weight 77 (50-118) kg] were induced clinically with fentanyl/propofol with sevoflurane after placement of the laryngeal mask airway. The cerebral state index (CSI) was blindly recorded 4 min prior to and 4 min after incision. During the 4 min prior to incision, the mean CSI was 45 (16-62) and increased by 9 (-13-40) when the mean value for the first 4 min after incision was subtracted from the value prior to incision, corresponding to a relative change of 21% (-21-118). The change in CSI did not show any consistent relation to the value before incision. Five patients showed minor movements after incision and six patients had > 25% increase in blood pressure. Neither CSI nor the change in index differed between patients who did or did not respond somatically or autonomically to incision. The last CSI value just prior to incision was 44 for non-responders and 40 and 42 for somatic and autonomic responders, respectively. The CSI in the majority of patients was within acceptable ranges during clinically adjusted anaesthesia prior to incision but seems not to be able to reliably predict an autonomic or somatic response to incision.

Awareness Under Anesthesia During Electroconvulsive Therapy Treatment

Awareness under general anesthesia is an infrequent phenomenon during which patients become cognizant of some or all events during surgery or any procedure conducted under anesthesia. Awareness experiences can frighten patients and impact their memories in ways that can leave emotional and psychological problems that, over time, may develop into posttraumatic stress disorder. Inadequate anesthesia has been implicated in the causation of awareness under anesthesia. We report first case of patient gaining awareness while under anesthesia undergoing electroconvulsive therapy treatment. The case reported here would suggest that clinicians administering electroconvulsive therapy should be alert to the possibility of awareness during anesthesia and take appropriate measures to maintain professional conduct and adjust anesthetic medication dose to avoid reoccurrence.

Gerard W. Ostheimer “What’s New in Obstetric Anesthesia” Lecture

Gerard W. Ostheimer “What’s New in Obstetric Anesthesia” Lecture

Failure to obtain adequate anaesthesia associated with a bifid mandibular canal: a case report

The inferior alveolar nerve (IAN) block is the most common method for obtaining mandibular anaesthesia in dental practice but it is estimated to have a success rate of only 80 to 85 per cent. Causes of failure include problems with operator technique and anatomical variation between individuals. This case report involves a patient who received IAN blocks on two separate occasions that resulted in only partial anaesthesia of the ipsilateral side of the mandible. Radiographic assessment disclosed the presence of bifid mandibular canals that were present bilaterally and that may have affected the outcomes of the local anaesthetic procedures. Previous studies of bifid mandibular canals are reviewed and suggestions provided that should enable clinicians to differentially diagnose, and then manage, cases where IAN blocks result in inadequate mandibular anaesthesia.

Assessment of ketamine and medetomidine anaesthesia in the domestic rabbit

ObjectiveTo study the effects of ketamine and two doses of medetomidine administered by two routes of injection in a genetically diverse population of rabbits. Study designProspective, randomized, clinical trial. AnimalsOne hundred and five domestic rabbits of mixed breed, sex and age. Materials and methodsRabbits undergoing orchiectomy or ovariohysterectomy received ketamine (15 mg kg−1) combined with medetomidine at 0.25 or 0.5 mg kg−1, by subcutaneous (SC) or intramuscular (IM) injection. Anaesthesia was supplemented with 1.5–2% isoflurane when signs of regular jaw movements and/or slight limb twitching indicated inadequate anaesthesia. Heart and respiratory rate, blood oxygen saturation, end-tidal carbon dioxide concentration and rectal temperature were monitored at several time points. Duration of surgical anaesthesia and anaesthesia time were measured. At completion of surgery, atipamezole (1.0 or 0.5 mg kg−1, IM or SC) was administered. Statistical analysesmanova was used to compare variables over time between males and females, anaesthetic doses and routes of drug administration. ResultsAll reflexes were lost significantly more rapidly after IM drug administration (p < 0.05). The times (in minutes) from drug injection to loss of reflexes for the respective groups were: righting reflex: 6.3 (15.0 + 0.25, SC), 5.5 (15.0 + 0.5, SC), 2.9 (15.0 + 0.25, IM) and 2.3 (15.0 + 0.5, IM); ear pinch: 9.2, 8.5, 4.8, 3.6; pedal withdrawal: 12.8, 10.4, 6.6, 5.2. Heart and respiratory rates during surgery did not differ between groups, however the highest end-tidal CO2 concentration during surgery was significantly affected by dose, with the highest concentration occurring in group 15.0 + 0.5 IM. The number of animals requiring isoflurane tended to decrease with increasing dose of anaesthetic and significantly more females required supplementation than males (p < 0.05). Recovery from anaesthesia (return of righting reflex) was not significantly different between dose groups (p > 0.1) but was more rapid in animals given IM atipamezole (13.6 ± 13 versus 21 ± 17, p = 0.037). No anaesthetic-related mortality occurred and all but three animals recovered uneventfully. Five animals were killed whilst under anaesthesia because of unrelated disease. Conclusion and clinical relevanceKetamine–medetomidine combinations reliably produced surgical anaesthesia in domestic rabbits that could easily be deepened for brief periods with low concentrations of isoflurane. Subcutaneous administration was better tolerated, but the speed of induction was slower compared with IM injection. Atipamezole was an effective antagonist and produced most rapid effects when administered IM.

Dural Ectasia: A Likely Cause of Inadequate Spinal Anaesthesia in Two Parturients with Marfan's Syndrome

Dural Ectasia: A Likely Cause of Inadequate Spinal Anaesthesia in Two Parturients with Marfan's Syndrome

Changes in the Bispectral Index During Intraabdominal Irrigation in Patients Anesthetized with Nitrous Oxide and Sevoflurane

Surgical stimulation typically results in an activation of electroencephalographic activity. In some instances, painful stimulation in the presence of inadequate anesthesia results in a suppression of the electroencephalogram. This phenomenon has been referred to as a "paradoxical arousal." In our daily practice, we have noted a marked decrease in the bispectral index (BIS) with large delta waves during abdominal surgery when the abdominal cavity was irrigated with normal saline. In the present study, we sought to evaluate changes in BIS during intraabdominal irrigation. Eighteen ASA physical status I-II patients scheduled for elective abdominal surgery were enrolled in the study and allocated randomly to the control group (group C) or the fentanyl group (group F). Anesthesia was induced with 3 mg/kg of thiopental and was maintained with sevoflurane and 50% nitrous oxide. BIS, 95% spectral edge frequency (SEF95), and burst-suppression ratio were recorded using a BIS monitor. Near the end of the procedure, but before irrigation of the abdominal cavity, 1.5 microg/kg fentanyl was given IV to group F. There was no significant change in BIS or SEF95 in group F patients during subsequent irrigation of the abdominal cavity. In contrast, BIS and SEF95 decreased significantly after start of irrigation in group C patients. These data show that the stimulation occurring during intraabdominal irrigation might cause a paradoxical arousal response, as evidenced by a decrease in processed electroencephalographic parameters. Pretreatment with fentanyl suppressed these changes. Anesthesiologists should be aware of this paradoxical arousal response to avoid an inappropriate decrease in the anesthetic concentration in such situations.

The importance of myorelaxants in anesthesia

Neuromuscular blocking drugs were introduced into clinical practice in 1942. Although these drugs made new surgical techniques possible, they also led to morbidity and mortality owing to respiratory muscle paralysis and paralysis in the face of inadequate anesthesia. Newer competitive antagonists at the neuromuscular junction have been developed that have a more rapid onset of action, including rocuronium and mivacurium, making them suitable for use at the onset of anesthesia. Rapid titratable offset of action has been more difficult to achieve, but has been attempted with the inclusion of ester bonds (mivacurium) and binding agents that are in clinical trials. These novel approaches to pharmaceuticals, along with improved understanding of the physiology of the neuromuscular junction in health and disease, have made surgical treatment possible in a wide breadth of clinical situations.

Inadequate anaesthesia in lethal injection for execution

Anaesthesia during lethal injection is essential to minimise suffering and to maintain public acceptance of the practice. Lethal injection is usually done by sequential administration of thiopental, pancuronium, and potassium chloride. Protocol information from Texas and Virginia showed that executioners had no anaesthesia training, drugs were administered remotely with no monitoring for anaesthesia, data were not recorded and no peer-review was done. Toxicology reports from Arizona, Georgia, North Carolina, and South Carolina showed that post-mortem concentrations of thiopental in the blood were lower than that required for surgery in 43 of 49 executed inmates (88%); 21 (43%) inmates had concentrations consistent with awareness. Methods of lethal injection anaesthesia are flawed and some inmates might experience awareness and suffering during execution.

Response Entropy Increases During Painful Stimulation

Frontal electromyography (FEMG) may increase during painful stimulation and indicate patient arousal. The Datex-Ohmeda Entropy Module calculates state entropy (SE) of the electroencephalogram (EEG; 0.8-32 Hz) and response entropy (RE) of EEG and FEMG (0.8-47 Hz). We determined whether RE increases above SE (RE--SE), an indication of FEMG, increase during painful stimuli and if this is related to paralysis or level of anesthesia. With the unanesthetized baseline measurement, SE was 89 +/- 2 and RE was 98 +/- 2. During paralysis and anesthesia with either 0.8% (n = 10) or 1.4% (n = 10) isoflurane, SE decreased to 63 +/- 7 and 34 +/- 14, respectively, and the RE--SE difference decreased 90%. Before recovery from paralysis, arterial catheter or head pin placement increased RE--SE above unanesthetized levels in eight patients (five treated with 0.8% and three with 1.4% isoflurane), consistent with an increase in FEMG. The elevated RE--SE difference was related to a significant increase in SE, blood pressure, and heart rate. After recovery from paralysis, tetanic stimulation of the ulnar nerve increased the RE--SE difference above unanesthetized levels in 8 of 20 patients (6 treated with 0.8% and 2 with 1.4% isoflurane). In these patients, SE increased significantly. The remaining 12 patients did not show an increase in RE--SE during tetanic stimulation and SE did not increase. We conclude that increased RE during painful stimulation was not dependent on recovery from paralysis but was seen more often in patients anesthetized with 0.8% compared with 1.4% isoflurane. This suggests that RE reflects FEMG and may be useful to identify inadequate anesthesia and patient arousal during painful stimuli.

Spinal 2-Chloroprocaine: A Comparison with Small-Dose Bupivacaine in Volunteers

Ambulatory surgery continues to increase nationwide. Because spinal lidocaine is associated with transient neurologic symptoms, many clinicians have switched to small-dose bupivacaine for outpatient spinal anesthesia. However, bupivacaine often produces inadequate surgical anesthesia and has an unpredictable duration. Preservative-free 2-chloroprocaine (2-CP) has reemerged as an alternative for outpatient spinal anesthesia. We designed this double-blind, randomized, crossover, volunteer study to compare 40 mg of 2-CP with small-dose (7.5 mg) bupivacaine with measures of pinprick anesthesia, motor strength, tolerance to tourniquet and electrical stimulation, and simulated discharge criteria. Peak block height (2-CP average T7 [range T3-10]; bupivacaine average T9 [range T4-L1]), regression to L1 (2-CP 64 +/- 10 versus bupivacaine 87 +/- 41 min), and tourniquet tolerance (2-CP 52 +/- 11 versus bupivacaine 60 +/- 27 min) did not differ between drugs (P = 0.15, 0.12, and 0.40, respectively). However, time to simulated discharge (including time to complete block regression, ambulation, and spontaneous voiding) was significantly longer with bupivacaine (2-CP 113 +/- 14, bupivacaine 191 +/- 30 min, P = 0.0009). No subjects reported transient neurologic symptoms or other side effects. We conclude that spinal 2-CP provides adequate duration and density of block for ambulatory surgical procedures, and has significantly faster resolution of block and return to ambulation compared with 7.5 mg of bupivacaine.

A Case of Coronary Artery Spasm Possibly due to Inadequate Anesthesia as Indicated by Bispectral Index

A Case of Coronary Artery Spasm Possibly due to Inadequate Anesthesia as Indicated by Bispectral Index

This Month in Anesthesiology

This Month in Anesthesiology