The impact of a cadaver-based airway lab on critical care fellows' direct laryngoscopy skills.

This study sought to determine the impact of a cadaver-based airway lab on critical care medicine fellows' direct laryngoscopy skills and hypothesised that fellows can improve their self-reported percentage of glottic opening (POGO) scores in cadaver models to achieve POGO scores similar to that of expert faculty. Nineteen fellows attended an airway management skills laboratory utilising five modified cadavers. Initial fellow POGO (POGOi) visualised was recorded at the onset with direct laryngoscopy. Maximum fellow POGO score with optimised direct laryngoscopy was recorded after two additional hours of teaching and also during a testing phase several days later. Data was assessed for significant differences between trainee POGO scores at each time interval and between trainee POGO scores and expert scores. A departmental procedural database was utilised to examine success rates of intubation as a clinical correlation. Fellows' mean POGOi scores, averaged across all five specimens, were significantly lower than both their maximum POGO scores and their testing phase POGO scores. Mean POGOi scores for fellows, averaged over all five cadavers, were lower than the instructors' POGOi scores. There was no difference between fellows' and instructors' mean maximum POGO or mean testing phase POGO scores. Clinical success rates of intubation were over 98%. A short training session using modified cadavers can be utilised to teach new critical care medicine fellows additional techniques for airway management and assist them in obtaining higher POGO scores, similar to those of expert instructors. Success rates of clinical intubations were favourable in the wake of this training.

The impact of local anesthetic distribution on block onset in ultrasound-guided interscalene block.

BACKGROUND: Recent investigations of local anesthetic distribution in the lower extremity have revealed that completely surrounding the sciatic nerve with local anesthetic provides the advantage of more rapid and complete anesthesia in the territory served by the nerve. We hypothesized that a pattern of distribution that entirely envelops the targeted nerve roots during interscalene block would provide similar benefits of more rapid anesthesia onset. METHODS: During interscalene block guided by ultrasound with nerve stimulator confirmation, the pattern of local anesthetic distribution was recorded and later classified as complete or incomplete envelopment of the visible nerve elements in 50 patients undergoing ambulatory shoulder arthroscopic surgery. The pattern was then compared with the extent of block setup at pre-determined intervals, as well as to post-operative pain levels and block duration. RESULTS: Twenty-two patients (44%) had complete envelopment of the nerves in the plane of injection during ultrasound imaging of the interscalene block. There was no difference in the fraction of blocks that were fully set-up at 10 min with regards to complete or incomplete envelopment of the nerves by local anesthetic. All of the patients had complete setup of the block by 20 min. In addition, the post-operative pain levels and duration of block did not vary among the two groups with complete vs. incomplete local anesthetic distribution around the nerves. CONCLUSION: The presence or absence of complete envelopment of the nerve elements in the interscalene groove by local anesthetic did not determine the likelihood of complete block effect at pre-determined time intervals after the procedure.

Sonoanatomy of the vasculature at the supraclavicular and interscalene regions relevant for brachial plexus block.

BACKGROUND: Our aim in this observational study was to utilize ultrasound, as well as anatomic dissection, to document the frequency with which branches of the subclavian vessels are found in close association with the brachial plexus at the locations of supraclavicular and interscalene brachial plexus block. METHODS: Ultrasound was utilized to document the presence of branches of the subclavian vein and artery, adjacent to the brachial plexus in the supraclavicular and in the interscalene region in 50 patients undergoing shoulder surgery. The position, depth, and dimensions of the vessels were described, and the origin determined when possible. In addition, the posterior triangle of the neck on both sides of three non-preserved cadavers was dissected to evaluate the vascular anatomy and correlate the ultrasound findings. RESULTS: Ultrasound scanning revealed an arterial branch adjacent to, or passing directly through, the brachial plexus in the supraclavicular region in 43/50 (86%) patients. Within the interscalene region, an artery was identified coursing in a lateral direction in 45/50 (90%) of cases, while a corresponding small vein, coursing medial to lateral in this area, was noted in 23/50 (46%) of cases. CONCLUSIONS: Small branch vessels from the subclavian artery and vein were frequently evident, on ultrasound imaging, in close association with the nerve elements of the brachial plexus in the supraclavicular and interscalene regions. Appreciation of the presence of these vessels and their likely origin and course will aid the anesthesiologist in planning a safe nerve block.

Ultrasound decreases the failed labor epidural rate in resident trainees.

BACKGROUND: Epidural analgesia is widely used for pain relief during labor. The purpose of this study was to determine if ultrasound measurement of the depth from skin to epidural space before the epidural technique decreases the failure rate of labor analgesia. A secondary objective was to correlate ultrasound depth to the epidural space with actual depth of the needle at placement. METHODS: In this prospective, randomized, non-blinded study, 370 parturients requesting labor epidural analgesia were randomized to receive their epidural technique by first year anesthesia residents with or without prior ultrasound determination of epidural space depth. Outcome variables included the incidence of epidural catheter replacement for failed analgesia and the number of epidural attempts and accidental dural punctures. RESULTS: The ultrasound group had fewer epidural catheter replacements (P<0.02), and epidural placement attempts (P<0.01) compared to the control group. Pearson's correlation coefficients comparing the actual versus ultrasound estimated depth to the epidural space in the longitudinal median and transverse planes were 0.914 and 0.909, respectively. Pearson's correlation coefficient comparing the ultrasound estimated depths to the epidural space in the transverse and longitudinal median planes was 0.940. No significant differences were noted with respect to staff interventions, top-ups, accidental dural punctures, and delivery outcome. CONCLUSIONS: Ultrasound measurement of the epidural space depth before epidural technique placement decreases the rate of epidural catheter replacements for failed labor analgesia, and reduces the number of epidural attempts when performed by first year residents and compared to attempts without ultrasound guidance.

Interscalene block using ultrasound guidance: impact of experience on resident performance.

BACKGROUND: We evaluated the weekly progress of anesthesiology residents performing an interscalene block with ultrasound guidance (UG) for block success rates and for the specific time intervals: (i) time to image the brachial plexus and (ii) time from insertion of the block needle until motor stimulation occurred. Our primary objective was to characterize the influence of experience over the course of the regional anesthesia rotation on the performance of a UG interscalene block by anesthesiology residents. METHODS: Residents conducted an interscalene block with UG under the supervision of attending anesthesiologists experienced in this technique. Block efficacy, time intervals required to perform the block, and acute complications were recorded. We compared success rates over the course of the rotation, and analyzed process time data with respect to trainee level of experience, week of the trainee rotation, and patient body habitus. RESULTS: Twenty-one trainees conducted 222 blocks over a consecutive 7-month period. Block success rate was 97.3%, and did not change significantly over the course of the 4-week rotation. Total block time and imaging time significantly decreased over the 4-week rotation, while the needle insertion-to-stimulation time did not change. Slower imaging time was predicted by obesity. CONCLUSION: The success rates for a UG interscalene block provided by supervised residents were initially high, and remained so throughout the 4-week rotation. Trainees required less time to image the nerves and to perform the block over the course of the rotation.

Impact of a regional anesthesia rotation on ultrasonographic identification of anatomic structures by anesthesiology residents.

OBJECTIVE: The specific aim of this study was to determine the ability of anesthesiology residents to independently identify a series of anatomic structures in a live model using ultrasound, both before and after a 4-week regional anesthesia rotation that incorporates a standardized ultrasound training curriculum for peripheral nerve blockade. METHODS: Ten CA2 and CA3 anesthesiology residents volunteered to participate in this study. Each resident was subjected to a pre-rotation practical exam, in which he attempted to identify 15 structures at four sites of peripheral nerve blockade, in a test subject. Each resident then received specific training for ultrasound-guided nerve blocks during a 4-week regional anesthesia rotation, and then completed a post-rotation exam. The mean number of structures correctly identified on the exams was compared for significant differences utilizing a paired t-test. RESULTS: Residents were able to identify significantly more anatomic structures on the post-rotation exam as compared with the pre-rotation exam (mean 14.1 vs. 9.9, P<.001), as well as more peripheral nerve targets. The most frequently misidentified structures on the pre-rotation exam were the subclavian vein, the sciatic nerve in the popliteal fossa, and the femur. CONCLUSIONS: Ultrasound-naive anesthesiology residents, who received instruction and experience with ultrasound-guided peripheral nerve blocks on a 4-week regional anesthesia rotation, significantly improved their ability to independently identify relevant anatomic structures with ultrasonography.

Succinylcholine: adverse effects and alternatives in emergency medicine.

Succinylcholine has long been the favored neuromuscular blocking agent for emergent airway management because of its rapid onset, dependable effect, and short duration. However, it has a plethora of undesirable side effects, ranging from the inconsequential to the catastrophic. When patients requiring tracheal intubation present with potential contraindications to succinylcholine use, the emergency physician will need to substitute a rapid-onset nondepolarizing neuromuscular blocking agent, such as rocuronium or mivacurium. An understanding of the pharmacology of these agents is essential.

Initiation of mechanical ventilation in the emergency department.

Mechanical ventilation is frequently initiated by emergency physicians. Further, the physician on duty in the emergency department is frequently responsible for evaluating ventilated patients who decompensate in the intensive care unit when other physicians are not present in the hospital. A bewildering array of features on new mechanical ventilators has made their appropriate and effective use increasingly complex. Knowledge of the pathophysiology of acute respiratory failure and changes in lung physiology during positive pressure ventilation will aid the emergency physician in choosing an appropriate ventilator modality and initial settings to maximally benefit patients with respiratory insufficiency due to various causes. An appreciation of the adverse effects of mechanical ventilation and problems commonly encountered in patients on ventilators will prepare the emergency physician to rapidly assess and effectively manage the patient who deteriorates in this setting.

Intravenous versus intramuscular midazolam in treatment of chemically induced generalized seizures in swine.

Midazolam is a water-soluble benzodiazepine proven to be efficacious in sedation, hypnosis, and induction and maintenance of anesthesia. Because of its water solubility, it is a desirable drug for the control of status epilepticus when intravenous (IV) access is not obtainable. This study compares intramuscular (IM) versus IV routes of administration of midazolam in the control of tonic-clonic activity produced by chemically induced generalized seizures in a swine model. When midazolam was administered by IV route, tonic-clonic activity lasted a mean of 34 +/- 5.4 seconds, and when administered by IM route, the tonic-clonic activity lasted a mean of 116 +/- 41 seconds. Both were considerably abbreviated when compared with the expected duration of pentylenetetrazol-induced seizures in the swine model. Serum levels of midazolam achieved by the IV route were considerably higher than those achieved by the IM route. It is concluded that midazolam is effective in the control of tonic-clonic manifestations of generalized seizures when administered by the IV or the IM route and that no correlation exists between serum levels achieved and the time to control the seizure.

Normal amylase levels in the presentation of acute pancreatitis.

Recent literature suggests that serum amylase levels are not an appropriate screen for the diagnosis of acute pancreatitis because specificity and sensitivity are poor. Evidence from several studies supports the use of lipase determinations to diagnose acute pancreatitis, and recent improvements in this assay have made it more readily available to the emergency physician. This retrospective review compares the use of serum amylase to lipase levels in the diagnosis of acute pancreatitis in 52 patients who presented to the emergency department, with the hospital discharge diagnosis serving as the gold standard to which the assays were compared. Serum lipase was found to be more sensitive than serum amylase (95% vs 79%); serum amylase levels decreased to normal significantly faster than lipase levels.

Venous air embolism: clinical and experimental considerations.

OBJECTIVE: To examine the existing literature concerning venous air embolism. Causes, pathophysiology, and management are emphasized. DATA SOURCES: The literature that was reviewed was retrieved from the MEDLINE System under the headings "venous air embolism," "air embolism," "therapy of air embolism," "etiology of venous air embolism," and "pathophysiology of venous air embolism" for the years 1970 to 1991. A manual search, derived from the references of these papers, was performed to obtain relevant citations for the years preceding 1970. STUDY SELECTION: Experimental (animal) data, case reports, case series, and clinical investigations are included. CONCLUSIONS: Venous air embolism is an infrequent complication of invasive diagnostic and therapeutic maneuvers. The cardiovascular, pulmonary, and central nervous systems may all be affected, with severity ranging from no symptoms to immediate cardiovascular collapse. Therapeutic interventions include mechanical measures, such as positioning, withdrawal of air from the right atrium, and measures aimed at reducing bubble size. Hyperbaric oxygen therapy holds some promise in accomplishing the latter, but randomized, controlled trials demonstrating efficacy have yet to be performed.

Intravenous adenosine therapy accelerating rate of paroxysmal supraventricular tachycardia.

Two cases of paroxysmal supraventricular tachycardia are reported in which the administration of adenosine produced sustained elevation of the rate of paroxysmal supraventricular tachycardia. In each case, sinus rhythm was restored readily through the use of intravenous verapamil. This adverse reaction to adenosine has not been previously described.

Post-traumatic intracerebral pneumatocele: case report.

Pneumocephalus occurs in 0.5 to 1.0% of head trauma, but may also occur after neurologic surgery, or as a result of eroding infection or neoplasm. The pathophysiology involves the presence of craniodural fistula allowing ingress of air. A ball-valve mechanism may allow air to enter but not exit the cranium, or CSF leak permits air entrance as fluid leaves the intracranial space. While a "succession splash" is considered diagnostic of pneumocephalus, most patients have nonspecific signs and symptoms such as headache. Therefore, a high index of suspicion in a patient with recent head trauma is necessary. The diagnosis is made radiographically by CT scan. This is generally performed to rule out intracranial hematoma or cerebral contusion in head trauma, but will reveal even very small quantities of air to the unsuspecting physician. Therapy is often noninvasive, allowing the craniodural defect to heal spontaneously. Selected situations require immediate operative repair of the fistula.