Cervical spine motion during airway management: A cinefluoroscopic study of the posteriorly destabilized third cervical vertebrae in human cadavers.

University of Queensland, Department of Anesthesia and Intensive Care, Cairns Base Hospital, Australia. Department of Anesthesia and Intensive Care Medicine, and Institute of Anatomy, Leopold-Franzens University, Innsbruck, Austria.

We conducted a randomized, controlled, crossover study to determine cervical spine motion for six airway management techniques in human cadavers with a posteriorly destabilized third cervical (C-3) vertebra. A destabilized C-3 segment was created in 10 cadavers (6-24 h postmortem).

Cervical motion was recorded by continuous lateral fluoroscopy. The following airway management techniques were performed in random order on each cadaver with manual in-line stabilization applied: face mask ventilation (FM), laryngoscope-guided orotracheal intubation (OETT), fiberscope-guided nasal intubation (FOS-NETT), esophageal tracheal Combitube((R)) insertion (ETC), intubating laryngeal mask insertion with fiberscope-guided tracheal intubation (ILM-OETT), and laryngeal mask airway insertion (LMA). Afterward, maximum head-neck flexion (FLEX-MAX) and maximum head-neck extension (EXT-MAX) without manual in-line stabilization was performed to determine maximum motion.

The maximum posterior displacement of C-3 and the maximum segmental sagittal motion of C2-3 were determined. There was a significant increase in posterior displacement for the FM (1.9 +/- 1.2 mm, P: < 0.01), OETT (2.6 +/- 1.6 mm, P: < 0.0001), ETC (3.2 +/- 1.6 mm, P: < 0.0001), ILM-OETT (1.7 +/- 1.3 mm, P: < 0. 01), LMA (1.7 +/- 1.3 mm, P: < 0.01), FLEX-MAX (3.7 +/- 1.9 mm, P: < 0.0001), EXT-MAX (1.8 +/- 1.7, P: < 0.01), however, not for FOS-NETT (0.1 +/- 0.7 mm). Posterior displacement was less for the ILM-OETT and LMA than for the ETC (both P: < 0.04). There were no significant increases in segmental sagittal motion with any airway manipulation other than with FLEX-MAX (-4.5 +/- 4.0 degrees, P: < 0.01). Posterior displacement was similar to FLEX-MAX for the OETT and ETC; however, it was less for the FM, FOS-NETT, ILM-OETT, and LMA (all P: < 0.01). Posterior displacement was similar to EXT-MAX for all airway manipulations other than for FOS-NETT (P: < 0.001).

For cervical motion and the techniques tested, the safest method of airway management in a patient with a posteriorly destabilized C-3 segment is FOS-NETT. LMA devices may be preferable to the ETC.

Implications: In the cadaver model of a destabilized third cervical vertebrae, significant displacement of the injured segment occurs during airway management with the face mask, laryngoscope-guided oral intubation, the esophageal tracheal Combitube((R)) (Kendall-Sheridan, Neustadt, Germany), the intubating and standard laryngeal mask airway; but not with fiberscope-guided nasal intubation. For cervical motion and the techniques tested, the safest airway technique with this injury is fiberscope-guided nasotracheal intubation. Laryngeal mask devices are preferable to the esophageal tracheal Combitube.

 

 

BACKGROUND: In the present study, we compared an automatic external defibrillator (AED) that delivers 150-J biphasic shocks with traditional high-energy (200- to 360-J) monophasic AEDs. Methods and Results-AEDs were prospectively randomized according to defibrillation waveform on a daily basis in 4 emergency medical services systems. Defibrillation efficacy, survival to hospital admission and discharge, return of spontaneous circulation, and neurological status at discharge (cerebral performance category) were compared. Of 338 patients with out-of-hospital cardiac arrest, 115 had a cardiac etiology, presented with ventricular fibrillation, and were shocked with an AED. The time from the emergency call to the first shock was 8.9+/-3.0 (mean+/-SD) minutes.

 

CONCLUSIONS: The 150-J biphasic waveform defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation. Although survival rates to hospital admission and discharge did not differ, discharged patients who had been resuscitated with biphasic shocks were more likely to have good cerebral performance.

 

 

BACKGROUND: The ability of intravenous lidocaine to prevent intubation-induced bronchospasm is unclear. The authors performed a prospective, randomized, double-blind, placebo-controlled trial to test the ability of intravenous lidocaine and inhaled albuterol to attenuate airway reactivity after tracheal intubation in asthmatic patients undergoing general anesthesia.

 

METHODS: Sixty patients were randomized to receive either 1.5 mg/kg intravenous lidocaine or saline, 3 min before tracheal intubation. An additional 50 patients were randomized to receive 4 puffs of inhaled albuterol or placebo 15-20 min before tracheal intubation. Anesthesia was induced with propofol. Immediately after intubation and at 5-min intervals, transpulmonary pressure and airflow were recorded, and lower pulmonary resistance (RL) was calculated. Isoflurane was administered after the initial two measurements to assess reversibility of bronchoconstriction. A bronchoconstrictor response to intubation was defined as RL greater than or equal to 5 cm H2O. l-1. s-1 in the first two measurements after intubation and RL subsequently decreasing by 50% or more after isoflurane.

 

RESULTS: The lidocaine and placebo groups were not different in the peak RL before administration of isoflurane (8.2 cm H2O. l-1. s-1 vs. 7.6 cm H2O. l-1. s-1) or frequency of airway response to intubation (lidocaine 6 of 30 vs. placebo 5 of 27). In contrast, the albuterol group had lower peak RL (5.3 cm H2O. l-1. s-1 vs. 8.9 cm H2O. l-1. s-1; P < 0.05) and a lower frequency of airway response (1 of 25 vs. 8 of 23; P < 0.05) than the placebo group.

 

CONCLUSIONS: Inhaled albuterol blunted airway response to tracheal intubation in asthmatic patients, whereas intravenous lidocaine did not.

 

 

Charles D Deakin, consultant anaesthetist a, J Lorraine Low, medical statistician b. a Shackleton Department of Anaesthetics, Southampton General Hospital NHS Trust, Southampton SO16 6YD, b Health Care Research Unit, Southampton General Hospital NHS Trust, Southampton SO16 6YD

The advanced trauma life support course teaches that if only the patient's carotid pulse is palpable, the systolic blood pressure is 60-70 mm Hg; if carotid and femoral pulses are palpable, the systolic blood pressure is 70-80 mm Hg; and if the radial pulse is also palpable, the systolic blood pressure is more than 80 mm Hg.¹ The only study to examine the accuracy of this model used non-invasive blood pressure measurements, which have a tendency to underestimate systemic arterial blood pressure during hypotension.² No reliable data are therefore available to support the advanced trauma life support guidelines on which clinical decisions are made. We assessed whether the guidelines accurately predict systolic blood pressure by palpation of radial, femoral, and carotid pulses in hypovolaemic patients in whom blood pressure was measured using invasive arterial monitoring.

Methods and Results

After obtaining approval of the study by the ethics committee, we studied sequential patients with hypotension secondary to hypovolaemic shock and in whom invasive arterial blood pressure monitoring had been established. An observer blinded to the blood pressure palpated the radial, femoral, and carotid pulses, and the invasive systolic blood pressure was recorded.

The 20 sequential patients studied over the three year period were aged 18-79 years. Not all pulses were palpable when a reading was taken because a sterile operating field impaired access to the patients. The radial pulse always disappeared before the femoral pulse, which always disappeared before the carotid pulse. The data were split into four subgroups: radial, femoral, and carotid pulses present (group 1), femoral and carotid pulses only (group 2), carotid pulse only (group 3), and radial, femoral, and carotid pulses absent (group 4).

 

Impact of accident and emergency work on mental health and emotional well-being

Department of Mental Health, Medical School, University of Aberdeen and Centre for Trauma Research, Royal Cornhill Hospital, Aberdeen, UK

Background The association between mental health and occupational factors among ambulance personnel has not been thoroughly investigated in the UK.

Aims To identify the prevalence of psychopathology among ambulance personnel and its relationship to personality and exposure to critical incidents.

Method Data were gathered from ambulance personnel by means of an anonymous questionnaire and standardised measures.

Results Approximately a third of the sample reported high levels of general psychopathology, burnout and posttraumatic symptoms. Burnout was associated with less job satisfaction, longer time in service, less recovery time between incidents, and more frequent exposure to incidents. Burnout and GHQ-28 caseness were more likely in those who had experienced a particularly disturbing incident in the previous 6 months. Concerns aboutconfidentiality and career prospects deter staff from seeking personal help.

Conclusions The mental health and emotional well-being of ambulance personnel appear to be compromised by accident and emergency work.

 

 

Department of Surgery and The Cara Phelan Centre for Trauma Research, St Michael's Hospital, University of Toronto, Ontario, Canada.

BACKGROUND: Understanding the etiology of missed injuries is essential in minimizing its occurrence. A retrospective review was conducted to identify the incidence, contributing factors, and clinical outcomes of missed injuries.

METHODS: All trauma patients assessed by St Michael's Hospital trauma service from April 1, 1995, to July 31, 1997, were included in the study. Demographic and medical data were compared and statistically analyzed in two patient groups to identify factors associated with missed injuries.

RESULTS: Forty six of 567 patients (8.1%) had missed injuries. Patients with missed injuries had higher mean Injury Severity Scores and longer stays in the hospital and intensive care unit compared with patients without missed injuries (p < 0.05). Patients with missed injuries were more likely to have lower Glasgow Coma Scale scores and to have required pharmacologic paralysis (p < 0.05). Of the factors contributing to missed injuries, 56.3% were potentially avoidable and 43.8% were unavoidable. Seven patients with missed injuries had clinically significant outcomes, including one patient death. Of the seven clinically significant missed injuries, five were attributable to potentially avoidable factors.

CONCLUSION: Patients with missed injuries tend to be more severely injured with initial neurologic compromise. The majority of missed injuries are potentially avoidable with repeat clinical assessments and a high index of suspicion.

 

 

Department of Emergency Medicine, Lincoln Medical and Mental Health Center, Bronx, New York 10451, USA. richlanoix@aol.com

OBJECTIVE: To determine the incidence of C-spine injury (CSI) associated with gunshot wounds (GSWs) to the head.

METHODS: A retrospective chart review including patients with GSWs to the head and excluding those with penetrating facial/neck trauma was performed. Cervical clearance was by clinical/radiologic criteria in survivors, and autopsy in nonsurvivors. A MEDLINE literature search was performed and relevant articles reviewed.

RESULTS: One hundred seventy-four charts were available for review; 90 had C-spine radiographs (complete series [49], lateral [33], and computed tomographic scan [8]). Of 84 with no radiographs, 29 were clinically cleared, and 55 died (32 cleared at autopsy). Twenty-three died without evaluation. None of the remaining 151 (87%) had CSI. Literature search yielded only three relevant articles. Combining the data from these articles yielded 534 patients, and CSI was excluded in 507 (95%).

CONCLUSION: C-spine immobilization and diagnostic radiography are probably not necessary in patients with isolated GSWs to the head and may complicate and delay emergency airway management.

 

 

Study Objectives: Blind nasotracheal intubation (BNTI) is used to secure the airway in patients who are spontaneously breathing. The success rate for BNTI is often lower than for orotracheal intubation. We conducted this study to determine whether the use of an endotracheal tube (ETT) capable of directional tip control can improve the BNTI success rate.

METHODS: This prospective, experimental study was conducted by a state emergency medical services agency during 1997, 1998, and 1999. Consecutive patients undergoing attempted BNTI or orotracheal intubation were included. Five paramedic units were trained to use an ETT with triggeractivated distal tip directional control for BNTIs (intervention group). Ten units used conventional ETTs for BNTIs and served as concurrent controls (control group). Subjects in the 2 groups were enrolled concurrently with nonrandomized allocation based on the agency providing service. An intubation attempt was defined by tube passage, and success was defined as confirmed endotracheal placement.

RESULTS: A total of 219 BNTIs were studied (141 in the control group and 78 in the intervention group). BNTI was successful in 82 (58%) of 141 cases using conventional ETTs, and in 56 (72%) of 78 cases using directional tip control (P =.04). The overall success rate was 63%.

CONCLUSION: Use of ETTs with distal directional control is associated with a higher success rate for BNTI than conventional ETTs. Use of ETTs with directional tip control significantly improves the success rates for BNTIs.

 

OBJECTIVE: To determine whether clinical data available in the emergency department can accurately predict a subset of patients at low risk of developing recurrent seizures following one or more initial alcohol-related seizures in the out-of-hospital arena. METHODS: This was a retrospective secondary analysis of data obtained from the placebo arms of two prospective, randomized trials of drug treatments for the prevention of recurrent alcohol-related seizures. Subjects with and without one or more recurrent alcohol-related seizures during the study period were compared according to the following characteristics: 1) age, 2) gender, 3) daily ethanol consumption, 4) years of ethanol abuse, 5) previous alcohol-related seizure, 6) previous seizure of other etiology, 7) temperature, 8) heart rate, 9) systolic blood pressure, 10) diastolic blood pressure, 11) respiratory rate, and 12) ethanol level. Data were analyzed with t-tests and chi-square where appropriate. RESULTS: One hundred five placebo-treated patients were analyzed and 31 (30%) developed recurrent alcohol-related seizures. None of the listed characteristics were statistically different between the two groups except for the initial ethanol level. Subjects with an ethanol level higher than 100 mg/dL were less likely (0%) to develop recurrent seizures than patients with a level equal to or below 100 mg/dL (36%) (p < 0.01). CONCLUSIONS: An initial ethanol level higher than 100 mg/dL was significantly associated with a low risk for recurrent alcohol-related seizures during the observation period. No other low-risk clinical characteristics could be identified.

 

STUDY OBJECTIVE: Although several trials have been published evaluating intravenous magnesium sulfate as treatment for acute bronchospasm, its effectiveness for this indication remains unclear, prompting this meta-analysis.

METHODS: All randomized controlled trials of adjuvant bolus intravenous magnesium sulfate for acute bronchospasm in the emergency department were eligible. Trials were identified using MEDLINE, EMBASE, bibliographies of selected articles, and review of abstracts of 4 scientific societies. Two reviewers abstracted data, one of whom was blinded to author and journal. Because studies used different spirometric outcome measures, effect size was calculated for each study by Hedges' method. The analysis used a fixed-effects model. One-way sensitivity analyses were performed to assess the influence of study quality and to search for publication bias.

RESULTS: Abstracts from 210 articles were reviewed, yielding 40 trials, of which 9 were specific to bolus intravenous magnesium sulfate in the ED, in doses from 1.2 to 2 g, or an equivalent pediatric dose. Combined results across 9 studies including 859 patients showed a posttreatment effect size of 0.162 for patients treated with intravenous magnesium sulfate (95% confidence interval 0.028, 0.297; P =.02). In sensitivity analyses exploring the effects of study quality and publication bias, the summary effect ranged from 0.127 to 0.206. No serious adverse events were reported.

CONCLUSION: Adjuvant bolus intravenous magnesium sulfate in acute bronchospasm appears statistically beneficial in improving spirometric airway function by 16% of a SD. Although the clinical significance of this is uncertain, given the safety of intravenous magnesium sulfate therapy and its relatively low cost, it should be considered, absent contraindications, in patients with moderate to severe acute bronchospasm.

 

STUDY OBJECTIVE: To describe the effectiveness and safety of succinylcholine administration by paramedics to out-of-hospital patients requiring endotracheal intubation. METHODS: A consecutive case series was collected by retrospective review of patient care records from a large, private ambulance agency serving an urban and rural county of 600,000 residents over a 40-month period. All patients for whom endotracheal intubation was facilitated by succinylcholine use were identified. Data were systematically collected on demographics, paramedic diagnosis, intubation attempts, and complications. RESULTS: Succinylcholine was used in 150 patients with a mean age (+/-SD) of 50+/-23 years. Paramedic diagnosis was coma in 43% (64/150; 95% confidence interval [CI] 35% to 51%), trauma in 26% (39/150; 95% CI 19% to 33%), and respiratory failure in 31% (47/150; 95% CI 23% to 39%). No patient was in cardiac arrest at the time of succinylcholine use. The intubation success rate was 92% (138/150; 95% CI 88% to 96%), with success achieved on the first attempt in 82% of patients (123/150; 95% CI 76% to 88%). Four patients who received succinylcholine developed cardiac arrest, and 3 others had symptomatic bradycardia. CONCLUSION: The use of succinylcholine by paramedics to assist intubation appears to aid in intubation of patients who are not in cardiac arrest. However, significant cardiac complications can occur.

College of Pharmacy and Department of Pathology, School of Medicine, University of New Mexico, Albuquerque, USA.

The purpose of this study was to test the hypothesis that lidocaine is systemically absorbed after administration via a Combitube placed in the esophagus, and that therapeutically significant plasma lidocaine concentrations can be attained using this route with standard endotracheal doses (2.0 mg/kg). During general anesthesia, 27 elective surgical patients received 2.0 mg/kg lidocaine (diluted as necessary with 0.9% saline to a minimum total volume of 10 mL) via a Combitube (study group, n = 13) or an endotracheal tube (control group, n = 14). Venous blood samples were drawn for 3 h after lidocaine administration and plasma concentrations determined by gas chromatography using a nitrogen-phosphorus detector (NPD). Overall, average lidocaine concentrations were maximal after 5 min, reaching 0.8+/-0.7 and 1.7+/-0.7 microg/mL in the Combitube and endotracheal tube groups, respectively. Individual patient peak concentrations averaged 1.0+/-0.7 and 2.2+/-1.1 microg/mL in the same two groups, 19+/-16 and 10+/-15 min after lidocaine administration, respectively. No patients reported chest discomfort or dyspnea upon awakening, and no other side effects were noted. In support of the hypothesis, administration of lidocaine via an esophageal Combitube results in systemic drug uptake; however, at conventional endotracheal doses, plasma concentrations are subtherapeutic. It remains to be determined whether higher doses of lidocaine administered via an esophageal Combitube will result in therapeutic plasma concentrations.

Sunnybrook and Women's College Health Science Centre, 2075 Bayview Ave, Suite BG-20, Toronto, Ontario, Canada M4N 3M5. l.morrison@utoronto.ca

CONTEXT: Early administration of thrombolysis for acute myocardial infarction (AMI) may improve survival if safely and appropriately delivered. No systematic reviews that have comprehensively examined this topic exist in the literature.

OBJECTIVE: To perform a meta-analysis of randomized controlled trials of prehospital vs in-hospital thrombolysis for AMI measuring in-hospital mortality.

DATA SOURCES: The Cochrane search strategy was used to search MEDLINE, EMBASE, and the Science Citation Index (1982-1999); Dissertation Abstracts (1987-1999); and Current Contents (1994-1999) for the terms thrombolysis, thrombolysis therapy, prehospital, and acute myocardial infarction. In addition, text and journal article bibliographies were hand searched, the National Institutes of Health Web site was reviewed, and primary authors and thrombolytic drug manufacturers were contacted for unpublished studies.

STUDY SELECTION: Randomized controlled trials of prehospital vs in-hospital thrombolysis for AMI measuring all-cause hospital mortality were included. Two authors independently reviewed 175 citations by title, abstract, or complete article. After exclusion of 30 duplicate citations, 145 studies remained, of which 6 studies and 3 follow-up studies met the inclusion criteria.

DATA EXTRACTION: Independent data abstraction by 2 reviewers blinded to the journal, title, and author was confirmed by consensus. Trial quality was independently assessed by 2 other coauthors, blinded to the author, title, journal, introduction, and discussion.

DATA SYNTHESIS: The results of the 6 randomized trials (n=6434) were pooled and indicated significantly decreased all-cause hospital mortality among patients treated with prehospital thrombolysis compared with in-hospital thrombolysis (odds ratio, 0.83; 95% confidence interval, 0.70-0.98). Results were similar regardless of trial quality or training and experience of the provider. Estimated (SE) time to thrombolysis was 104 (7) minutes for the prehospital group and 162 (16) minutes for the in-hospital thrombolysis group (P=.007). CONCLUSIONS: Our meta-analysis suggests that prehospital thrombolysis for AMI significantly decreases the time to thrombolysis and all-cause hospital mortality. JAMA. 2000;283:2686-2692.

Abstract: Intensive Care and Anesthesia Unit, Mutual de Seguridad Hospital C. CH.C., Santiago, Chile. The esophageal-tracheal Combitube((R)) (ETC; Kendall-Sheridan Catheter Corp., Argyle, NY) is a new device designed for difficult airways and emergency intubation. The manufacturer recommends that the ETC model 37F SA be used in patients with a height of between 122 and 152 cm. The aim of this study was to evaluate whether ventilation is effective and reliable in patients taller than 152 cm by using the ETC 37F SA in the esophageal position. Also, we evaluated whether the airway protection is adequate and whether direct intubation of the trachea with the ETC inserted in the esophagus is possible. We studied 25 anesthetized, paralyzed adult patients, 150 to 180 cm in height. Methylene blue was given orally to all patients before anesthesia induction. Under direct vision, a ETC 37F SA was inserted in the esophagus of all patients. The pharyngeal balloon inflation volume was titrated to air leak and cuff pressures were measured. During surgery, a laryngoscope was inserted into the pharynx with the pharyngeal balloon deflated and the laryngoscopic view was evaluated by using the Cormack-Lehane scale. The presence of methylene blue in the hypopharynx was investigated by direct laryngoscopic vision. Ventilation was effective and reliable in all 25 patients who were 150 to 180 cm in height (average 169 +/- 7 cm). In addition, a direct relationship between the pharyngeal balloon volume and patient height was established (P < 0.05), by using linear regression models. The laryngoscopic view of the glottis was adequate to allow direct tracheal intubation. No trace of methylene blue was detected in the hypopharynx. The ETC Model 37F SA may be used in patients from 122 to 185 cm in height. The trachea could be directly intubated with the ETC in the esophageal position in patients with normal airways. The airway protection appears to be adequate.

IMPLICATIONS: The esophageal-tracheal Combitube((R)) Model 37F SA (Kendall-Sheridan Catheter Corp., Argyle, NY) may be used in patients from 122 to 185 cm in height. The trachea could be directly intubated with the Combitube((R)) in esophageal position in patients with normal airways. The airway protection appears to be adequate.

Abstract: Akron General Medical Center, Emergency Medicine Residency Program, Ohio 44307, USA. lwhite@agmc.org

INTRODUCTION: Pain and its control have been studied extensively in the emergency department. Numerous studies indicate that inadequate treatment of pain is common, despite the availability of myriad analgesics. It has been suggested that oligoanesthesia is also a common practice in the prehospital setting.

OBJECTIVE: To assess the use of prehospital analgesia in patients with suspected extremity fracture.

METHODS: Emergency medical services (EMS) call reports were reviewed for all patients with suspected extremity fractures treated from June 1997 to July 1998 in a midwestern community with a population base of 223,000. Data collected included demographic information, mechanism of injury, medications given, and field treatment. Standing orders for administration of analgesia were available and permitted paramedics to give either morphine sulfate or nitrous oxide per protocol.

RESULTS: The EMS call reports were analyzed for 1,073 patients with suspected extremity fractures. The mean patient age was 47 years. Accidental injuries comprised 86.5% of those reviewed. Suspected leg fractures were most common (20%), followed by hips (18%), arms (11%), knees (10%), ankles (9%), shoulders (7.2%), hands (5.5%), and wrists (5.3%). Multiple trauma and assorted broken digits accounted for the remaining 14%. The most common mechanisms of injury were: fall (43%), motor vehicle collision (21%), and human assault (10%). Intravenous lines were placed in 9.4% of patients; 17% received ice packs; 16% received bandage/dressings; 25% received air splints; and 19% were fully immobilized. Analgesia was administered to 18 patients (1.8%): 16 patients received nitrous oxide and two received morphine.

CONCLUSION: Administration of analgesics to prehospital patients with suspected fractures was rare. Prehospital identification and treatment of pain for patients with musculoskeletal trauma could be improved.