The effect of order on pain of local anesthetic infiltration.

OBJECTIVE: To define the relationship between order of injection and pain of infiltration of buffered lidocaine. METHODS: Volunteers > or = 18 years of age were enrolled in a prospective, double-blind experimental protocol. Subjects received a 0.5-mL intradermal injection of anesthetic in each forearm. All injections were given by the same individual in the same manner. Immediately following each injection, the subjects rated the pain of infiltration on a standardized 100-mm visual analog pain scale. Both the subjects and the individual giving the injections were blinded to the anesthetic being administered. They were told that the injections could be either plain or buffered lidocaine. They were further informed that any individual subject could receive 2 of the same anesthetics or 1 of each in either order. In reality, all injections were buffered lidocaine for all subjects. Pain scores were converted to a numerical score by making measurements to the nearest millimeter and analyzed by a Wilcoxon signed-rank test with p < 0.05 considered significant. RESULTS: Fifty subjects were enrolled. The first injection had a median pain score of 13.5 mm, compared with 23.5 mm for the second (p = 0.007). CONCLUSION: The second injection of buffered lidocaine was found to be statistically more painful than the first in this protocol that controlled for all variables except for order of injection. Future studies involving paired comparisons should take this information into account.

The significance of out-of-hospital hypotension in blunt trauma patients.

OBJECTIVE: To determine the significance of a low out-of-hospital systolic blood pressure (SBP) reading in blunt trauma patients who have a normal SBP upon ED arrival. METHODS: A retrospective case-control study compared admitted blunt trauma patients who were hypotensive (SBP < or = 90 mm Hg) in the field and normotensive in the ED (group 1) with those who were normotensive both in the field and in the ED (group 2). The groups were compared for mortality, intensive care unit (ICU) admission, injury severity scale (ISS) score, need for transfusion in the ED, incidence of intra-abdominal injury, and incidence of pelvic or femur fracture. RESULTS: Each group consisted of 52 patients. The groups were similar with respect to age, gender, and initial ED SBP. The group 1 patients had a higher mortality (10 vs 1, p = 0.008), a higher number of ICU admissions (28 vs 12, p = 0.001), more pelvic or femur fractures (16 vs 7, p = 0.03), and a higher ISS score (19.0 vs 10.5, p = 0.01). Although not significant, group 1 also had higher incidences of intra-abdominal injury (10 vs 3, p = 0.07) and transfusion (8 vs 2, p = 0.09). CONCLUSION: The injured patients who were hypotensive in the out-of-hospital setting but normotensive upon ED arrival were more severely injured and had more potential for blood loss than were the patients who were normotensive both in the out-of-hospital setting and in the ED. Out-of-hospital hypotension may be a clinical predictor of severe injury, even in the face of normal ED SBP. Prospective studies are indicated to validate this hypothesis.

Does topical lidocaine attenuate the pain of infiltration of buffered lidocaine?

OBJECTIVE: To determine whether topical lidocaine attenuates the pain of buffered lidocaine infiltration. METHODS: This was a prospective, randomized, double-blind, placebo-controlled trial conducted at a university-based ED. The subjects were adults who had lacerations being repaired using local anesthesia. Two 0.5-mL injections of buffered lidocaine were given in a standardized manner. The first was given prior to application of topical study solution. The second was given on the opposite side of the laceration after topical application of study solution, which was 5 mL of either 2% lidocaine or saline placebo. The pain of each infiltration was measured using a visual analog pain scale. Pain scores were calculated and compared using a Wilcoxon test with significance defined as p < or = 0.05. RESULTS: A total of 54 subjects participated; 29 received lidocaine topically and 25 received placebo. The groups were similar with respect to age, gender, wound length, wound location, and initial pain score. Pain scores decreased by 11.6 +/- 18.6 mm for lidocaine and 10.9 +/- 20.9 mm for placebo (p > 0.5). The study had the power to detect a 15-mm pain score difference (alpha = 0.05 and beta = 0.20) on a 100-mm scale. CONCLUSION: Topical 2% lidocaine does not attenuate the pain of infiltration of buffered lidocaine more than does topical normal saline. Investigation of other topical anesthetics with and without epinephrine in conjunction with buffered lidocaine is warranted.

A comparison of proparacaine and tetracaine eye anesthetics.

OBJECTIVE: To compare two topical eye anesthetics, proparacaine and tetracaine, for pain of instillation and duration of activity. METHODS: Volunteers received both anesthetics in a prospective, randomized, double-masked protocol. The subjects were given one drop of a study solution in the lower lid fornix of the left eye. Immediately after receiving the medication, they rated the pain of instillation on a previously validated visual-analog pain scale. This procedure was then repeated in the right eye with the other study solution. Pain scales were quantified by making measurements to the nearest millimeter from the point of scale origin to the point marked by the patient. The time interval until return of the corneal blink reflex was determined using a cotton wisp. Pain scores and the time to return of corneal reflex were analyzed by the Sign test and Wilcoxon rank-sum test, respectively, with significance defined as p < 0.05. RESULTS: Twenty-three subjects were available for analysis. Twenty subjects reported proparacaine hurt less than tetracaine, two felt the pain was the same for the two agents, and only one reported that proparacaine was more painful. The mean pain score for tetracaine was 24 mm (100 mm maximum) higher than that for proparacaine (p < 0.0002). Proparacaine lasted 1.3 minutes longer than tetracaine, 10.7 minutes versus 9.4 minutes (p = 0.0001). CONCLUSION: Proparacaine eye drops cause less pain than tetracaine eye drops upon instillation. Anesthesia from proparacaine last slightly longer. These properties make proparacaine preferable to tetracaine.

Local anesthesia for lacerations: pain of infiltration inside vs outside the wound.

OBJECTIVE: To compare the pains of infiltration of a local anesthetic for simple lacerations when used from within the wound vs through intact skin. METHODS: A randomized, prospective, single-blind, experimental protocol was conducted on a convenience sample of adults with simple lacerations. Subjects received two 0.5-mL injections of buffered lidocaine in each of the sites being compared. Immediately following each injection, pain was measured using a visual analog pain scale. Pain scores were converted to a numerical score and analyzed by a Wilcoxon signed-rank test. Subjects also were asked which injection hurt more, the first or the second (analyzed by a chi2 test). RESULTS: A total of 63 subjects were enrolled. The first injection was within the wound and the second injection through intact skin (group 1) for 32 patients, and the order was reversed for 31 patients (group 2). Median pain scores for all inside-the-wound injections (14 mm) were lower than those with intact skin injections (37 mm; p < 0.0001). In group 1, 4 subjects reported the first injection (within wound) hurt most, 23 thought the second (intact skin) hurt most, and 5 found no difference. In group 2, 18 subjects reported the first injection (intact skin) hurt most, 5 believed the second injection (within wound) hurt most, and 8 found no difference, p < 0.0001. CONCLUSION: Local anesthesia is less painful when injected from within a laceration as compared with intact skin.

The effects of warming and buffering on pain of infiltration of lidocaine.

OBJECTIVES: To investigate the effects of warming vs buffering, and warming with buffering, on the pain of lidocaine infiltration. METHODS: A randomized, double-blind clinical trial was conducted using volunteers aged 18 years or more and without an allergy to lidocaine. The study consisted of two parts, each comparing two solutions. The solutions for Part I were warm (38.9 degrees C; 102 degrees F) plain lidocaine and room-temperature buffered lidocaine. Warm buffered lidocaine and room-temperature buffered lidocaine were used for Part II. The subjects received two standardized 0.5-mL intradermal injections, one study solution in each forearm. Immediately after each injection, pain was assessed using a 100-mm visual analog pain scale. Pain scores were analyzed by the sign test, with significance defined as p < 0.05. RESULTS: Part I (n = 10): Nine subjects reported room-temperature buffered lidocaine to be less painful than warm plain lidocaine. Mean pain scores were 28 mm lower for room-temperature buffered lidocaine than they were for warm plain lidocaine (p < 0.01). Part II (n = 24): Eleven subjects found warm buffered lidocaine to be the least painful, 11 reported room-temperature buffered lidocaine to be the least painful, and two reported no difference. A mean pain score difference of 2.1 mm favoring warm buffered lidocaine was not statistically significant. Part II had a power of 80% to detect a 10-mm difference between the two solutions at alpha = 0.05. CONCLUSION: To reduce the pain of lidocane infiltration, buffering is more effective than warming. Warming does not enhance buffering.

Ketorolac tromethamine use in a university-based emergency department.

OBJECTIVE: To assess the use of parenteral ketorolac tromethamine (KT) in the emergency department (ED). METHODS: During a six-month period, KT was administered in an uncontrolled, nonblinded fashion to a series of ED patients experiencing acute pain. The patients rated pain on a previously validated visual analog pain scale before receiving KT. They repeated this procedure one hour after KT administration, prior to additional analgesia, or preceding release, whichever came first. Analgesic response was assessed by comparing pretreatment and posttreatment pain scores for the entire study population by the Wilcoxon rank sum test. Possible effects of specific variables (patient age, gender, race, indication for KT, route, dose, previous use of NSAIDs, and concurrent administration of muscle relaxants) were assessed using the Kruskal-Wallis test. RESULTS: Of the 445 patients enrolled, 375 (84%) reported pain relief with KT, only seven (2%) worsened, and the remainder (14%) reported no change. Overall pain reduction was 37.6 +/- 27.2 (SD) mm (100-mm scale) for the entire study population. The pain scores obtained after KT administration were significantly lower than those obtained prior to KT administration (p < 0.001). The only variable that significantly influenced pain score reduction was indication for KT (p = 0.001). Nephrolithiasis and toothache patients had the largest mean reductions in pain. No significant side effect was reported. CONCLUSION: Parenteral KT is a useful and safe analgesic for ED patients. The agent generally provides analgesia and is particularly promising for patients with nephrolithiasis or toothache.

Topical tetracaine attenuates the pain of infiltration of buffered lidocaine.

OBJECTIVE: To determine whether topical tetracaine attenuates the pain of buffered lidocaine infiltration. METHODS: A prospective, randomized, double-blind trial was conducted involving adults with lacerations being repaired following local anesthesia. Two 0.5-mL injections of buffered lidocaine were given in a standardized manner. Injection 1 was given prior to application of topical study solution. Injection 2 was given on the opposite side of the laceration after topical application of a study solution that was 4 mL of either tetracaine or normal saline. Pain of each infiltration was measured using a visual analog pain scale. Pain score differences (injection 1 - injection 2) were compared for the 2 study solutions using a Wilcoxon 2-sample signed-rank test. RESULTS: Of 57 subjects studied, 29 received tetracaine and 28 received saline. The groups were similar in age, gender, wound length, wound location, and initial pain score. Pain scores decreased significantly in the tetracaine group as compared with the saline group. The median pain score difference for tetracaine was 12.0 mm, with an interquartile range (IQR) of 2 to 43 mm, as compared with 2 mm, with an IQR of - 17 to 21 mm for saline (p = 0.048). CONCLUSION: Topical tetracaine attenuates the pain of infiltration of buffered lidocaine.

Accuracy of microcentrifuged hematocrits in the emergency department.

This study tests whether hematocrits (Hcts) can be accurately measured in an emergency department by microcentrifuge technique. Prior to obtaining the results of a laboratory Hct (LAB Hct), microcentrifuged Hcts (MC Hcts) were determined on 204 emergency department patients. The average difference for LAB Hct--MC Hct was -0.539 +/- 1.64 (SD). The 95% confidence interval was (-0.76, -0.31) for the difference scores and (1.49, 1.81) for the SD. The two techniques had excellent correlation (r = 0.96). Plotting the MC Hct against the LAB Hct produced a line of best fit that essentially passed through the origin (Y intercept = 0.31) and had a slope of 1.006 (both t's < 1). When only the Hct is desired, MC Hcts can be performed in place of LAB Hcts without compromising accuracy.

Benzyl alcohol with epinephrine as an alternative to lidocaine with epinephrine.

A randomized, prospective, double-blind study comparing benzyl alcohol with epinephrine, 1:100,000 (BA), and lidocaine with epinephrine, 1:100,000 (LID), as local anesthetics was carried out on adult patients with simple lacerations. The two study groups were compared for pain of infiltration (100 mm visual analog scale) and need for additional anesthesia. Pain scores were compared by a Mann Whitney Independent Rank Sum test and need for additional anesthesia by a Fishers Exact test. A total of 52 subjects (26 per group) were analyzed. The groups were similar in demographics and wound characteristics. The median pain score for BA, 7.5 mm, was less than for LID, 19.5 mm (p = 0.049). Although more patients receiving BA required additional anesthesia as compared to LID (8/26 versus 2/26), this difference did not reach statistical significance. BA is a reasonable alternative local anesthetic to LID for patients who are allergic to LID.

Safe out-of-hospital treatment of chest pain without direct medical control.

INTRODUCTION: The use of direct medical control (DMC) in the out-of-hospital setting often is beneficial, but has the disadvantage of consuming emergency medical services (EMS) resources. HYPOTHESIS: Uncomplicated, nontrauma, adult patients with chest pain can be treated safely and transported by paramedics without DMC. METHODS: Retrospective chart review of all nontrauma, adult patients with chest pain treated in a combined rural and suburban EMS system during a 2-year period (December 1990 through November 1992) was conducted. Before November 1991, DMC was mandatory for all patients with chest pain. Beginning 01 November 1991, if a patient had resolution of a pain either spontaneously, with administration of oxygen, or after a single dose of nitroglycerin, DMC was at the discretion of the paramedic. Using the above criteria for inclusion, three study groups were defined: Group 1, before protocol change; Group 2, after protocol change without DMC; and Group 3, after protocol change when physician contact was obtained, but not required. These groups were compared for the following parameters: 1) scene time; 2) time to administration of first dose of nitroglycerin; 3) time interval between measurement of vital signs; 4) oxygen use; 5) intravenous access; and 6) electrocardiographic monitoring. Continuous and categorical variables were analyzed by multivariate and univariate analysis of variance and chi-square tests, respectively. RESULTS: Of 308 nontrauma, adult patients with chest pain, 71 met inclusion criteria in Group 1, 40 in Group 2, and 34 in Group 3. No statistically significant differences were identified in any of the study parameters. CONCLUSION: Adult patients with chest pain who have no other symptoms or complicating conditions can be treated appropriately be paramedics without DMC.

Outcomes of anticoagulated trauma patients.

Patients on warfarin are at high risk for potentially life-threatening hemorrhage even after relatively minor trauma. Outcomes of these patients and the potential complications of reversing the effects of anticoagulation have received little attention. This study was performed to determine the overall outcome of orally anticoagulated patients who sustained injury as well as to determine any untoward effects of reversing their anticoagulated states. A retrospective study of injured patients on warfarin was conducted on patients admitted to an urban, university, tertiary-referral, level I trauma center between 1/1/93 and 12/31/96. Surviving patients were followed for a period of at least 1 month. Injuries were grouped by anatomic site. Charts were reviewed for degree of anticoagulation on admission (ie, initial international normalized ratio [INR]), survival, adverse effects of reversal of anticoagulation, and reinstitution of warfarin therapy. Discharged patients were contacted at home for follow-up. Thirty-five consecutive patients, 18 men and 17 women, on warfarin therapy at the time of their injuries were reviewed. The mean age was 75 years, with a range of 39 to 96. The mean follow-up period was 12.7 months. Reasons for anticoagulation included atrial fibrillation, prosthetic heart valves, revascularized limb, hypercoagulable state, deep venous thrombosis, pulmonary embolism, phlebitis, and aortic stenosis. Mean admission INR was 3.2, with a range of 1.6 to 10.0. There were 8 in-hospital deaths. Intracranial hemorrhages accounted for the majority of injuries. Ten patients were not given reversal therapy. Four complications were attributable to reversal therapy (upper extremity hemiplegia, transient ischemic attack, deep venous thrombosis, arterial thrombosis). Twenty-one patients had their warfarin reinstituted. Follow-up of surviving patients ranged from 1.5 to 42 months. Patients on warfarin are at high risk for intracranial hemorrhage following trauma. Patients on warfarin may be reversed during the acute period following injury, but transient complications may arise. Further prospective studies need to be conducted to determine which anticoagulated trauma patients may not require reversal therapy.

Human rabies: a review.

Human rabies is a rarely observed but frequently prophylaxed disease in North America. Presented in this review is a typical emergency department case and a summary of the epidemiology of the rabies virus, its clinical appearances, diagnosis, and management. Emphasis is placed on issues pertinent to the emergency physician practicing in the United States. Current recommendations for the administration of both active and passive immunotherapy for preexposure and postexposure prophylaxis are discussed. A treatment algorithm to aid in the decisions faced by a practicing physician regarding proper animal management and patient therapy and future prospects for the control of rabies in wild animal populations are also included.

Traumatic atlanto-occipital dislocation: a potentially survivable injury.

Although survival with traumatic atlanto-occipital dislocation (AOD) is rare, there have been reports of victims who have sustained this injury with good neurological outcome. Plain lateral cervical spine radiography is the initial diagnostic procedure but may miss subtle dislocations. Several methods for the interpretation of the normal atlanto-occipital alignment have been devised and are discussed. Computed tomography (CT) and magnetic resonance imaging (MRI) are valuable studies in the diagnosis and management of AOD. Halo immobilization and posterior spinal fusion are the preferred modes of treatment. Vascular injury may contribute to the neurological deficits seen with AOD and is potentially reversible. Three cases are reported, two with survival of 1 day, and one long-term survivor with poor neurological outcome because of associated cerebral trauma.

Buffered versus plain lidocaine for digital nerve blocks.

STUDY OBJECTIVES: To test whether buffered lidocaine is less painful to administer as a digital nerve block than plain lidocaine. DESIGN: Randomized, double-blind, prospective clinical trial. SETTING: University hospital emergency department. PARTICIPANTS: Adults not allergic to lidocaine requiring a digital nerve block. INTERVENTIONS: Subjects received digital nerve blocks by injection of buffered lidocaine on one side and plain lidocaine on the other in a predetermined, randomized order. Pain of infiltration was assessed. Scores were compared using a two-tailed t-test. Standard 1% lidocaine was used if additional anesthetic was required. MEASUREMENTS AND MAIN RESULTS: Thirty-one patients were enrolled. Buffered lidocaine was significantly less painful to administer than plain lidocaine (P < .001; t = 4.21). Supplemental anesthesia was required less often for buffered lidocaine (two times) compared with plain lidocaine (six times), although this difference was not statistically significant. CONCLUSION: Because it causes less pain and is equally efficacious, buffered lidocaine is preferable to plain lidocaine for digital nerve blocks in adults.

Randomized trial of diphenhydramine versus benzyl alcohol with epinephrine as an alternative to lidocaine local anesthesia.

STUDY OBJECTIVES: We compared the pain of infiltration and anesthetic effects of.9% benzyl alcohol with epinephrine, 1% diphenhydramine, and.9% buffered lidocaine. METHODS: A prospective, randomized, double-blind study comparing benzyl alcohol, diphenhydramine, and lidocaine was carried out on adult volunteers. Each subject received all 3 injections in a standardized manner. Pain of infiltration was measured on a 100-mm visual analog pain scale and analyzed with a Kruskal-Wallis test. Duration of anesthesia was assessed at 5-minute intervals for a maximum of 45 minutes and compared with the use of survival analysis techniques by a log-rank test. Return of sensation by 45 minutes was evaluated with an exact chi2 test. All tests were 2-tailed, with significance defined as P <.05. RESULTS: Thirty subjects were enrolled. The diphenhydramine median pain score was 55 mm, compared with 12.5 mm for lidocaine and 5 mm for benzyl alcohol (P =.001). Pairwise comparisons showed that all possible combinations were statistically significant. The 3 anesthetics were different with respect to duration of anesthesia (P <.001). Pairwise comparisons revealed a longer duration of anesthesia for lidocaine than for diphenhydramine or benzyl alcohol, but no significant difference was found between diphenhydramine and benzyl alcohol. Pain sensation returned within the 45-minute study period in only 3 of 30 lidocaine injections, compared with 11 of 30 benzyl alcohol injections and 19 of 30 diphenhydramine injections (P =.001). CONCLUSION: Benzyl alcohol is a better alternative than diphenhydramine as a local anesthetic for lidocaine-allergic patients.

Empiric treatment of gonorrhea and chlamydia in the ED.

A retrospective study was conducted on female patients who were screened for Chlamydia trachomatis and Neisseria gonorrhea. The purpose of the study was to determine if any factors predict empiric therapy at the index visit. Of 911 patients enrolled in the study, 100 were found to have positive DNA screens and 54 were given empiric therapy. A logistic regression was used to test the ability of age, ethnicity, DNA probe result and provider type (physician or midlevel provider), to predict empiric treatment. DNA probe result and provider type were the only 2 factors that were found to predict empiric therapy. A subsequent analysis using a Cochran-Mantel-Hanszel test to control for DNA probe result revealed that the provider type remained the only variable that predicted empiric treatment.

Neonatal fever: utility of the Rochester criteria in determining low risk for serious bacterial infections.

The purpose of this study was to test the utility of the Rochester criteria in determining which febrile neonates are at low risk for serious bacterial infections (SBI). This was a retrospective study over a 5-year period of 134 patients younger than 29 days old with fever without a source evaluated in the emergency department. Results of urinalysis, lumbar puncture, peripheral white blood cell count, and cultures of blood, urine, cerebrospinal fluid, and stool were recorded. Of the 134 neonates, 71 were high-risk, 48 low-risk, and 15 were not classifiable by the available data. Nineteen of the 71 high-risk patients (26.8%) had SBI (2 patients had 2 SBI). Three of the 48 low-risk neonates (6.3%) had SBI (1 patient had 2 SBI). None of the 15 nonclassifiable patients had SBI. Employing the Rochester criteria to the fully cultured neonates who could be risk-stratified, the sensitivity, specificity, positive predictive value, and negative predictive value were 86.4%, 46.4%, 26.8%, and 93.8%, respectively. Although outpatient management of febrile neonates may be feasible, a small percentage of neonates meeting low-risk criteria will have a SBI.

Incidence of aspiration after urgent intubation.

This study sought to determine the incidence of aspiration after urgent endotracheal intubation (ET) performed in the emergency department (ED), and to offer a descriptive evaluation of these intubations. In a retrospective review of 133 charts, 87 patients met inclusion criteria. Aspiration occurred in 3 (3.5%) patients (95% confidence interval, 0%, 7.4%). One had witnessed aspiration, and 2 had positive sputum cultures. None of the 87 patients had a positive chest radiograph or unexplained hypoxemia up to 48 hours after ET. Rapid-sequence induction and oral ET was performed in 79 (91%) patients, whereas 4 spontaneously breathing patients were nasally intubated. Seventy percent of patients underwent ET by PGY I or II residents, 29% by PGY III or IV residents, and 1% by ED attending physicians. Seventy-seven patients were intubated on the first attempt, and airway blood or vomitus during ET was noted in 11 patients. This study offers significant descriptive information regarding urgent ET performed in the ED, and shows that aspiration after urgent ET occurs infrequently in ED patients.