Robert G. Buckley

Prospective comparison of unenhanced spiral computed tomography and intravenous urogram in the evaluation of acute flank pain

OBJECTIVES To prospectively compare the diagnostic ability of unenhanced spiral computed tomography (NCCT) and intravenous urogram (IVU) in the evaluation of adults with acute flank pain. METHODS After giving informed consent, 106 adult patients with acute flank pain suspected of having urolithiasis underwent NCCT followed by IVU. Subsequent follow-up was scheduled within 72 hours in the Urology Clinic. Each NCCT was read by a single radiologist who was unaware of clinical history and IVU results. Each IVU was read by a different radiologist who was unaware of clinical history and NCCT results. Sensitivity, specificity, and positive and negative predictive values were determined for NCCT and IVU. RESULTS The diagnosis of ureterolithiasis was defined as unequivocal evidence of urolithiasis on either NCCT or IVP. Seventy-five of 106 patients evaluated were diagnosed with ureterolithiasis. Clinical follow-up was available in 74 (98%) stone patients and in 31 (100%) of 31 non-stone patients. In 72 of the 75 patients diagnosed with ureteral calculi, the NCCT made the diagnosis. IVU made the diagnosis in 65 of the 75 patients. Of the 31 patients without ureterolithiasis, the NCCT was negative in all cases. IVU was negative in 29 of the 31 cases. Unenhanced spiral CT was 96% sensitive and 100% specific (P <0.001). IVU was 87% sensitive and 94% specific (P <0.001). Compared with IVU, using the log odds ratio and Fishers exact test, NCCT was significantly better able to predict the presence of urolithiasis (P=0.015). CONCLUSIONS NCCT accurately diagnoses ureterolithiasis in patients presenting with acute flank pain. NCCT is significantly better than IVU in determining the presence of urolithiasis.

The Pulse Oximetry Gap in Carbon Monoxide Intoxication

STUDY OBJECTIVE Pulse oximetry has been reported to be falsely elevated in the presence of carbon monoxide (CO). However, the degree to which pulse oximetry overestimates measured oxyhemoglobin saturation (O2Hb) has not been investigated in patients with CO exposure. This study quantifies the effect of CO on pulse oximetry and O2Hb in a series of patients with elevated carboxyhemoglobin (COHb) levels. METHODS A prospective case series of 25 pulse oximetry measurements, with concurrent arterial blood gas sampling, were obtained on 16 adults with CO exposure. RESULTS COHb levels (mean, 16.1%; SD, 11.6%; range, 2.2% to 44%) did not significantly correlate with pulse oximetry saturation (mean, 97.7%; SD, 1.5%; range 96% to 100%) (r = .45; P = .1 [NS]). Compared with COHb, a pulse oximetry gap (mean, 17.5%; SD, 1.5%; range, 2.3% to 42%), defined as pulse oximetry saturation minus O2Hb, yielded a linear regression model: pulse oximetry gap = 1.82 + 0.94 x COHb (SEM = 0.07; F = 204; R2 = .90; P < .0001). CONCLUSION Oxygen saturation as measured by pulse oximetry failed to decrease to less than 96% despite COHb levels as high as 44%. Regression between the pulse oximetry gap and COHb suggests that pulse oximetry overestimates O2Hb by the amount of COHb present. Pulse oximetry is unreliable in estimating O2Hb saturation in CO-exposed patients and should be interpreted with caution when used to estimate oxygen saturation in smokers.

History and Physical Examination to Estimate the Risk of Ectopic Pregnancy: Validation of a Clinical Prediction Model☆☆☆

STUDY OBJECTIVE To prospectively validate a clinical prediction model for ectopic pregnancy (EP). METHODS Prospective cohort with 14-month derivation and 12-month validation phases. All hemodynamically stable, first-trimester patients with abdominal pain or vaginal bleeding who presented to a military teaching hospital emergency department underwent follow-up until an outcome of intrauterine pregnancy (IUP) or EP was established. Patients were separated into the high-risk group, defined as having either peritoneal signs or definite cervical motion tenderness; intermediate-risk group, defined as the presence of pain or tenderness, other than midline cramping, plus absence of fetal heart tones, and absence of tissue visible at the cervical os; and low-risk group (neither high- nor intermediate-risk) using recursive partitioning. RESULTS Summarizing both phases, 915 patients had 845 (93%) IUPs and 70 (7.6%) EPs, with 18 (1.9%) lost to follow-up. The clinical prediction model classified 75 (8.2%) into the high-risk group (sensitivity 31%, 95% confidence interval [CI] 21% to 44%; specificity 94%, 95% CI 92% to 95%); and 644 (70%) in the intermediate-risk group (sensitivity 98%, 95% CI 89% to 100%; specificity 25%, 95% CI 22% to 29%). The remaining 196 (21%) patients who met neither high-risk nor intermediate-risk criteria were classified into the low-risk group. On the basis of EP prevalence of 7.7%, the risk of EP was less than 1% (95% CI 0% to 3%) for the low-risk group, 7% (95% CI 5% to 10%) for the intermediate-risk group, and 29% (95% CI 19% to 41%) for the high-risk group. CONCLUSION This clinical prediction model is useful for estimating the risk of EP in first-trimester patients, particularly when ancillary testing is equivocal or not readily available.

Bedside estimation of patient height for calculating ideal body weight in the emergency department.

BACKGROUND Ideal body weight (IBW), which can be calculated using the variables of true height and sex, is important for drug dosing and ventilator settings. True height often cannot be measured in the emergency department (ED). OBJECTIVES Determine the most accurate method to estimate IBW using true height-based IBW that uses true height estimated by providers or patients compared to true height estimated by a regression formula using measured tibial length, and compare all to the conventional 70 kg male/60 kg female standard IBW. METHODS Prospective, observational, double-blind, convenience sampling of stable adult patients in a tertiary care ED from September 2004 to April 2006. Derivation set (215 patients) had blinded provider and patient true height estimates and tibial length measurements compared to gold-standard standing true height. A validation set (102 patients) then compared the accuracy of IBW using true height calculated from the regression formula vs. IBW using gold-standard true height. Regression formula for men tibial length-IBW (kg) = 25.83 + 1.11 × tibial length; for women tibial length-IBW = 7.90 + 1.20 × tibial length; R(2) = 0.89, p < 0.001. Inter-rater correlation of tibial length was 0.94. RESULTS Derivation set: percent within 5 kg of true height-based IBW for men/women = PATIENT 91.1%:/85.7%; Physician: 66.1%/45.1%; Nurse: 65.7%/ 47.3%; tibial length: 66.1%/63.7%; and 70 kg male/60 kg female standard 46%/75%. Validation set: tibial length-IBW estimates were within 5 kg of true height-ideal body weight in only 56.2% of men and 42.2% of women. CONCLUSIONS PATIENT-reported height is the best bedside method to estimate true height to calculate ideal body weight. Physician and nurse estimates of true height are substantially less accurate, as is true height obtained from a regression formula that uses measured tibial length. All methods were more accurate than using the conventional 70 kg male/60 kg female IBW standard.

Comparison of Two Regimens of β-Adrenergics in Acute Asthma

Background and Methods:Inhaled adrenergics and steroids are the main agents used in acute asthma. Dosing recommendations for adrenergics, while generally becoming more aggressive, lack prospective validation. A double blind, randomized trial of two regimens of nebulized metaproterenol was conducted in patients presenting to an Emergency Department with an acute asthma exacerbation. Asthmatics age 16–55, with no other cardio-pulmonary disease, presenting with peak expiratory flow rate (PEFR) <30% of predicted and greater than 80L/m were enrolled. All patients received 125 mg of methylprednisolone and theophylline, if needed, to reach therapeutic levels. The experimental group received 0.3 cc metaproterenol in 2.5 cc of saline at times 0, 20″, 40″, 1′, 2′, 3′, 4′, 5′, 6′, and 7′. The control group received metaproterenol at times 0,1 hr, and hours 3, 5, and 7. Placebo was given to control group patients at 20″, 40″, 2′, 4′, and 6′. PEFR and vital signs were measured 10 min after each treatment. Study end points included discharge upon reaching set criteria or admission if patients were not discharged following the hour 7 treatment.Results:Seventy one patients were enrolled, 40 in experimental group and 31 in the control group. The group characteristics did not differ at entry in any significant way, and the groups began with mean expected PEFR of 23.4% and 24.5%, respectively. There were no significant differences at any point in PEFR outcomes, time to discharge, or admission rate. The experimental group showed a greater increase in pulse rate and a reduced diastolic blood pressure at 20, 40 and 60 min. The experimental group had a 12- and 8-fold increase in the risk of a pulse rate >140 at 40 and 60 min, respectively. This group also had two moderate complications, both near the 60-minute mark. These were an induction of atrial fibrillation in one patient and ischemic electrocardiographic changes in another.Conclusion:Three treatments in the first hour, and hourly thereafter showed no benefit over treatments initially, at one hour, and every other hour in acute, moderate, or severe exacerbation of asthma. Side effects were markedly increased in the control group. Such dosing should not be recommended as routine therapy.

Reliability of Subjective Fever in Triage of Adult Patients

STUDY OBJECTIVE To determine whether a historical complaint of fever is predictive of fever on emergency department triage. METHODS We prospectively questioned 651 ambulatory adult patients in a military tertiary care emergency department as to whether they had fever before oral temperature was taken. Fever was defined as a temperature of 38 degrees C (100.4 degrees F) or greater. RESULTS Sensitivity and specificity were 84% (95% confidence interval [CI], 71% to 95%) and 83% (95% CI, 80% to 86%), respectively. The prevalence of objective fever was 6.4%, yielding positive and negative predictive values of 25% (95% CI, 18% to 32%) and 99% (95% CI, 93% to 100%), respectively. Overall accuracy was 83% (95% CI, 80% to 86%). CONCLUSION In this study, outpatients were fairly accurate in predicting fever. However, in an outpatient population with a low overall prevalence of objective fever, the predictive value of a complaint of fever representing an objective fever remained low. Therefore the complaint of subjective fever should be interpreted with caution when it is used to support a given diagnosis in an ambulatory care setting.

Symptomatic bradycardia following the administration of sublingual nitroglycerin

A case of severe bradycardia with junctional escape immediately following sublingual nitroglycerin is described. Bradycardia is a rare, but well-documented, complication of nitroglycerin and is often reported in the setting of myocardial ischemia or infarction. This particular case reported was complicated by the presence of an angiographically documented congenital coronary anomaly, but did not have either electrocardiographic or enzymatic evidence of ischemia or infarction during this event. Previously reported cases were reviewed, as well as potential mechanisms for this phenomenon. All cases reported to date were easily corrected with passive leg elevation or atropine.