Current Issues In Emergency Medicine - A Selected Update

Selected Current Issues In Emergency Medicine

K.S. ChewSchool of Medical Sciences

Universiti Sains Malaysia

Sensitivity, Specificity, PPV and NPVDisease POSITIVE Disease NEGATIVE

Test POSITIVE A (True POSITIVE) B (False POSITIVE)

Test NEGATIVE C (False NEGATIVE) D (True NEGATIVE)

A + C B + D

Sensitivity: The probability of the test able to detect the disease among the population WITH the diseaseSensitivity = A/ (A+C)

Specificity: The probability of the test NOT detecting the disease among the population who DO NOT have the diseaseSpecificity = D/(B+D)




A + C B + D

Positive Predictive Value (PPV): The percentage of people with a positive test result who actually have the disease.PPV = A/(A+B)

Negative Predictive Value (NPV): The percentage of people with a negative test who do NOT have the disease.NPV = D/ (C+D)




A + C B + D

Sensitivity is useful to rule-out a disease. When a diagnostic test or sign has a high sensitivity, a negative result rules out the diagnosis. Mnemonic “SnOUT” Why? Sensitivity and Negative Predictive Value share false negative (C). As Sensitivity increases toward 100%, FN decreases toward 0. As FN decreases toward 0, Negative Predictive Value increases toward 100%.




A + C B + D

Specificity is useful to rule-in a disease. When a diagnostic sign or test has a high specificity, a Positive result rules in the diagnosis. Mnemonic “SpIN”

Why? Specificity and Positive Predictive Value share false positive (B). As Specificity increases toward 100%, FP decreases toward 0. As FP decreases toward 0, Positive Predictive Value increases toward 100%.

Acute Decompensated Heart Failure – The Role of BNP

B-type natriuretic peptide (BNP)

is secreted by the right and left ventricles as a pro-hormone in response to increased pressure.

cleaved into BNP and NT-proBNP. BNP decreases preload and afterload,

increases the glomerular filtration rate, and decreases sodium reabsorption.

Natriuretic peptides have been shown to be elevated in persons with ADHF.

The Role of BNP

Wang CS, FitzGerald JM, Schulzer M, Mak E, Ayas NT. Does this dyspneic patient in the emergency

department have congestive heart failure? JAMA 2005;294(15):1944–56.

ACEP Guidelines BNP <100 pg/dL or NT-proBNP <300 pg/dL acute

heart failure syndrome unlikely (Approximate negative likelihood ratio [LR-] = 0.1)

BNP >500 pg/dL or NT-proBNP >1,000 pg/dL acute heart failure syndrome likely (Approximate positive likelihood ratio [LR+] =6)

Silvers SM, Howell JM, Kosowsky JM, Rokos IC, Jagoda AS, American College of Emergency Physicians Clinical Policies Subcommittee. Clinical policy: critical issues in the evaluation and management of adult patients presenting to the emergency department with acute heart failure syndromes. Ann Emerg Med 2007 May;49(5):627-69.

Acute Decompensated Heart Failure – Nesiritide

Nesiritide Nesiritide is a recombinant form of B-type

(brain) natriuretic peptide that dilates veins, peripheral arteries, and coronary arteries.

As a result, nesiritide reduces preload and afterload and has been studied in acute heart failure syndromes.

Due to the neuro-hormonal effects, and the increased serum levels of BNP in the setting of heart failure, it has been speculated that recombinant BNP may be a therapeutic addition to the treatment of acute exacerbations of heart failure.

VMAC Group Significant reductions in PCWP were noted in the

nesiritide group when compared to either nitroglycerin or placebo (p < 0.05).

After 24 hours, the reduction in PCWP was still significantly greater in the nesiritide group when compared to the nitroglycerin group (p = 0.04).

There was no difference, however, in resolution of dyspnea between the nitroglycerin and nesiritide groups, although both treatments were significantly more effective than placebo at 3 hours.

VMAC Investigators. Intravenous nesiritide vs nitroglycerin for treatment of decompensated congestive heart failure: a randomized controlled trial. JAMA 2002;287(12):1531–40.

Sackner-Bernstein JD, Kowalski M, Fox M, Aaronson K. Short-term risk of death after treatment with nesiritide for decompensated heart failure: a

pooled analysis of randomized controlled trials. JAMA 2005;293(15):1900–905.

Sackner-Bernstein JD, Skopicki HA, Aaronson KD. Risk of worsening renal function with nesiritide in patients with acutely decompensated heart failure.

Circulation 2005;111(12):1487-91

ACEP Guidelines Because of the lack of clear superiority of

nesiritide over nitrates in acute heart failure syndrome and the current uncertainty regarding its safety, nesiritide generally should NOT be considered first line therapy for acute heart failure syndromes.


Acute Decompensated Heart Failure – The Role of NIV

Non-Invasive Ventilation (NIV) The two basic forms of NIV: continuous positive airway pressure (CPAP)

and Noninvasive positive pressure ventilation

[NPPV, or BiPAP (bi-level positive airway pressure)].

CPAP – usually set at 5 – 10 cm H2O BiPAP

IPPV – average 5 cm H2O EPPV – average 15 cm H2O

NIV in Heart Failure? Pang et al. performed a meta-analysis of NIV versus

standard oxygen therapy in 1998. Data were pooled from three studies that compared CPAP and/or BiPAP to standard medical therapy.

The authors specifically investigated the effect(s) of NPPV on mortality and the need for intubation.

They found that CPAP was associated with a reduced rate of intubation (RR = −26%; 95% CI: −14% to −38%) and a trend toward decreased mortality (RR = −6.6%; 95% CI: −16% to +3%) when compared to standard oxygen therapy.

The pooled analysis neither confirmed nor excluded the value of BiPAP compared to standard therapy alone.

Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive pressure airway support on mortality and the need for intubation in cardiogenic pulmonary edema: a systematic review. Chest

1998;114(4):1185–92.

NIV in Heart Failure? Masip et al. performed a meta-analysis of trials

comparing NIV (i.e., CPAP and BiPAP) to standard oxygen therapy in the treatment of acute cardiogenic pulmonary edema.

Fifteen trials were included and involved data from 727 patients. Primary endpoints were in-hospital mortality and intubation rate. The secondary endpoint was myocardial infarction.

From this review, it was shown that NIV significantly decreased the relative mortality risk by 43% (CPAP 46%, BiPAP 37%). This was statistically significant for CPAP, but BiPAP results failed to reach statistical significance.

Masip J, Roque M, Sanchez B, Fernandez R, Subirana M, Exposito JA. Noninvasive ventilation in acute cardiogenic pulmonary edema: systematic review and meta-analysis. JAMA

2005;294(24):3124–30.

NIV in Heart Failure? It was also shown that NIV significantly

reduced the relative intubation risk by 57% (P < 0.001), and the results were statistically significant for both CPAP and BiPAP (P<0.001 and P = 0.002, respectively).

Overall rates of myocardial infarction were not significantly different between standard oxygen therapy and either mode of non-invasive ventilation (RR = 0.89; 95% CI: 0.69 to 1.17).


2005;294(24):3124–30.


2005;294(24):3124–30.

Systematic reviews evaluating non-invasive positive pressure ventilation in the treatment of acute decompensated heart failure.

Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive pressure airway support on mortality and the need for intubation in cardiogenic pulmonary edema: a systematic review. Chest

1998;114(4):1185–92.Masip J, Roque M, Sanchez B, Fernandez R, Subirana M, Exposito JA. Noninvasive ventilation in

acute cardiogenic pulmonary edema: systematic review and meta-analysis. JAMA

2005;294(24):3124–30..Collins SP, MielniczukLM, Whittingham HA, Boseley ME, Schramm DR, StorrowAB. The use of

noninvasive ventilation in emergency department patients with acute cardiogenic pulmonary edema: a systematic review. Ann Emer Med 2006;48(3)260–69, e1–4.

ACEP Guidelines A moderate clinical certainty recommendation

for the use of CPAP, while Bi-PAP was given a preliminary, inconclusive or conflicting evidence, or based on panel consensus recommendation due to the concern for potential myocardial ischemia and/or infarction


ACEP Guidelines Use 5 to 10 mm Hg continuous positive airway

pressure (CPAP) by nasal or face mask as therapy for dyspneic patients with acute heart failure syndrome without hypotension or the need for emergent intubation to improve heart rate, respiratory rate, blood pressure, and reduce the need for intubation, and possibly reduce inhospital mortality.


Atrial Fibrillation

Atrial Fibrillation >48 Hours In patients with atrial fibrillation that lasts for

more than 48 hours, the immediate risk of experiencing a thromboembolic event is between 5% and 7% if not preceded by anticoagulation.

This risk decreases to 0–1.6% if 2–4 weeks of prophylactic anticoagulation and TEE are performed.

Manning WJ, Silverman DI, Keighley CS, Oettgen P, Douglas PS. Transesophageal echocardiographically facilitated early cardioversion from atrial fibrillation using short-term anticoagulation: final results of a prospective 4.5 year study. J Am Coll Cardiol 1995;25:1354–61.

Atrial Fibrillation <48 Hours The rate of thromboembolic events - 0.8% (95% CI:

0.2% to 2.4%).

In addition, no significant difference was found in the incidence of thromboembolism after rhythm conversion between patients for whom anticoagulation therapy was initiated on presentation, 0.8% (95% CI: 0.02% to 4.1%), and those for whom it was not, 0.9% (95% CI: 0.1% to 3.1%)

Wegner MJ, Caulfield TA, Danias PG, et al. Risk for clinical thromboembolism associated with conversion to sinus rhythm in patients with atrial fibrillation lasting less than 48 hours. Ann Intern Med 1997;126(8):615–20.

ACC/AHA Recommendations The risk of thromboembolic phenomena

associated with cardioverting AF of >48 hours’ duration is unacceptably high; as such, rhythm control or conversion in this group (>48 hours) is not recommended

Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation – executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001Guidelines for the Management of Patients with Atrial Fibrillation). Circulation 2006;114:700–752.

All-cause Mortality and Thromboembolic Stroke: Rate Control vs Rhythm Control

Testa L, Biondi-Zoccai GG, Dello Russo A, Bellocci F, Andreotti F, Crea F. Rate-control vs. rhythm-control in patients with atrial fibrillation: a meta-analysis. Eur Heart J

2005;26(19):2000–2006.

Major Bleeding Complications In Rate Vs Rhythm Control In Atrial Fibrillation


2005;26(19):2000–2006.

Overall, the rate control strategy had a significantly lower risk of all-cause death and thromboembolic stroke (OR = 0.85; 95% CI: 0.73 to 0.98)

The rate of major bleeding (intracranial and extracranial) was similar between the rate and rhythm control strategies (OR=1.12; 95% CI: 0.82 to 1.53)

The results of these five trials contradict the commonly held perception that maintaining sinus rhythm is superior to rate control.

Rate Control vs Rhythm Control


2005;26(19):2000–2006.

Beta-Blocker vs CCB For Ventricular Rate Control for Atrial Fibrillation In a randomized, blinded controlled study that

compared the effectiveness of IV diltiazem and metoprolol in 40 patients with AF, both were safe and effective for the management of rapid ventricular rate.

However, rate control was achieved more quickly and the percentage decrease in ventricular rate was higher with diltiazem (0.25 mg/kg IV, maximum 25 mg) than with metoprolol (0.15 mg/kg, maximum 10 mg).

Demircan C, Cikriklar HI, Engindeniz Z, et al. Comparison of the effectiveness of intravenous diltiazem and metoprolol in the management of rapid ventricular rate in atrial fibrillation. EmergMed J 2005;2(6):411–14.

The CHADS2 (Cardiac Failure, Hypertension, Age, Diabetes, Stroke (Doubled)) scoring system ranks patients from 0 to 5, giving 2 points for TIA or stroke and 1 point for all other risk factors

The CHADS2 index was the most accurate predictor of stroke compared to the Atrial Fibrillation Investigators (AFI) and the Stroke Prevention in Atrial Fibrillation (SPAF) predictors.

Gage BF, Waterman AD, ShannonW, et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864–70.

van Walraven WC, Hart RG, Wells GA, et al. A clinical prediction rule to identify patients with atrial fibrillation and a low risk for stroke while taking aspirin. Arch Intern Med 2003;163:936–43.

CHADS2 Score for Non-Valvular AF To Predict Thromboembolic Risk

CHADS2 Score for Non-Valvular AF Not Treated With Anticoagulants

C = Cardiac FailureH = HypertensionA = Age >70D = DMS = Stroke Previously

Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation – executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001Guidelines for the Management of Patients with Atrial Fibrillation). Circulation 2006;114:700–752

Thromboembolic Risk Factors For AF

“C-H-A-D”

ACC/AHA/ESC 2006 Recommendations

Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation – executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001Guidelines for the Management of Patients with Atrial Fibrillation). Circulation 2006;114:700–752

Which one – Antiplatelet or Warfarin?

Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857–67.

Which one – Antiplatelet or Warfarin? In summary, warfarin was more effective than

ASA and/or clopidogrel in preventing strokes in patients with AF.

The safety profile of warfarin poses a risk for major bleeding, especially intracranial hemorrhage.

The need to establish a risk–benefit profile for each patient is essential prior to commencing treatment.

Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857–67.

Chest Pain Syndromes: Clinical Features

Chest Pain

A systematic review by Panju et al, was published to address this question based on literature of patients evaluated for myocardial infarction.

In that paper, data from over a dozen trials were collected to provide estimates of diagnostic performance and agreement for a variety of clinical elements.

Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. Is this patient having a myocardial infarction? JAMA 1998;280:1256.

Panju AA, Hemmelgarn BR, Guyatt GH, Simel DL. Is this patient having a myocardial infarction? JAMA 1998;280:1256.

Chest Pain

Panju’s work suggests there are no clinical features with sufficient diagnostic performance to rule in or rule out the diagnosis of myocardial infarction.

What is perhaps notable is that radiation of chest pain to the right shoulder is actually suggestive of a cardiac etiology and that radiation in both arms should make the emergency physician suspect ACS.

Panju AA,Hemmelgarn BR, Guyatt GH, Simel DL. Is this patient having a myocardial infarction? JAMA 1998;280:1256.

Community-Acquired Pneumonia: CURB-65 vs PSI

Clinical Decision Rules To Determine Admission of Community Acquired Pneumonia Patients

The two tools in common use for this purpose are the pneumonia severity index (PSI), developed in the USA, and the CURB-65 rule adapted from the British Thoracic Society.

Fine MJ, Auble TE, Yealy DM, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med 1997;336:243–50.

Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 2003;58:377–82.

Pneumonia Severity Index

Pneumonia Severity Index Scoring Class 1: Points 0: Mortality 0.1% (low risk) Class 2: Points <70: Mortality 0.6% (low risk) Class 3: Points 71-90: Mortality 2.8% (low risk) Class 4: Points 91-130: Mortality 8.2%

(moderate risk) Class 5: Points >130: Mortality 29.2% (high risk)

Interpretation Class 1-2: Outpatient management Class 3: Consider short observation hospital stay Class 4-5: Inpatient management

CURB-65 C = confusion U = urea >7 mmol/L R = respiratory rate >30 breaths/min, B = Blood pressure low; systolic BP (<90

mmHg) or diastolic (<60 mmHg) 65 = and age (>65 years) with one point being assigned for the

presence of each.

Lim WS, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax 2003;58:377–82.

CURB-65 Scoring

Score 0 - 0.7% Score 1 - 3.2% Score 2 - 13.0% Score 3 - 17.0% Score 4 - 41.5% Score 5 - 57.0%

CURB-65 Pneumonia Severity Index (PSI)

Simpler to remember and use Complex

Disadvantage:

Fails to take into account the effect of co-morbidities that may be destabilized by even mild episodes of CAP

Advantage:

More selective in identifying patients with a low risk of mortality (for outpatient treatment), thus avoiding unnecessary hospitalization

Advantage:

More discriminating between the risks of death among sicker patients, because it defined high-risk patients as those with a score of 2, 3, 4 or 5, with each of these classes having a progressivelyincreasing risk of death

Disadvantage:

Only defined two groups (classes IVand V) as severely ill with mortalities of 8.1% and 24%, respectively.

Both systems predicted mortality with a similar level ofaccuracyAujeski D, Auble TE, Yealy DM, et al. Prospective validation of three validated prediction

rules for prognosis in community-acquired pneumonia. Am J Med 2005;118:384–92.

PSI vs CURB-65 To identify which patients can be safely treated as

outpatient, use PSI

To make disposition decisions among sick patients, use CURB-65

Combining both?

Aujeski D, Auble TE, Yealy DM, et al. Prospective validation of three validated prediction rules for prognosis in community-acquired pneumonia. Am J Med 2005;118:384–92.

Niederman MS, Feldman C, Richards GA. Combining information from prognostic scoring tools for CAP: an American view on how to get the best of all worlds. Eur Respir J 2006;27:9–11.

Syncope: San Francisco Syncope Rule

San Francisco Syncope Rule The absence of all of the following risk-factors was

96% sensitive and 62% specific for identifying serious outcomes at seven days (CHESS): C = a history of congestive heart failure H = hematocrit of less than 30% E = an abnormal ECG S = a complaint of shortness of breath S = triage systolic blood pressure of less than 90 mmHg

A validation of this rule subsequently in a similar population to that from which it was derived found that the rule was 98% sensitive (95% CI: 89–100) and 56% specific (95% CI: 52–60). Quinn, J., McDermott, D., Stiell, I., et al. (2006) Prospective validation of the San

Francisco syncope rule to predict patients with serious outcomes. Annals of Emergency Medicine 47: 448–454.

Quinn, J.V., Steill, I.G., McDermott, D.A., et al. (2004) Derivation of the San Francisco syncope rule to predict patients with short-term serious outcomes. Annals of

Emergency Medicine 43: 224–232.

An independent validation of the SFSR rule was performed in an ED population in a single academic center

The primary outcome of the study was the sensitivity of the San Francisco syncope rule for predicting serious events at seven days.

A secondary outcome of the study was the prediction of any serious clinical events that were not detected during the initial ED visit.

They reported a sensitivity of 89% (95% CI: 81–97) and a specificity of 42% (95% CI: 37–48) for the San Francisco syncope rule in predicting seven-day serious outcomes.

They also reported a sensitivity of 69% (95% CI: 46–95) and 42% (95% CI: 37–48) for a serious diagnosis that was not identified during the initial ED evaluation

San Francisco Syncope Rule

Sun, B.C., Mangione, C.M., Merchant, G., et al. (2007) External validation of the San Francisco syncope rule. Annals of Emergency Medicine 49: 420–

427.

While the San Francisco syncope rule does provide a good risk stratification scheme for determining which patients are at a low risk for serious short-term outcomes, it does not provide us with a definitive guide for determining which patients should be admitted or discharged.

San Francisco Syncope Rule

Transient Ischemic Attack

Transient Ischemic Attack (TIA) Two clinical prediction rules have been

independently developed: The California Rule derived by Johnston et al. The ABCD Rule by Rothwell et al.

Investigators from both of these studies collaborated to derive a unified score optimized for prediction of 2-day stroke risk following presentation with a suspected TIA. This is called the ABCD2 score.

Transient Ischemic Attack (TIA) The ABCD2 score (0–7 points) is calculated by

evaluating five factors: A = age (≥60 years, 1 point) B = blood pressure at presentation (≥140/90mmHg, 1

point), C = clinical features (unilateral weakness, 2 points;

speech disturbance without weakness, 1 point) D = duration of symptoms (≥60 minutes, 2 points;

10–59 minutes, 1 point) and D = diabetes (1 point)

Subsequent 2-day stroke risk based on the ABCD2 score is 1% (0–3 points), 4% (4–5 points) or 8% (6–7 points).

TIA – ABCD2 Score The ABCD2 score was retrospectively validated using the

datasets from four previously conducted cohort studies. It appears to be the best available tool in risk stratifying

patients at short-term (2-day) risk of stroke after a suspected TIA.

Patients identified as being high risk (score 6–7 points) by the ABCD2 score are candidates for immediate evaluation, optimization for stroke prevention and possibly therapeutic intervention should symptoms recur.

Patients with a score <3 may be suitable for further outpatient evaluation following discharge on an antiplatelet agent.

However, this score has not been prospectively validated.

Acute Asthma in Emergency Department

Role of IV Beta-2 Agonists For Acute Asthma: A Cochrane Review 2001 Reviewed 15 randomized trials over a period of 25 yearsConclusions:1 No statistically significant difference in effect between IV

beta2-agonists and all other treatments combined (inhaled beta2-agonists, or IV methylxanthines).

2 IV beta2-agonists administered either by bolus or infusion did not lead to significant improvements in any of the outcome measures of clinical success (i.e. pulmonary functions, vital signs, adverse events, clinical scores)

3 Use of IV beta2-agonists was associated with an non-significant increase in risk of autonomic side effects (2-12 times), and higher heart rates (4-10 beats per minute)

Travers A, Jones AP, Kelly K, Barker SJ, Camargo CA, Rowe BH. Intravenous beta2-agonists for acute asthma in the emergency department. Cochrane Database Syst Rev.

2001(2):CD002988.

Role of IV Beta-2 Agonists For Acute Asthma: A Cochrane Review 2001 Reviewed 15 randomized trials over a period

of 25 years

Conclusions: The only recommendations for IV beta2-

agonists use should be for those patients in whom inhaled therapy cannot be used, however there have been no tests of its efficacy in such situations.

Travers A, Jones AP, Kelly K, Barker SJ, Camargo CA, Rowe BH. Intravenous beta2-agonists for acute asthma in the emergency department. Cochrane Database Syst Rev.

2001(2):CD002988.

Role of Inhaled Beta Agonists With Holding Chambers Vs Nebulized Beta Agonists in Acute Asthma

This review has been updated in January 2008, involves 2295 children and 614 adults in 27 trials from both emergency room and community settings.

Conclusions:1 Method of delivery of ß2-agonist did not appear

to affect hospital admission rates. 2 In adults, the relative risk of admission for

spacer versus nebuliser was 0.97 (95% CI 0.63 to 1.49).

3 The relative risk for children was 0.72 (95% CI: 0.47 to 1.09).

Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev. 2006(2):CD000052.


4 In children, length of stay in the emergency department was significantly shorter when the spacer was used, with a mean difference of -0.53 hours (95% CI: -0.62 to -0.44 hours).

5 Length of stay in the emergency department for adults was similar for the two delivery methods.

6 Peak flow and forced expiratory volume were also similar for the two delivery methods.

7 Pulse rate was lower for spacer in children, mean difference -6.27% baseline (95% CI: -8.29 to -4.25% baseline).Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-

agonist treatment of acute asthma. Cochrane Database Syst Rev. 2006(2):CD000052.


An Important caveat in this Cochrane Review: These data DO NOT include patients with severe or

near fatal asthma For patients with severe asthma, the benefits and

ease of continuous nebulization makes it a more attractive choice for emergency bronchodilator

The recent worldwide severe SARS outbreak and its apparent spread following nebulization has discouraged routine use of nebulized treatment; in some settings these factors facilitate conversion to MDIs to holding chambers

Varia M, Wilson S, Sarwal S, et al. Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada. Can Med Assoc J 2003;169(4):285–92.

Cates CJ, Crilly JA, Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev. 2006(2):CD000052.

Varia M, Wilson S, Sarwal S, et al. Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada. Can Med Assoc J 2003;169(4):285–92.

165 trials were reviewed and eight were included; a total of 461 patients have been studied (229 with CBA; 232 with intermittent beta-agonists).

Conclusions Overall, admission to hospital was reduced

with CBA compared to intermittent beta-agonists (RR: 0.68; 95% CI: 0.5 to 0.9) patients with severe airway obstruction at

presentation appeared to benefit most from this intervention (RR: 0.64; 95% CI: 0.5 to 0.9).

Continuous Nebulization vs Intermittent Nebulization of Beta-agonists for Acute Asthma

Camargo CA, Jr., Spooner CH, Rowe BH. Continuous versus intermittent beta-agonists in the treatment of acute asthma. Cochrane Database Syst Rev. 2003(4):CD001115.

Patients receiving CBA demonstrated small but statistically significant improvements in pulmonary function tests when all studies were pooled.

Patients receiving CBA had greater improvements in % predicted FEV-1 and

PEFR this effect was observed by 2-3 hours.



Continuous treatment was generally well tolerated, with no clinically important differences observed in

pulse rate or blood pressure between the treatment groups. Tremor was equally common in both groups (OR:

0.81; 95% CI: 0.5 to 1.3) and potassium concentration was unchanged



Role of Magnesium Sulfate Magnesium is an important cofactor in many

enzymatic reactions and is linked to cellular homeostasis.

In addition, magnesium has an effect on smooth muscle cells, with hypomagnesaemia causing contraction and hypermagnesaemia causing relaxation.

There is some evidence that when magnesium is infused into asthmatic patients, it can provide additional bronchodilation (Okayama 1987; Rolla 1988).

In addition, evidence suggests that magnesium may reduce the neutrophilic burst seen with the inflammatory response (Cairns 1996). Manser R, Reid D, Abramson M. Corticosteroids for acute severe asthma in hospitalised

patients. Cochrane Database Syst Rev. 2001(1):CD001740.

Magnesium Sulfate: A Cochrane ReviewA total of 665 patients were involved.

Seven trials were included (5 adult, 2 pediatric). As a whole, this systematic review failed to

demonstrate statistically significant evidence of a beneficial effect of magnesium sulfate in terms of admission rates or pulmonary functions.

But those with severe asthma appeared to benefit from the use of IV magnesium sulfate, both in terms of pulmonary functions and admission rates. Improvement of approx 10% predicted FEV-1 or 50

L/min PEFRRowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA, Jr. Magnesium sulfate for

treating exacerbations of acute asthma in the emergency department. Cochrane Database Syst Rev. 2000(2):CD001490

Magnesium Sulfate: A Cochrane ReviewConclusion: Current evidence does not support routine use of

intravenous magnesium sulfate in all patients with acute asthma presenting to the emergency department although it appears to be safe and beneficial in patients who present with severe acute asthma.

In this review, severe acute asthma is defined by: PEFR < than 25-30% predicted after initial beta2-

agonist therapy in adults and/or non-response to treatment (adults and children), or peak expiratory flow rates of < 60% predicted

(children).

Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA, Jr. Magnesium sulfate for treating exacerbations of acute asthma in the emergency department. Cochrane

Database Syst Rev. 2000(2):CD001490

Mild Head Injury

Mild Head Injury Definition: A blow to the head (or rapid deceleration) with

witnessed or self reported with either loss of consciousness of less than 30 minutes, or Amnesia of less than 24 hours, or any alteration in mental state (feeling dazed,

disoriented, confused) at the time of the injury

with A GCS of 13 – 15 at 30 minutes of more after the

injury

Kay T,Harrington DE, Adams R, et al. Definition of mild traumatic brain injury. J Head Trauma Rehab 1993;8(3):86–7.

Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PMC. Indications for computed tomography in patients with minor head injury. N Engl J Med 2000;343(2):100–105.

H = HeadacheA = AmnesiaY = Years old >60D = DrugsE = EmesisL = Level injury above clavicleS = Seizure

HAYDEL’S NOC

NOC vs CCHRPredicting need for neurosurgical intervention Sensitivity for predicting need for neurosurgical

intervention was 100% for both the NOC and the CCHR, but

the CCHR was more specific (76.3% vs 12.1%; P < .001).

Predicting clinically important brain injury For clinically important brain injury, sensitivity

was 100% for both the CCHR and the NOC (95% confidence interval [CI], 96% - 100%), but

the CCHR had higher specificity (50.6% vs 12.7%; P <.001) and would result in lower CT rates (52.1% vs 88.0%; P < .001).

Stiell, I.G., Clement, C.M., Rowe, B.H., et al. (2005) Comparison of the Canadian CT head rule and the New Orleans criteria in patients with minor head injury. JAMA 294(12): 1511–

1518.


1518.

Applying the NOC resulted in significantly more false positives (i.e. the rule indicated that the patient was not at low risk and the head CT showed no injury), which yielded a lower specificity.

The authors concluded that given the equivalent sensitivities, using the CCHR would be likely to result in fewer head CTs being ordered.

NOC vs CCHR


1518.

Smits M, Dippel DWJ, de Haan GG, et al. External validation of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA 2005;294(12):1519–

25.

NEXUS II Criteria The study identified eight criteria that were independently

and highly associated with intracranial injuries. These include:

evidence of significant skull fracture scalp haematoma neurologic deficit altered level of alertness abnormal behaviour coagulopathy persistent vomiting age 65 or more

The study showed that patients who did not have any of the above criteria were unlikely to have significant injuries revealed by CT imaging and could therefore be safely discharged following a thorough evaluation without the use of CT.

Mower WRHJ, Herbert M,Wolfson AB, Pollack CV, Jr., Zucker MI, and NI Investigators. Developing a decision instrument to guide computed tomographic imaging of blunt head

injury patients. J Trauma Injury Infect Crit Care 2005;59(4):954–9.

CT in Head Injury Patients (CHIP Prediction Rules)This prediction rule developed in the Netherlands includes those patients with blunt injury to the head who have a normal or minimally altered level of consciousness on presentation in the emergency department, that is, - a Glasgow Coma Scale (GCS) score of 13 to 15, and

- a maximum loss of consciousness of 15 minutes, - posttraumatic amnesia for 60 minutes, or both.

External validation remains to be done in different populations.

Smits M, et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head injury: The CHIP prediction rule. Ann Int Med 2007; 146: 397-

405.

CT in Head Injury Patients (CHIP Prediction Rules)

A CT is indicated in the presence of 1 major criterion

A CT is indicated in the presence of at least 2 minor criteria

Pedestrian or cyclist versus vehicle

Fall from any elevation

Ejected from vehicle Persistent anterograde amnesia

Vomiting Posttraumatic amnesia of 2 to 4 hours

Posttraumatic amnesia 4 hr or more

Contusion of the skull

Clinical signs of skull fracture Neurologic deficit

GCS score <15 Loss of consciousness

GCS deterioration 2 points or more (1 h after presentation)

GCS deterioration of 1 point (1 hour after presentation)

Use of anticoagulant therapy Age 40 to 60 years

Posttraumatic seizure

Age 60 years or more

Smits M, et al. Predicting intracranial traumatic findings on computed tomography in patients with minor head injury: The CHIP prediction rule. Ann Int Med 2007; 146: 397-

405.

The Need for Cervical Radiographic Imaging In Stable Blunt Trauma

NEXUS Low Risk Criteria (NLC) N = Neurological deficit S = Spine tenderness A = Alertness I = Intoxication D = Distracting Injuries

Whenever a component of the NLC was unassessable, the patient was considered not to have met that criterion.

Patients that met all five criteria were considered to be at low risk for clinically significant cervical spine injury and these patients would not require imaging of the cervical spine in the ED.

The Canadian C-spine rules. ED, emergency department; MVC, motor vehicle collision. (Source: Journal of the American Medical Association 2001; 286:1841

Canadian C-spine Rule

Stiell, I.G., Clement, C.M., McKnight, R.D., et al. (2003) The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. New England Journal of Medicine

349(26): 2510–2518.

Validation results of the Canadian C-spine rule (CCR) and test performance from Stiell et al

NEXUS Low-Risk Criteria

Stiell, I.G., Clement, C.M., McKnight, R.D., et al. (2003) The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. New England Journal of Medicine

349(26): 2510–2518.

NEXUS low-risk criteria (NLC): results and test performance from Stiell et al.

NLC vs CCR The NLC and the CCR have both been validated

in large cohorts of patients in ED patients with blunt trauma to the neck.

In the validation cohorts, both have high sensitivities (>99.3%) and negative predictive values (>99.9%), making both decision rules safe.

When comparing the two rules, Stiell and colleagues concluded that the CCR performed better than the NLC.

The NLC are somewhat easier to use clinically because they are less difficult to remember. The CCR are more complex and must be employed

in a stepwise fashion.

While both the NLC and the CCR have roughly equal high sensitivity and high negative predictive values, the CCR are more specific than the NLC CCR will have many fewer false positives

The very low specificity of the NLC will lead to more unnecessary imaging (i.e. false positives—when the prediction rule indicates that the patient is not low risk and therefore recommends imaging).

NLC vs CCR

Ottawa Knee, Ankle and Foot Rules

Ottawa Knee Rules O – Older age group

Older than 55 years old T – Tenderness head of fibula T – Tenderness of patella

Isolated patella tendernes, no other bony tenderness

AW – Ability to walk? Inability to walk four steps immediately after

injury and in ED A – Ability to flex?

Knee Flexion to 90 degrees

Ottawa Knee Rules

Six studies reporting sensitivity and specificity of the Ottawa knee rules

Ottawa Ankle Rules

Ottawa Foot Rules

Sensitivities and specificities of OAR and OFR in pooled studies from Bachmann et al.

Bachmann, L.M., Kolb, E., Koller, M.T., et al. (2003) Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. British Medical Journal

326(7386): 417.

Current Issues In Emergency Medicine - A Selected Update

Health & Medicine

Transcript of Current Issues In Emergency Medicine - A Selected Update