Hrev_master [page 2] [Emergency Care Journal 2013; 9:e2] The role of bedside ultrasound in the diagnosis and outcome of patients with acute respiratory failure Andrea Bellone,1 Massimiliano Etteri,1 Carlo Maino,2 Chiara Bonetti,2 Anna Natalizi2 1Emergency Department, Sant’Anna Hospital, San Fermo della Battaglia; 2Emergency Department, Valduce Hospital, Como, Italy Abstract The aim of the present study was to evaluate the relationship between a bedside ultrasound evaluation during an episode of acute respira- tory failure and the patient’s outcome. A retro- spective observational study was conducted in the emergency departments (EDs) of two hos- pitals in Como (Sant’Anna Hospital and Valduce Hospital) over two years. Two hundred and twenty eight adult patients with acute res- piratory failure were recruited for the study. One hundred and eight patients (group A) received immediately a bedside ultrasound diagnostic test by expert investigastors at the time of ED admission, while 120 patients (group B) were evaluated and managed with- out a preliminary ultrasound diagnostic approach. The concordance between initial and final diagnosis was statistically significant in group A vs group B (P<0.01). In-hospital mortality was significantly lower in group A as compared with group B [3 (2.7%) vs 6 (5%), respectively; P<0.01]; in group A only nine patients (8.3%) compared with seventeen patients (14.1%) in group B (P<0.01) were transferred to the intensive care unit for mon- itoring and treatment. The study proposed is not able to recommend the procedure because it is a retrospective design. In spite of this, our study supports the routine use of ultrasonogra- phy for the evaluation of patients having acute respiratory failure. Introduction Acute respiratory failure is one of the most distressing and more frequent conditions for patients in emergency departments (EDs). The immediate and accurate diagnosis is always imperfect and this sometimes compro- mises the patients’ outcome.1-5 Ultrasound has long shown its utility for screening organs.6 Currently, the integrated ultrasound evaluation in the acute setting is becoming a standard tool for a rapid diagnosis and treatment of acute respiratory failure.7,8 A recent study demonstrated a high concordance between radiography and ultrasonography and the latter proved to be more accurate in distin- guishing free pleural effusion.9 Moreover, Reissig et al. evaluated the role of emergency ultrasound of the chest and they stated that sonography allows immediate diagnosis of pul- monary embolism, pneumothorax, pneumonia, pleural effusion and provides a basis for fur- ther treatment-related decisions.10 The aim of our observational study was to compare the outcome of patients admitted to the hospital with acute respiratory failure according to a preliminary approach, the bedside ultrasound evaluation. Materials and Methods The present observational and retrospective study was conducted in the EDs of two hospi- tals in Como (Sant’Anna Hospital and Valduce Hospital). From January 2009 to December 2010, 256 consecutive adult patients admitted to the ED with acute respiratory failure were enrolled. Twenty-eight patients were excluded due their prompt intubation (n=17) or absence of final diagnosis (n=11). A total of 228 patients were evaluated for the study: 108 patients (group A) received a bedside ultra- sound at admission by expert investigators, while 120 patients (group B) were managed without the ultrasound approach, due its prompt unavailability or the absence of a sono- grapher at admission. The competence of 11 out of 20 emergency physician ultrasonogra- phers was demonstrated through multiple steps. Initially, they underwent a training course of fast echography in emergency set- ting and then they performed at least 100 non- cardiac and 200 cardiac ultrasounds with a cre- dentialed supervision. In addition, before the start of this study, all emergency physicians were given a course focusing on echocardiog- raphy. The institutional review board of the two hospitals evaluated the study protocol and declared that the need for informed consent was waived. Patients The inclusion criteria were the following: age >18 years, signs of acute or acute on chronic respiratory failure, acute onset of severe respiratory distress (breathing rate >35 breaths/min), peripheral arterial oxygen satu- ration (SpO2) <88%, and breathing air <90% with inhaled oxygen. The patients excluded from the study were the following: i) patients immediately intubat- ed and transferred to the intensive care unit (ICU) if they presented acute dyspnea, respira- tory distress with Glasgow coma scale <13, res- piratory arrest, SpO2 <88% [or arterial oxygen tension (PaO2) <55 mmHg] despite inspired oxygen fraction >50%, systolic arterial blood pressure (BP) <90 mmHg, and signs of periph- eral hypoperfusion; ii) patients presented with acute myocardial infarction signs or requiring dialysis for renal insufficiency. Conversely, patients who presentend acute dyspnea and/or respiratory distress, and/or SpO2 <88% during oxygen therapy, and/or a worsening in level of consciousness after 2 h of optimal treatment – thus meeting the crite- ria of the hospital protocol for admitting patients from ED to ICU – were transferred to the ICU or to the intermediate care unit for monitoring and treatment and were part of the study. All the patients who received the ultra- sound examination at admission belonged to group A. If ultrasound was not available, the patients were managed traditionally with clin- ical evaluation and chest x-ray and they were assigned to group B. The first diagnosis was made at the time of moving patients from the ED to either the ICU or the intermediate care unit or the respiratory/cardiology/general med- icine division in both group of patients. The final diagnosis was made at the end of in-hos- Emergency Care Journal; volume 9:e2 Correspondence: Andrea Bellone, Emergency Department, Sant’Anna Hospital, via Ravona 1, 22020 San Fermo della Battaglia, Italy. Tel. +39.02.48703668 - Fax: +39.031.5855853. E-mail: andreabellone@libero.it Key words: ultrasound, emergency, acute respira- tory failure, diagnosis, outcome. Contributions: AB and ME contributed to study design, subject enrollment, measurements, data management and analysis, and manuscript preparation. All other authors contributed to sub- ject enrollment and manuscript preparation. Conflict of interests: the authors declare no potential conflict of interests. Conference presentation: the present paper was orally presented at the Italian Congress of the Academy of Emergency Medicine and Care (AcEMC) held in Rome on 2 November 2011 and it won the first prize. Received for publication: 15 February 2013. Revision received: 9 April 2013. Accepted for publication: 11 April 2013. This work is licensed under a Creative Commons Attribution 3.0 License (by-nc 3.0). ©Copyright A. Bellone et al., 2013 Licensee PAGEPress, Italy Emergency Care Journal 2013; 9:e2 doi:10.4081/ecj.2013.e2 No n- co mm er cia l u se on ly [Emergency Care Journal 2013; 9:e2] [page 3] pital patients’ course on the basis of the hospi- tal protocols. Ultrasound approach Ultrasound was performed using a machine (Vivid-I; General Electric Company, Fairfield, CT, USA) equipped with a 5-MHz microconvex probe. Patients were investigated in a semi- supine position. The time spent for ultrasound evaluation at the time of ED admission was about 10 min. Ultrasound examination was made for a dif- ferential diagnosis among the most common causes of acute or acute on chronic respiratory failure [pulmonary edema, pulmonary embolism, pneumonia, acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and acute asthma, pneumothorax and pericardial effusion] in order to manage patients adequately. We focused our attention on 8 items: i) prevalent A pattern (i.e. horizon- tal lines arising from the pleural line and found at regular intervals equalling the dis- tance between the skin and the pleural line); ii) prevalent B pattern (i.e. a hydroaeric comet- tail artefact arising from the pleural line and indicating interstitial syndrome); iii) lung sliding (i.e. visceral pleura sliding against the parietal pleura); iv) presence of alveolar con- solidation and/or pleural effusion; v) qualita- tive diameter of right ventricle; vi) pericardial effusion; vii) inferior vena cava (IVC) collapsi- bility; and viii) femoral and/or poplitea venous compressibility.11-15 In group A, the ultrasound evaluation together with clinical findings, electrocardio- gram, arterial blood gases, venous blood sam- ples, and chest x-ray data allowed an initial diagnosis that was compared with the final one. The same evaluation – except for the bed- side ultrasound – was used for diagnosis and treatment in group B. Statistical analysis Physiologic data of patients are reported as means (±standard deviation). Means are com- pared using the Student test. Fisher’s exact test was employed to compare the rates of admission in ICU and in-hospital mortality in the two groups. The concordance between the first and the final diagnosis was analyzed using the χ2 test. P value <0.05 was considered statistically significant. Results This study included 256 patients admitted to the hospitals because of an acute respiratory failure between January 2009 to December 2010. Twenty-eight patients were excluded either because they were immediately intubat- ed in ED and then transferred to ICU according to the hospital protocol (n=17), or because they did not received a definite final diagnosis (n=11). Two hundred and twenty-eight patients were analyzed for the study. According to the bedside ultrasound evaluation (group A), a prevalent bilateral B lines was observed in 52 cases (forty-eight were defined as pulmonary edema, while 4 patients were identified as affected by acute lung injury); while a predom- inant bilateral A lines was found in 28 cases (20 patients were defined as affected by AECOPD and/or acute asthma and 8 patients presented with an enlargement of the right ventricle diameter thus suggesting a diagnosis of pulmonary embolism) (5 of these patients the ultrasound veins compressibility test was positive). Twenty patients presented with an alveolar consolidation/pleural effusion. Five patients presented with an abolished lung slid- ing with predominant A lines (pneumothorax). Pericardial effusion was seen in 3 patients. Ultrasound was possible in all patients (feasi- bility of 100%). In group B, 67 patients were initially defined as affected by pulmonary edema, while 12 patients were identified as affected by pneu- monia/acute lung injury. Twenty patients were defined as affected by AECOPD and/or acute asthma, 11 by pulmonary embolism, and 6 patients by pneumothorax. Pericardial effu- sion was diagnosed in 4 patients. The diagno- sis of patients belonging to group B was done by the emergency physicians on the basis of the clinical, laboratory and chest x-ray. Patients were similar in terms of age, sex, arterial blood gases, arterial BP, heart and res- piratory rate, and acute physiologic chronic health evaluation II (APACHE II). Furthermore, comorbilities were not significantly different (Table 1). In-hospital mortality was significant- ly lower in group A as compared with group B [3 (2.7%) vs 6 (5%), P<0.01]. Only 9 patients of group A (8.3%) vs 17 patients (14.1%) of group B (P<0.01), were transferred to the ICU for monitoring and treatment (Table 2). Article Table 1. Physiologic measurements and comorbilities of patients. Group A Group B P value (n=108)° (n=120)° Age (years) 74.7±6.7 76.1±5.7 ns Male/female ratio 69/108 75/120 ns pH 7.30±0.16 7.31±0.18 ns PaO2/FiO2 ratio 173±85 177±96 ns PaCO2 (mmHg) 54±29 53±31 ns Bicarbonate (mEq) 23±8 24±9 ns Respiratory frequency (breaths/min) 37±18 38±22 ns Heart rate (beats/min) 98±30 103±33 ns Systolic BP (mmHg) 116±41 112±35 ns Diastolic BP (mmHg) 78±23 68±27 ns APACHE II score 18.4±2.6 18.9±4.6 ns Chronic heart failure (n) 31±48 35±51 ns Arterial hypertension (n) 59±46 54±42 ns Diabetes (n) 23±21 26±19 ns Atrial fibrillation (n) 9±14 12±18 ns Chronic renal failure (n) 9±15 6±18 ns Ischemic heart disease (n) 26±50 24±43 ns ns, not significant; PaO2, arterial oxygen tension; FiO2, inspiratory oxygen fraction; PaCO2, arterial carbon dioxide tension; BP, blood pres- sure; APACHE II, acute physiologic chronic health evaluation II. °Values are expressed as means±standard deviation. Table 2. Patients’ outcomes. Group A Group B P value (n=108) (n=120) Admission to ICU – no. (%) 9 (8.3) 17 (14.1) 0.01 In-hospital death – no. (%) 3 (2.7) 6 (5) 0.01 ICU, intensive care unit. No n- co mm er cia l u se on ly [page 4] [Emergency Care Journal 2013; 9:e2] Finally, the concordance between the initial and final diagnosis was significantly superior in group A in comparison with group B (P<0.01) (Tables 3 and 4). Discussion Bedside ultrasound in the EDs as a diagnos- tic approach to the acute respiratory failure resulted to be very useful and favorable in terms of in-hospital mortality and the need of intensive care assistance. In addition, the con- cordance between initial and final diagnosis was significantly in favour of patients submit- ted to the early ultrasound evaluation. It is well known that lung and cardiac ultra- sound immediately provide diagnosis of acute respiratory failure in 90.5% of cases.8 A recent review reported that ultrasonography is more accurate than auscultation or chest radiogra- phy for the detection of pleural effusion, con- solidation, and alveolar interstitial syndrome in the critical care setting.16 No previous studies have analyzed the rela- tionship between the bedside ultrasound approach and the patients’ outcome. Only one previous study has shown that incorporating a goal-directed ultrasound protocol in nontrau- matic, symptomatic hypotensive patients results in a more accurate physician impres- sion of final diagnosis.17 The present retro- spective study evaluated patients with acute respiratory failure from different causes. Results showed that the diagnosis of acute pul- monary edema is overestimated when the early bedside ultrasound is lacking. The possi- ble explanation is that the clinical signs of acute pulmonary edema are often less specific, therefore the differential diagnosis is often complex. Moreover, it is possible to hypothe- size an added value of saving time and resources when using ultrasound in severely dyspneic patients where the percent of misdi- agnosis is about 20% avoiding a wrong and sometimes dangerous treatment.18,19 In our opinion, lung and cardiac ultrasound is an opportunity for those physicians who practice emergency medicine. Indeed, ultrasound, together with IVC collapsibility estimation, improves the possibility to perform a correct differential diagnosis and an appropiate man- agement. It is known that the perception about lung ultrasound learning is a difficult exercise. Viceversa, appreciating lung sliding, B lines or IVC collapsibility has an extremely short learn- ing curve.12,20 The relevance of our study was the evidence of a relationship between the bedside ultrasound approach and the prognosis of these patients. This result needs further studies to confirm the impact of diagnostic approach and the outcome of patients with acute respiratory failure. Lastly, this study had some limitations. Most importantly, limitations include a retrospective design, the lack of uniformity between groups of treating physicians and a lack of analysis of what specific interventions or other factors could have accounted for the mortality benefit observed for patients in the ultrasound group. Second, the investigators in this study who have performed a bedside ultrasound evalua- tion were not blinded to the patient’s manage- ment but in our acute setting this was not ful- filled. Third, we included patients with final several official diagnoses. Conclusions In conclusion, the study proposed is not able to recommend the procedure because it is ret- rospective design. In spite of this, our study supports the routine use of ultrasonography for the evaluation of patients having acute res- piratory failure. References 1. Wasserman K. Dyspnea on exertion: is it the heart or the lung? JAMA-J Am Med Assoc 1982;248:2039-43. 2. Aronchick J, Epstein D, Gefter WB, et al. Evaluation of the chest radiograph in the emergency department patient. Emerg Med Clin N Am 1985;3:491-501. 3. Ray P, Birolleau S, Lefort Y, et al. Acute res- piratory failure in the elderly: etiology, emergency diagnosis and prognosis. Crit Care 2006;10:R82. 4. Greenbaum DM, Marschall KE. The value of routine daily chest X-rays in intubated patients in the medical intensive care unit. Crit Care Med 1982;10:29-30. 5. Lichtenstein D, Goldstein G, Mourgeon E, et al. Comparative diagnostic performanc- es of auscultation, chest radiography and lung ultrasonography in acute respiratory distress syndrome. Anesthesiology 2004; 100:9-15. 6. Dénier A. Les ultrasons, leur application au diagnostic. Press Méd 1946;22:307-8. 7. Irwin RS, Rippe JM. Intensive care medi- cine. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008. 8. Lichtenstein DA, Meziere GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the blue protocol. Chest 2008;134:117-25. 9. Zanobetti M, Poggioni C, Pini R. Can chest ultrasonography replace standard chest radiography for evaluation of acute dysp- nea in the ED? Chest 2011;139:1140-7. Article Table 3. Comprehensive results: first and final diagnosis of the two groups. Group Diagnosis Pathology ACPE AECOPD Pneumothorax Pneumonia-ALI-ARDS Pulmonary embolism Pericardial effusion A (n=108) First 48 20 5 24 8 3 Final 44 23 5 26 7 3 B (n=120) First 67 20 6 12 11 4 Final 46 29 5 29 8 3 ACPE, acute cardiogenic pulmonary edema; AECOPD, acute exacerbation of chronic obstructive pulmonary disease; ALI-ARDS, acute lung injury-acute respiratory distress syndrome. Table 4. Concordance between first and final diagnosis of the two groups. Final diagnosis Positive diagnosis Negative diagnosis Total P value Group A 98 10 108 - Group B 68 52 120 - Total 166 62 228 - Group A vs group B - - - <0.01 No n- co mm er cia l u se on ly [Emergency Care Journal 2013; 9:e2] [page 5] 10. Reissig A, Copetti R, Kroegel C. Current role of emergency ultrasound of the chest. Crit Care Med 2011;39:839-45. 11. Lichtenstein DA, Meziere G, Lascols N, et al. Ultrasound diagnosis of occult pneu- mothorax. Crit Care Med 2005;33:1231-8. 12. Lichtenstein DA, Meziere G, Biderman, et al. 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Eur J Heart Fail 2006;8:706-11. 19. Kristensen MS. Ultrasonography in the management of the airway. Acta Anaesth Scand 2011;55:1155-73. 20. Lichtenstein D, Meziere G. Training of general ultrasound by the intensivist. Réan Urg 1988;7(Suppl. 1):s108 (abstr.). Article No n- co mm er cia l u se on ly