The vexatious vital: neither clinical measurements by nurses nor an electronic monitor provides accurate measurements of respiratory rate in triage.

STUDY OBJECTIVE Of all the vital signs, only respiratory rate is still measured clinically in most US triage systems. Previous studies have demonstrated the inaccuracy, poor interobserver agreement, and low variability of routine measurements of respiratory rate. We assess the variability and accuracy of triage nurses' measurements of respiratory rate against a criterion standard. Also, we assess electronic measurement of respiratory rate against the same criterion standard. METHODS Consecutive patients presenting to an urban teaching emergency department (ED) were enrolled in this prospective study. Electronic measurement of respiratory rate was recorded throughout the triage encounter when nurses were recording measurements of respiratory rate. Electronic respiratory rate was measured using transthoracic impedance plethysmography. Immediately after each triage evaluation, criterion standard measurements of respiratory rate were made by research assistants using the World Health Organization recommendation of auscultation or observation for 60 seconds. RESULTS We enrolled 159 patients. Variability was low for triage nurses' measurements of respiratory rate (SD 3.3) and electronic measurement of respiratory rate (SD 4.1) compared with criterion standard measurements of respiratory rate (SD 4.8; P <.05). Triage nurses' measurements of respiratory rate and electronic measurement of respiratory rate showed low sensitivity in detecting bradypnea and tachypnea. In a Bland-Altman analysis, triage nurses' measurements of respiratory rate and electronic measurement of respiratory rate showed poor agreement with criterion standard measurements of respiratory rate. Subgroup analysis of patients presenting with cardiac and respiratory symptoms yielded similar results. CONCLUSION Neither triage nurses nor an electronic monitor provides accurate measurements of respiratory rate in the ED. Emergency physicians should search for new electronic modalities for measuring respiratory rate to bring respiratory rate into line with other vital signs. Emergency physicians should also consider new clinical strategies for measuring respiratory rate.

[1]  P A Oberg,et al.  Experimental evaluation of two new sensors for respiratory rate monitoring , 1993, Physiological measurement.

[2]  B. Krieger,et al.  Continuous noninvasive monitoring of respiratory rate in critically ill patients. , 1986, Chest.

[3]  J H Auchincloss,et al.  Changes in tidal volume, frequency, and ventilation induced by their measurement. , 1972, Journal of applied physiology.

[4]  A. Greenough,et al.  Tidal breathing parameters in young children: Comparison of measurement by respiratory inductance plethysmography to a facemask pneumotachograph system , 1999, Pediatric pulmonology.

[5]  M. Fine,et al.  A prediction rule to identify low-risk patients with community-acquired pneumonia. , 1997, The New England journal of medicine.

[6]  P Safa,et al.  A comparison of pulse oximetry and respiratory rate in patient screening. , 1996, Respiratory medicine.

[7]  R C Kory,et al.  An electrical impedance ventilometer to quantitate tidal volume and ventilation. , 1967, Medical research engineering.

[8]  P. Öberg,et al.  Presentation and evaluation of a new optical sensor for respiratory rate monitoring , 1994, International journal of clinical monitoring and computing.

[9]  A. Beckett,et al.  AKUFO AND IBARAPA. , 1965, Lancet.

[10]  M. Clancy,et al.  The respiratory rate. , 1991, Archives of emergency medicine.

[11]  B Hök,et al.  A new respiratory rate monitor: development and initial clinical experience , 1993, International journal of clinical monitoring and computing.

[12]  M. Marks,et al.  Measurement of respiratory rate and timing using a nasal thermocouple , 1995, Journal of Clinical Monitoring.

[13]  B. Carlson,et al.  Evaluation of a non-invasive respiratory monitoring system for sleeping subjects , 1999, Physiological measurement.

[14]  J. L. Rau,et al.  Evaluation of two electronic respiratory rate monitoring systems. , 1981, Respiratory care.

[15]  D. Haborne.  Measuring respiratory rate. , 1992, Archives of emergency medicine.

[16]  J. Alihanka,et al.  A new method for long-term monitoring of the ballistocardiogram, heart rate, and respiration. , 1981, The American journal of physiology.

[17]  J. G. Weg,et al.  Respiratory rate as an indicator of acute respiratory dysfunction. , 1980, JAMA.

[18]  J. Spinelli,et al.  Early discharge of patients with presumed opioid overdose: development of a clinical prediction rule. , 2000, Academic emergency medicine : official journal of the Society for Academic Emergency Medicine.

[19]  R. C. Kory.  Routine measurement of respiratory rate; an expensive tribute to tradition. , 1957, Journal of the American Medical Association.

[20]  E. Ruiz,et al.  Emergency Medicine: A Comprehensive Study Guide , 1996 .

[21]  J R Mallard,et al.  AURA: a new respiratory monitor and apnoea alarm for spontaneously breathing patients. , 1991, British journal of anaesthesia.

[22]  E A Hooker,et al.  Respiratory rates in emergency department patients. , 1989, The Journal of emergency medicine.

[23]  J. Carlin,et al.  Reference ranges for respiratory rate measured by thermistry (12-84 months). , 1993, Archives of disease in childhood.

[24]  L. Murdin,et al.  Respiratory rate--an under-documented clinical assessment. , 2001, Clinical medicine.

[25]  L. Nilsson,et al.  Monitoring of respiratory rate in postoperative care using a new photoplethysmographic technique , 2004, Journal of Clinical Monitoring and Computing.

[26]  D. Dodds,et al.  The PEP transducer: a new way of measuring respiratory rate in the non-intubated patient. , 1999, Journal of accident & emergency medicine.

[27]  J. Abisheganaden,et al.  Respiratory monitoring using an air-mattress system , 2000, Physiological measurement.

[28]  M. A. Lambert,et al.  Capnography for monitoring non-intubated spontaneously breathing patients in an emergency room setting. , 1997, Journal of accident & emergency medicine.

[29]  P. Öberg,et al.  Monitoring of respiratory and heart rates using a fibre-optic sensor , 1992, Medical and Biological Engineering and Computing.

[30]  E. Simões,et al.  Respiratory rate and pneumonia in infancy. , 1991, Archives of disease in childhood.

[31]  J H Auchincloss,et al.  Impedance pneumograph and magnetometer methods for monitoring tidal volume. , 1974, Journal of applied physiology.

[32]  G. Town,et al.  Usefulness of d-dimer, blood gas, and respiratory rate measurements for excluding pulmonary embolism , 1998, Thorax.

[33]  Hal B. Jenson,et al.  Nelson Textbook of Pediatrics , 1965 .

[34]  T. Cole,et al.  Respiratory rate and severity of illness in babies under 6 months old. , 1990, Archives of disease in childhood.

[35]  E. Simões,et al.  Respiratory rate: measurement of variability over time and accuracy at different counting periods. , 1991, Archives of disease in childhood.

[36]  Lee Goldman,et al.  Cecil Textbook of Medicine , 1985 .

[37]  M L Terrin,et al.  Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease. , 1991, Chest.

[38]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[39]  H. Cai,et al.  Optical aspects of a fibre-optic sensor for respiratory rate monitoring , 1996, Medical and Biological Engineering and Computing.

[40]  E. L. Holmes,et al.  VOLUMETRIC DYNAMICS OF RESPIRATION AS MEASURED BY ELECTRICAL IMPEDANCE PLETHYSMOGRAPHY. , 1964, Journal of applied physiology.

[41]  W. Mower,et al.  The reliability of vital sign measurements. , 2002, Annals of emergency medicine.

[42]  A. Worster,et al.  Reliability of vital signs measured at triage , 2003, European journal of emergency medicine : official journal of the European Society for Emergency Medicine.

[43]  D. Slosman,et al.  Prediction of Pulmonary Embolism Extent by Clinical Findings, D-dimer Level and Deep Vein Thrombosis Shown by Ultrasound , 2001, Thrombosis and Haemostasis.

[44]  T. Ahrens.  Respiratory monitoring in critical care. , 1993, AACN clinical issues in critical care nursing.

[45]  M. D. Del Beccaro,et al.  Establishing clinically relevant standards for tachypnea in febrile children younger than 2 years. , 1995, Archives of pediatrics & adolescent medicine.