DO MEDICATIONS AFFECT VITAL SIGNS IN THE PREHOSPITAL TREATMENT

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1 DO MEDICATIONS AFFECT VITAL SIGNS IN THE PREHOSPITAL TREATMENT OF ACUTE DECOMPENSATED HEART FAILURE? Karl A. Sporer, MD, Jeff A. Tabas, MD, Roland K. Tam, BS, Karen L. Sellers, RN, Jon Rosenson, BS, Chris W. Barton, MD, Mark J. Pletcher, MD ABSTRACT Introduction. Prehospital treatment of patients with acute decompensated heart failure (ADHF) has been shown to decrease mortality and morbidity. Vital sign changes have been proposed as clinical endpoints in the evaluation of prehospital treatment for this condition. Objective. To examine the effect of prehospital treatments on vital signs among patients with ADHF. Methods. Records of an urban emergency medical services system from September 1, 2002, through September 1, 2003, were queried for patients who had a paramedic impression of shortness of breath or respiratory distress and had received nitroglycerin and/or furosemide. Demographics, initial and repeat vital signs (blood pressure, heart rate, respiratory rate, and oxygen saturation), and medications and doses were collected. Results. Three hundred nineteen patients were included; the average age was 77 (±12) years and 47% were male. Treatments administered to these patients included nitroglycerin, 296 (93%); furosemide, 194 (61%); albuterol, 189 (59%); aspirin, 57 (18%); morphine, 20 (6%); and prehospital intubation, 15 (5%). Patients were initially hypertensive [mean ± standard deviation of systolic blood pressure (SBP) was 167 ±37 mm Hg], tachycardic (heart rate 106 ± 24 beats/min), tachypneic (respiratory rate 33 ± 7 breaths/min), and hypoxic (pulse oximetry 88% ± 9.5%). After treatment, mean changes included decreases (95% confidence interval) in (SBP), 10.6 mm Hg ( 14.1 to 7.1), heart rate, 2.3 beats/min ( 4.0 to 0.7), and respiratory rate, 3.0 ( 3.6 to 2.3), and an increase in oxygen saturation, +8.2 (7.1 to 9.3). Changes in blood pressure and oxygen saturation after treatment correlated with initial values. There was no independent association of either nitroglycerin, furosemide, albuterol, or morphine with improvement in vital signs. Conclusion. Prehospital patients with ADHF are a heterogeneous group of patients with significant variability in vital signs. The change in systolic blood pressure or oxygen saturation after treatment Received November 18, 2004, from the Department of Medicine, University of California, San Francisco (KAS, JAT, KLS, JR, CWB, MJP), San Francisco, California; the Department of Emergency Services, San Francisco General Hospital (KAS, JAT, KLS, CWB), San Francisco, Califonia; and the Department of Epidemiology and Biostatistics (MJP), Albert Einstein School of Medicine (RKT), New York, New York. Revisions received April 28, 2005, and July 20, 2005; accepted for publication July 25, Presented as an abstract as the National Association of EMS Physicians annual meeting, Tucson, Arizona, January Address correspondence and reprint requests to: Karl A. Sporer, MD, Emergency Services, Room 1E21, 1001 Potrero Avenue, San Francisco, CA <ksporer@sfghed.ucsf.edu>. doi: / depends greatly on the patient s starting point. There was no association of either nitroglycerin or other medications with the improvement in vital signs. Key words: acute decompensated heart failure; vital signs; congestive heart failure; nitroglycerin; drugs; acute pulmonary edema. PREHOSPITAL EMERGENCY CARE 2006;10:41 45 Many patients with acute decompensated heart failure (ADHF) and a subset with acute pulmonary edema will require prehospital treatment and ambulance transport. 1 Some studies have suggested that prehospital treatment can decrease mortality and morbidity in these patients. 2 4 There has been little research defining the appropriate medications, their dosing, and their effect on this prehospital patient population. 1 Acute decompensated heart failure represents the second most frequent medical condition treated by paramedics and makes up 5 6% of all prehospital medical calls. 2,5 Hospitalization of patients with acute pulmonary edema transported by ambulance is associated with a 10 15% rate of short-term mortality, as well as significant rates of acute myocardial infarction (15%) and the need for mechanical ventilation (15%). 6,7 The overall cost for all treatments of heart failure exceeded $38 billion in ,9 Optimizing the prehospital treatment of these patients may have a beneficial effect on these outcomes. Patients with ADHF requiring prehospital evaluation and management may represent a sicker subgroup more amenable to early treatment than those who do not activate the prehospital system. The hospital mortality for all ADHF patients has been described in the Acute Decompensated Heart Failure National Registry (ADHERE) study as 4%. 10 Of patients who present to the emergency department (ED) with ADHF, only 5% present within the first three hours of symptoms. 11 One prior nonrandomized study examined the effect of high-dose (0.8 mg) or low-dose (0.4 mg) administration of sublingual nitroglycerin on vital signs in ADHF patients. 12 Univariate analysis revealed that higher doses of nitroglycerin were associated with a greater improvement in vital signs, including decreases in heart rate, systolic blood pressure, and respiratory rate. Patients whose initial vital signs (blood pressure and respiratory rate) were higher were more likely to receive higher doses of nitroglycerin. Pulse oximetry was not measured in this study. This finding could be important because the same vital signs have been 41

2 42 PREHOSPITAL EMERGENCY CARE JANUARY/MARCH 2006 VOLUME 10 /NUMBER 1 proposed as promising clinical endpoints in the evaluation of prehospital treatment for ADHF. 13,14 In an attempt to confirm and extend these findings in our patient population, we measured medications administered and vital signs in prehospital patients with ADHF. METHODS San Mateo County is a 552-square-mile urban/ suburban county with a population of 700,000. A single public/private partnership provides emergency medical services (EMS) to 95% of the county. This singletiered system consists of a fire department singleparamedic first response and an emergency medical technician/paramedic-staffed private transport ambulance. During the time of this study, approximately 80% of all patients had their prehospital evaluation and management data collected via an electronic patient care record that was stored in an electronic database. Paramedic protocols allowed the administration of sublingual nitroglycerin, intravenous furosemide, aspirin, intravenous morphine sulfate, or nebulized albuterol for patients with presumed ADHF. Prehospital treatment protocols during the study period de-emphasized the use of morphine but were tolerant of the use of albuterol in cases with wheezing. Nitroglycerin, 0.4 mg sublingually, was allowed every 5 minutes, up to six doses, as clinically indicated so long as the systolic blood pressure was greater than 90 mm Hg. The dosing of nitroglycerin was based on the clinical evaluation and was not limited by prior self-administered medication. The database was queried for records of adult (>18 years old) patients treated during the 12 months from September 1, 2002, through September 1, 2003, who had a paramedic impression of shortness of breath or respiratory distress and had received nitroglycerin and/or furosemide. These records were defined as patients with ADHF. This case definition has been used in the prehospital setting in a prior study with reasonable ED diagnostic accuracy based on ultimate ED diagnosis. 15 Demographic information, initial and repeat vital signs [systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), respiratory rate (RR), and pulse oximetry (O 2 Sat)] and medication and doses were collected. The changes in vital signs were computed as the difference between the initial vital signs and the last complete set of subsequent vital signs. Vital signs were considered to have improved from their initial values if there was a statistically significant decrease in SBP, DBP, HR, or RR (without declining below commonly accepted normal values) or an increase in O 2 Sat after prehospital treatment. Prospective definitions included severe hypoxia, defined as an O 2 Sat of less than 90%, and hypotension, defined as an SBP of less than 100 mm Hg. The study was approved by the Institutional Review Board of the University of California, San Francisco. All patient identifiers were removed from the records and, therefore, informed consent was waived. We analyzed the association between doses administered of each medication and change in vital signs. Because we know that different kinds of patients are likely to be treated with different medications, 1 we adjusted our results for age, gender, initial vital sign abnormalities, lung examination findings (clear, rales, diminished breath sounds, wheezing, other/unknown, or unequal), skin examination findings (normal, diaphoretic, dry, moist, or, unknow), and other medications administered using linear regression models. RESULTS During the study period, there were 23,552 patient care records entered into the database for patients treated by San Mateo County EMS; 1,682 (7%) were patients with a complaint of shortness of breath or respiratory distress. There were 319 (1.4%) patients who met the study criteria for a patient with ADHF. The study group had an average age of 77 (±12) years; 47% were men. The prehospital treatments administered to these patients (in addition to supplemental oxygen) included nitroglycerin, 296 (93%); furosemide, 194 (61%); albuterol, 189 (59%); aspirin, 57 (18%); morphine, 20 (6%); and prehospital intubation, 15 (5%) (see Table 1). The initial mean SBP in this group was 167 (±37) mm Hg. Approximately 77% of the patients had an initial SBP greater than 140 mm Hg, while 8% presented with an SBP of 120 mm Hg or less and only 3% presented with 100 mm Hg or less. After prehospital treatment, 60% of the patients had a final SBP greater than 140 mm Hg, 17% had an SBP of 120 mm Hg or less, and 5% were hypotensive with an SBP of 100 mm Hg or less. The change in SBP after treatment for ADHF depended greatly on the patient s starting point (see Figure 1). Patients with a low initial SBP (<100 mm Hg) had significant increases on average, while the hypertensive group had decreases in SBP. The changes in all groups demonstrated a large variability with wide confidence TABLE 1. Prehospital Acute Decompensated Heart Failure (ADHF) Patients Number Percentage Total EMS patients 23, % Respiratory distress patients 1,682 7% ADHF patients % Treatment Nitroglycerin % Furosemide % Albuterol % Aspirin 57 18% Morphine 20 6% Prehospital intubation 15 5% EMS = emergency medical services.

3 Sporer et al. MEDICATION EFFECT ON VITAL SIGNS 43 FIGURE 1. Change in systolic blood pressure (SBP) after treatment for acute decompensated heart failure (ADHF). intervals. Similarly, the improvement in (O 2 Sat) was greatest in those patients who started with the lowest initial O 2 Sat (see Figure 2). The initial mean O 2 Sat of all patients, including those given supplemental oxygen, was 88% (±9.5%), with 123 patients (38%) presenting with an O 2 Sat of less than 90%. Two hundred three patients (64%) had their initial O 2 Sat measured without supplemental oxygen. The initial mean HR was 106 (±24) beats/min and the initial mean respiratory rate was 33 (±7) breaths/min. Vital signs globally improved after prehospital treatment (see Table 2), but there was significant individual variation in SBP change and O 2 Sat (Figures 1 and 2). There was no association between the various doses of nitroglycerin (none, 0.4, 08, and mg) and the decrease in SBP or increase in O 2 Sat by multivariate analysis. There was no association between patients who received other medications (furosemide, morphine, or albuterol), as compared with those who did not receive those medications, and the decrease in SBP or increase in O 2 Sat by multivariate analysis. A similar subgroup analysis of the severely hypoxic group (O 2 Sat < 90%) also did not demonstrate any relationship between these treatment groups and any vital sign changes between groups. DISCUSSION Many patients who develop ADHF, especially those with acute pulmonary edema, will require prehospital treatment and transport. The demographics of the patients with ADHF in this study were similar to those in other published studies, revealing an older population and female preponderance. 1,16 The case definition FIGURE 2. Change in oxygen saturation (O 2 Sat) with treatment for acute decompensated heart failure (ADHF).

4 44 PREHOSPITAL EMERGENCY CARE JANUARY/MARCH 2006 VOLUME 10 /NUMBER 1 TABLE 2. Initial and Final Vital Signs after Prehospital Treatment Vital Sign Initial Final Change (95% CI) Systolic blood 166 ± ± ( 14.1 to 7.1) pressure (mm Hg) Mean arterial 114 ± ± ( 8.2 to 4.1) pressure (mm Hg) Heart rate (beats/min) 105 ± ± ( 4.0 to 0.7) Respiratory rate 33 ± 7 30± ( 3.6 to 2.3) (breaths/min) Pulse oximetry (%) 88 ± ± (7.1 to 9.3) CI = confidence interval. required the use of nitroglycerin and/or furosemide. The rate of albuterol administration was higher (59%) than that reported by Mosesso et al., and the use of morphine was much lower (6%). 1 We have demonstrated that prehospital patients with ADHF are a heterogeneous group. This study examined the range of vital signs of patients with ADHF in the prehospital field, their distribution, and their change with treatment. Measurement of the initial vital signs of these patients demonstrated significant systolic hypertension, tachycardia, and hypoxia. Our initial prehospital SBP (167 ± 37 mm Hg) was significantly higher than that measured in the ED (146 ± 35 mm Hg) in a similar study and may represent treatment effects. 15 Thirty-eight percent of the patients in this study were severely hypoxic in initial prehospital evaluation, and only 3% were hypotensive (SBP < 100 mm Hg). This study also demonstrated that the changes in SBP depended on the patients starting points. Those with initial hypotension (SBP < 100 mm Hg) all had an increase in SBP, and most of those with severe hypertension (SBP > 160 mm Hg) had a decrease in SBP after treatment (see Figure 1). The improvement in O 2 Sat was greatest in those patients who started with the lowest initial O 2 Sat (see Figure 2). Some studies have suggested that prehospital treatment can decrease mortality and morbidity in these patients. 2 4 It is unclear from these studies whether all patients benefit equally. It is possible that patients with mild ADHF and adequate oxygenation may only require treatment with supplemental oxygen and positioning. It is also likely that most of the benefit from prehospital treatment for ADHF is derived by those patients with the most severe hypoxia. Any future outcome studies would want to clearly define the subgroup of prehospital patients with respiratory distress by initial vital signs. Those most likely to improve with medical therapy would include those with hypertension (SBP > 140 mm Hg) and/or severe hypoxia (O 2 Sat < 90% on room air). We found no medication effect on the change in vital signs. There was no association between change in vital signs and the dose response of nitroglycerin, or treatment with furosemide, morphine, or albuterol. Similar evaluation of the subgroup of severely hypoxic patients demonstrated no significant difference in vital sign changes. This finding could be interpreted to mean either that these medications, in addition to supplemental oxygen, have no clinical effect on ADHF patients or that they have a collective improvement but vital sign changes are too variable to be useful in teasing out subtle differences in treatment modalities. Future research should examine the efficacy of the various treatments stratified by initial O 2 Sat and SBP. LIMITATIONS There are several limitations to this study. This was a retrospective study and the diagnosis was explicitly documented for only 29% of patients who ultimately were treated as having ADHF. This results from the common practice among paramedics of using a nondescript impression such as respiratory, other. Our study was unable to measure the diagnostic accuracy of our paramedics. Patients with milder symptoms of ADHF would not be included in this cohort because they did not receive medications. Patients with ADHF and hypotension would be less likely to receive furosemide or nitroglycerin because of our current protocols and would also not be included in this study. The initial measurement of pulse oximetry was not standardized, with 64% of the patients being measured without supplemental oxygen. The pattern of drug administration may be different from those in other communities. The limited use of morphine is a consequence of an effort to limit its use, and the relatively high use of albuterol may be due to the permissive nature of our protocols. The use of morphine has been demonstrated to increase morbidity, 4,17 and the use of albuterol in these patients is controversial. 1,18 Future protocols will encourage more aggressive use of nitroglycerin in patients with an adequate blood pressure and a more restricted use of furosemide because of concerns about its limited short-term efficacy in ADHF and the possibility for harm when the prehospital diagnosis is incorrect. 4 CONCLUSION Prehospital patients with ADHF are a heterogeneous group of patients with significant variability in vital signs. The change in systolic blood pressure or oxygen saturation after treatment depends greatly on the patient s starting point. There was no association of either nitroglycerin or other medications with the improvement in vital signs. The initial vital signs of patients

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