Paramedic System Research Articles

Prehospital venous access in an urban paramedic system--a prospective on-scene analysis.

Prehospital intravenous access has been central to the debate of paramedic intervention during management of trauma in the field. Some have suggested that excessive time requirements for IV access are detrimental to patient salvage. This prospective study objectively quantified the time required to place a peripheral IV line in our urban paramedic system. A third-party observer, nonparamedic, timed the procedure on scene with a stopwatch. Total intravenous time, including obtaining a 30-cc blood sample, was defined as the period from removal of the catheter cover until the catheter was taped. The study group included 125 patients (51 trauma and 74 nontrauma). The average total time to obtain IV access and sample blood was 2.20 +/- 0.20 and 2.71 +/- 0.18 minutes in trauma and nontrauma patients, respectively. In a subset of 63 patients in whom blood sampling time was determined separately, subtracting that from total IV time provided a net of 0.58 +/- 0.09 minutes to obtain access. Fourteen patients had a second IV line started (without blood sampling), requiring 1.25 +/- 0.38 and 0.70 +/- 0.24 minutes, respectively, for trauma and nontrauma patients. Paramedics were successful on their first IV attempt in 90% of trauma and 84% of nontrauma patients; ultimate success was 100%. This on scene study documents the time required for prehospital IV access, performed by a well-trained paramedic in an E.M.S. system with strong medical control, is less than 90 seconds.

Limitations of prehospital predictors of acute myocardial infarction and unstable angina

Studies have attempted to define predictive indicators of diagnosis and/or prognosis for acute myocardial infarction (AMI) in the emergency department and to identify the need for hospital admission in patients with chest pain. Because prehospital predictors have not been defined, dispatchers, paramedics, and base station physicians continue to triage based on patient history. We reviewed 401 patients presenting in one year to an urban paramedic system with chest pain, normal vital signs, and stable rhythms to identify predictors of AMI and unstable angina. Thirty-one percent (123) had a diagnosis of AMI, 26% (105) unstable angina, and 43% (173) "other" diagnoses. Two-hundred seventy-eight patients required nitroglycerin administration, 182 required IV morphine, 14 developed arrhythmias requiring lidocaine, and two suffered cardiac arrest in the field. Nine other patients had a cardiac arrest after arrival in the ED. When comparing AMI and unstable angina patients to the "others," 64% (132) versus 36% (74) had radiation of pain (P less than .003), 72% (95) versus 28% (37) had diaphoresis (P less than .0001). Neither difficulty breathing, nausea/vomiting, vital signs, initial rhythm, nor past history of myocardial infarction were helpful in discriminating AMI and unstable angina from others. Comparing AMI alone versus others, the presence of ST segment elevation on lead II was present in 15% (18) AMIs, 3% (3) unstable angina, and 8% (14) others (P = .005). Diaphoresis also was a predictor of diagnosis with 51% (63) of the AMIs and 25% (69) of others exhibiting this sign (P less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Digoxin levels in prehospital sudden-death syndrome.

Digitalis toxicity is common and has been associated with ventricular dysrhythmias. Digoxin levels in patients who suffer prehospital sudden death have never been studied. This study measured digoxin levels in a population of sudden-death patients. During the 15-week study period, 252 patients in cardiac arrest were seen by an urban paramedic system. During daytime hours, paramedics were requested to obtain a blood sample from sudden-death patients; the samples were subsequently analyzed for digoxin by means of radioimmunoassay. Thirty-nine patients had measured digoxin levels drawn; 28 (71.8%) were in the therapeutic range (0.5-2.1 ng/mL), and four (10.2%) were in the toxic range (greater than 2.1 ng/mL). The patients with toxic dogoxin levels and those with nontoxic levels had similar resuscitation rates (50.0% vs. 34.3%, P = NS), but none were found in ventricular fibrillation. Emergency medical services personnel should consider digoxin toxicity as a potential etiology of arrest.

Considerations for improving survival from out-of-hospital cardiac arrest

Since the implementation of a paramedic system in Seattle, yearly survival rates from out-of-hospital cardiac arrest due to ventricular fibrillation have averaged 25% without any significant increase over the years. Outcome for cardiac arrest associated with other rhythms has been poor: when asystole was the first rhythm recorded, only 1% of patients survived; when electromechanical dissociation was initially present, only 6% survived. For cases of electromechanical dissociation, neither the type of rhythm nor the rate appear to influence outcome. Survival from ventricular fibrillation can be improved by shortening the delay to initiation of CPR and to defibrillation. When outcome in 244 witnessed arrests was related to the times to beginning CPR and to initial defibrillation, mortality increased 3% each minute until CPR was begun and 4% a minute until the first shock was delivered. New strategies that minimize delays appear to have the greatest promise for improving survival after cardiac arrest.

Prophylactic lidocaine in the prehospital patient with chest pain of suspected cardiac origin

The prophylactic use of lidocaine in the patient with cardiac chest pain has been reported to reduce the incidence of sudden death from ventricular dysrhythmias in the hospital setting, but few studies have been done in the early prehospital phase. We conducted a randomized, prospective study comparing the effects of lidocaine versus no lidocaine in stable patients presenting with chest pain to a paramedic system. In a one-year period, 446 patients qualified for the study; 222 received lidocaine and 224 did not. The overall hospital mortality of the two groups was 8.1% and 6.7%, respectively (P = .35). Four patients in each group developed sudden death in the prehospital and emergency department settings with ventricular dysrhythmia as the precipitating rhythm. One hundred twenty-nine (29%) had an acute myocardial infarction. The lidocaine and control group contained 68 and 61 of the patients, respectively, with an overall mortality rate of 14.7% and 13.1% (P = .45). The development of significant dysrhythmias (frequent premature ventricular contractions, ventricular tachycardia, bradycardia, second- and third-degree heart blocks) after initiation into the study was similar in both groups of patients. The use of lidocaine was a factor in decreasing systolic blood pressure (P less than 0.03) but did not appear to be clinically significant. For stable patients presenting with chest pain of suspected cardiac origin, prophylactic lidocaine in the prehospital setting was not effective in preventing life-threatening dysrhythmias, but clinically significant side effects were not noted either.

Bystander/first responder CPR: Ten years experience in a paramedic system

The effectiveness of bystander CPR recently has been challenged. We undertook a ten-year retrospective review of our prehospital experience with witnessed cardiorespiratory arrest to ascertain save rates in patients receiving and not receiving CPR before paramedic advanced life support (ALS). Traumatic and poisoning arrests and children less than 18 years old were excluded. A total of 1,905 patients presenting to a paramedic system from November 1, 1973, to October 31, 1983, were bystander-witnessed arrests and attempted paramedic resuscitations. Four hundred five paramedic-witnessed arrests were excluded. One hundred eighty-two of 1,248 (14.6%) who had CPR initiated before paramedic ALS arrival were saves, compared to 38 of 252 (15%) who had no CPR initiated until paramedic arrival (P = NS). A save was defined as a patient discharged from the hospital. The respective save rates for coarse ventricular fibrillation were 148 of 628 (23.6%) (CPR before paramedic arrival) vs 35 of 151 (CPR delayed until paramedic arrival) (23.2%); electromechanical dissociation (EMD), 11 of 209 (5.3%) vs 0 of 38; asystole, 19 of 401 (4.7%) vs 3 of 61 (4.9%); and ventricular tachycardia, four of ten (40%) vs 0 of two. In this prehospital system, bystander/first responder CPR was found not to improve hospital discharge rates except in patients with initially documented rhythm of EMD.

Prehospital Cardiopulmonary Resuscitation

To the Editor.— The article by Cummins and Eisenberg 1 in the April 26, 1985, issue ofThe Journal, Prehospital Cardiopulmonary Resuscitation, confuses serious scientific questions with irresponsible assaults on a national institution, that is, cardiopulmonary resuscitation (CPR). Moreover, their review omits large patient data bases that are not as favorable to conventional CPR as those presented. Cummins and Eisenberg included series totaling 2,558 patients in their review (some series as small as 19 patients) in support of their claim of positive results with conventional CPR. However, there are at least four other significant studies totaling nearly 4,200 patients, the results of which are appropriate for scientific criticism of their thesis. Mirick et al 2 in 1982 reported on 98 Minneapolis patients in whom they could find no significant effect of bystander CPR. Kowalski et al 3 reported on 363 patients with ventricular fibrillation in the Milwaukee County paramedic system. Resuscitation

Bystander/first responder CPR: Ten-year experience in a paramedic system

Bystander/first responder CPR: Ten-year experience in a paramedic system

Pre-hospital IAC-CPR versus standard CPR: Paramedic resuscitation of cardiac arrests

Recent studies evaluating interposed abdominal compression cardiopulmonary resuscitation (IAC-CPR) have demonstrated a significant increase in cardiac output, mean arterial pressure, and cerebral perfusion, as compared with standard CPR. A clinical evaluation of IAC-CPR effectiveness on resuscitation out-come has not been reported. A prospective randomized study comparing IAC-CRP with standard CPR for resuscitation of pre-hospital cardiopulmonary arrest was undertaken using the Milwaukee County Paramedic System. The patients were randomized following endotracheal intubation into IAC-CPR and standard CPR groups. Since October 1983, 291 patients have qualified for the study group. Of these, 146 patients had standard CPR, and 45 (31%) were successfully resuscitated. Of the 145 patients treated with IAC-CPR, 40 (28%) were successfully resuscitated. Chi-square analysis reveals no significant difference between these groups. To determine whether abdominal compression increases regurgitation, the frequency of emesis before and after intubation was analyzed. No significant difference was found between the IAC-CPR and standard CPR groups. Thus, IAC-CPR applied by paramedics in the field to patients following intubation does not improve cardiac resuscitation rates.

Bystander CPR in prehospital coarse ventricular fibrillation

Prehospital bystander cardiopulmonary resuscitation (CPR) was studied to determine if it affected the outcome of defibrillation. Four hundred twenty-one consecutive witnessed cardiopulmonary arrests presenting with the initial rhythm of coarse ventricular fibrillation treated by the Milwaukee County Paramedic System from January 1980 to June 1982 were analyzed. Pediatric, trauma, and poisoning patients and those receiving intravenous or endotracheal medications before defibrillation (58) were excluded. Immediate professional bystander CPR (physician, nurse, EMT) and citizen bystander CPR were compared to a control group receiving no bystander CPR until arrival of EMS personnel. A successful defibrillation occurred if defibrillation prior to administration of medication produced an effective cardiac rhythm with pulses. Eighty-eight of the 363 remaining patients (24%) converted with initial defibrillations. While the group receiving professional bystander CPR had a higher successful defibrillation rate than did the no-CPR group (35% vs 22%, P less than .04), citizen bystander CPR and no-CPR groups had similar successful defibrillation rates (24% vs 22%, no significant difference). One hundred eighty-six of the 363 patients (51%) were transported to a hospital with a rhythm and a pulse (a successful resuscitation). Ninety-seven of the 363 patients (27%) were discharged alive from the hospital (a save). Patients who were converted successfully using initial "quick-look" defibrillations were far more likely to be successfully resuscitated (79/88 [90%] vs 107/275 [39%], P greater than .0001) and to be discharged alive from the hospital (54/88 [61%] vs 43/275 [16%], P greater than .0001) than were those who required further advanced cardiac life support techniques.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized comparison study of bretylium tosylate and lidocaine in resuscitation of patients from out-of-hospital ventricular fibrillation in a paramedic system

A prospective, randomized study using either bretylium tosylate (BT) or lidocaine (L) as the first-line antiarrhythmic for patients in refractory ventricular fibrillation was conducted using the Milwaukee County Paramedic System. If the patient did not respond to the initial American Heart Association protocol, BT (10 to 30 mg/kg total) or L (2 to 3 mg/kg total) was given randomly as the first antiarrhythmic. If the patient failed to convert, the alternate antiarrhythmic was given. In the L group, 81% (39/48) of the patients obtained an organized electrical rhythm and 56% (27/48) converted to a rhythm with a pulse. The resuscitation rate (admission to an emergency department with pulse) was 23% (11/48), and the save rate was 10.4% (5/48). In the BT group, 74% (32/43) obtained an organized electrical rhythm, 35% (15/43) were converted, 23% (10/43) were resuscitated, and 5% (2/43) were saved. The only significant difference in outcome was that L converted patients better than did BT (P less than .05). Of the 24 patients known to be on digitalis preparations prior to arrest, 41% (5/12) in the L group were resuscitated and 16% (2/12) were resuscitated in the BT group. Data were analyzed for witnessed arrest outcome and for patients given multiple antiarrhythmics.

The precordial thump

The American Heart Association (AHA) currently recommends the precordial thump as the initial maneuver in treatment of ventricular tachycardia (VT) and monitored ventricular fibrillation (VF). These recommendations are based largely on anecdotal reports of successful "thump-version" of asystole, VF, and VT. The Milwaukee County Paramedic System follows the AHA guidelines in the treatment of VT and VF. The precordial thump is included in the advanced cardiac life support (ACLS) paramedic training program, and has been used in our approach to the pulseless, nonbreathing patient. During an eight-month period, 50 pulseless, nonbreathing patients received precordial thumps during ACLS resuscitative attempts. Twenty-seven patients who developed monitored VT and 23 patients with monitored VF were thumped. Three of 27 patients (11%) with VT were thumped into a supraventricular rhythm, 12 of 27 patients (44%) remained in VT, and 12 of 27 patients were thumped from VT into more malignant rhythms: three, into asystole; eight, into VF; and one, into an idioventricular/electromechanical dissociation rhythm. A total of 23 patients were thumped without effect. Subsequently, using countershock and medications, 12 of these 23 patients were successfully resuscitated. In the prehospital setting the precordial thump is usually not beneficial, and may be detrimental. Thus its use as the initial maneuver in treating the cardiac arrest patient with VT or VF in this setting cannot be supported. The presence of acidosis and hypoxia may explain why prehospital precordial thump responses differ from those seen in the hospital environment.

Immediate countershock treatment of asystole

While rapid intervention with basic cardiac life support and prompt delivery of prehospital care using advanced cardiac life support (ACLS) have yielded impressive results in the resuscitation of other arrest rhythms, very little improvement has been shown in the rates of resuscitation from asystole. Anecdotal reports list instances in which patients in asystole have had normal cardiac activity restored after defibrillation. Current ACLS protocols for initial evaluation recommend a single-lead "quick-look" interpretation of cardiac rhythm using portable defibrillator paddles. Under these conditions, ventricular fibrillation could masquerade as, or be misinterpreted as, asystole. We report preliminary field results in a medically controlled paramedic system using "quick-look" interpretation and immediate defibrillation of "asystole" by well-trained paramedics. Following initial countershock, standard ACLS protocols for asystole were used. For an eight-month period 119 patients were entered into the study and compared to system controls of asystolic patients presenting in the previous year. While ten patients (8.4%) showed an immediate rhythm change after initial countershock and six of ten reached the hospital with a rhythm and a pulse, no statistically significant comparison could be made regarding improved resuscitation or survival rates. The finding of no statistically significant deterioration of resuscitation or survival rates, however, justifies the continuation of the study.

Interposed abdominal compression CPR versus standard CPR in prehospital cardiopulmonary arrest: Preliminary results

Recent studies evaluating interposed abdominal compression cardiopulmonary resuscitation (IAC-CPR) have demonstrated a significant increase in cardiac output, mean arterial pressure, and cerebral perfusion compared with standard CPR. A clinical evaluation of IAC-CPR effectiveness on resuscitation outcome has not been reported. A prospective, randomized study comparing IAC-CPR with standard CPR for resuscitation of prehospital cardiopulmonary arrest was developed utilizing the Milwaukee County Paramedic System. When the paramedics arrive, standard CPR is initiated or continued, and countershocks are delivered when appropriate. The patients are randomized into IAC-CPR and standard CPR groups immediately following endotracheal intubation. Abdominal compression force is standardized to 100 mm Hg +/- 20 mm Hg by using a simple airfilled bladder and gauge to monitor each compression. Resuscitations are conducted according to standard advanced cardiac life support guidelines through continuous radio-telemetry contact with a base physician. Since October 1983, 140 patients have qualified for the study group. Seventy patients had standard CPR and 30% (21/70) were admitted to the emergency department with a rhythm and pulse, as were 34% (24/70) of the patients treated with IAC-CPR. The difference between study groups was not significant. To determine if abdominal compression increases regurgitation, the frequency of emesis before and after intubation was analyzed. No significant difference was found between the IAC-CPR and standard CPR groups.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized comparison study of bretylium tosylate and lidocaine in resuscitation of patients from out-of-hospital ventricular fibrillation in a paramedic system

A randomized comparison study of bretylium tosylate and lidocaine in resuscitation of patients from out-of-hospital ventricular fibrillation in a paramedic system

Resuscitation time in ventricular fibrillation — a prognostic indicator

Length of resuscitation in prehospital ventricular fibrillation patients was studied to define its relationship to survival. Five hundred sixty-five patients presenting with the initial rhythm of ventricular fibrillation to the Milwaukee County Paramedic System between January 1978 and April 1982 were resuscitated successfully. Pediatric patients and patients with trauma, poisoning, and drowning were excluded. Of the 565 resuscitated patients, 262 (46%) were discharged alive and 303 (54%) died during hospitalization. For all 565 patients the resuscitation time and times from arrival of paramedics until the first sustained pulse were plotted against survival to define a curve. The curve demonstrated rapidly declining survival rates for resuscitation time up to 20 minutes; thereafter, survival declined more gradually with respect to resuscitation time. The mean resuscitation time for those eventually discharged alive was 12.6 minutes, which was statistically shorter (P less than .0001) than the mean resuscitation time of 23.9 minutes for those who eventually died. The overall survival curve of witnessed arrest patients was not statistically different from that of unwitnessed patients. The survival curve of those patients receiving bystander cardiopulmonary resuscitation (CPR) was similar to the curve of those who received no CPR. We conclude that resuscitation time is a heretofore undefined significant predictor of survival of resuscitated prehospital ventricular fibrillation patients.

The effect of a paramedic system on mortality of major open intra-abdominal vascular trauma.

In a 12-year period (1970-1981), there were 112 patients operated on with major open intra-abdominal vascular trauma (MOIVT). These were any penetrating injuries to the aorta, inferior vena cava, portal vein, or their primary branches. Sixty-four patients were treated without benefit of paramedics. Only four of 43 patients who had emergency department blood pressures of 60 mm Hg or greater upon entry died (9.3%), whereas 18 of 21 (85.7%) patients with blood pressures of less than 60 mm Hg died (p less than 0.0001). Forty-eight of the 112 patients have been treated by paramedics during the past 4 years. Entry level blood pressures are those first recorded by the paramedics in the field. The mortality in those with blood pressures of 60 mm Hg or greater remained essentially unchanged. However, 11 of 22 patients with blood pressures of less than 60 mm Hg survived compared to three of 21 (p less than 0.025). Over the past 12 years, the community's homicide rate has been stable (71/yr), but the case incidence of MOIVT has risen from an average of 8/yr to 12/yr during the paramedic years. The average annual aggravated assault rate increased from 796 to 1,119. It is believed the improvement in the salvage rate is due to early intervention by trained paramedics functioning within a trauma care system.

Evaluation of prehospital emergency medical service (EMS): defining areas for improvement.

The changing economy and greater public awareness of medical costs has created a need to assess efficacy, quality of care, and cost of prehospital treatment by paramedics. The purpose of the present study was to design a simple method for analysis of EMS function using a small number of variables to clearly identify parts of the system needing improvement. The method was used to evaluate EMS in a moderate-sized city over a 1-year period. The log books of paramedic activities and ambulance time records were reviewed and a microcomputer used to abstract the following information felt to comprise the minimum number of variables necessary to assess the system: 1) origin of call; 2) time of call; 3) case type; 4) response time; 5) time spent on scene; 6) transit time to hospital; 7) use of advanced life support (ALS) skills; 8) evaluation of overall run (Category A = Paramedics clearly needed; Category B = Paramedics probably of benefit; Category C = Paramedics clearly not needed, EMT perhaps of benefit; Category D = EMT not needed, first-aid treatment only required). In 1981, the Mobile paramedic system was accessed 4, 698 times. The false alarm rate was 80.4%. Of the 919 cases requiring treatment, 27%, 46%, 11%, 13%, 2%, and 1% were for major medical, minor medical, major trauma, minor trauma, major surgical, and minor surgical problems, respectively. Analysis of patients requiring treatment revealed that 25% of cases fell in Category A, 30% in Category B, 36% in Category C, and 8% in Category D. ALS skills were used in 82% of the 919 cases treated. This included two thirds of the Category C and D cases. Thirty per cent of the Category A cases occurred within 5 minutes of a fullystaffed emergency department; however, in 66% of these cases more than 20 minutes and in 15% more than 30 minutes were spent at the scene. Twenty-six per cent of the Category B cases were within 5 minutes of hospital, yet 32.3% of these cases required 20 minutes and 70% required more than 30 minutes in the field. Evaluation of the Mobile EMS System using this simple format has helped formulate the following priorities to improve cost benefit ratio, to: 1) decrease the false alarm rate; 2) improve the efficacy of EMS dispatchers; 3) improve the appropriateness of field use of ALS skills; 4) reevaluate paramedic training curricula.

Use of calcium in prehospital cardiac arrest

All records of patients presenting to the Milwaukee County Paramedic System for the period of January 1 to December 31, 1980 were reviewed retrospectively. One hundred seventy-nine patients initially presented in asystole, and 116 patients initially presented in electromechanical dissociation (EMD). All patients with trauma and poisoning were excluded. The in-field successful resuscitation rates for asystole were 8/105 (8%) in the calcium group versus 8/24 (33%) in the no-calcium group (P less than .002); for EMD they were 10/63 (16%) in the calcium group versus 8/18 (44%) in the no-calcium group (P less than .02). A successful resuscitation is defined as the conveyance of a patient to the emergency department with a pulse and cardiac rhythm. There were no significant differences between the calcium and no-calcium groups in both the asystole and EMD patients. The use of calcium in the prehospital setting in the currently recommended dosage for cardiac arrest with initial arrest rhythms of asystole and EMD is highly suspect.

Modeling the effectiveness and cost-effectiveness of an emergency service system

Survival from out-of-hospital cardiac arrest is in large part determined by the time from collapse to initiation of cardiopulmonary resuscitation (CPR) and the time from collapse to initiation of definitive care. A model utilizing these two crucial times was developed to examine various prehospital emergency medical services (EMS). The effectiveness (percent survival) and cost-effectiveness (cost divided by effectiveness) of four different EMS systems were examined. Two of the systems are already operational in various parts of the country: (1) basic life support consisting of CPR as provided by emergency medical technicians (EMT's); and (2) advanced life support consisting of definitive care as provided by paramedics. Two proposed systems are: (1) rapid defibrillation by EMTs; and (2) rapid defibrillation by EMT's with paramedic backup response. Both of these proposed systems are currently under experimental study. The four systems were examined using various parameters such as ratio of paramedic to EMT vehicles, percentage of citizens trained in CPR and response time. Compared to the basic EMT system, the paramedic system is more effective and cost-effective. The proposed system using rapid defibrillation by EMT's is less effective than the paramedic system but is the more cost-effective. The proposed system incorporating rapid defibrillation by EMT's with paramedic backup is the most effective but also the most costly. The resulting cost-effectiveness is less than with rapid defibrillation by EMT's alone. As demonstrated in this analysis, the two proposed systems offer possibilities for improved resuscitation following out-of-hospital cardiac arrest.