Comparison of clinical CPR studies in Milwaukee and elsewhere in the United States

As we mark the 25th anniversary of the clinical application of closed-chest cardiopulmonary resuscitation (SCPR), it is time to look back and analyze the progress we have made in the resuscitation of sudden death syndrome. Recent studies of SCPR's effectiveness have yielded mixed results, in comparison to early studies that were universally favorable. The continued toll of neurologic injury following SCPR resuscitation, and reinforcement of the importance of defibrillation in resuscitation, stimulate us to find improved forms of SCPR and improved methods of resuscitation delivery in emergency medical systems.

Traumatic cardiac arrest: scope of paramedic services

The challenge of the 1960s to ambulance care provision was the stimulus for the emergence of prehospital advanced life support (ALS) being provided by paramedic personnel. While services for cardiac disease have been accepted, paramedic activities for the trauma victim continue to be a concern for many trauma surgeons. The capability and success rate of treatment, and the time spent at the scene and during transport to the hospital have raised questions about the overall need for paramedic services. Our study period was from January 1, 1981, to December 31, 1982, and it covered 95 clinically dead trauma victims who were first seen and subsequently treated by paramedics working in a medically controlled emergency medical services system. Endotracheal intubation was successful in 81 of the patients (85%). Esophageal obturator airway use was viewed as unsuccessful intubation. Intravenous (IV) access utilizing 16-gauge angiocaths was placed successfully by a peripheral or jugular vein in 70 patients (74%). Thirty-three patients averaged 860 mL volume infusion (30 to 3,000 mL). Average scene time was 22 minutes. Scene time of patients with unsuccessful IV and endotracheal intubation was 14 minutes (P = .07). Fourteen patients (14.7%) were admitted to the operating room or intensive care unit. Only three of the study group (3.2%) survived.

Effects of high infusion pressure and large-bore tubing on intravenous flow rates

An in vitro study was conducted to determine the maximum flow rates that can be obtained with commercially available intravenous (IV) catheters, when infusion pressure and IV tubing size are modified. Standard tubing (3.2 mm ID) and two sizes of experimental large-bore tubing (5.0 mm and 6.4 mm ID) were tested with tap water and diluted packed cells (hematocrit 45) at 600 mm Hg, 300 mm Hg, and gravity flow infusion pressure. The maximum flow rate obtained was 3,158 ml/min for tap water and 3,000 ml/min for diluted packed cells. The increases in flow rates from gravity to 300 mm Hg and from gravity to 600 mm Hg are significant (P less than 0.05) and provide up to 197% and 341% increases, respectively, for all catheter/tubing combinations tested. Large-bore tubing is most effective when used in conjunction with large-bore catheters. For the 8.5 French catheter, a change from standard (3.2 mm ID) to large-bore (6.4 mm ID) tubing resulted in a statistically significant (P less than 0.05) increase in flow rate of more than 200% regardless of infusion pressure.

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 outcome has not been reported. A prospective randomized study comparing IAC-CRP with standard CPR for resuscitation of prehospital 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.

Effect of circumferential pneumatic compression devices on digital flow

We reviewed the effects of circumferential pneumatic compression suits (CPCS) when applied to normal and ischemic limbs without prior application of prehospital orthopedic traction devices beneath the garment. The digital arterial toe pressures of 11 normal and six claudicating limbs were measured with the trouser applied and the limbs pressurized to 40, 60, 80, and 100 mm Hg. In addition, normal limbs had the Hare traction device and the Sager splint applied prior to application of the trouser and retesting of the digital arterial flow. We conclude that CPCS prevents flow into the limbs, and this may potentiate the development of compartment syndromes in the previously traumatized or ischemic limbs. Normal limbs with traction devices already applied may be at a higher risk for compartment syndromes, and we suggest that patients with fractured limbs who are in need of CPCS not have the traction device applied.

Cardiorespiratory arrest and resuscitation of children

Ninety-one patients had cardiorespiratory arrest in a children's hospital emergency department over six years. Only five children survived, three with severe neurologic sequelae. The records of 40 other children in the same community resuscitated by paramedics, but taken to other hospitals, were reviewed and there were three survivors. The causes and outcomes of resuscitation of children are clearly different from those of adults. Cardiac disease and ventricular arrhythmias are uncommon. Neurologically intact survival was seen only in those children who received immediate resuscitation and responded promptly. Research in cerebral resuscitation at the cellular level is promising for the future. Prevention of some cardiorespiratory arrests through accident prevention and earlier recognition of serious infections is possible now.

"PALS for life!" A required trauma-oriented pediatric advanced life support course for pediatric and emergency medicine housestaff

While advanced cardiac life support (ACLS) and advanced trauma life support (ATLS) courses have become accepted standards for physicians who care for the critically ill and injured patient, only recently have pediatric advanced life support (PALS) courses been developed. The American Academy of Pediatrics has shown renewed interest in pediatric cardiopulmonary arrest after impressive gains made in adult resuscitation. The American Heart Association filled a void by including new chapters on Pediatric and Neonatal Resuscitation in the Textbook of Advanced Cardiac Life Support, 1981. A joint committee of AHA and AAP is seeking to unify course objectives and materials for standard curriculum. Because trauma is the most common cause of death and disability in children, pediatric trauma life support measures should be incorporated into any program directed toward emergency physicians and pediatricians who function in an emergency department or rural primary care setting. The Department of Pediatrics and Surgery and its division of Emergency Medicine has developed and implemented a PALS curriculum which is different from most other programs in that emphasis has been placed on pediatric trauma in addition to traditional cardiac (ACLS) resuscitation. This 20-hour program combines a modified ACLS curriculum with specific pediatric trauma lectures and laboratory sessions. It includes a canine surgical procedure lab and modified ATLS skill stations. At the completion of the course, students are eligible for ACLS certification. In the two years in which the course was given, 39 pediatric houseofficers were enrolled in the course.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Recommended helmet removal techniques in a cervical spine injured patient

Helmet removal techniques in the absence of C-spine injuries have been developed and promulgated. Utilizing a cadaver model, these techniques were demonstrated to adversely affect pre-existing C-spine injury. Removal of helmets with cast cutters is recommended.

Atropine in asystole: human studies

Current research supporting the use of atropine for asystole is limited. Reported in the literature are the cases of 26 patients who presented with a rhythm of asystole. Of these, only eight were clearly in refractory asystole after epinephrine and sodium bicarbonate, only seven were prehospital patients, and only two were delineated as being intubated. Despite such limited data, atropine has been advocated for asystole, and use of the drug is included in the recommendations of the American Heart Association. We undertook a retrospective review of our prehospital experience with refractory asystole for a four-year period from January 1979 to December 1982. All patients with trauma or poisoning and all pediatric arrests were excluded. All patients who received calcium chloride during resuscitation also were excluded. One hundred seventy patients presented in cardiorespiratory arrest with an initial rhythm of asystole. Of these, 84 remained in refractory asystole after receiving epinephrine and sodium bicarbonate. Forty-three patients in this group received atropine. The successful resuscitation rate in the atropine group was 14% (6/43), while in the control group it was 0% (0/41) (P less than .04). A successful resuscitation was defined as conveyance of a patient with a rhythm and a pulse to an emergency department. Patients were compared for age, sex, witnessing of arrest, cardiac history, and cardiac drugs. No other significant differences were noted between groups. No patient who received atropine for refractory asystole was discharged alive.

Calcium chloride: reassessment of use in asystole

Calcium chloride has been advocated since the 1920s for resuscitation of asystole and ventricular fibrillation. Most reports have been anecdotal, and have failed to substantiate its effectiveness. In two large retrospective series with a collective experience of 181 patients, investigators reviewed the effectiveness of calcium chloride in asystole and did not support its use. A prospective, randomized, double-blind study comparing calcium chloride with saline in the prehospital setting was done. Patients with trauma or pediatric arrests were excluded. During the period from October 1982 to October 1983, a total of 32 patients with witnessed arrests presented with a rhythm of asystole and were refractory to epinephrine, bicarbonate, and atropine. The rate of successful resuscitation in the calcium group was 5.6% (1/18), and there were no successful resuscitations (0/14) in the saline group (P = .37). A successful resuscitation was defined as conveyance of a patient with a rhythm and pulse to an emergency department. Groups were analyzed for sex, age, cardiac history, and cardiac drugs, and there were no statistically significant differences. No patient who was successfully resuscitated in the field was discharged alive from the hospital. Calcium chloride is of no value in resuscitating refractory asystole in the prehospital cardiac arrest setting.

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 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.

Experimental cervical spine injury model: evaluation of airway management and splinting techniques

We evaluated airway management maneuvers and the effects of cervical splinting on a model of an injured spinal column. X-ray films of a fresh cadaver verified a normal cervical spine. C5-C6 instability was created surgically and documented radiologically with flexion and extension maneuvers. Basic and advanced airway techniques were performed and were documented radiologically. The procedures were then repeated using different types of splinting. Chin lift, jaw thrust, esophageal obturator airway (EOA), and endotracheal intubation can cause extension, widening, and/or anterior subluxation. A two-piece, semirigid soft cervical collar may minimize flexion but not extension of the spine. With the Velcro in back, soft collars minimize flexion; with Velcro in front, they minimize extension. Standard nonsurgical airway management techniques appear to aggravate preexisting injuries. The soft collar and semirigid collar do little to prevent movement, and their presence may serve only as a warning to physicians that a neck injury may be present.

The effect of tensional load on isolated embryonic chick tendons in organ culture

Digital flexor tendons isolated from 17-18 day embryonic chickens were cultured intact, either on steel mesh grids, or in an apparatus designed to apply a mechanical load to the tissue. Tendons cultured without an applied load continued to synthesize protein and glycosaminoglycans throughout a 7-day period, but DNA synthesis decreased during this time. Increases in both protein and DNA synthesis were observed in tendons experimentally loaded for 48-72 h. Glycosaminoglycan production by tendons isolated from 17-day embryos was also increased in loaded tendons, sulfated GAG being increased more than hyaluronic acid. The same loading regime applied to tendons from 18-day embryos produced a smaller, yet significant increase in sulfated glycosaminoglycans but hyaluronate production was reduced. These investigations demonstrate that embryonic chicken tendons can be maintained in a viable state in organ culture and may provide a useful model for studies of the effects of mechanical forces on the synthetic capability and structure of connective tissue cells.

The relationship of the level of training and area of medical specialization with registrant performance in an advanced trauma life-support course

Approved advanced trauma life-support (ATLS) programs were given to 160 residents and practitioners of various specialties, utilizing a standardized 50-item, multiple-choice posttest. Level of training (practitioner v resident) and area of medical specialization with registrant performance on total score and in specific subcontent areas of ATLS were evaluated by subjecting total and subcontent percent scores to a two-way analysis of variance and Newman-Keuls pairwise comparisons. Practitioners outperformed the residents in the subcontent area of abdominal injuries, P less than .05. In specialization, emergency medicine outperformed internal medicine specialists, P less than .05. Pairwise differences among specialists were not statistically significant. In airway problems, surgeons and internists were outperformed by emergency medicine, whereas in burns, emergency medicine and family practitioners significantly outperformed the surgeons. Emergency medicine outperformed internal medicine, P less than .05, in subcontent area of extremity injuries. We conclude that registrants are likely to benefit from an ATLS course, but preliminary evidence would seem to justify some "tailoring" of the ATLS curriculum for different registrant specialty groups.

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.