The effect of different levels of relative humidity and air movement on litter conditions, ammonia levels, growth, and carcass quality for broiler chickens

An experiment using 4,800 commercial broiler males (Ross x Ross) was conducted in 12 climatic chambers. Three levels of relative humidity (RH) (45, 40, to 80, and 75%) and two levels of internal air circulation (7.7 to 9.9 and 17.8 to 24.5 cm/s), with each level replicated and, therefore, forming a 3 x 2 x 2 factorial arrangement of treatments, arrangement of treatments, were imposed as the main effects. Broilers were group weighed and feed efficiencies calculated at 14, 28, and 42 days of age. Percentage dry matter of the litter and a subjective evaluation of general litter conditions (moisture and caking) were scored weekly, with the percentage nitrogen and total quality of litter produced in each chamber measured at the conclusion of the study. Ammonia levels were measured in each chamber every second day. A sample of birds (36) from each chamber was processed at 42 days and scored for litter spots and ammonia burns on the breast and for the incidence and severity of twisted legs, crooked toes, and infected and calloused hocks and foot pads. Mean body weight was significantly greater (32 g) at 42 days of age in birds exposed to 45% RH compared with the two higher regimens of RH. Both the incidence and severity of ammonia burns on the breast and infected foot pads were significantly higher with 75 versus 45% RH. Increases in RH significantly increased caking and litter moisture and reduced the percentage of dry matter and the percentage of nitrogen found in the litter. Ammonia levels were more variable but generally increased with increases in RH. The two levels of air movement within the chambers produced less influence on the environment than RH, although the scores for both litter moisture and caking were significantly lower with increased levels of internal air circulation.

The dilemma of sensitivity versus specificity in computer-interpreted acute myocardial infarction

The use of thrombolytic therapy and out-of-hospital electrocardiogram (ECG) acquisition capability has put even greater importance on the diagnostic accuracy of computerized ECG interpretation programs. Such programs must have extremely high specificity to minimize the possibility of clinicians treating inappropriate patients; thereby needlessly subjecting the patients to the risk of potentially life-threatening complications of the medication. At the same time, studies have shown that both prehospital personnel and emergency department (ED) physicians are aided by automated ECG interpretation programs with high sensitivity. These programs assist the attending personnel in rapidly identifying patients with suspected acute coronary thrombosis, which might otherwise have been undetected or not diagnosed until more obvious ECG abnormalities were present. In previous studies, clinically correlated databases have been used to develop and test sensitivity and specificity of the acute infarction detection algorithm in the Marquette 12SL ECG interpretation program. One program revision resulted in a marked increase in sensitivity (21-53%) without loss of specificity (99.5% to 99%). More recent studies have shown the sensitivity of the interpretation program to be influenced greatly by infarct location with sensitivity lower in anterior than inferior injury. Further refinement of the acute infarction interpretation criteria along with the methodology and data used are presented. Increased sensitivity without appreciable loss of specificity has been possible for detection of both acute inferior and anterior infarction; however, different methods were used for each location. Consideration of reciprocal or concomitant repolarization changes are found to be more useful for inferior than anterior injury. Methodological approaches are presented as they relate to the compromise between sensitivity and specificity.

Early recognition and treatment of the patient suffering from acute myocardial infarction. A description of the Myocardial Infarction Triage and Intervention Project

Involving emergency medical personnel in the evaluation and treatment of the AMI patients is feasible. A standard, organized approach saves time. Obtaining an ECG in the prehospital setting is also feasible and decreases the delay to diagnosis and subsequent treatment for patients after hospital arrival. Early findings from the MITI registry suggests that only 20% to 30% of patients with AMI are currently eligible to receive thrombolytic medications. This seems to indicate that either current treatment guidelines need to be broadened or that thrombolytic therapy is not appropriate for all AMI patients and, therefore, alternative acute treatment approaches need to be investigated further.

Effect of epinephrine and lidocaine therapy on outcome after cardiac arrest due to ventricular fibrillation

One hundred ninety-nine patients with out-of-hospital cardiac arrest persisted in ventricular fibrillation after the first defibrillation attempt and were then randomly assigned to receive either epinephrine or lidocaine before the next two shocks. The resulting electrocardiographic rhythms and outcomes for each group of patients were compared for each group and also compared with results during the prior 2 years, a period when similar patients primarily received sodium bicarbonate as initial adjunctive therapy. Asystole occurred after defibrillation with threefold frequency after repeated injection of lidocaine (15 of 59, 25%) compared with patients treated with epinephrine (four of 55, 7%) (p less than 0.02). There was no difference in the proportion of patients resuscitated after treatment with either lidocaine or epinephrine (51 of 106, 48% vs. 50 of 93, 54%) and in the proportion surviving (18, 19% vs. 21, 20%), respectively. Resuscitation (64% vs. 50%, p less than 0.005) but not survival rates (24% vs. 20%) were higher during the prior 2-year period in which initial adjunctive drug treatment for persistent ventricular fibrillation primarily consisted of a continuous infusion of sodium bicarbonate. The negative effect of lidocaine or epinephrine treatment was explained in part by their influence on delaying subsequent defibrillation attempts. Survival rates were highest (30%) in a subset of patients who received no drug therapy between shocks. We conclude that currently recommended doses of epinephrine and lidocaine are not useful for improving outcome in patients who persist in ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Time delays in the diagnosis and treatment of acute myocardial infarction: a tale of eight cities. Report from the Pre-hospital Study Group and the Cincinnati Heart Project

To establish the magnitude of prehospital and hospital delays in initiating thrombolytic therapy for acute myocardial infarction, the time from telephone 911 emergency medical system (EMS) activation to treatment and its components were analyzed from eight separate ongoing trials. This included estimates of ambulance response time, prehospital evaluation and treatment time, and time from admission to the hospital to initiation of thrombolytic therapy. The average time from EMS activation to patient arrival at the hospital was prospectively determined to be 46.1 +/- 8.2 minutes in 3715 patients from eight centers. The time from admission to the hospital to initiation of thrombolytic therapy was retrospectively determined to be 83.8 +/- 55.0 minutes in a separate group of 730 patients from six centers. Both the prehospital and hospital time delays were much longer than those perceived by paramedics and emergency department directors. Shorter hospital time delays were observed in patients in whom a prehospital ECG was obtained as part of a protocol-driven prehospital diagnostic strategy and a diagnosis of acute infarction made before arrival at the hospital (36.3 +/- 11.3 minutes in 13 patients). These results show that the magnitude of time required to evaluate, transport, and initiate thrombolytic therapy will preclude initiation of treatment to most patients within the first hour of symptoms. Implementation of a protocol-driven prehospital diagnostic strategy may be associated with a reduction in time to thrombolytic therapy.

The potential for prehospital thrombolytic therapy

Several large trials of thrombolytic therapy have shown that treatment initiated in the first 1 or 2 hours following the onset of symptoms of acute myocardial infarction (AMI) is more effective than therapy started later in the course of illness. From our experience in three thrombolytic trials we concluded it would be difficult to reduce the total time from symptom onset to therapy without a major change in patient management. To accomplish this goal we have initiated MITI (Myocardial Infarction Triage and Intervention Project), a program for the prehospital diagnosis of AMI using specially trained paramedics, a checklist to establish eligibility for and contraindications to thrombolytic therapy, and a portable, battery-powered 12-lead electrocardiography (ECG) cellular telephone system that allows an electrocardiographic diagnosis to be made remotely by an emergency department physician. In the feasibility phase of MITI, 2,472 patients with chest pain of presumed cardiac origin were evaluated; 677 (27%) met the rigorous history and physical exam inclusion and exclusion criteria for potential thrombolytic therapy and had an ECG performed in the field. Of these ECGs, 522 were transmitted successfully by cellular telephone to a base station physician. Of the 522 patients, 107 had ST-segment elevation and met our criteria for initiation of thrombolytic therapy. Of the 2,472 patients with chest pain evaluated by the emergency medical technicians, 453 (18%) were diagnosed with AMI during hospitalization. Of these AMI patients, only 105 (23%) met the clinical examination and ECG criteria for pre-hospital thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial Infarction Triage and Intervention Project--phase I: patient characteristics and feasibility of prehospital initiation of thrombolytic therapy

Prehospital initiation of thrombolytic therapy by paramedics, if both feasible and safe, could considerably reduce the time to treatment and possibly decrease the extent of myocardial necrosis in patients with acute coronary thrombosis. Preliminary to a trial of such a treatment strategy, paramedics evaluated the characteristics of 2,472 patients with chest pain of presumed cardiac origin; 677 (27%) had suitable clinical findings consistent with possible acute myocardial infarction and no apparent risk of complication for potential thrombolytic drug treatment. Electrocardiograms (ECGs) of 522 of the 677 patients were transmitted by cellular telephone to a base station physician; 107 (21%) of the tracings showed evidence of ST segment elevation. Of the total 2,472 patients, 453 developed evidence of acute myocardial infarction in the hospital; 163 (36%) of the 453 had met the strict prehospital screening history and examination criteria and 105 (23.9%) showed ST elevation on the ECG and, thus, would have been suitable candidates for prehospital thrombolytic treatment if it had been available. The average time from the onset of chest pain to prehospital diagnosis was 72 +/- 52 min (median 52); this was 73 +/- 44 min (median 62) earlier than the time when thrombolytic treatment was later started in the hospital. Paramedic selection of appropriate patients for potential prehospital initiation of thrombolytic treatment is feasible with use of a directed checklist and cellular-transmitted ECG and saves time. This strategy may reduce the extent and complications of infarction compared with results that can be achieved in a hospital setting.

Effects of various feeding regimens on reproduction in broiler-breeder males

A study was conducted using commercial broiler-breeder males and females maintained in all-litter pens allowed to mate naturally. Using a separate feeding arrangement, males were given a diet containing either 12% or 14% protein. Body weights were maintained at either 90% or 100% of the recommended level. Females were provided feeders with grills which denied males access to the feed, while male feeders were elevated 46 cm above the floor to deny female access to that feed. In control pens, males and females ate from the same feeders and received a breeder diet with 14% protein. Eggs produced in pens where the males and females were fed separated showed significantly higher fertility (4.2%) than eggs from control pens. No differences in percentage fertility were noted between the two dietary-protein levels or body-weight groups of males fed separately. Furthermore, no differences were measured in percentage hatch of fertile eggs among any of the treatment groups. Males in control pens showed significantly heavier body weights and breast-angle measurements starting at 32 and 40 wk of age, respectively. No treatment effect was measured for male pododermatitis. The male control birds had heavier testes weights than the males in the groups with restricted body weights. However, semen concentration was not affected. This indicates that the improved fertility was related to the size and weight of the males, not to their ability to produce semen. The reduced fertility associated with excess male body weight may be both physical and physiological in nature.

Neonatally-induced thermotolerance: physiological responses

1. Broiler cockerels exposed to neonatal heat (35-37.8 degrees C for 24 hr) at 5 days of age experienced significantly lower mortality upon exposure to elevated temperatures (35-37.8 degrees C) at 43 days of age than did cockerels not given neonatal heat exposure. 2. No differences were found between neonatally stressed and neonatal control groups in water consumption, core and surface temperature, plasma T3 and T4, protein or glucose concentration when exposed to juvenile heat stress. 3. Heterophil to lymphocyte ratios were significantly lower in the neonatally stressed than in the neonatal control group when exposed to heat at 44 days of age. 4. The results indicate that lower mortality during periods of high environmental temperature in the neonatally stressed chicks may involve homeostatic mechanisms different from those utilized during acclimation to high environmental temperature.

Potential use of thrombolytic therapy before hospitalization

Three trials of thrombolytic therapy in myocardial infarction (MI) up to 12 hours after symptom onset were conducted to measure the mean time from onset of chest pain to hospital arrival, and mean time to therapy. The trials, using intracoronary streptokinase, intravenous streptokinase and tissue plasminogen activator (t-PA), indicated a progressive shortening of time between symptom onset and hospital arrival. The Seattle Myocardial Infarction, Triage and Intervention (MITI) trial is evaluating the safety and efficacy of thrombolytic therapy initiated by paramedics in the prehospital setting. Phase I of the trial indicates that one-half of the patients would receive prehospital therapy in the field within the first hour of symptoms, substantially sooner than what can be achieved in the hospital. Phase II of MITI, in a nonrandomized trial, will compare the use of intravenous t-PA in the field with t-PA administered in the emergency department.

Emergency medical care requirements for large public assemblies and a new strategy for managing cardiac arrest in this setting

During the 1986 World's Exposition held in Vancouver, British Columbia, the types and frequencies of emergency medical problems were assessed. The average number of patients seeking care was 3.93 +/- 0.95 per 1,000 visitors (daily range, 1.94 to 6.8). Patient loads were linearly related to gate attendance, but the correlation was imperfect (P less than .001, r = .63). Only 4.4% of patients evaluated on site by nurses and paramedics were referred for additional testing and treatment: of these patients, 30% had suspected serious musculoskeletal injury, 16% had abdominal pain, and 25% had complaints of chest pain, dizziness, or loss of consciousness. Lay employees (security personnel) were trained to use automatic external defibrillators. There were six cardiac arrests (0.3 per million visitors). Two patients collapsed with ventricular fibrillation, were defibrillated by lay personnel, quickly regained consciousness, and survived. The other arrests were associated with asystole or electromechanical dissociation; no shocks were inappropriately given, and all four died. We conclude that four of every 1,000 persons at this assembly sought emergency medical care, that 95% of the problems seen were minor with few requiring physician skills, and that the automatic external defibrillator was suited for this setting and could be used by lay responders to provide early definitive treatment.

Use of the automatic external defibrillator in the management of out-of-hospital cardiac arrest

The automatic external defibrillator is a simple device that can be used by nonprofessional rescuers to treat cardiac arrest. In 1287 consecutive patients with out-of-hospital cardiac arrest, we assessed the results of initial treatment with this device by firefighters who arrived first at the scene, as compared with the results of standard defibrillation administered by paramedics who arrived slightly after the firefighters. Of 276 patients who were initially treated by firefighters using the automatic defibrillator, 84 (30 percent) survived to hospital discharge (expected rate according to a logistic model, 17 percent; P less than 0.001), as compared with 44 (19 percent) of 228 patients when fire-fighters delivered only basic cardiopulmonary resuscitation and the first defibrillation was performed after the arrival of the paramedic team. Few patients with conditions other than ventricular fibrillation survived. In a multivariate analysis of characteristics that influenced survival after ventricular fibrillation, a better survival rate was related to a witnessed collapse (odds ratio, 3.9; 95 percent confidence interval, 2.0 to 7.6), younger age (odds ratio, 1.2; 95 percent confidence interval, 1.0 to 1.4), the presence of "coarse" (higher-amplitude) fibrillation (odds ratio, 4.2; 95 percent confidence interval, 1.6 to 11.0), a shorter response time for paramedics (odds ratio, 1.4; 95 percent confidence interval, 1.0 to 2.1), and initial treatment by firefighters using an automatic external defibrillator (odds ratio, 1.8; 95 percent confidence interval, 1.1 to 2.9). These findings support the widespread use of the automatic external defibrillator as an important part of the treatment of out-of-hospital cardiac arrest, although the overall impact of the use of this device on community survival rates is still uncertain.

Hemodynamics in humans during conventional and experimental methods of cardiopulmonary resuscitation

High-fidelity hemodynamic recordings of aortic and right atrial pressures and the coronary perfusion gradient (the difference between aortic and atrial pressure) were made in nine patients during cardiopulmonary resuscitation (CPR). Findings during conventional manual CPR were compared with those during high-impulse CPR (rate, 120 cycles/min with a shorter compression:relaxation ratio) as well as during pneumatic vest CPR with and without simultaneous ventilation and abdominal binding. Aortic peak pressure during conventional CPR averaged 61 +/- 29 mm Hg but varied widely (range, 39-126 mm Hg) among patients. Although the magnitude of improvement was modest, the high-impulse method was the only technique tested that significantly elevated both aortic peak pressure and the coronary perfusion gradient during cardiac arrest. During conventional CPR, aortic pressure rose from 61 +/- 29 to 80 +/- 39 mm Hg during high-impulse CPR, and the gradient rose from 9 +/- 11 to 14 +/- 15 mm Hg, respectively; p less than 0.01. The pneumatic vest method significantly improved peak aortic pressure but not the coronary perfusion gradient. Simultaneous ventilation and chest compression created high end-expiratory pressure and lowered the coronary perfusion gradient. Abdominal binding had no significant hemodynamic effects. This evaluation of experimental resuscitation methods in humans shows that the high-impulse chest compression method augments aortic pressure over levels achieved during conventional CPR methods; however, the improvement in pressure is modest and may not be clinically important. Simultaneous ventilation as well as abdominal binding during CPR were associated with no benefit; in fact, simultaneous ventilation appears to adversely affect cardiac perfusion and, therefore, should not be used during clinical resuscitation.

Effects of feeder space on body weight uniformity of broiler breeder pullets during an alternate day feeding program

The effect of feeder space on body weight uniformity of adolescent broiler breeder females during a feed restriction program was evaluated. From 2 to 20 wk of age, broiler breeder pullets were fed a starter/developer diet containing 16.0% protein and 2,944 kcal ME/kg feed. Feed allocations, predicated on mean pen body weight, were fed on an every other day basis. Feeder space was 45 or 90% of that recommended for use with a feed restriction program. The mortality, feed efficiency and body weight uniformity data all support the hypothesis that it is not necessary to provide enough feeder space to enable all birds to eat simultaneously. Broiler breeder pullets provided only 45% of the recommended feeder space responded as well as, or better than, those given 90% of the recommended feeder space.

Effect of heat stress early in life on mortality of broilers exposed to high environmental temperatures just prior to marketing

A study was conducted to investigate the effects of heat stress during the 1st wk of life on subsequent mortality resulting from exposure to high environmental temperature and feed restriction just prior to marketing of broiler cockerels. Birds were raised under standard husbandry procedures except that at 5 days of age, half the broilers were heat stressed by exposure to an environmental temperature ranging from 35.0 to 37.8 C for 24 h while the remaining birds were held at 29.4 C. At 44 and 45 days of age, half the unstressed controls and half the birds stressed at 5 days of age were exposed to temperatures ranging from 35.0 to 37.8 C for 8 h/day. In a factorial arrangement of treatments, the effect of restricting feed for 8 h/day on Days 43, 44, and 45 was also examined. Exposing birds to high environmental temperatures at 5 days of age resulted in a significant decrease in mortality when birds were exposed to a high environmental temperature later in life. In addition, feed efficiency was improved significantly in early heat-stressed birds whereas body weight and body weight gain were not affected. Feed restriction had no significant effect on mortality, body weight, or feed efficiency. It appears, therefore, that exposing broiler cockerels to mild heat stress for 24 h at 5 days of age can significantly decrease mortality resulting from high environmental temperature later in life.

Automatic external defibrillators: importance of field testing to evaluate performance

A new automatic external defibrillator was tested first against a tape-recorded data base of rhythms and then during use by first-responding fire fighters in a tiered emergency system. The sensitivity for correctly classifying ventricular fibrillation and ventricular tachycardia was substantially less during clinical testing in 298 patients than would have been predicted from preclinical results: 52% of ventricular fibrillation analyses in patients were correctly classified versus 88% of episodes in the data base, and 22 versus 86%, respectively, for ventricular tachycardia (p less than 0.001). The detection algorithm was modified and evaluated further in another 322 patients. The modified detector performed substantially better than did the one that had been designed from prerecorded rhythms: with its use, 118 (94%) of 125 patients in ventricular fibrillation were counter-shocked compared with 91 (77%) of 118 similar patients with use of the initial algorithm (p less than 0.001). No inappropriate shocks were delivered. This improvement resulted in a shorter time to first shock (p less than 0.01) and more shocks being delivered for persistent or recurrent episodes of ventricular fibrillation (p less than 0.05). Of 620 patients treated with the automatic defibrillator, 243 (39%) had ventricular fibrillation; 57 (23%) of the 243 regained pulse and blood pressure before paramedics arrived, 141 (58%) were admitted to hospital and 71 (29%) were discharged.(ABSTRACT TRUNCATED AT 250 WORDS)

CPR training for patients' families: do physicians recommend it?

All Seattle-area cardiologists and 25 per cent of selected other physicians were queried by mail to determine whether they recommended CPR (cardiopulmonary resuscitation) training for families of their patients. Two-thirds reported that they advocated training for some patients' families, but only 52 per cent of cardiologists and 37 per cent of the others did so for families of at least half of the patients considered at risk. Physicians who had performed out-of-hospital CPR or had received advanced or recent training were more likely to recommend instruction.

Calcium-channel blockers and advanced cardiac life support

Calcium channel-blocking drugs have potent antiarrhythmic and antianginal effects and in addition may reduce the extent of cellular injury after anoxia/ischemia. Verapamil is the treatment of choice (90% effective) for uncomplicated episodes of paroxysmal supraventricular tachycardia. All three calcium-channel blockers available, diltiazem, nifedipine, and verapamil, can reduce the frequency of angina occurring both at rest and with exertion. Calcium may mediate several cytotoxic events during the reperfusion period after prolonged ischemia that lead to irreversible cell injury. There is experimental evidence that calcium-channel blockers may reduce the cellular influx of calcium after ischemia and reperfusion, and thereby attenuate cerebral and myocardial injury, although most studies have failed to show benefit of treatment unless the drug is administered before the onset of ischemia. Most trials using calcium-channel blockers in the setting of acute myocardial infarction have failed to show a benefit of treatment. The safety and efficacy of calcium-channel blockers have yet to be shown in controlled studies of human resuscitation, although the potential for such treatment, if it is effective in attenuating myocardial cerebral cellular injury, could be enormous.

Influence of hatcher holding times on several physiological parameters associated with the immune system of chickens

Two experiments were conducted with broiler chicks to study the effects of posthatch holding time in the incubator on physiological and disease parameters. In each experiment, half of the chicks were removed shortly after hatching and half of the chicks were allowed to remain in the hatcher for an additional 30 hr. Bursa weights, hematocrits, total plasma protein, and blood glucose concentrations were measured at various times up to 35 and 28 days of age in Experiments 1 and 2, respectively. In addition, chicks hatched from eggs with one of two specific gravities (less than or equal to 1.065 and greater than or equal to 1.075) were tested in the second experiment. Spleen weights, heterophil:lymphocyte ratios and the influence of an aerosol Newcastle disease-Mycoplasma gallisepticum vaccine challenge were also measured in the second experiment. In Experiment 1, when chicks were held in the hatcher for an additional 30 hr, bursa weights were reduced through 8 days of age; however, they were significantly heavier by 21 days of age. In Experiment 2, both bursa and spleen weights were significantly reduced through 14 days of age when chicks were held in the incubator. Total plasma protein and glucose concentrations, hematocrits, and heterophil:lymphocyte ratios were all significantly higher for chicks held in the incubator. Chicks held in the incubator and then exposed to an aerosol vaccine challenge at 1 day of age had a significantly greater percentage of air sac lesions and the lesions were more severe at 28 days of age. Egg specific gravity had no influence on any of the parameters measured.(ABSTRACT TRUNCATED AT 250 WORDS)

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.