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Biomedical subjects

P A Maningas

Publications and source records attributed to P A Maningas.

16 recordsLinked to original sources
PubMed1994

Guidelines for the prehospital use of thrombolytic agents.

Recognizing that prehospital thrombolytic therapy may provide benefit to certain subsets of patients, the routine prehospital use of thrombolytic agents should be discouraged pending further scientific delineation and documentation of those subgroups. ACEP encourages further investigation to document feasibility, efficacy, cost-effectiveness, and safety of use of these agents in this environment. Detailed education is needed in such areas as contraindications and the mechanics of drug administration. Online medical direction is paramount to the successful use of these agents in the prehospital setting.

Clinical Protocols↗
PubMed1991

Prehospital hypertonic saline/dextran infusion for post-traumatic hypotension. The U.S.A. Multicenter Trial.

The safety and efficacy of 7.5% sodium chloride in 6% dextran 70 (HSD) in posttraumatic hypotension was evaluated in Houston, Denver, and Milwaukee. Multicentered, blinded, prospective randomized studies were developed comparing 250 mL of HSD versus 250 mL of normal crystalloid solution administered before routine prehospital and emergency center resuscitation. During a 13-month period, 422 patients were enrolled, 211 of whom subsequently underwent operative procedures. Three hundred fifty-nine patients met criteria for efficacy analysis, 51% of whom were in the HSD group. Seventy-two per cent of all patients were victims of penetrating trauma. The mean injury severity score (19), Trauma Score plus Injury Severity Score (TRISS) probability of survival, revised trauma scores (5.9), age, ambulance times, preinfusion blood pressure, and etiology distribution were identical between groups. The total amount of fluid administered, white blood cell count, arterial blood gases, potassium, or bicarbonate also were identical between groups. The HSD group had an improved blood pressure (p = 0.024). Hematocrit, sodium chloride, and osmolality levels were significantly elevated in the Emergency Center. Although no difference in overall survival was demonstrated, the HSD group requiring surgery did have a better survival (p = 0.02), with some variance among centers. The HSD group had fewer complications that the standard treatment group (7 versus 24). A greater incidence of adult respiratory distress syndrome, renal failure, and coagulopathy occurred in the standard treatment group. No anaphylactoid nor Dextran-related coagulopathies occurred in the HSD group. Although this trial demonstrated trends supportive of HSD in hypotensive hemorrhagic shock patients requiring surgery, a larger sample size will be required to establish which subgroups of trauma patients might maximally benefit from the prehospital use of a small volume of hyperosmolar solution. This study demonstrates the safety of administering 250 mL 7.5% HDS to this group of patients.

Adolescent↗
PubMed1989

Hypertonic saline-dextran solutions for the prehospital management of traumatic hypotension.

We report the results of the first clinical study on the use of a hypertonic saline-dextran solution for the prehospital management of hypotensive victims of penetrating trauma. During a 4-month period, 48 trauma patients with penetrating injuries and a prehospital systolic blood pressure of 90 mm Hg or less were infused in-field with 250 ml of either a hypertonic saline-dextran solution or the crystalloid plasmalyte A. There were no complications associated with the infusion of the hypertonic saline-dextran solution, and execution of the protocol by paramedic personnel was both safe and uniformly successful. The potential impact of this solution on medical care and the results of this feasibility study justify the initiation of a larger prospective, randomized clinical trial on the efficacy of this solution in the prehospital setting.

Adolescent↗
PubMed1989

Combat casualty care research and informed consent.

Combat casualty care research on far-forward resuscitation is necessary for optimizing the future care of the wounded soldier. Present legal directives pertaining to the use of humans as subjects in Department of Defense (DOD)-funded research require that prior informed consent from the subjects or their legal representatives be obtained. Application of these legal directives to present and future combat casualty care research will ultimately obstruct significant progress toward optimizing the care of the injured soldier. This article reviews the medical considerations surrounding resuscitation research that make obtaining traditional informed consent impossible, the present legal directives pertaining to DOD-funded research and informed consent, and the ethical issues that influence the conduct of human research. The necessary changes required to continue resuscitation research without informed consent, while still safeguarding the welfare of the patient, are suggested.

Ethics Committees, Clinical↗
PubMed1987

Resuscitation with 7.5% NaCl in 6% dextran-70 during hemorrhagic shock in swine: effects on organ blood flow.

We previously reported that small volume infusions of 7.5% NaCl in 6% dextran-70 (HSD) are superior to equal volumes of normal saline (NS) or 7.5% NaCl in the ability to resuscitate animals from an otherwise lethal hemorrhage. In the present experiment, we evaluated organ blood flow in unanesthetized swine bled 46 ml/kg in 15 min and subsequently infused with a volume of HSD (n = 5) or NS (n = 5) equal to 25% of the shed blood. Radiomicrospheres were injected before hemorrhage, immediately after hemorrhage, and 5 and 30 min after treatment. At the end of hemorrhage, cardiac output had fallen to one-third of baseline values. Five minutes after the infusion of HSD, cardiac output had returned to baseline levels, while cardiac output in the NS-treated controls had increased to only one-half of prehemorrhage values. Blood flows to the brain, diaphragm, skin, muscle, and fat were not different between the two groups. Infusion with HSD, however, produced flows to the myocardium, kidneys, liver, small intestine, and pancreas that were significantly greater than post-hemorrhage and NS-treated control values. NS was unable to increase these flows significantly above post-hemorrhage levels. We conclude that small volumes of HSD can significantly improve organ blood flow after hemorrhagic shock. This improvement in flow may explain the increased survival observed with this solution and may attenuate some of the later complications of hemorrhagic shock.

Animals↗
PubMed1986

Regional blood flow during hypothermic arrest.

Little is known about the efficacy of CPR in the setting of hypothermia-induced cardiac arrest. We measured organ blood flow produced by conventional closed-chest CPR in eight swine following normothermic KCl-induced cardiac arrest and in seven swine surface-cooled until cardiac arrest occurred. Radiomicrospheres were injected in the unanesthetized basal state, after five minutes of CPR, and after 20 minutes of CPR. After five minutes of CPR, the cardiac output and cerebral and myocardial blood flows (mean +/- SD) of hypothermic animals were 15.3 +/- 7.5 mL/min/kg, 0.16 +/- 0.11 mL/min/g, and 0.20 +/- 0.15 mL/min/g, respectively. Mean percentage flows were 7%, 15%, and 8%, respectively, of those measured in the unanesthetized prearrest state, and 50%, 55%, and 31%, respectively, of the flow produced during CPR in normothermic animals. Blood flow during hypothermic CPR did not change significantly over time; however, during normothermic CPR, cardiac output and cerebral and myocardial flows decreased so that at 20 minutes there were no significant differences from those values measured in hypothermic animals. The reduction in organ flow produced by external chest compression in hypothermic animals may be a result of the changes in the viscoelastic properties of the thorax that occur during profound hypothermia.

Animals↗
PubMed1986

Small-volume infusion of 7.5% NaCl in 6% Dextran 70 for the treatment of severe hemorrhagic shock in swine.

In the initial treatment of the hypovolemic trauma patient, commonly used crystalloids have little clinical benefit in the small volumes generally infused during transport. We evaluated the efficacy of a small-volume infusion of 7.5% NaCl in 6% Dextran 70 as a treatment modality for an otherwise lethal hemorrhage in swine. Sixty chronically instrumented swine were randomized into one of four treatment groups: 0.9% NaCl (NS, n = 15), 7.5% NaCl (HS, n = 15), 6% Dextran 70 (DEX, n = 16), and 7.5% NaCl in 6% Dextran 70 (HSD, n = 14). Each animal was bled 46 mL/kg in 15 minutes. Five minutes after the completion of hemorrhage, the animals were infused with their respective treatment in a volume (11.5 mL/kg) equal to 25% of the shed blood. Of those animals receiving HSD, 100% survived until euthanized at 96 hours. In comparison, animals infused with NS, HS, and DEX had 96-hour survival values of 13%, 53%, and 69%, respectively. The survival rate of the HSD group was significantly better than that of the NS group (P less than .001) and the HS group (P less than .01). The infusion of HSD increased mean arterial pressure, PCO2, and plasma bicarbonate to a significantly greater extent than NS alone (P less than .05). These results demonstrate that a small-volume infusion of the hypertonic sodium chloride/dextran solution is superior to equal volumes of a standard crystalloid in resuscitating animals from hemorrhagic shock.

Animals↗
PubMed1986

Lack of efficacy of naloxone in a fixed-volume hemorrhage model.

Animal studies using a reservoir model of hemorrhagic shock have shown the narcotic antagonist naloxone to be of value in reversing the hemodynamic effects of severe hemorrhage. We conducted a study to evaluate the ability of naloxone to limit the deleterious effects of a fixed-volume hemorrhage. Fifteen mongrel dogs were bled 50% of their estimated blood volumes during one hour. This was followed by a one-hour stabilization period; reinfusion during a 30-minute period; and finally, an additional one-hour monitoring period. Eight dogs received 2 mg/kg IV naloxone 30 minutes prior to hemorrhage and 2 mg/kg/hr for the duration of the study. Seven control dogs received an equivalent volume of saline without naloxone. Pulmonary capillary wedge pressure, central venous pressure, cardiac output, heart rate, blood pressure, arterial and mixed venous blood gases, and serum lactate were measured at 19 intervals throughout the study period. Mean arterial pressure, cardiac index, and systemic vascular resistance were calculated for each sampling period. With the exception of serum lactates, which were higher in the naloxone group, there were no significant differences between the groups in the mean values calculated for each sampling interval (P less than .05, two-tailed independent t test). Furthermore, the changes in hemodynamic parameters observed during the hemorrhage, stabilization, reinfusion, and monitoring periods were not significantly different. We conclude that in this fixed-volume hemorrhage model, naloxone does not prevent or reverse hemodynamic deterioration.

Animals↗
PubMed1986

Epidemiology of trauma: military experience.

Battle injuries sustained in conventional warfare are more likely to be lethal than are injuries sustained by civilians. Depending on the tactical situation, mortality may range from 20% to more than 80% of all casualties. The American experience indicates that about 90% of the total mortality occurs on the battlefield. Such casualties, those classified as killed in action, die before reaching medical care. More than 90% of all battle injuries (morbidity) are caused by penetrating missiles. Exsanguination from wounds of the heart/great vessels and penetrating/perforating wounds of the skull cause the majority of battlefield deaths. The frequency distribution of injury severity appears to be bimodal. A large peak occurs at low injury severity and indicates a population of casualties with relatively benign soft tissue wounds. A smaller peak at high injury severity represents those killed in action.

Adult↗
PubMed1986

Current shock models and clinical correlations.

No useful purpose is served by developing therapeutic interventions that are applicable only in nonexistent patient populations. The history of laboratory hemorrhagic shock research may be a case in point because although many interventions have been proposed on the basis of animal experimentation, few if any have found a place in the treatment of human beings. For a laboratory shock model to have clinical relevance, it must replicate important aspects of shock as seen in human beings during or following massive blood loss. The difficulty in developing an animal model that incorporates these human aspects--hypothermia, hypoxia, hypotension, acidosis, coagulopathy, etc--must not be underestimated. Four methodological factors to consider are animal species, anesthesia, tissue trauma, and nociceptive effects. The development of an animal shock model will require several compromises and the results, whether dealing with mechanisms or therapeutic outcomes, must be considered suspect until confirmatory data are obtained from human studies.

Animals↗
PubMed1986

Hypertonic sodium chloride solutions for the prehospital management of traumatic hemorrhagic shock: a possible improvement in the standard of care?

Acute hemorrhage is a major cause of death in both civilian and military trauma. The suboptimal effect of the volume of standard crystalloids that can be infused during transport has resulted in a need for a more efficacious fluid for the prehospital management of both civilian and military trauma. Markedly hypertonic sodium chloride solutions have been shown to improve transiently the hemodynamic consequences of shock in animal models. The use of small volumes of 7.5% NaCl in 6% dextran 70 has resulted in a solution superior to equal volumes of standard crystalloids in the ability to resuscitate animals from hemorrhagic shock. The hypertonic sodium chloride/dextran solution has the potential advantages of improving survival, producing a beneficial hemodynamic effect with smaller fluid volumes, reducing total fluid requirements during resuscitation, and being stored easily. This solution may prove valuable in the early resuscitation of the hypovolemic trauma patient and merits further clinical trials.

Animals↗
PubMed1985

Transcutaneous oxygen tension measurements during graded hemorrhage and reinfusion.

Measurement of transcutaneous oxygen tension (PtCO2) has been suggested as a useful monitoring tool in the hypovolemic patient. Our study was undertaken to evaluate changes in PtCO2 that occur during graded hemorrhage and reinfusion, and to compare PtCO2 values to standard cardiorespiratory and biochemical parameters during hypovolemia. Seven mongrel dogs were bled 50% of their estimated blood volume (44 mL/kg) over one hour. This was followed by a one-hour monitoring period, a 30-minute reinfusion period, and an additional one-hour monitoring period. Pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), cardiac output (CO), mean arterial pressure (MAP), mixed venous oxygen tension (MvO2), arterial blood gases, and PtCO2 were measured serially throughout the study period. Cardiac index (CI), peripheral vascular resistance (PVR), O2 consumption, delivery, and percentage of extraction were calculated for each sampling period. A statistically significant fall in CI, MvO2 and PCWP occurred following the first 10% of blood loss; PtCO2 and MAP fell significantly after 20% hemorrhage; CVP fell after 30% hemorrhage. PtCO2 rose significantly after the first 10% of reinfusion, and it continued to rise during the entire reinfusion period, as did MvO2, CO, MAP, CVP, and PCWP. In contrast to the other measured variables, the elevations in PtCO2, and MvO2 were more pronounced early in the reinfusion period. During postreinfusion monitoring, PtCO2, MvO2, CO, and PCWP fell significantly despite maintenance of prehemorrhage MAP and CVP. Overall PtCO2 correlated well with MvO2 and the O2 extraction ratio, and to a lesser extent with CI, MAP, and O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Diaphragmatic rupture during G-maneuvers in a T33 jet trainer.

A 26-year-old white male, radar operator, participated in a flight in a U.S. Air Force T33 jet trainer. The patient experienced nausea and vomiting followed by several episodes of retching during maneuvers of positive acceleration. Upon landing, he noted severe epigastric pain and shortness of breath. After 3 h of persistent symptoms, he presented to the base hospital's emergency department where he was diagnosed as having diaphragmatic herniation of abdominal viscera into the left hemithorax. At laparotomy, a large traumatic paraesophageal tear was discovered. The abdominal viscera were reduced and the defect repaired. The postoperative course was uncomplicated. The pathophysiology of blunt, nonpenetrating diaphragmatic herniation is discussed. Another mechanism for diaphragmatic rupture resulting from the forces of vomiting and acceleration is proposed.

Acceleration↗
PubMedDate not supplied

The EMS response to the Oklahoma City bombing.

This is a descriptive study of the Emergency Medical Services response to a bombing of a United States Federal Building in Oklahoma City, Oklahoma on 19 April 1995. The explosion emanated from a rented truck parked in the front of the building. The force of the explosion destroyed three of the four support columns in the front of the building and resulted in a pancaking effect of the upper floors onto the lower floors. There were three distinct phases of the medical response: 1) Immediately available local EMS ambulances and staff; 2) Additional ambulances staffed by recalled, off-duty personnel; and 3) mutual-aid ambulances and personnel from the surrounding communities. There were 361 persons in the building at the time of the explosion, 163 of these perished. Within the first hour of the explosion, 139 patients were transported to area hospitals. Of these, 32% were in critical condition. During the day of the explosion, 444 persons were treated for physical injuries: 410 of these were related to the explosion and 14, including one with fatal injuries, were sustained during search and rescue attempts. A total of 354 (80%) were treated and released from emergency departments, and 90 (20%) were admitted to hospitals. Six of the transported victims either were dead on arrival to the emergency department or died after admission to the hospital. Of those who died, 95% of the deaths were related to blunt trauma associated with the collapse of the structure. Only three persons were extricated alive after the first five hours following the explosion. The scene became flooded with volunteers who, although their intentions were to provide help and aid to those injured, created a substantial logistical problem for Incident Command. Several other lessons were learned: 1) Telephone lines and cells became overloaded, but the Hospital Emergency Administrative Radio system was operational only in three of the 15 hospitals; 2) Volunteer personnel should have responded to the hospitals and not to the scene; and 3) Training was an essential for the success of such a response. Thus, the success of this operation was a function of the intense training, practice, and coordination between multiple agencies.

Emergency Medical Services↗