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Biomedical subjects

T S Neuman

Publications and source records attributed to T S Neuman.

At least 19 recordsLinked to original sources
PubMed1994

Elevation of serum creatine kinase in divers with arterial gas embolization.

BACKGROUND: Arterial gas embolism due to pulmonary barotrauma and the resultant cerebral gas embolism are catastrophic complications of diving. Previous studies have only rarely noted evidence of gas embolism to noncranial sites. METHODS: Among 142 persons with diving-related injuries evaluated between January 1982 and July 1991, we identified 29 who had arterial gas embolism and who underwent biochemical studies indicative of muscle injury. Of the 29 patients, 4 were excluded because cardiopulmonary resuscitation had been performed and 3 were excluded because the duration of their dives met or exceeded standard limits set for dives not requiring staged decompression. The outcome at the time of hospital discharge in the remaining 22 patients was correlated with clinical factors and the results of biochemical studies. We also studied 22 subjects after uncomplicated dives and 11 patients who had sustained blunt trauma. RESULTS: All the patients with diving-associated gas embolism had elevated serum creatine kinase activity (normal, < or = 175 U per liter); the values were markedly elevated (> 900 U per liter) in 14. The MB isoenzyme of creatine kinase was detected in the serum of 13 of 20 patients in whom it was measured and was > or = 4 percent of total creatine kinase activity in 6 patients. In three patients electrocardiography showed myocardial injury. Changes in serum creatine kinase activity of similar magnitude were not present in the subjects who had uncomplicated dives or in the patients with blunt trauma. Thirteen patients recovered fully, four had minor residual neurologic deficits, three were severely impaired, and two died. Logistic-regression analysis revealed a significant correlation between peak serum creatine kinase values and clinical outcome. CONCLUSIONS: Biochemical evidence of muscle injury is frequently found after diving-associated arterial gas embolism. The correlation between serum creatine kinase activity and outcome suggests that serum creatine kinase is a marker of the size and severity of arterial gas embolism.

Adolescent↗
PubMed1994

Asthma and diving.

BACKGROUND: Approximately 10 to 15 million Americans are scuba divers. The prevalence of scuba diving and asthma makes it likely some asthmatics will be interested in scuba diving and some scuba divers will have asthma. Conditions present during scuba diving may provoke airway obstruction in asthmatic patients. Further, asthmatic patients may, in theory, face a greater than normal risk of pulmonary barotrauma from lung overdistension on ascent through the water column. OBJECTIVE: The purpose of this paper is to review the theoretical issues underlying the prohibition against scuba diving for asthmatic patients as advanced by most major diving organizations in the United States and critically examine the relevant accident data. METHODS: All reports that dealt with asthma and diving, and all available American accident data including both fatal and nonfatal accidents were reviewed. RESULTS: Actuarial data on the risk of scuba accidents attributable to asthma do not define several important variables likely to affect accident risk during scuba diving. Despite these limitations, careful review indicates the risks of serious morbidity or mortality during scuba diving appears to be inconsequentially elevated in subjects whose asthma was not characterized. CONCLUSIONS: Additional data are needed to define accurately risks of diving in subjects with different forms of asthma, however, the available data suggest asthmatic patients with normal airway function at rest, and with little airway reactivity in response to exercise or cold air inhalation, have a risk of pulmonary barotrauma similar to that of normal subjects.

Airway Obstruction↗
PubMed1990

Effect of hyperbaric oxygen on murine neutrophil and T-lymphocyte functions.

We investigated the effect of repeated hyperbaric oxygen (HBO) exposure on PMN and T-lymphocyte functions in a murine model. Animals received eight 90-min exposures twice daily to 2.4 ata and 100% or 10% oxygen. Control animals were maintained in room air. On the ninth day spleens and peritoneal cell exudates were harvested. Phagocytosis was measured by flow-cytometric analysis of the ability of PMN to engulf formalin-killed, fluorescence-labeled Staphylococcus aureus. PMN-killing capacity was measured by the ability of PMN to undergo an oxidative burst after stimulation with N-formyl methionyl-leucyl-phenylalanine, phorbol myristate, or opsonized zymosan. T-lymphocyte subpopulations were identified using monoclonal antibodies and two-color flow cytometry after 48 h stimulation with phytohemagglutinin, and lymphocyte proliferation was measured by 3 H-thymidine incorporation. We found PMN phagocytosis and oxidative burst were unchanged after HBO treatment. Lymphocyte proliferation was decreased, and an activated population of CD8+ T cells appeared after mitogen stimulation. We conclude that, although PMN function is not affected by prior HBO, lymphocyte proliferation is decreased.

Animals↗
PubMed1990

Combined arterial gas embolism and decompression sickness following no-stop dives.

Decompression sickness (DCS) has been clinically classified as Type I (predominantly joint pain) or Type II (predominantly spinal cord lesions). We present 3 cases that are all characterized by severe (Type II) DCS with signs and symptoms of spinal cord injury occurring in conjunction with arterial gas embolism (AGE). We consider the AGE "minor" because only 2 of the 3 subjects initially lost consciousness, and in all cases the signs and symptoms of the AGE had essentially resolved within 1 h or by the time recompression therapy began. DCS was resistant to recompression therapy, even though treatment began promptly after the accident in 2 of the 3 cases. None of the cases had a good neurologic outcome and there has been one death. None of the divers exceeded the U.S. Navy "no-stop" limits for the depths at which they were diving. We have observed a previously unreported clinical syndrome characterized by severe Type II DCS subsequent to AGE following pressure-time exposures that would normally not be expected to produce DCS. We postulate that AGE may have precipitated or predisposed to this form of DCS.

Adult↗
PubMed1989

The impact of a regionalized trauma system on trauma care in San Diego County.

A review of autopsy reports on traumatic deaths in 1986 was conducted to determine the impact on trauma mortality of the regionalized trauma system instituted in San Diego County in 1984. Determination of preventable death was made by a panel of experts and compared with an identical review of traumatic deaths in 1979, five years before the institution of regionalized trauma care. Of 211 traumatic deaths reviewed from 1986, two (1%) were classified as preventable, compared with 20 of 177 (11.4%) deaths in 1979 (P less than .001). A breakdown of trauma deaths into central nervous system and noncentral nervous system categories revealed the overall decline was in large part a consequence of the decline in non-central nervous system deaths from 16 of 83 in 1979 to one of 62 in 1986 (P less than .005). The decrease in central nervous system-related preventable deaths from four of 94 in 1979 to one of 149 in 1986 (P less than .10) was not statistically significant. Although it is likely the trauma system introduced in 1984 contributed to the decline in preventable death, it is not possible to isolate this variable from other changes that occurred during the interval between studies. A review of trauma deaths over the same time interval in a community with similar demographics but without a trauma system might help determine the relative contribution of the trauma system.

Adult↗
PubMed1987

Barotraumatic cerebral air embolism and the mental status examination: a report of four cases.

Barotraumatic cerebral air embolism is described as sudden loss of consciousness accompanied by major motor disturbances. However, arterial gas embolism can have disturbances of cortical function that are much more subtle. Four patients presented with significant abnormalities of mental status. In two patients, the findings were subtle enough that the patients were initially regarded as normal. In the other two, cortical dysfunction was relatively resistant to therapy and might have gone unrecognized without careful examination. In order to detect disturbances in cortical function the neurologic examination should include testing beyond the usual emergency evaluation of consciousness and degree of orientation.

Adolescent↗
PubMed1987

Diving medicine.

This article orients the practicing physician to the physical and physiologic basis for the more common medical problems encountered in diving, discusses the common presenting manifestations for these disorders, and provides a framework for their treatment. Medical fitness for diving is also briefly addressed.

Barotrauma↗
PubMed1986

Fatal poisoning from acute hydrofluoric acid ingestion.

A case of accidental oral poisoning with hydrofluoric acid in an adult is presented. The patient ingested the product from a drinking glass, mistaking it for water, and died approximately 90 minutes after the exposure. Severe acidemia and hypocalcemia were present, which resulted in refractory asystole. A plasma fluoride determination showed an extremely high fluoride level.

Adult↗
PubMed1982

An autopsy study of traumatic deaths; San Diego County, 1979.

All traumatic deaths in San Diego County were analyzed for the year of 1979. Death certificates, coroner's reports, and autopsy data served as the basis for this review. A total of 177 deaths were studied, of which 94 were associated with CNS injury and 83 were not. Sixteen (20 percent) of the deaths not CNS-associated and four (5 percent) of the CNS-associated deaths were classified as preventable. One hundred seventeen deaths were due to motor vehicle accidents, of which 11 of 35 (31 percent; all not CNS-associated) were deemed preventable. Preventable causes of death included hemorrhage, unrecognized hemopneumothorax, and unrecognized epidural hematoma.

Adolescent↗
PubMed1980

Cardiopulmonary consequences of decompression stress.

Clinically undetectable venous gas emboli (VGE) can be routinely demonstrated in both animals and men undergoing clinically uneventful decompression from hyperbaric environments. The effect of VGE on gas exchange and pulmonary hemodynamics in this setting is unclear. We therefore have studied the cardiopulmonary effects of clinically uneventful decompression on unanesthetized sheep. Sheep were instrumented with a femoral arterial catheter, Swan-Ganz catheter, chronic tracheostomy, and were loosely restrained in the prone position. Following baseline measurements of pulmonary artery pressure (pPA), mean pulmonary artery wedge pressure (pPAw), cardiac output (CO), arterial and mixed venous blood gases, Doppler ultrasonic bubble detection, and V/Q scans using 133Xe, the animals were exposed to: (a) a 15-min exposure to 6.03 ATA (n = 8), (b) a 17.5-min exposure to 6.03 ATA, or (c) a 15-min control period at 1 ATA (n = 7). All measured parameters remained unchanged in the control group. VGE were detected in all animals exposed to pressure. In both exposure groups CO fell 20% (P < 0.05) and pulmonary vascular resistance (PVR) rose 60% (P < 0.05) compared to the control group. This rise in PVR was significantly in excess of that predicted for the observed fall in CO. Analysis of pPA and pPAw suggested neither right nor left ventricular failure. No significant abnormalities of gas exchange were detected. V/Q scans remained unchanged in all animals. We conclude that CO and PVR are altered by clinically uneventful decompression stress.

Animals↗
PubMed1979

Urinary excretion of water and electrolytes during open-sea saturation diving to 850 fsw.

The dive was carried out in the open sea to a depth of 850 fsw (26.7 ATA) for 6 days (DD 1--6) in the saturated mode, with personnel transfer capsule (PTC) excursions between 0 and 150 fsw and diver excursions between 0 and 50 fsw from the saturation base. Each diver had two excursion dives on alternate days. Although each PTC excursion lasted approximately 7 h, the actual time spent in the water averaged 10.5 min per diver. For 12 divers, daily excretion of water, electrolytes, aldosterone, and antidiuretic hormone (ADH) was studied, along with plasma composition (including prolactin), before, during, and after hyperbaric exposure. A significant increase in urine flow was observed on DD2--4 (1604 ml/day predive vs. 2300 ml/day on DD 4; P less than 0.05), after which the degree of diuresis decreased to about 1800 ml/day. Urine osmolality changed inversely with urine flow, with the lowest value of 532 mOsm/kg on DD 4. During the postdive period, both urine flow and urine osmolality returned to the predive level. The endogenous creatinine clearance was maintained at about 200 liters/day throughout the dive. The fractional excretion of Na+ remained unchanged while that of K+ increased significantly during hyperbaric exposure, thus decreasing the urinary Na+/K+ ratio. The fractional excretion of total osmotic substances showed a small hyperbaric exposure. Body weight decreased progressively during the initial 4 days of pressure exposure, equalling 2.6 kg on DD 4. These findings suggest that the observed diuresis may be accompanied by a net loss of body water. Neither the plasma prolactin level nor urinary excretion of aldosterone and ADHshowed any consistent change throughout the dive. It thus appears that, although there is a small osmotic component, the observed diuresis is primarily due to the ADH-independent inhibition of fre water reabsorption from the collecting duct by means of a mechanism yet to be identified.

Adult↗
PubMed1978

Diving experience and emotional factors related to the psychomotor effects of nitrogen narcosis.

Simple and complex psychomotor performance were tested among 21 Navy divers under normal conditions and during nitrogen narcosis in simulated dives to 170 ft of sea water. Complex psychomotor performance was impaired significantly during narcosis, while simple psychomotor performance remained essentially normal. Differences between baseline scores for complex psychomotor performance (pre- and post-dive combined) and scores obtained from the two combined testing sessions administered during narcosis were correlated with official Navy records of diving experience and self-reported moods. None of the diving experience measures was associated significantly with these difference scores. The moods of Fatigue and Happiness were, however, correlated significantly with impairment. These results indicate that, although previous experience with nitrogen narcosis and diving tasks do not mediate the performance effects of nitrogen narcosis, the complex psychomotor effects nitrogen narcosis are related to emotional traits.

Adult↗
PubMed1977

Venous gas bubbles: production by transient, deep isobaric counterdiffusion of helium against nitrogen.

When awake goats were subjected to isobaric gas switching from saturation (17 hours) on 4.7 atmospheres of nitrogen (0.3 atmosphere of oxygen) to 4.7 atmospheres of helium (0.3 atmosphere of oxygen), bubbles detected by 5-megahertz Doppler ultrasound in the posterior vena cava 20 to 60 minutes after the switch continued for 4 hours. Similar experiments carried out at 6.7 atmospheres of inert gas and 0.3 atmosphere of oxygen produced more bubbles for as long as 12 hours after the gas switch. This is believed to be the first objective demonstration of the phenomenon of deep isobaric supersaturation under transient operational diving conditions at relatively shallow diving depths. Detection of bubbles by Doppler ultrasound confirms the potential importance of the phenomenon to shallow saturation diving and holds promise for better quantitification of its effects as well as those of its counterpart, isobaric undersaturation, which can confer a decompression advantage.

Animals↗
PubMed1976

Blood viscosity in man following decompression: correlations wiht hematocrit and venous gas emboli.

Whole blood viscosities were measured in U.S. Navy personnel before and after chamber compressions to 5 ATA (132FSW) and 7.4 ATA (210 FSW) by a new method described here. Bubble scores as a quantitative measure of venous gas emboli were determined during decompression and for 30 min thereafter. Hematocrit was measured both before and after each dive. There were five cases of decompression sickness in the two groups. No significant changes in whole blood viscosity, or hematocrit, were noted either in the group that was affected by decompression sickness or in all of the subjects taken as a group. No correlations between total bubble score and changes in viscosity or hematocrit could be made. These results imply that no major changes in viscosity occur in the usual forms of decompression sickness encountered in human beings.

Blood Viscosity↗