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Biomedical subjects

D J Bohn

Publications and source records attributed to D J Bohn.

35 records · Page 2Linked to original sources
PubMed1990

Unsuspected diaphragmatic hernia: a potential cause of sudden and unexpected death in infancy and early childhood.

Congenital diaphragmatic hernias are usually found in neonates who present with respiratory distress. However, a significant number may remain clinically undiagnosed until much later in life. Of interest, the prognosis is felt to be better in this latter group. We describe three previously well patients (aged 2, 4, and 24 months) who suffered unexpected cardiorespiratory arrests due to unsuspected congenital diaphragmatic defects with intestinal herniation. Deaths resulted from cardiovascular and respiratory compromise due to visceral herniation that caused mediastinal and pulmonary compression.

Child, Preschool↗
PubMed1990

Effect of hypothermia and cardiac arrest on outcome of near-drowning accidents in children.

We conducted a retrospective review of 55 near-drowning victims (mean age 4.75 years) admitted to the intensive care unit during a 5-year period, to determine the factors that may influence survival both before and after hospital admission. All patients who remained comatose after resuscitation received ventilation for an initial 24 hour period, after which an assessment of central nervous system injury was made. Intracranial pressure was not monitored, and barbiturate therapy was used only for seizure control. Thirty-seven children survived and 18 died; five survivors had profound neurologic damage resulting in a persistent vegetative state: the remaining 32 (58%) survived intact. The major factors that separated intact survivors from those who died and from survivors in a persistent vegetative state were the presence of a detectable heartbeat and hypothermia (less than 33 degrees C) on examination in the emergency department. Thirteen patients with absent vital signs and a temperature of greater than 33 degrees C either died or survived in a persistent vegetative state. Fourteen patients had a combination of absent vital signs and hypothermia and were resuscitated; eight died, two survived in a persistent vegetative state, and four survived intact. All intact survivors had been submerged in cold water for prolonged periods, and all underwent prolonged cardiopulmonary resuscitation. All patients with a detectable pulse, regardless of temperature, survived without neurologic sequelae. The 58% intact survival rate in this series compares favorably with the 50% we reported previously when high-dose barbiturate therapy and hypothermia were used to control intracranial pressure; at the same time, the number of survivors with a persistent vegetative state has been reduced by 50%. We conclude that prolonged in-hospital resuscitation and aggressive treatment of near-drowning victims who initially have absence of vital signs and are not hypothermic either results in eventual death or increases the number of survivors with a persistent vegetative state.

Child, Preschool↗
PubMed1990

Early nosocomial infections in pediatric cardiovascular surgery patients.

All patients undergoing cardiovascular surgery between July 1, 1987 and February 29, 1988 were followed from admission to the pediatric ICU (PICU) daily by an intensivist/anesthetist. Patients were characterized by surgical procedure and PRISM score on ICU admission. Of 310 patients, 40 patients (nosocomially infected patient ratio 12.9) developed 78 infections (nosocomial infection ratio 25.2), of which 28% (n = 22) were wounds, within 2 months of surgery. Early wound infection followed 8% of closed, nonpump cases and 6.7% of open, pump cases. Wound infection was more likely if the sternum was open on the ward (elective or emergency) (27.6% open vs. 5.0% closed, p less than .001) or if the PRISM score was greater than or equal to 10 on PICU admission (10.7% greater than or equal to 10 vs. 2.3% less than 10, p less than .01). The causative agents in wound infections in closed cases were Staphylococcus aureus (70%) and coagulase negative staphylococci (CONS) (30%) while in open, pump cases the agents were CONS (33%), Pseudomonas aeruginosa (27%), Candida spp. (27%), and S. aureus (20%). Nonwound infections accounted for 72% of infections (n = 56). The number of bacteremias and other central and arterial line-related infections approximated wound infection in incidence at 6.8/100 patients. Wound infections are more likely if the sternum has been left open on the ward, if the patient has a high PRISM score on PICU admission, and after specific surgical procedures.

Cardiac Surgical Procedures↗
PubMed1989

Preventable pediatric trauma deaths in a metropolitan region.

All pediatric trauma deaths occurring in metropolitan Toronto (population, 2.2 million) in 1986 were analyzed from the regional coroner's records. Injuries sustained were scored using the Abbreviated Injury Scale (1985; AIS) and Injury Severity Score (ISS). Victims with injuries graded AIS 6 (any region), AIS 5 head/neck (excluding acute epidural hematoma), or ISS greater than 59 were deemed unsalvageable. All other injuries were considered survivable and the deaths from them preventable. Use of these objective criteria indicated that 8/38 of the children (21%) who died from trauma had survivable injuries. Since in three cases medical aid was not sought because of social circumstances, 5/38 (13%) was considered a realistic estimate of preventable death rate (PDR). These results suggest that when objective criteria are used, the PDR in pediatric trauma may be less than that reported in adult trauma victims. Defining the PDR on the basis of objective criteria may prove useful in the conduct of further studies of this kind and permit valid comparisons to be made.

Adolescent↗
PubMed1989

Evaluation of pediatric trauma care in Ontario.

Three hundred sixty-seven consecutive pediatric trauma deaths which occurred in Ontario between 1985 and 1987 were analyzed from the coroners' records. Injuries were classified as survivable or unsurvivable, and a preventable death rate of 20% was identified. Rural preventable deaths occurred mainly before arrival at hospital, but 55% of urban preventable deaths occurred in hospitals. The causes of death in children with survivable injury suggest that the institution of prehospital resuscitation and improvement in trauma care education for physicians might reduce mortality. The high incidence of unsurvivable injury suggests that injury prevention will be more cost effective in the long term.

Adolescent↗
PubMed1989

Severe acute asthma in a pediatric intensive care unit: six years' experience.

The management of children with severe acute asthma who required admission to the intensive care (ICU) of this hospital during 1982 to 1988 was reviewed retrospectively. A total of 89 children were admitted to the ICU on 125 occasions. During the study period, 24% of the patients were admitted to the ICU on more than one occasion. Prior to admission to this hospital, patients had been symptomatic for a mean of 48 hours. Although all patients had received bronchodilators before admission to hospital, only 23% of patients had received oral corticosteroids. According to initial arterial blood gas values determined in the ICU, 77% of the patients had hypercapnia (PaCO2 greater than 45 mm Hg). The pharmacologic agents used in the ICU included nebulized beta 2-agonists (100% of admissions), theophylline (99%), steroids (94%), nebulized ipratropium bromide (10%), IV albuterol (38%), and IV isoproterenol (10%). Mechanical ventilation was necessary in 33% of admissions; the mean duration of ventilation was 32 hours. Ten patients had pneumothorax; in six cases, these were related to mechanical ventilation. Three of the patients who received mechanical ventilation died, representing a mortality of 7.5%. In each of these patients, sudden, severe asthma episodes had developed at home, resulting in respiratory arrest. They had evidence of hypoxic encephalopathy at the time of admission to the ICU and eventually were declared brain dead. It was concluded that delay in seeking medical care and underuse of oral corticosteroids at home may have contributed to the need for ICU admission.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Timing of surgery for congenital diaphragmatic hernia: is emergency operation necessary?

Congenital diaphragmatic hernia (CDH) is considered by most researchers to be a surgical emergency. However, early repair does not necessarily improve respiratory function or reverse fetal circulation, and many patients deteriorate postoperatively. As a result, in 1985, we began to employ a protocol in which surgery was delayed until the PCO2 was maintained below 40 and the child was hemodynamically stable; children in whom these criteria could not be achieved died without surgical repair. Sixty-one consecutive infants with CDH were managed over 4 years; 31 from 1983 to 1984 (group 1) and 30 from 1985 to 1986 (group 2). The groups were similar with respect to sex, side of the defect, birth weight, gestational age, incidence of pneumothorax, and blood gases. High frequency oscillation was used with increasing frequency during the study period, for patients with refractory hypercarbia (13% in group 1, 30% in group 2). All patients were initially paralyzed and ventilated. Mean time from admission to surgery was 4.1 hours in group 1 and 24.4 hours in group 2 (P less than .05). In group 1, 87% of patients had surgical repair (77% within eight hours of admission, 10% after eight hours), and in group 2 only 70% of patients had surgery (10% within eight hours, 60% after eight hours). All patients who were not operated on died. Overall mortality was 58% in group 1 and 50% in group 2; this difference was not statistically significant. These data indicate that our current approach has not increased overall mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergencies↗
PubMed1988

The use of inotropic and afterload-reducing agents in neonates.

Vasodilators have demonstrated efficacy in neonates with depressed myocardial function. The magnitude of benefit depends on the preexisting hemodynamic state and concurrent treatment modalities. In patients with increased filling pressures, vasodilators increase cardiac output with negligible effect on MAP, with volume resuscitation to restore pretreatment filling pressures offering additional benefit. The rationale for use in neonatal respiratory disease remains less clear, with no vasoactive drug showing selective pulmonary vasodilatation. Benefit no doubt accrues from the improved coronary perfusion that occurs with reduction in filling pressures. In addition, reduced interventricular diastolic dependence and thereby improved ventricular compliance, as well as the afterload-reducing effect of decreased chamber size, may significantly reduce the effect of the lung disease on myocardial functioning.

Cardiac Output↗
PubMed1987

Effect of surgical repair on respiratory mechanics in congenital diaphragmatic hernia.

To determine whether surgical repair of congenital diaphragmatic hernia (CHD) results in improvement in respiratory mechanics, we measured respiratory system compliance in nine patients (five survivors and four nonsurvivors) before and after operation. In all nine infants, CHD was diagnosed within 6 hours of life, and surgical repair was through an abdominal approach after a period of stabilization. Measurements were made noninvasively, using the passive expiratory flow-volume technique. In only one of the nine infants did compliance immediately improve after surgical repair, and in another it showed no change. Both of these infants survived, with an uneventful postoperative course. In the remaining seven infants, however, postoperative compliance immediately decreased to 10% to 77% from the preoperative value. The four infants with more than 50% decrease in compliance died with increasing hypoxemia and acidosis. These results suggest that respiratory mechanics in CHD, far from improving, frequently deteriorate as a result of repair of the hernia. The role of urgent surgery in this malformation should be reevaluated.

Hernia, Diaphragmatic↗
PubMed1986

Influence of hypothermia, barbiturate therapy, and intracranial pressure monitoring on morbidity and mortality after near-drowning.

We retrospectively evaluated the clinical and pathologic effects of hypothermia and high-dose barbiturate therapy on hypoxic/ischemic cerebral injury after near-drowning in children. Of 40 near-drowned patients admitted to the ICU, 13 died, seven had permanent cerebral damage, and 20 survived. Twenty-four patients (group 1) were treated with a regime of hyperventilation, hypothermia, and high-dose phenobarbitone while intracranial pressure (ICP) was continuously monitored. Of ten who died in this group, three were diagnosed as having cerebral death shortly after admission; autopsy revealed severe cerebral edema with herniation. The remaining seven nonsurvivors had severe cerebral hypoxia without raised ICP and had the features of severe adult respiratory distress syndrome and hypoxic/ischemic damage to other organs. Six of these seven patients developed septicemia which was invariably associated with a profound neutropenia. Sixteen patients (group 2) were treated with a similar protocol but without hypothermia. Three of these patients died but only one developed septicemia. Neutropenia after resuscitation from near-drowning seemed to indicate a poor prognosis; the mean polymorphonuclear leukocyte count in nonsurvivors (1.9 +/- 0.5 X 10(9) cell/L) was significantly (p less than .01) lower than that in survivors (6.4 +/- 1.1 X 10(9) cell/L). Hypothermia was associated with a decreased number of circulating PMNs but did not increase the number of neurologically intact survivors. Similarly, although barbiturates may control ICP, their use did not improve outcome. Because severe cerebral edema and herniation after near-drowning is usually associated with irreversible brain damage, measures to control brain swelling such as hypothermia and barbiturates will be of little benefit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Pulse oximetry in pediatric intensive care: comparison with measured saturations and transcutaneous oxygen tension.

We evaluated a new pulse oximeter designed to monitor beat-to-beat arterial oxygen saturation (SaO2) and compared the monitored SaO2 with arterial samples measured by co-oximetry. In 40 critically ill children (112 data sets) with a mean age of 3.9 years (range 1 day to 19 years), SaO2 ranged from 57% to 100%, and PaO2 from 27 to 128 mm Hg, heart rates from 85 to 210 beats per minute, hematocrit from 20% to 67%, and fetal hemoglobin levels from 1.3% to 60%; peripheral temperatures varied between 26.5 degrees and 36.5 degrees C. Linear correlation analysis revealed a good agreement between simultaneous pulse oximeter values and both directly measured SaO2 (r = 0.95) and that calculated from measured arterial PaO2 (r = 0.95). The device detected several otherwise unrecognized drops in SaO2 but failed to function in four patients with poor peripheral perfusion secondary to low cardiac output. Simultaneous measurements with a tcPO2 electrode showed a similarly good correlation with PaO22 (r = 0.91), but the differences between the two measurements were much wider (mean 7.1 +/- 10.3 mm Hg, range -14 to +49 mm Hg) than the differences between pulse oximeter SaO2 and measured SaO2 (1.5% +/- 3.5%, range -7.5% to -9%) and were not predictable. We conclude that pulse oximetry is a reliable and accurate noninvasive device for measuring saturation, which because of its rapid response time may be an important advance in monitoring changes in oxygenation and guiding oxygen therapy.

Adolescent↗
PubMed1984

The relationship between PaCO2 and ventilation parameters in predicting survival in congenital diaphragmatic hernia.

Fifty-eight infants with congenital diaphragmatic hernia presenting within the first 6 hours of life, who underwent surgical repair, were analysed prospectively in order to produce a reliable index of severity of disease that would reliably predict eventual outcome. All were treated with paralysis hyperventilation and intravenous (IV) isoproterenol for the first 48 hours. There were 30 survivors and 28 deaths in this series (mortality 48%). Using arterial PCO2 values measured 2 hours after surgical repair and correlating them with an index of mechanical ventilation (mean airway pressure and respiratory rate), we have been able to clearly define two groups of diaphragmatic hernia based on their response to IPPV. The first group, with CO2 retention and severe preductal shunting, was unresponsive to hyperventilation with high rates and pressures; the mortality was 90%. The second group responded well to hyperventilation and demonstrated reversable ductal shunting only. Survival in this group was 97%. Only four patients out of 58 exhibited the "honeymoon period," with a period of stability followed by severe ductal shunting. Arterial CO2 accurately reflects the degree of lung development in this disease and separates those patients with severe pulmonary hypoplasia, where the outcome is invariably fatal, from those with a well-developed contralateral lung where there is excellent potential for survival.

Carbon Dioxide↗
PubMed1984

Neutrophil migration in vitro and in vivo during hypothermia.

The effect of hypothermia on pig leukocyte migration in vitro and in vivo was studied. Neutrophil chemotaxis in vitro under agarose was significantly impaired at 29 degrees C (2.7 +/- 0.6 [mean +/- standard error]; 37 degrees C, 7.1 +/- 1.1). Leukocytes isolated from hypothermic pigs and tested at 37 degrees C migrated normally (7.8 +/- 0.6). Neutrophil and monocyte migration in vivo was markedly reduced at 29 degrees C. Reduced inflammatory responses may contribute to increased infections during hypothermia.

Animals↗
PubMed1980

Hemodynamic effects of dobutamine after cardiopulmonary bypass in children.

The synthetic inotropic agent, dobutamine, has reportedly increased cardiac output in adults after cardiopulmonary bypass with minimal side effects. Its use in children, after surgical correction of congenital heart disease, was tested by infusing the drug at 1, 4, 7, and 10 micrograms/kg x min in 11 children. While significant increases in cardiac index above control (23, 23, and 16% at 4, 7, and 10 micrograms/kg x min, respectively) were observed, this was achieved at the expense of significant increases in heart rate (15, 24, and 10%). This increase in heart rate (47% in one child) necessitated discontinuing the infusion in 4 subjects. There were also significant increases in systolic and mean blood pressure with no change in stroke volume or peripheral vascular resistance. The authors conclude that in children, dobutamine is an effective inotropic agent acting principally by stimulating beta 1-receptors in the myocardium producing a predominantly chronotropic effect without significant changes in peripheral vascular resistance. Given the intrinsically higher heart rate of children, the levels of tachycardia produced by the drug in some instances reach unacceptable levels and as such, may make dopabutamine unsuitable for use in children after cardiopulmonary bypass.

Blood Pressure↗
PubMed1980

Ventilation by high-frequency oscillation.

The effect of applying a high-frequency small-volume sinusoidal oscillation at the airway was investigated in anesthetized apneic beagle dogs (mean wt 11 kg, mean VDphys 6.6 +/- 0.6 ml/kg). Oscillations generated by a piston in a cylinder were transmitter to the lungs through an uncuffed endotracheal tube (4.5 mm ID, 6.0 mm OD), which allowed a substantial leak back through the vocal cords. A bias flow of fresh gas presented inspired air to the midtracheal level. The minimum distal airway pressure (measured at the end of the endotracheal tube) was maintained between 0 and 2 cmH2O. Peak airway pressures were 4-8 cmH2O. The optimal frequency for CO2 elimination was 15 Hz. Using volumes of 1.9 ml/kg (range 1.7-2.3) at this frequency the mean PaCO2 was 33.1 +/- 0.5 Torr. In four dogs breathing 100% O2 the PaO2 was 594 +/- 9 Torr during spontaneous ventilation and 580 +/- 9 Torr after 5 h of uninterrupted oscillation. In four experiments using room air the PaO2 was 95 +/- 5 Torr during spontaneous respiration and 106 +/- 1 Torr after 5 h of oscillation. In an additional seven studies there was no difference in mean cardiac output between oscillation and conventional mechanical ventilation. This study demonstrates that high-frequency small-volume oscillations can maintain gas exchange for many hours presumably by markedly enhancing the diffusivity of gases in the lung.

Animals↗