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Biomedical subjects

D Bohn

Publications and source records attributed to D Bohn.

At least 19 recordsLinked to original sources
PubMed2006

Hypotonic versus isotonic saline in hospitalised children: a systematic review.

BACKGROUND: The traditional recommendations which suggest that hypotonic intravenous (i.v.) maintenance fluids are the solutions of choice in paediatric patients have not been rigorously tested in clinical trials, and may not be appropriate for all children. AIMS: To systematically review the evidence from studies evaluating the safety of administering hypotonic versus isotonic i.v. maintenance fluids in hospitalised children. METHODS DATA SOURCES: Medline (1966-2006), Embase (1980-2006), the Cochrane Library, abstract proceedings, personal files, and reference lists. Studies that compared hypotonic to isotonic maintenance solutions in children were selected. Case reports and studies in neonates or patients with a pre-existing history of hyponatraemia were excluded. RESULTS: Six studies met the selection criteria. A meta-analysis combining these studies showed that hypotonic solutions significantly increased the risk of developing acute hyponatraemia (OR 17.22; 95% CI 8.67 to 34.2), and resulted in greater patient morbidity. CONCLUSIONS: The current practice of prescribing i.v. maintenance fluids in children is based on limited clinical experimental evidence from poorly and differently designed studies, where bias could possibly raise doubt about the results. They do not provide evidence for optimal fluid and electrolyte homoeostasis in hospitalised children. This systematic review indicates potential harm with hypotonic solutions in children, which can be anticipated and avoided with isotonic solutions. No single fluid rate or composition is ideal for all children. However, isotonic or near-isotonic solutions may be more physiological, and therefore a safer choice in the acute phase of illness and perioperative period.

Adolescent↗
PubMed2006

Hypothermia pediatric head injury trial: the value of a pretrial clinical evaluation phase.

BACKGROUND: The utility of a pretrial clinical evaluation or run-in phase prior to conducting trials of complex interventions such as hypothermia therapy following severe traumatic brain injury in children and adolescents has not been established. METHODS: The primary objective of this study was to prospectively evaluate the ability of investigators to adhere to the clinical protocols of care including the cooling and rewarming procedures as well as management guidelines in patients with severe traumatic brain injury (Glasgow Coma Scale<or=8) treated with 24 h of hypothermia therapy. A secondary objective was to evaluate the ability of study research assistants to complete the study case report form using a procedures manual. The study was conducted at 18 sites in Canada, the United Kingdom and France prior to proceeding to a randomized controlled trial (RCT). After 2 patients were enrolled at each center, an independent clinical evaluation committee examined the process of care and the completeness of data collection. Centers were permitted to enroll patients in the RCT once they met pre-established adherence criteria. RESULTS: Seventeen of the 18 centers completed the pretrial clinical evaluation phase demonstrating compliance with study procedures and proceeded to an RCT of hypothermia therapy. One center enrolled only 1 patient in the pretrial clinical evaluation phase due to small numbers of patients with traumatic brain injury, and therefore, did not proceed to the RCT. Three centers were required to enroll more than 2 patients in the pretrial clinical evaluation phase prior to proceeding to the RCT because of problems with adherence to the clinical protocols at two centers and the training of new study personnel at another center. Of the 39 patients enrolled during the pretrial clinical evaluation phase, 8 (20.5%) died and 22 (62.9%) had a good outcome defined as normal, mild or moderate disability assessed using the Pediatric Cerebral Performance Category score at 6 months following injury. DISCUSSION: The pretrial clinical evaluation phase was useful to ensure compliance with complex hypothermia therapy and consensus-based clinical management guidelines of care successfully implemented across 17 of 18 centers. This study maneuver allowed us to complete a subsequent RCT in 225 children following severe traumatic brain injury.

Algorithms↗
PubMed2005

Acute and fatal hyponatraemia after resection of a craniopharyngioma: a preventable tragedy.

Central diabetes insipidus developed for the first time in a 14-year-old female during the resection of a craniopharyngioma. The water diuresis persisted until a vasopressin analogue (dDAVP) was given. Professor McCance was asked to explain why hypernatraemia developed, to anticipate dangers that might develop in the salt and water area with therapy, and to provide insights into why this patient died, due to the subsequent development of hyponatraemia that caused a lethal rise in intracranial pressure. The team specifically wanted Professor McCance's opinions as to why a PNa of 124 mmol/l was uniquely dangerous for this patient, and this was a particularly challenging conundrum. Nevertheless, with the aid of a mini-experiment, a careful chart review, and creative thinking, he was able to offer a novel solution, and to suggest ways to prevent its occurrence in other patients.

Adolescent↗
PubMed2005

Anterior versus posterior treatment of stable thoracolumbar burst fractures without neurologic deficit: a prospective, randomized study.

OBJECTIVE: A prospective randomized study was conducted to determine whether there exist any differences in radiographic, clinical, or functional outcomes when individuals with stable burst fractures of the thoracolumbar junction without neurologic deficit are treated with either a posterior fusion with instrumentation or anterior reconstruction, fusion, and instrumentation. There exists relatively little literature evaluating the outcomes of individuals treated with anterior surgery, and no prospective randomized studies exist comparing the two treatment approaches. METHODS: From May 1995 to March 2001, a consecutive series of subjects with acute isolated burst fractures of the thoracolumbar junction (T10-L2) without neurologic deficit were randomized to receive either an anterior fusion with instrumentation or a posterior fusion with instrumentation. Radiographs including computed tomography (CT) were obtained. Radiographs were repeated at 2, 4, 6, 12, and 24 months. The CT scan was also repeated at 24 months. Hospital stay, cost, operating time, blood loss, complications, and patient-related functional outcomes were measured. RESULTS: Of 43 enrolled, 38 completed a minimum of 2-year follow-up (average: 43 months; range: 24-108 months). Eighteen received a posterior spine fusion and 20 an anterior approach. Hospital stay and operating time were similar. Blood loss was higher in the group treated anteriorly; however, the incidence of transfusion was the same. There were 17 "complications" including instrumentation removal for pain in 18 patients treated posteriorly, but only 3 minor complications in 3 patients treated anteriorly. Patient-related functional outcomes were similar for the two groups. CONCLUSIONS: Although patient outcomes are similar, anterior fusion and instrumentation for thoracolumbar burst fractures may present fewer complications or additional surgeries.

Adolescent↗
PubMed2003

How to select optimal maintenance intravenous fluid therapy.

Hyponatraemia is the commonest electrolyte abnormality in hospitalized patients. If the plasma sodium concentration (P(Na)) declines to approximately 120 mM in <48 h, brain cell swelling might result in herniation, with devastating consequences. The volume and/or the composition of fluids used for intravenous therapy often contribute to the development of acute hyponatraemia. Our hypothesis is that the traditional calculation of the daily loss of insensible water overestimates this parameter, leading to an excessive daily recommended requirement for water. We offer suggestions to minimize the risk of iatrogenic hyponatraemia.

Body Water↗
PubMed2003

Importance of timing of risk factors for cerebral oedema during therapy for diabetic ketoacidosis.

Cerebral oedema is the most common cause of mortality and morbidity during the first day of conventional treatment for diabetic ketoacidosis in paediatric patients. It is possible that therapy contributes to its development. Risk factors that predispose to cerebral oedema should lead to an expansion of the intracellular and/or the extracellular fluid compartment(s) of the brain because water normally accounts for close to 80% of brain weight. With respect to the intracellular fluid compartment, the driving force to cause cell swelling is a gain of effective osmoles in brain cells and/or a significant decline in the effective osmolality of the extracellular fluid compartment. Factors leading to an expansion of the intracerebral extracellular fluid volume can be predicted from Starling forces acting at the blood-brain barrier. Some of these risk factors have an early impact, while others have their major effects later during therapy for diabetic ketoacidosis. Based on a theoretical analysis, suggestions to modify current therapy for diabetic ketoacidosis in children are provided.

Adolescent↗
PubMed2001

Tonicity balance, and not electrolyte-free water calculations, more accurately guides therapy for acute changes in natremia.

The usual way to decide why hyponatremia or hypernatremia has developed and to plan goals for its therapy is to analyze events in electrolyte-free water (EFW) terms. We shall demonstrate that an EFW balance does not supply this information. Rather, one must calculate mass balances for water and sodium plus potassium separately (a tonicity balance) to understand the basis for the change in natremia and the proper goals for its therapy. These points are illustrated with a clinical example.

Adolescent↗
PubMed2001

Lung salvage and protection ventilatory techniques.

Physicians are in the beginning of an era in intensive care medicine in which they finally are starting to see improved outcomes in patients with AHRF. At the same time, intensivists are presented with a bewildering choice of ventilator options and adjunctive therapies. Trying to sort out which are "cosmetic," that is, improve the blood gases as opposed to influencing the outcome, remains a challenge and will be resolved only with additional RCTs. Principles of ventilator management that are driven by mimicking normal physiology are inappropriate and must be rethought.

Extracorporeal Membrane Oxygenation↗
PubMed2001

The history of high-frequency ventilation.

High-frequency ventilation was first introduced 30 years ago as a method for reducing intrathoracic pressure during thoracic and laryngeal surgery. High-frequency oscillation was developed in the 1970's for the treatment of lung disease of prematurity but is now used for acute hypoxemic respiratory failure in all ages. High-frequency jet ventilation is still most commonly used as a rescue therapy.

Animals↗
PubMed2001

Use of hypertonic saline in the treatment of cerebral edema in diabetic ketoacidosis (DKA).

Cerebral edema is the primary cause of morbidity and mortality in children and adolescents with diabetic ketoacidosis (DKA). We report a case of an adolescent female with life-threatening DKA-related cerebral edema who responded to a combination of mannitol and hypertonic saline. This is the first report of the use of hypertonic saline in the treatment of cerebral edema due to DKA.

Journal Article↗
PubMed2001

Acute asthma.

OBJECTIVE: Asthma is the most common medical emergency in children. It is associated with significant morbidity and mortality rates and poses a tremendous societal burden worldwide. Management of the acute attack involves a stepwise approach that includes beta-agonist and steroid therapy, the mainstay of emergency treatment. Most patients will respond to this regime and can be discharged from the emergency department. Failure to respond to treatment necessitates hospital admission and sometimes admission to the intensive care unit (ICU). Management in the ICU involves intensification of pharmacologic therapy, including nonstandard therapies, in an attempt to avoid intubation and ventilation. When needed, mechanical ventilatory support can be rendered fairly safe with little morbidity if the likely cardiorespiratory physiologic derangements are appreciated and if appropriate ventilatory strategies are used. In the past two decades, the availability of newer potent medications and changes in approach to monitoring and ventilatory strategies have resulted in a decrease in ICU morbidity and mortality rates. Research endeavors are presently underway to further characterize the underlying mechanisms of the disease and are likely to lead to novel therapies. This article reviews the approach to management of acute severe asthma.

Journal Article↗
PubMed2001

A method to estimate urinary electrolyte excretion in patients at risk for developing cerebral salt wasting.

OBJECT: Two major criteria are necessary to diagnose cerebral salt wasting (CSW): a cerebral lesion and a large urinary excretion of Na+ and Cl- at a time when the extracellular fluid (ECF) volume is contracted. Nevertheless, it is difficult for the physician to confirm from bedside observation that a patient has a contracted ECF volume. Hyponatremia, although frequently present, should not be a criterion for a diagnosis of salt wasting. A contracted ECF volume is unlikely if there are positive balances of Na+ and Cl-. The goal of this study was to assess the accuracy of calculating balances for Na+ plus K+ and of Cl- over 1 to 10 days in an intensive care unit (ICU) setting. METHODS: A prospective comparison of measured and estimated quantities of Na+ plus K+ and of Cl- excreted over 1 to 10 days in 10 children and 12 adults who had recently received a traumatic brain injury or undergone recent neurosurgery. Plasma concentrations of electrolytes were recorded at the beginning and end of the study period. The total volumes infused and excreted and the concentrations of Na+, K+, and Cl- in the infusate were obtained from each patient's ICU chart. The electrolytes in the patients' urine were measured and calculated. Correlations between measured and calculated values for excretions of Cl- and of Na+ plus K+ were excellent. CONCLUSIONS: Mass balances for Na+ plus K+ and for Cl- can be accurately estimated. These data provide information to support or refute a clinical diagnosis of CSW. The danger of relying on balances for these electrolytes measured within a single day to diagnose CSW is illustrated.

Adolescent↗
PubMed2001

Extracorporeal life support in heart and lung transplantation.

Extracorporeal life support is a technology that is being increasingly used to support children with cardiac and respiratory failure who fail conventional measures. Both extracorporeal membrane oxygenation and ventricular assist devices have been used in cardiac failure with the opportunity to support patients who fail repair of congenital heart disease and in primary myocardial disease. Outcomes in the latter are superior to the surgical patients which has lead to increasing use of extracorporeal life support as a bridge to transplantation. Experience with membrane oxygenation as a support mode after lung transplantation is limited to adult series with similar outcomes.

Catheterization↗
PubMed2000

Inhaled nitric oxide for acute hypoxemic respiratory failure in children and adults.

OBJECTIVES: To determine the effect of iNO, compared with inhaled placebo, on outcome in AHRF in children and/or adults. SEARCH STRATEGY: Randomised controlled trials (RCT's) were identified from electronic databases; MEDLINE, EMBASE, the Cochrane Library, and CINAHL, as well as from bibliographies of retrieved articles. Relevant journals and conference proceedings were hand searched and authors published in this field were contacted for knowledge of unpublished ongoing trials. SELECTION CRITERIA: RCT's comparing iNO with maximal conventional therapy and inhaled placebo, for AHRF in either children or adults. DATA COLLECTION AND ANALYSIS: Data were extracted and the analyses performed independently by two reviewers. All 5 authors were contacted for missing data. Qualitative assessment of each trial was made according to methodology described by Schulz (Schulz 1995), and analyses according to statistical methods in Review Manager MetaView 3.1. The fixed effect model was applied. Where possible, sub-group analyses were performed to assess the impact of iNO in varied doses. MAIN RESULTS: Five RCT's were evaluated, assessing 535 patients with AHRF. Inhaled nitric oxide made no impact on mortality in trials without cross-over (RR 0.98, 95%CI 0.66, 1.44), or with cross-over of treatment failures to open-label iNO (RR 1.22, 95%CI 0.65, 2.29). Published evidence from one study demonstrated that iNO resulted in a transient improvement in oxygenation in the first 24 hours of treatment: the oxygenation index (OI) showed a mean difference of -3 [95% CI -5.354, -0.646], and PaO2/FiO2 ratio, a mean difference of 35 [95% CI 20.236, 49.764]. Limited data demonstrated no difference in ventilator-free days between treatment and placebo groups, and no specific dose of iNO was significantly advantageous over another. Other clinical indicators of effectiveness, such as duration of hospital and intensive care stay, were inconsistently reported. There were no complications reported to be directly attributable to this treatment. REVIEWER'S CONCLUSIONS: From the data provided to date, iNO had no effect on mortality and only transiently improved oxygenation in AHRF in children and/or adults. There was a lack of data to assess other end points. The long term adverse effects of this drug are not known, as no long term follow-up of trial participants has been reported. If further trials comparing iNO with an inhaled placebo are to proceed, they should be stratified for primary disease and must specifically evaluate clinically relevant outcomes, before any benefit of iNO in AHRF can be excluded.

Acute Disease↗
PubMed2000

Treatment of acute hyponatremia: ensuring the excretion of a predictable amount of electrolyte-free water.

BACKGROUND: Hypertonic saline is the recommended therapy to shrink swollen brain cells in patients with acute hyponatremia accompanied by seizures. OBJECTIVES: In the absence of hypertonic saline, hypertonic mannitol will shrink the cell volume. Because mannitol is excreted rapidly, our aim was to ensure that it would be excreted with electrolyte-free water (EFW) and to evaluate the renal mechanisms responsible for EFW excretion. DESIGN: A randomized, prospective, placebo-controlled study in rats was carried out in a research laboratory. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: The control group of rats (n = 6) was administered hypotonic saline, a loop diuretic, vasopressin, and glucose by the intraperitoneal route; in the experimental group (n = 6), glucose was replaced with mannitol. Plasma electrolytes were measured at 0 and 210 mins, and balances for water, sodium, and potassium were obtained from 0 to 90 mins and from 90 to 210 mins. MEASUREMENTS AND MAIN RESULTS: Virtually 100% of the administered mannitol was excreted within 210 mins, and half was excreted in the first 90 mins. The urine contained EFW only in the mannitol group because of a larger volume in the first 90 mins (EFW, 3.7 mL) and to a lower excretion of NaCl in the next 120 mins (EFW, 3.5 mL). CONCLUSIONS: The combined use of mannitol and a loop diuretic caused the excretion of a predictable volume of EFW because the urine was iso-osmotic to plasma and contained all the administered mannitol. The calculated decrease in intracellular fluid volume was equivalent when mannitol was retained or excreted.

Acute Disease↗
PubMed2000

Comparison of hyperventilation and inhaled nitric oxide for pulmonary hypertension after repair of congenital heart disease.

BACKGROUND: Pulmonary hypertension is associated with congenital heart lesions with increased pulmonary blood flow. Acute increases in pulmonary vascular resistance (PVR) occur in the postoperative period after repair of these defects. These increases in PVR can be ablated by inducing an alkalosis with hyperventilation (HV) or bicarbonate therapy. Studies have shown that these patients also respond to inhaled nitric oxide (iNO), but uncertainty exists over the relative merits and undesirable effects of HV and iNO. HYPOTHESIS: Alkalosis and iNO are equally effective in reducing PVR and pulmonary artery pressure (PAP) in children with pulmonary hypertension after open heart surgery. SETTING: Critical care unit of a tertiary care pediatric hospital. DESIGN: Prospective, randomized, crossover design. PATIENTS: Twelve children with a mean PAP > 25 mm Hg at normal pH after biventricular repair of congenital heart disease. INTERVENTIONS: Patients were assigned to receive iNO or HV (pH > 7.5) in random order, and the effect on hemodynamics was measured. Each treatment was administered for 30 mins with a 30-min washout period between treatments. Finally, both treatments were administered together to look for a possible additive effect. MEASUREMENTS AND MAIN RESULTS: Cardiac output and derived hemodynamic parameters using the dye dilution technique. Hyperventilation, achieved by an increase in ventilator rate without a change in mean airway pressure, decreased Pa(CO2) from a mean (SD) of 43.7+/-5.3 to 32.3+/-5.4 mm Hg and increased pH from 7.40+/-0.04 to 7.50+/-0.03. This significantly altered both pulmonary and systemic hemodynamics with a reduction in PAP, PVR, central venous pressure, and cardiac output and an increase in systemic vascular resistance. In comparison, iNO selectively reduced PAP and PVR only. The reduction in PVR was comparable between treatments, although addition of iNO to HV resulted in a small additional reduction in PVR. An additional decrease in PAP was seen when HV was added to iNO, attributable to a reduction in cardiac output rather than a further decrease in PVR. CONCLUSIONS: Inhaled NO and HV are both effective at lowering PAP and PVR in children with pulmonary hypertension after repair of congenital heart disease. The selective action of iNO on the pulmonary circulation offers advantages over HV because a decrease in cardiac output and an increase in SVR are undesirable in the postoperative period.

Administration, Inhalation↗