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Biomedical subjects

N B Hampson

Publications and source records attributed to N B Hampson.

At least 19 recordsLinked to original sources
PubMed2003

Hyperbaric oxygen treatment protocols for mandibular osteoradionecrosis.

To determine hyperbaric oxygen (HBO2) treatment practices for osteoradionecrosis (ORN) of the mandible in North America, we surveyed hyperbaric facilities listed in the 1998 UHMS Chamber Directory. A survey response rate of 99.7% was achieved. Among the 316 facilities listed, 280 treat or would treat mandibular ORN with HBO2. Twelve different hyperbaric treatment protocols for the condition were reported. Approximately three-quarters of facilities utilize a protocol administering 90 minutes of 100% oxygen breathing at a treatment pressure of 2.4-2.5 atmospheres absolute (atm abs). The remaining one-quarter of facilities apply alternate hyperbaric treatment protocols. In summary, mandibular ORN is commonly treated at North American hyperbaric facilities but there is a lack of uniformity with regard to the protocol utilized for hyperbaric oxygen administration. There are no clinical data to support that any one treatment protocol is superior in out come to any other.

Clinical Protocols↗
PubMed2002

A systematic review of the literature reporting the application of hyperbaric oxygen prevention and treatment of delayed radiation injuries: an evidence based approach.

The treatment of delayed radiation injuries (soft tissue and bony radiation necrosis) is one of thirteen conditions approved by the Hyperbaric Oxygen Therapy Committee of the Undersea and Hyperbaric Medical Society as appropriate indications for hyperbaric oxygen (HBO2). This paper provides a systematic review of the literature reporting the results of HBO2 therapy in the treatment and/or prophylaxis of delayed radiation injury. Since the introduction of the concept of evidence based medicine, the medical community in general has set out to apply more critical and stringent standards in evaluating published support for therapeutic interventions. Evidence based medicine is designed to discover the best evidence available and apply it in daily practice for treatment of the individual patient. The preferred level of evidence is the randomized controlled trial, however, other evidence has merit as well. In this review, seventy-four publications are represented reporting results of applying HBO2 in the treatment or prevention of radiation injuries. These are appraised in an evidence-based fashion by applying three established systems of evaluation. All but seven of these publications report a positive result when HBO2 is delivered as treatment for or prevention of delayed radiation injury. These results are particularly impressive in the context of alternative interventions. Without HBO2, treatment often requires radical surgical intervention, which is likely to result in complications. Other alternatives including drug therapies are rarely reported, and for the most part have not been the subject of randomized controlled trials. Based on this review, HBO2 is recommended for delayed radiation injuries for soft tissue and bony injuries of most sites. Of note, an increasing body of evidence supports HBO2 for radiation-induced necrosis of the brain. For other radiation-induced neurological injuries, additional study is required before recommendations for routine hyperbaric therapy can be made.

Breast Diseases↗
PubMed2002

Diving methods and decompression sickness incidence of Miskito Indian underwater harvesters.

Diving conditions, dive profiles, and symptoms of decompression sickness (DCS) in a group of Miskito Indian underwater seafood harvesters are described. Dive profiles for 5 divers were recorded with dive computers, and DCS symptoms were assessed by neurological examination and interview. Divers averaged 10 dives a day over a 7-day period with a mean depth of 67 +/- 7 FSW (306 +/- 123 kPa) and average in-water time of 20.6 +/- 6.3 minutes. Limb pain was reported on 10 occasions during 35 man-days of diving. Symptoms were typically managed with analgesic medication rather than recompression. Indices of the decompression stress were estimated from the recorded profiles using a probabilistic model. We conclude that the dives were outside the limits of standard air decompression tables and that DCS symptoms were common. The high frequency of limb pain suggests the potential for dysbaric bone necrosis for these divers.

Adult↗
PubMed2001

Outcome of patients experiencing cardiac arrest with carbon monoxide poisoning treated with hyperbaric oxygen.

STUDY OBJECTIVE: We sought to examine the outcome of a subgroup of patients with extreme carbon monoxide (CO) poisoning, specifically those discovered in cardiac arrest, resuscitated, and subsequently treated with hyperbaric oxygen (HBO(2)). Opinions of hyperbaric medicine physicians regarding the treatment of such patients were also sought. METHODS: Records of patients treated with HBO(2) for acute CO poisoning at Virginia Mason Medical Center in Seattle from September 1987 to August 2000 were reviewed. Those who were resuscitated from cardiac arrest in the field before HBO(2) treatment were selected for detailed analysis. Patient demographic data and information regarding circumstances of the poisoning, resuscitation, HBO(2) treatment, and subsequent course were extracted and collated. In addition, a postal survey of medical directors of North American HBO(2) treatment facilities regarding opinions about the management and outcome of such patients was performed. RESULTS: A total of 18 patients were treated with HBO(2) after resuscitation from CO-associated cardiac arrest. They included 10 female and 8 male patients ranging in age from 3 to 72 years. Sources of CO included house fires (10 patients) and automobile exhaust (8 patients). Patient carboxyhemoglobin levels averaged 31.7%+/-11.0% (mean+/-SD), and arterial pH averaged 7.14+/-0.19. Presenting cardiac rhythm was a bradydysrhythmia in 10 of 18 patients. HBO(2) treatment was administered an average of 4.3 hours after poisoning (< or = 3 hours in 10 patients and < or = 6 hours in 15 patients). Despite this, all 18 patients died during their hospitalizations. Medical directors of hyperbaric treatment facilities estimated a 74% likelihood of survival for a hypothetical patient with this presentation. CONCLUSION: In this consecutive case series, cardiac arrest complicating CO poisoning was uniformly fatal, despite administration of HBO(2) therapy after initial resuscitation. Survey results suggest that physician education regarding this subset of CO-poisoned patients is needed. The prognosis of this condition should be considered when making triage and treatment decisions for patients poisoned to this severity.

Acute Disease↗
PubMed2001

Carbon monoxide poisoning: interpretation of randomized clinical trials and unresolved treatment issues.

Since hyperbaric oxygen therapy (HBO2) appeared as a treatment for CO poisoning in 1960, whether and when to use it for CO poisoning have often been debated. HBO2 has been advocated to treat severe CO poisoning to limit delayed and permanent neurologic sequelae. Initially, inferences about efficacy were based on clinical experience and uncontrolled studies, but since1989, six prospective clinical trials have been reported comparing HBO2 and normobaric O2 administration to treat patients with acute CO poisoning. Of the six trials, four found better clinical outcomes among patients receiving HBO2 while two have shown no treatment effect. The most recent and best-designed randomized controlled clinical trial, performed in Salt Lake City, supports the efficacy of HBO2 in severe acute CO poisoning in accordance with scientific rationale and clinical experience. However, a number of important issues remain for future investigation, which could be addressed in a large multi-center trial. Such a trial should attempt to determine the optimal number of HBO2 treatments and the maximum treatment delay from CO poisoning for HBO2 to provide efficacy in patients with specific risk factors for a poor outcome.

Carbon Monoxide Poisoning↗
PubMed2000

Carbon monoxide poisoning--a public health perspective.

Carbon monoxide (CO) may be the cause of more than one-half of the fatal poisonings reported in many countries; fatal cases also are grossly under-reported or misdiagnosed by medical professionals. Therefore, the precise number of individuals who have suffered from CO intoxication is not known. The health effects associated with exposure to CO range from the more subtle cardiovascular and neurobehavioral effects at low concentrations to unconsciousness and death after acute or chronic exposure to higher concentrations of CO. The morbidity and mortality resulting from the latter exposures are described briefly to complete the picture of CO exposure in present-day society. The symptoms, signs, and prognosis of acute CO poisoning correlate poorly with the level of carboxyhemoglobin (COHb) measured at the time of hospital admission; however, because CO poisoning is a diagnosis frequently overlooked, the importance of measuring COHb in suspicious settings cannot be overstated. The early symptoms (headache, dizziness, weakness, nausea, confusion, disorientation, and visual disturbances) also have to be emphasized, especially if they recur with a regular periodicity or in the same environment. Complications occur frequently in CO poisoning. Immediate death is most likely cardiac in origin because myocardial tissues are most sensitive to the hypoxic effects of CO. Severe poisoning results in marked hypotension, lethal arrhythmias, and electrocardiographic changes. Pulmonary edema may occur. Neurological manifestation of acute CO poisoning includes disorientation, confusion, and coma. Perhaps the most insidious effect of CO poisoning is the development of delayed neuropsychiatric impairment within 2-28 days after poisoning and the slow resolution of neurobehavioral consequences. Carbon monoxide poisoning during pregnancy results in high risk for the mother by increasing the short-term complication rate and for the fetus by causing fetal death, developmental disorders, and chronic cerebral lesions. In conclusion, CO poisoning occurs frequently; has severe consequences, including immediate death; involves complications and late sequelae; and often is overlooked. Efforts in prevention and in public and medical education should be encouraged.

Carbon Monoxide Poisoning↗
PubMed2000

Effects of weather on incidence of attempted suicide by carbon monoxide poisoning.

Depressive illness and related suicide attempts have been reported to have seasonal variation, possibly related to weather. This study sought to determine the effects of weather and time of year on suicide attempts by carbon monoxide (CO) poisoning. Cases of patients in western Washington State attempting suicide by CO poisoning and referred to a regional hyperbaric oxygen treatment center from 1981-1995 were reviewed retrospectively. Information from the National Climatic Data Center was used to compare date of treatment to local weather data on the day of attempted suicide and on each day of the preceding week. The study population consisted of 264 patients attempting suicide by CO poisoning on 251 days of the 15-yr period. Mean and total precipitation in the preceding 7 days strongly correlated with attempted suicide rate, with incident rate ratios ranging from 1.75 to 2.77 and 1.14 to 1.75, respectively (P values <0.05). A decrease in minimum daily temperature also correlated with attempted suicide rate. No other weather variables showed significant correlation with dates of CO suicide attempts. February, March, and October were seen to be separate factors related to a higher incidence of attempted suicide by CO poisoning. Precipitation in Seattle, change in minimum temperature, and month of the year correlated with the regional incidence of suicide attempts with CO poisoning.

Carbon Monoxide Poisoning↗
PubMed1998

Delivery of hyperbaric oxygen therapy to critically ill, mechanically ventilated children.

PURPOSE: The purpose of this article is (1) to describe our method of mechanical ventilation and monitoring of critically ill children during administration of hyperbaric oxygen therapy (HBO2) in a multiplace chamber; and (2) to review the complications they experienced during transport to the HBO2 chamber and HBO2 treatment. MATERIALS AND METHODS: A case series from a university-affiliated children's hospital and regional hyperbaric medicine treatment facility. Patients studied included all children who required HBO2 therapy while mechanically ventilated at any time between April 1985 and June 1995. RESULTS: Thirty-two children were treated with HBO2 while mechanically ventilated. Ages ranged from 3 days to 11.3 years (mean 4.8+/-3.5 years). There were 22 males. Twenty-one children had necrotizing infections, 9 had carbon monoxide (CO) poisoning, and 2 had iatrogenic arterial air embolism. Complications or events occurring during HBO2 therapy included hypotension (63%), bronchospasm (34%), hemotympanum (13%), and progressive hypoxemia (6%). The only complication during transport was one accidental extubation (3%). CONCLUSION: Hyperbaric oxygen therapy can be administered safely to most critically ill children in a multiplace chamber if they are monitored closely. Although complications are not uncommon, most can be managed easily by a team skilled in treating ill children and knowledgeable of possible complications of HBO2 therapy.

Child↗
PubMed1998

Pulse oximetry in severe carbon monoxide poisoning.

STUDY OBJECTIVES: To evaluate the accuracy and quantitate the error of pulse oximetry measurements of arterial oxygenation in patients with severe carbon monoxide (CO) poisoning. DESIGN: Retrospective review of patient clinical records. SETTING: Regional referral center for hyperbaric oxygen therapy. PATIENTS: Thirty patients referred for treatment of acute severe CO poisoning who demonstrated carboxyhemoglobin (COHb) levels >25%, with simultaneous determinations of arterial hemoglobin oxygen saturation by pulse oximetry (SpO2) and arterial blood gas (ABG) techniques. MEASUREMENTS AND RESULTS: COHb levels and measurements of arterial oxygenation from pulse oximetry, ABG analysis, and laboratory CO oximetry were compared. SpO2 did not correlate with COHb levels. SpO2 consistently overestimated the fractional arterial oxygen saturation. The difference between arterial hemoglobin oxygen saturation (SaO2) calculated from ABG analysis and SpO2 increased with increasing COHb level. CONCLUSIONS: Presently available pulse oximeters overestimate arterial oxygenation in patients with severe CO poisoning. An elevated COHb level falsely elevates the SaO2 measurements from pulse oximetry, usually by an amount less than the COHb level, confirming a prior observation in an animal model. Accurate assessment of arterial oxygen content in patients with CO poisoning can currently be performed only by analysis of arterial blood with a laboratory CO-oximetry.

Adult↗
PubMed1997

Clinical aspects of pulmonary embolism.

Pulmonary embolism is a common disease in the United States, affecting as many as 500,000 persons annually. Unfortunately, this disorder is commonly undiagnosed, resulting in significant excess morbidity and mortality. The clinical symptoms and signs caused by pulmonary embolism are nonspecific and may be confused with a variety of other cardiopulmonary disorders having similar presentations. However, accurate diagnostic tests are available for diagnosing pulmonary embolism, even in the face of coexistent cardiopulmonary disorders. This article describes the clinical characteristics of pulmonary venous thromboembolism, reviewing its typical symptoms and signs, its routine laboratory tests, and chest radiographic abnormalities.

Acute Disease↗
PubMed1997

The diagnosis of ventilator-associated pneumonia: a comparison of histologic, microbiologic, and clinical criteria.

STUDY OBJECTIVE: To evaluate histologic, microbiological, and clinical criteria in the recognition of ventilator-associated pneumonia (VAP) in patients who died while mechanically ventilated. METHODS: The study group consisted of 39 patients who died after a mean of 14 days of mechanical ventilation. Postmortem fiberoptic bronchoscopy (FOB) and open lung biopsy were performed with collection of specimens initiated <1 h after death. The microbiological specimens included suction catheter aspirate of tracheal secretions, FOB-guided protected specimen brush (PSB) of tracheal secretions, blindly placed PSB in a distal airway, FOB-guided PSB in a distal airway, and FOB-guided BAL fluid (BALF) in a distal airway. Qualitative bacteriologic study was performed on all specimens, and quantitative bacteriologic study was performed on all but the suction catheter aspirate of the trachea. A biopsy specimen of peripheral lung parenchyma from the same region sampled by FOB was sent for quantitative culture and histologic analysis. The BALF was analyzed for cell population and percent of neutrophils containing intracellular organisms. The clinical criteria selected for comparison with histologic and microbiological results included a temperature > or =38.5 degrees C during the 48 h prior to death, a WBC count > or =15,000/mm3 in the 48 h prior to death, presence of a bacterial or fungal pathogen on the last sputum culture, radiographic worsening in the week prior to death, and worsening gas exchange defined as a 15% decrease in the PaO2/fraction of inspired oxygen ratio in the 72 h prior to death. RESULTS: None of the quantitative cultures had a reliable positive predictive value for histologic pneumonia. None of the five clinical criteria tested showed agreement with the presence or absence of histologic pneumonia. There was a significant correlation between qualitative and quantitative microbiological results from the distal airway/FOB-guided PSB, distal airway/BALF, and quantitative culture of the lung parenchyma. Also, suction catheter aspirate of the trachea had a sensitivity of 87% in recognizing the bacterial species simultaneously present in lung parenchyma. None of the patients with histologic pneumonia had <50% neutrophils in the BALF. CONCLUSIONS: Neither the bacterial, density from the four airway quantitative cultures, nor the bacterial density from quantitative culture of lung parenchyma accurately separated the histologic pneumonia and nonpneumonia groups. No clinical criteria or combination of clinical criteria correlated with the presence or absence of histologic pneumonia. A BALF with <50% neutrophils had a 100% negative predictive value for histologic pneumonia. A BALF quantitative culture had a sensitivity of 63%, specificity of 96%, and positive predictive value of 91% in recognizing sterile lung parenchyma. Thus, BALF may have a role in excluding pneumonia/infection in the ventilated patient. Antibiotic choice for the empiric therapy of VAP can be accurately guided by the microbial population recognized through culture of a tracheal suction catheter aspirate.

Aged↗
PubMed1997

Pulmonary edema of scuba divers.

A syndrome of acute pulmonary edema has been previously reported among scuba divers in cold, European waters. Because of the temperatures involved, the name "cold-induced pulmonary edema" was coined in the original 1989 description. We report six individuals who developed the identical syndrome, five while diving in Puget Sound and one in the Gulf of Mexico. The four women and two men ranged in age from 24 to 60 yr. They experienced one to six episodes apiece, each with the development severe dyspnea at depth without excessive exertion. Associated symptoms included cough, weakness, expectoration of froth, chest discomfort, orthopnea, wheezing, hemoptysis, and dizziness. Emergency medical evaluation of four divers revealed rales on examination and pulmonary edema on chest radiograph. In one diver with pulmonary edema on chest radiograph, pulmonary capillary wedge pressure was normal when measured acutely. Symptoms resolved either spontaneously over 1-2 days or with standard medial treatment for pulmonary edema. Prior history of cardiovascular disease was negative except for hypertension and mitral valve prolapse in one diver. Cardiac evaluations following recovery from the acute episodes were normal. Episodes in the cold waters of Puget Sound sometimes occurred despite the use of dry suits. Furthermore, one diver developed recurrent episodes in 27 degrees C water off Cozumel, Mexico. Development of pulmonary edema while scuba diving constitutes a distinct clinical entity which may occur in either "cold" or "warm" water. It is not associated with a decompression mechanism. Personnel caring for divers should be aware of the syndrome in order to provide optimal medical management.

Adult↗