STUDY OBJECTIVES: Pulmonary barotrauma (PBT) of ascent is a feared complication in compressed air diving. Although certain respiratory conditions are thought to increase the risk of suffering PBT and thus should preclude diving, in most cases of PBT, risk factors are described as not being present. The purpose of our study was to evaluate factors that possibly cause PBT. DESIGN: We analyzed 15 consecutive cases of PBT with respect to dive factors, clinical and radiologic features, and lung function. They were compared with 15 cases of decompression sickness without PBT, which appeared in the same period. RESULTS: Clinical features of PBT were arterial gas embolism (n = 13), mediastinal emphysema (n = 1), and pneumothorax (n = 1). CT of the chest (performed in 12 cases) revealed subpleural emphysematous blebs in 5 cases that were not detected in preinjury and postinjury chest radiographs. A comparison of predive lung function between groups showed significantly lower midexpiratory flow rates at 50% and 25% of vital capacity in PBT patients (p < 0.05 and p < 0.02, respectively). CONCLUSIONS: These results indicate that divers with preexisting small lung cysts and/or end-expiratory flow limitation may be at risk of PBT. (+info)
Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. The Acute Respiratory Distress Syndrome Network.
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BACKGROUND: Traditional approaches to mechanical ventilation use tidal volumes of 10 to 15 ml per kilogram of body weight and may cause stretch-induced lung injury in patients with acute lung injury and the acute respiratory distress syndrome. We therefore conducted a trial to determine whether ventilation with lower tidal volumes would improve the clinical outcomes in these patients. METHODS: Patients with acute lung injury and the acute respiratory distress syndrome were enrolled in a multicenter, randomized trial. The trial compared traditional ventilation treatment, which involved an initial tidal volume of 12 ml per kilogram of predicted body weight and an airway pressure measured after a 0.5-second pause at the end of inspiration (plateau pressure) of 50 cm of water or less, with ventilation with a lower tidal volume, which involved an initial tidal volume of 6 ml per kilogram of predicted body weight and a plateau pressure of 30 cm of water or less. The primary outcomes were death before a patient was discharged home and was breathing without assistance and the number of days without ventilator use from day 1 to day 28. RESULTS: The trial was stopped after the enrollment of 861 patients because mortality was lower in the group treated with lower tidal volumes than in the group treated with traditional tidal volumes (31.0 percent vs. 39.8 percent, P=0.007), and the number of days without ventilator use during the first 28 days after randomization was greater in this group (mean [+/-SD], 12+/-11 vs. 10+/-11; P=0.007). The mean tidal volumes on days 1 to 3 were 6.2+/-0.8 and 11.8+/-0.8 ml per kilogram of predicted body weight (P<0.001), respectively, and the mean plateau pressures were 25+/-6 and 33+/-8 cm of water (P<0.001), respectively. CONCLUSIONS: In patients with acute lung injury and the acute respiratory distress syndrome, mechanical ventilation with a lower tidal volume than is traditionally used results in decreased mortality and increases the number of days without ventilator use. (+info)
An approach to ventilation in acute respiratory distress syndrome.
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Appropriate management of patients with acute respiratory distress syndrome (ARDS) represents a challenge for physicians working in the critical care environment. Significant advances have been made in understanding the pathophysiology of ARDS. There is also an increasing appreciation of the role of ventilator-induced lung injury (VILI). VILI is most likely related to several different aspects of ventilator management: barotrauma due to high peak airway pressures, lung overdistension or volutrauma due to high transpulmonary pressures, alveolar membrane damage due to insufficient positive end expiratory pressure levels and oxygen-related cell toxicity. Various lung protective strategies have been suggested to minimize the damage caused by conventional modes of ventilation. These include the use of pressure- and volume-limited ventilation, the use of the prone position in the management of ARDS, and extracorporeal methods of oxygen delivery and carbon dioxide removal. Although the death rate resulting from ARDS has been declining over the past 10 years, there is no evidence that any specific treatment or change in approach to ventilation is the cause of this improved survival. (+info)
Acute confusion secondary to pneumocephalus in an elderly patient.
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PRESENTATION: an 83-year-old man was admitted to hospital with acute confusion 3 days after a direct flight from Australia. OUTCOME: computed tomography (CT) brain scan and magnetic resonance imaging head scan revealed the cause to be pneumocephalus, apparently the result of barotrauma caused by Valsalva manoeuvres when he attempted to unblock his nose during the flight. After 5 days of nursing in the vertical position the patient's Abbreviated Mental Score returned to normal. A CT brain scan 6 weeks later showed complete resolution of the pneumocephalus. (+info)
Neurologic complications of scuba diving.
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Recreational scuba diving has become a popular sport in the United States, with almost 9 million certified divers. When severe diving injury occurs, the nervous system is frequently involved. In dive-related barotrauma, compressed or expanding gas within the ears, sinuses and lungs causes various forms of neurologic injury. Otic barotrauma often induces pain, vertigo and hearing loss. In pulmonary barotrauma of ascent, lung damage can precipitate arterial gas embolism, causing blockage of cerebral blood vessels and alterations of consciousness, seizures and focal neurologic deficits. In patients with decompression sickness, the vestibular system, spinal cord and brain are affected by the formation of nitrogen bubbles. Common signs and symptoms include vertigo, thoracic myelopathy with leg weakness, confusion, headache and hemiparesis. Other diving-related neurologic complications include headache and oxygen toxicity. (+info)
Cancer mortality after nasopharyngeal radium irradiation in the Netherlands: a cohort study.
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BACKGROUND: Nasopharyngeal radium irradiation (NRI) was used widely from 1940 through 1970 to treat otitis serosa in children and barotrauma in airmen and submariners. We assessed whether NRI-exposed individuals were at higher risk for cancer-related deaths than were nonexposed individuals. METHODS: We conducted a retrospective cohort study of all-cause and cancer-related mortality in 5358 NRI-exposed subjects and in 5265 frequency-matched nonexposed subjects, who as children were treated at nine ear, nose, and throat clinics in The Netherlands from 1945 through 1981. We recorded personal and medical data from original patient medical records and assessed vital status through follow-up at municipal population registries. Risk of mortality was evaluated by standardized mortality ratios (SMRs). All statistical tests were two-sided. RESULTS: The average radiation doses were 275, 10.9, 1.8, and 1.5 cGy for the nasopharynx, pituitary, brain, and thyroid, respectively. The median follow-up was 31.6 years. Three hundred two NRI-exposed subjects had died, with 269.2 deaths expected (SMR = 1.1; 95% confidence interval [CI] = 1.0 to 1.3); among nonexposed subjects, 315 died, with 283.5 deaths expected (SMR = 1.1; 95% CI = 0.99 to 1.2). Cancer-related deaths of 96 exposed subjects (SMR = 1.2; 95% CI = 0.95 to 1.4) and 87 nonexposed subjects (SMR = 1.0; 95% CI = 0.8 to 1.3) were documented. There were no excess deaths from cancers of the head and neck area among exposed subjects. However, there were excess deaths from cancers of lymphoproliferative and hematopoietic origin (SMR = 1.9; 95% CI = 1.1 to 3.0), mainly from non-Hodgkin's lymphoma (SMR = 2.6; 95% CI = 1.0 to 5.3). We found no evidence that breast cancer deaths were less than expected (SMR = 1.7; 95% CI = 0.9 to 2.8) in contrast to an earlier study. CONCLUSIONS: Our findings do not indicate an increased cancer mortality risk in a population exposed to NRI in childhood. More prolonged follow-up of this and other NRI cohorts is recommended. (+info)
Proportional assist ventilation (PAV): a significant advance or a futile struggle between logic and practice?
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Proportional assist ventilation is a promising addition to other more conventional modes of mechanical ventilation with the theoretical advantage of improving patient-ventilator interaction. It may also be of use as a diagnostic tool in the control of breathing in mechanically ventilated patients. (+info)
Continuous left hemidiaphragm sign revisited: a case of spontaneous pneumopericardium and literature review.
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In pneumopericardium, a rare but potentially life threatening differential diagnosis of chest pain with a broad variety of causes, rapid diagnosis and adequate treatment are crucial. In upright posteroanterior chest radiography, the apical limit of a radiolucent rim, outlining both the left ventricle and the right atrium, lies at the level of the pulmonary artery and ascending aorta, reflecting the anatomical limits of the pericardium. The band of gas surrounding the heart may outline the normally invisible parts of the diaphragm, producing the continuous left hemidiaphragm sign in an upright lateral chest radiograph. If haemodynamic conditions are stable, the underlying condition should be treated and the patient should be monitored closely. Acute haemodynamic deterioration should prompt rapid further investigation and cardiac tamponade must be actively ruled out. Spontaneous pneumopericardium in a 20 year old man is presented, and its pathophysiology described. (+info)