Osmotic regulation of airway reactivity by epithelium.

Inhalation of nonisotonic solutions can elicit pulmonary obstruction in asthmatic airways. We evaluated the hypothesis that the respiratory epithelium is involved in responses of the airways to nonisotonic solutions using the guinea pig isolated, perfused trachea preparation to restrict applied agents to the mucosal (intraluminal) or serosal (extraluminal) surface of the airway. In methacholine-contracted tracheae, intraluminally applied NaCl or KCl equipotently caused relaxation that was unaffected by the cyclo-oxygenase inhibitor, indomethacin, but was attenuated by removal of the epithelium and Na+ and Cl- channel blockers. Na+-K+-2Cl- cotransporter and nitric oxide synthase blockers caused a slight inhibition of relaxation, whereas Na+,K+-pump inhibition produced a small potentiation. Intraluminal hyperosmolar KCl and NaCl inhibited contractions in response to intra- or extraluminally applied methacholine, as well as neurogenic cholinergic contractions elicited with electric field stimulation (+/- indomethacin). Extraluminally applied NaCl and KCl elicited epithelium-dependent relaxation (which for KCl was followed by contraction). In contrast to the effects of hyperosmolarity, intraluminal hypo-osmolarity caused papaverine-inhibitable contractions (+/- epithelium). These findings suggest that the epithelium is an osmotic sensor which, through the release of epithelium-derived relaxing factor, can regulate airway diameter by modulating smooth muscle responsiveness and excitatory neurotransmission.

Epidemiology of sharp object injuries in a children's hospital.

BACKGROUND: Limited data exist on the frequency, circumstances and management of sharp object injuries (SOIs) in pediatric facilities. METHOD: SOIs reported at a large children's hospital during a 2-year period were reviewed. RESULTS: One hundred thirteen SOIs were reported for an average of 6 injuries per 100 employees per year. The greatest number of injuries occurred among nurses (46%) and physicians (23%), but phlebotomists experienced the highest rate (25.5 injuries per 100 full time equivalent employees per year). Most common locations were the patient room (27%), operating room (25%) and intensive care units (17%). Needles accounted for 71% of injuries and procedural devices accounted for 22%. Forty-eight percent of injuries occurred during use of the item, 42% after use or during disposal and 7% after disposal. Twenty percent were associated with loose sharps and 15% with inadvertent patient movement. Only 2 injuries were associated with recapping. Eighty-eight percent of the objects were contaminated with blood or body fluid. Of 88 known source patients 1 tested positive for hepatitis B surface antigen, 2 for hepatitis C virus and none for HIV. One hundred four employees sought treatment: 36 received tetanus vaccine; 14 received hepatitis B vaccine; 9 received hepatitis B immunoglobulin; and 12 received zidovudine. No employee subsequently tested positive for HIV, hepatitis B virus, or hepatitis C virus. CONCLUSIONS: SOIs represent a frequent occurrence among pediatric health care workers. Minimizing the use of sharps, appropriately restraining patients during procedures and promptly disposing of sharp items after use might decrease the frequency of SOIs.