When the alveoli of the lung are ruptured, as occurs in pulmonary laceration, air may travel beneath the visceral pleura (the membrane lining the lung), to the hilum of the lung, up to the trachea, to the neck and then to the chest wall. The condition may also occur when a fractured rib punctures a lung; in fact, 27% of patients who have rib fractures also have subcutaneous emphysema. Rib fractures may tear the parietal pleura, the membrane lining the inside of chest wall, allowing air to escape into the subcutaneous tissues.Subcutaneous emphysema is frequently found in pneumothorax (air outside of the lung in the chest cavity) and may also result from air in the mediastinum, pneumopericardium (air in the pericardial cavity around the heart). A tension pneumothorax, in which air builds up in the pleural cavity and exerts pressure on the organs within the chest, makes it more likely that air will enter the subcutaneous tissues through pleura torn by a broken rib. When subcutaneous emphysema results from pneumothorax, air may enter tissues including those of the face, neck, chest, armpits, or abdomen.Pneumomediastinum can result from a number of events.
Contraindications
Acamprosate is primarily removed by the kidneys and should not be given to people with severely impaired kidneys (creatinine clearance less than 30 mL/min). A dose reduction is suggested in those with moderately impaired kidneys (creatinine clearance between 30 mL/min and 50 mL/min). It is also contraindicated in those who have a strong allergic reaction to acamprosate calcium or any of its components. Adverse effects
The US label carries warnings about increases of suicidal behavior, major depressive disorder, and kidney failure.Adverse effects that caused people to stop taking the drug in clinical trials included diarrhea, nausea, depression, and anxiety.Potential adverse effects include headache, stomach pain, back pain, muscle pain, joint pain, chest pain, infections, flu-like symptoms, chills, heart palpitations, high blood pressure, fainting, vomiting, upset stomach, constipation, increased appetite, weight gain, edema, sleepiness, decreased sex drive, impotence, forgetfulness, abnormal thinking, abnormal vision, distorted sense of taste, tremors, runny nose, coughing, difficulty breathing, sore throat, bronchitis, and rashes. Pharmacology
Pharmacodynamics
The pharmacodynamics of acamprosate are complex and not fully understood; however, it is believed to act as an NMDA receptor antagonist and positive allosteric modulator of GABAA receptors.Its activity on those receptors is indirect, unlike that of most other agents used in this context. An inhibition of the GABA-B system is believed to cause indirect enhancement of GABAA receptors.