When fissures are found laterally, tuberculosis, occult abscesses, leukemic infiltrates, carcinoma, acquired immunodeficiency syndrome (AIDS) or inflammatory bowel disease should be considered as causes. Some sexually transmitted infections can promote the breakdown of tissue resulting in a fissure. Examples of sexually transmitted infections that may affect the anorectal area are syphilis, herpes, chlamydia and human papilloma virus.Other common causes of anal fissures include:

childbirth trauma in women
anal sex
Crohns disease
ulcerative colitis
poor toileting in young children. Diagnosing
External anal fissures on the anal verge can be diagnosed by visual inspection.Internal anal fissures in adults on anterior side, posterior side or within any part of the inner circumference of the anal sphincter muscle can be diagnosed with beak proctoscope 23mm diameter, Chelsea Eaton anal speculum 23mm diameter, Park anal retractor or by digital rectal examination with a finger inside the anal sphincter muscle. Narrow anal fissures might not be felt by finger during rectal examination due to the glove.Note that colonoscopy, sigmoidoscopy, or normal proctoscopy is for diagnosing internal hemorrhoids and other internal rectal diseases and not for diagnosing anal fissures. Prevention
For adults, the following may help prevent anal fissures:

Avoiding straining when defecating. This includes treating and preventing constipation by eating food rich in dietary fiber, drinking enough water, occasional use of a stool softener, and avoiding constipating agents. Similarly, prompt treatment of diarrhea may reduce anal strain. Careful anal hygiene after defecation, including using soft toilet paper and cleaning with water, plus the use of sanitary wipes.
Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercapnia. Respiratory failure is classified as either Type 1 or Type 2, based on whether there is a high carbon dioxide level, and can be acute or chronic. In clinical trials, the definition of respiratory failure usually includes increased respiratory rate, abnormal blood gases (hypoxemia, hypercapnia, or both), and evidence of increased work of breathing. Respiratory failure causes an altered mental status due to ischemia in the brain. The typical partial pressure reference values are oxygen Pa O2 more than 80 mmHg (11 kPa) and carbon dioxide Pa CO2 less than 45 mmHg (6.0 kPa). Cause
Several types of conditions can potentially result in respiratory failure:

Conditions that reduce the flow of air into and out of the lungs, including physical obstruction by foreign bodies or masses and reduced breathing due to drugs or changes to the chest. Conditions that impair the lungs blood supply. These include thromboembolic conditions and conditions that reduce the output of the right heart, such as right heart failure and some myocardial infarctions. Conditions that limit the ability of the lung tissue to exchange oxygen and carbon dioxide between the blood and the air within the lungs. Any disease which can damage the lung tissue can fit into this category.