Causes
Central cyanosis
Central cyanosis is often due to a circulatory or ventilatory problem that leads to poor blood oxygenation in the lungs. It develops when arterial oxygen saturation drops below 85% or 75%.Acute cyanosis can be a result of asphyxiation or choking and is one of the definite signs that ventilation is being blocked. Central cyanosis may be due to the following causes:

Central nervous system (impairing normal ventilation):Intracranial hemorrhage
Drug overdose (e.g. heroin)
Generalized tonic–clonic seizure (GTCS)
Respiratory system:Pneumonia
Bronchiolitis
Bronchospasm (e.g. asthma)
Pulmonary hypertension
Pulmonary embolism
Hypoventilation
Chronic obstructive pulmonary disease, or COPD (emphysema)
Cardiovascular system:Congenital heart disease (e.g. Tetralogy of Fallot, right to left shunts in heart or great vessels)
Heart failure
Valvular heart disease
Myocardial infarction
Hemoglobinopathies:Methemoglobinemia 
Sulfhemoglobinemia 
Polycythemia
Congenital cyanosis (HbM Boston) arises from a mutation in the α-codon which results in a change of primary sequence, H → Y. Tyrosine stabilises the Fe(III) form (oxyhaemoglobin) creating a permanent T-state of Hb. Others:
High altitude, cyanosis may develop in ascents to altitudes >2400 m.
Hypothermia
Frostbite
Obstructive sleep apnea

Peripheral cyanosis
Peripheral cyanosis is the blue tint in fingers or extremities, due to an inadequate or obstructed circulation. The blood reaching the extremities is not oxygen-rich and when viewed through the skin a combination of factors can lead to the appearance of a blue color. All factors contributing to central cyanosis can also cause peripheral symptoms to appear but peripheral cyanosis can be observed in the absence of heart or lung failures. Small blood vessels may be restricted and can be treated by increasing the normal oxygenation level of the blood.
Sigmoid colon volvulus, also known as sigmoid volvulus, is volvulus affecting the sigmoid colon. It is a common cause of bowel obstruction and constipation. It is common in Asia, India (7% of intestinal obstruction) and especially South India because of the high fibre diet. It is a very common cause of large bowel obstruction in Peru and Bolivia due to high altitude. Signs and symptoms
Pain in abdomen – initially left-sided, eventually all over
Absolute constipation
Enormous distension of abdomen
Late vomiting and eventually dehydration
Features of peritonitis
Hiccup and retching may occur
Tyre-like feel of the abdomen is diagnostic

Cause
The condition is more common in males and with old age. It is also common in people with chronic constipation and laxative abuse. It is common in:
Ogilvie syndrome
Individuals with learning difficulties
Chagas disease
Hypothyroidism
Anticholinergic drugs
Multiple sclerosis
Scleroderma
Parkinsons diseaseIn sigmoid, volvulus rotation is always anticlockwise. It requires one and a half rotation to cause vascular obstruction and gangrene which eventually leads to perforation either at the root or at the summit of the sigmoid loop. Diagnosis
Plain X-ray (diagnostic in 70–80%): coffee bean sign is seen
Contrast enema: bird beak sign
CT scan: shows characteristic whirl pattern
Blood: haematocrit, renal functions, serum electrolytes

Treatment
RT aspiration
IV fluids
Catheterisation
Antibiotics
By flatus tube or sigmoidoscope, derotation is done
If derotation does not occur, then laparotomy through midline incision should be done. It is derotated manually. If viable, it can be fixed to lateral wall of abdomen or pelvis
If sigmoid colon is gangrenous, then Hartmanns operation or Paul Mikulicz operation is done

References


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