Introduction

Cyanosis in newborns

Cyanosis is a condition in which there is a reduced level of haemoglobin bound to oxygen circulating in the system, leading to a blue discolouration of the skin and the mucous membranes. Cyanosis can be categorised into two forms.¹

• Peripheral cyanosis: the short-term, benign blue discolouration of the feet and hands, especially in newborns, is known as peripheral cyanosis¹
• Central cyanosis: considered a serious condition as it spreads towards the lips and tongue¹

Significance of early diagnosis and management of cyanosis

It is very important to diagnose and manage cyanosis in a timely manner to prevent complications. To identify the cause, systemic approaches can be used to determine whether it is because of any airway obstruction, cardiac abnormality, lung abnormality, or any CNS disorder. For the correct diagnosis and timely management, it is important to understand the basic physiology. For management, it is crucial to stabilise the infant, meet their oxygenation needs, and provide specialised care and attention. Recognising the underlying situation and then managing it according to that will provide the best outcomes.³

Overview of tricuspid atresia

It is a congenital heart disorder in which the tricuspid valve is not present, which is involved in preventing the blood flow between the right atrium and right ventricle. There is poor oxygenation of the blood, leading to cyanosis. It may occur during embryogenesis, when an abnormality develops in the heart, without any confirmed genetic history. The mortality rate is extremely high in the initial 5 years of life.²

Pathophysiology of cyanosis in tricuspid atresia

The tricuspid valve that prevents the flow of blood from the right atrium to the right ventricle is not present in tricuspid atresia, which leads to a hypoplastic (underdeveloped) right ventricle. So the blood will be forced into the right ventricle through to left-to-right shunt (defect in the atrial septal or patent foramen ovale). The systemic deoxygenated blood is mixed with the pulmonary oxygenated blood in the left atrium, and as a result, oxygen saturation is reduced. The pulmonary blood flow will decide the severity of the cyanosis, and the blood flow is influenced by various conditions like pulmonary stenosis, atresia, and a ventricular septal defect. The pulmonary venous return is much lower in patients dealing with pulmonary obstruction, which causes reduced systemic arterial oxygen saturation and severe cyanosis. On the other hand, the individuals with no pulmonary restriction have increased pulmonary venous return, so the oxygen saturation is increased and cyanosis.²

Aetiology and diagnosis

Mainly, cyanosis occurs due to less oxygen saturation, which causes the blue discolouration of the skin and the mucous membranes.⁴

Aetiology of central cyanosis

Central cyanosis is when the arterial oxygen saturation is low. The following are the possible cause:

• In central nervous disorders, for instance, seizures, intracranial pressure, and drug overdoses, such as heroin, lead to hypoventilation
• Some pulmonary disorders impair the oxygen exchange, for example, asthma, COPD, pneumonia, bronchiolitis, pulmonary hypertension, and pulmonary embolism
• Cardiovascular disease also leads to cyanosis, which includes congenital heart abnormalities (right-to-left shunts), heart failure, and some other valvular diseases
• Methemoglobinemia and sulfhemoglobinemia, which are the abnormalities of haemoglobin, disturb the oxygen transport
• Some other factors involve obstructive sleep apnea, hypothermia, high altitude, and polycythemia⁴

Aetiology of peripheral cyanosis

In peripheral cyanosis, the distal extremities, like the hands, toes, and fingertips, become blue. However, mucous membranes are not generally involved. Peripheral cyanosis is due to reduced oxygen and blood flow. 

• Reduced cardiac output due to heart failure and shock
• Raynaud's disease, vasomotor instability, cold exposure, and vasoconstriction cause peripheral cyanosis
• Atherosclerosis, Buerger’s disease, and embolism cause arterial obstruction
• Deep vein thrombosis causes venous stasis
• Multiple myeloma and polycythemia are causing hyperviscosity⁴

Notably, central cyanosis can also cause peripheral cyanosis, and differential cyanosis is seen in conditions like patent ductus arteriosus with pulmonary hypertension.

Differential diagnosis

Few conditions exacerbate the appearance of cyanosis, but the underlying causes are different. So the central cyanosis in which the systemic oxygenation problems occur should be distinguished from the peripheral cyanosis, which could be due to blood flow problems. The cause in which the upper limbs become more bluish than the lower limbs is known as reversed differential cyanosis mostly common in individuals with transposition of the greater arteries, with particular shunting patterns.⁴

Some other reasons that are not related to cyanosis but cause the blue discolouration of the skin are the following:⁴

• Pigmentary birthmarks (which are benign skin changes, but not cyanosis)
• The consistent bluish-greyish skin, which is due to the large tattoos
• There can be drug-induced discolouration, for instance, caused by the amiodarone
• Skin could be stained from external sources, like any dye, leading to a misunderstanding 
• The lips and the tongue could be stained because of any stained or dyed food items, for example, popsicles

So these should be diagnosed as to what the underlying cause is, otherwise, it could lead to misunderstanding cyanosis. Proper diagnosis of cyanosis will cause appropriate management.⁴

Management of cyanosis

To treat cyanosis, the cause must be identified, the main thing is to maintain the oxygen level to improve the condition.

Central cyanosis treatment

• The oxygen support is provided via a mask or nasal tube. Ventilators can also be used if the condition is serious
• Calcium levels and blood sugar levels are maintained specifically in heart patients
• Urgent care is required by a heart specialist for patients dealing with heart problems like tricuspid atresia. To improve the blood flow, medications like prostaglandin E1 or surgery are needed
• Some drugs, for instance, inotropes, ACE Inhibitors, and diuretics, are used for better pumping action of the heart, particularly in patients with heart failure
• To prevent infections, antibiotics are used
• Methemoglobinemia disorder of haemoglobin, is treated by using methylene blue.
• To prevent skin discolouration, toxins, for example, silver and gold salts, should be avoided⁴

Peripheral cyanosis treatment

• The blood flow is improved by massaging and warming the affected area
• If cyanosis and shock happen together, urgent treatment should be provided to the patient
• The things that could lead to vasoconstriction, for instance, caffeine, smoking, and extreme temperatures, should be avoided
• Antihypertensives can help in this condition by dilating the blood vessels, whereas beta-blockers could worsen the condition that constricts the vessels⁴

Complications and prevention of cyanosis

It is very important to understand that cyanosis is not a disease; it is a symptom of the underlying causes, as discussed earlier. So, if cyanosis is not treated, it can cause the exacerbation of the underlying disease, like worsening of heart failure, or respiratory failure, or it could also lead to organ damage due to poor oxygenation.⁴

Patient education

Patients and their families must be aware of the risk factors that could worsen the condition, and also the preventive steps to stop the worsening. Important recommendations include

• Stop smoking as it could worsen cardiovascular health and oxygen levels
• The blood pressure of the individual must be in control to reduce the pressure in the heart
• Extreme temperatures must be avoided to bypass vasoconstriction and cyanosis
• To prevent vascular blockages, cholesterol levels must be maintained
• Activity must be maintained, and immobility should be avoided, so there should be proper blood and oxygen circulation

To maintain the overall health of the patient and to reduce the chances of cyanosis, these measures should be told to patients and their relatives.⁴

Prognosis and outcomes

The report by Tay and Yip (1982) proposed new prognostic criteria for children with cyanotic congenital heart disease (CCHD), emphasising the external and microenvironmental aspects of oxygen supply and delivery. These parameters were measured in 79 children between two weeks and 14 years of age at the time of cardiopulmonary catheterisation. Patients were followed for six months to assess survival without surgical intervention.⁵

Six-month survival rates were much lower among children with low available oxygen or low oxygen unloading capacity (24% and 49%, respectively) than among those with normal levels (90% and 96%, respectively). These measures proved superior to conventional prognostic markers like arterial oxygen content and arterial oxygen saturation. Survival could not be reliably forecast using hematocrit and haemoglobin levels.⁵

Emphasising its relevance in prognosis rating, together with regular anatomical assessments, the research found that available oxygen was the utmost survival predictor. This is especially vital in places with limited resources where surgical therapy must be a top priority. Because of these physical signs, medical professionals can more accurately spot those patients in critical need of immediate surgery, therefore benefiting outcomes for children with CCHD. The evidence stresses the need for physiological evaluations apart from anatomical considerations for establishing prognosis and urgency for therapy.⁵

Summary

In newborns with tricuspid atresia, cyanosis signifies a serious condition requiring early detection and treatment. Tricuspid atresia causes insufficient pulmonary blood flow due to the acquired absence of the tricuspid valve, which can lead to systemic desaturation and central cyanosis. Right-to-left shunting and hypoplastic right ventricle, along with variable perfusion of the lungs, are factors that shape the path of the disease and the severity of cyanosis. Diagnostic confirmation with clinical evaluation and imaging, such as echocardiography, is critical for effective management.

If treatment is available for the newborn on time, it is focused on stabilisation with oxygen support and prostaglandin E1, to keep the ductus patent, followed by stages of surgery (Blalock-Taussig shunt, Glenn procedure, Fontan completion) to augment systemic oxygenation. Their long-term outcome is influenced by continuous clinical surveillance, which is needed to prevent complications, including heart failure and arrhythmias, as well as by patient education in terms of lifestyle changes.

Emerging advances in neonatal care and surgical technology are improving some outcomes, including survival and quality of life for these individuals. Lifelong follow-up and multidisciplinary management are, nonetheless, crucial for promoting health in decedents. Knowing that cyanosis may be a red flag and how to manage it is key to ensuring that a newborn with tricuspid atresia can shoot for the best possible outcome.