CHARGE Syndrome

Anesthetic Management of Pt. with CHARGE Syndrome

Definition:

➧ A syndrome characterized by: 

1-Coloboma of the eye (Figure 1) 

2-Heart defects (ASD, VSD, PDA, TOF, Rt. Aortic arch, Double outlet Rt. ventricle) 

3-Atresia of the choanae (Figure 2) 

4-Retarded growth development and/or central nervous system abnormalities 

Severe sensorineural, visual, and vestibular deficits are suggested as the cause of delay in walking development, rather than retardation. 

5-Genital hypoplasia in males (Hypogonadism) 

6-Ear anomalies (Figure 3) and/or deafness (Figure 4) 

➧ Diagnosis is made on the presence of at least four of the criteria.

Figure 1: Coloboma of iris

Figure 2: Atresia of the choanae

Figure 3: Ear anomalies

Figure 4: Deafness (BAHA)

➧ Other abnormalities include:

Muscular hypotonia, facial palsy, tracheo-oesophageal fistula, cleft lip and palate, micrognathia, laryngomalacia, pharyngolaryngeal hypotonia (inability to maintain the patency of the pharyngolaryngeal passage), subglottic stenosis and other upper airway abnormalities. 

➧ There is a high incidence of abnormal blood gas levels and sleep problems. Cardio-respiratory arrest is common in this group of patients. 

➧ Gastroesophageal reflux has been reported. 

➧ Anesthesia may be required for choanal atresia repair, cardiac surgery, tracheoesophageal fistula, ear surgery, Nissen’s fundoplication, and tracheostomy.

Anesthetic Management:

Preoperative Management: 

1. Preoperative assessment of congenital cardiac defects. 

2. Preoperative assessment of upper airway abnormalities. Pharyngo-laryngeal hypotonia causes variable obstruction, which becomes more pronounced during sleep and during inspiration. 

3. Precautions against aspiration of gastric contents. 

Intraoperative Management: 

1. A range of sizes of endotracheal tubes should be available due to subglottic stenosis. 

2. If micrognathia is present, inhalational induction is advisable. 

3. Tendency for upper airway collapse during light anesthesia due to laryngomalacia or pharyngolaryngeal hypotonia. Edematous arytenoids may result from gastroesophageal reflux. 

4. Tracheal intubation difficulties have been recorded and intubation problems are increased with increasing age. 

5. Tracheostomy may be required for long-term management. Some authors felt that early tracheostomy helped to avoid hypoxemic events in infancy. 

Postoperative Management: 

1. Postoperative monitoring of apnea. 

2. Feeding difficulties and a high incidence of gastroesophageal reflux. 

Postoperative Mortality: 

1. Apnea due to pharyngolaryngeal hypotonia. 

2. Postoperative deaths were frequently associated with pulmonary aspiration. 

3. Patients require multiple anesthetics, with an increased incidence of postoperative mortality.

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Sodium Nitroprusside Toxicity

Sodium Nitroprusside Toxicity:

Mechanism of Action:

After parenteral injection, sodium nitroprusside enters red blood cells, where it receives an electron from the iron (Fe⁺²) of oxyhemoglobin. This non-enzymatic electron transfer results in unstable nitroprusside radical and methemoglobin (Hb Fe⁺³). The former moiety spontaneously decomposes into five cyanide ions and the active nitroso (NO) group. 

The cyanide ions can be involved in one of three possible reactions: 

1) Binding to methemoglobin to form cyan-methemoglobin.

2) Undergoing a reaction in the liver and kidney catalyzed by rhodanase enzyme to form thiocyanate + thiosulfate.

3) Binding to tissue cytochrome oxidase, which interferes with normal oxygen utilization.

N.B. Sodium nitroprusside toxicity is usually related to prolonged administration or occurs in patients with renal or hepatic failure. 

Mechanisms of Toxicity:

1) Direct vasodilation: resulting in hypotension and dysrhythmias (most common).

2) Thiocyanate toxicity: (occurs infrequently).

3) Cyanide toxicity: (in rare cases).

4) Methemoglobinemia: (in very rare cases).

Thiocyanate toxicity :

Symptoms:

Anorexia, nausea, abdominal pain, fatigue, and mental status changes, including psychosis, weakness, seizures, tinnitus, and hyperreflexia. 

Treatment: 

-Toxicity can be minimized by avoiding prolonged administration of nitroprusside and by limiting drug use in patients with renal insufficiency (as thiocyanate is usually excreted in the urine). 

-Thiocyanate can be removed by dialysis (if necessary). 

Cyanide toxicity:

-An early sign of cyanide toxicity is the acute resistance to the hypotensive effects of increasing doses of sodium nitroprusside (tachyphylaxis). (It should be noted that tachyphylaxis implies acute tolerance to the drug following multiple rapid injections, as opposed to tolerance, which is caused by more chronic exposure). 

-Acute cyanide toxicity occurs when the cyanide ions bind to tissue cytochrome oxidase and interfere with normal oxygen utilization. This leads to metabolic acidosis, cardiac arrhythmias, and increased venous oxygen content (as a result of the inability to utilize oxygen). 

Symptoms: 

-Cyanide toxicity is often associated with the odor of almonds on breath and can result in metabolic acidosis, tachycardia, mental status changes, respiratory arrest, coma, and death. 

Treatment: 

-Cyanide toxicity can usually be avoided if the cumulative dose of sodium nitroprusside is less than 0.5 mg/kg/h. 

-Mechanical ventilation with 100% oxygen to maximize oxygen availability. 

-Administering sodium thiosulfate (150 mg/kg over 15 min) or 3% sodium nitrate (5 mg/kg over 5 min), which oxidizes hemoglobin to methemoglobin, or by limiting the administration of nitroprusside. 

Methemoglobinemia:

-Methemoglobinemia occurs due to excessive doses of sodium nitroprusside or sodium nitrate, if the level is greater than 15 %, it can result in symptomatic cellular hypoxia.

Treatment: 

-Methylene blue (1–2 mg/kg of a 1% solution over 5 min), which reduces methemoglobin to hemoglobin.

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Carcinoid Crisis

Carcinoid Crisis

Definition:

-Carcinoid crisis is the most serious and life-threatening complication of carcinoid syndrome and is generally found in people who already have carcinoid syndrome.

-Carcinoid crisis occurs when all of the symptoms of carcinoid syndrome come at the same time. 

Causes:

➧ Spontaneous 

➧ Precipitating factors: 

-Stress, Sympathetic stimulation 

-Hypotension 

-Histamine-releasing drugs 

-Tumour manipulation 

-Regional anesthesia due to hypotension 

-Infection 

-Chemotherapy 

Clinical picture:

-Tachycardia, Arrhythmia 

-Hypotension, Shock 

-Flushing, Hyperthermia 

-Bronchospasm 

-Abdominal pain, Diarrhea 

Management:

Inhibit growth h. & vasoactive peptides release:

-Somatostatin analogs (Octreotide, Lanreotide) 

Anti-serotonin:

-Methesergide, Ketanserin, Cyproheptadine, Ondansetron, Alpha-methyl dopa 

Anti-kallikrein:

-Corticosteroids, Aprotinin

Anti-histamine:

-H1 blockers (Diphenhydramine) & H2 blockers (Ranitidine) 

R of Bronchospasm:

-Salbutamol, Aminophylline 

R of Diarrhea:

-Loperamide 

R of Hypotension:

-Vasopressin, Phenylephrine 

R of Hypertension:

-Alpha-blockers, Beta-blockers 

R of Rt. Heart failure:

-Digitalis, Diuretics

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