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Osteopetrosis is a rare genetic disorder of osteoclast dysfunction leading to anatomical and physiological disorders. We present the anesthesia management for the femur fracture of a 4-year-old girl with malignant infantile type of osteopetrosis. She had a ventriculoperitoneal shunt, impaired motion, visual disturbance, growth failure, facial deformity, heart murmur of moderate tricuspid regurgitation, and left ventricular heart failure, with splenomegaly and severe anemia.
The term osteopetrosis is derived from the Greek word “osteo” meaning bone and “petros” meaning stone. Osteopetrosis is also known as “marble bone disease,” “osteosclerosis,” and “Albers-Schonberg disease.”
The anesthesia literature contains little discussion and few recommendations for the management of these patients. The main problem in this disease is inability in effective bone resorption and regeneration, leading to anatomical and physiological disorders.[4,5]
Osteopetrosis has three clinical types: The malignant infantile type of osteopetrosis has poor prognosis and is inherited as an autosomal recessive genetic trait and the intermediate type and benign adult type of osteopetrosis have similar but milder clinical manifestations [Tables [Tables11 and and22].[6,7,8] We present a case report of an osteopetrosis child who needed a general anesthesia management for a femur fracture which illustrated the possibility of handling this type of patient's airway less invasively.
A 4-year-old girl with 8 kg weight and 90 cm height admitted for femur fracture [Figure 1]. The onset of the disease was manifested at 6 months of age with a bulging anterior fontanel due to hydrocephalus with a subsequent ventriculoperitoneal shunting. Physical examination revealed short stature, growth delay, facial deformity, optimal mouth opening and neck extension, heart murmur grade III/VI, and splenomegaly. Heart and respiratory rates of the patient were 150/min and 20/min, respectively, with a 100/56 mmHg blood pressure. Laboratory results of the patients at the baseline were as follows – hemoglobin: 3.5 g/dL (anisocytosis, hypochromia, ovalocytosis, and elliptocytosis) and platelet: 39 × 109/L, which reached to 9.1 g/dL and 91 × 109/L after receiving two units of blood and platelet, respectively. White blood cell: 8.6 × 103/μL, red blood cell: 3.9 × 106/μL, alkaline phosphatase: 1279 U/L, lactate dehydrogenase: 832 U/L, phosphorus 3.5 mg/dL, Na: 135 mEq/L, K: 4.2 mEq/L, and calcium 9.3 mg/dL.
Echocardiography showed that the left ventricle volume was increased and the left ventricular ejection fraction was 30–40%, moderate tricuspid regurgitation. Sonography showed normal-sized liver with splenomegaly. The patient was on medication: Captopril 2.5 mg PO three times daily and Lanoxin (digoxin) 8 cc PO two times daily. Because of the femur fracture, the patient was candidate for applying a Spica cast under general anesthesia.
Due to the probability of difficult airway management (regarding facial abnormality), necessary precautions were made in the setting of anesthesia before induction [Figure 2].
The equipment for difficult airway management was included into the preparation setting which were laryngoscopes with Mackintosh and Miller types blades (sizes 0-2), ventilation face masks sizes 1-2, stylets with endotracheal tubes sizes 3.5-4.5 mm ID (un-cuffed), a pediatric size Glidescope and fiberoptic, percutaneous jet-ventilation catheter.
Before anesthesia induction, the patient was monitored with electrocardiography, noninvasive blood pressure, oxygen saturation (SpO2), and end-tidal carbon dioxide (ETCO2). Balanced isotonic solution was administered with a rate of 10 cc/kg perioperatively due to heart failure during the anesthesia management.
Midazolam 0.15 mg/kg and fentanyl 1 μg/kg with 0.02 mg/kg atropine were administered as premedication. General anesthesia was induced and maintained by ketamine 1 mg/kg. The patient was ventilated by an anesthesia face mask. During the anesthesia, the heart rate was 110–120/min, blood pressure 100/70 mmHg, SPO2 = 99%, and ETCO2 28–30 mmHg. The course of anesthesia and recovery was uneventful.
Classic malignant autosomal type which occurs in infants and younger children is accompanied by multiple significant pathologies which are common and maybe sever. Bone resorption prevents the enlargement of bone pores, resulting in bone marrow damage that is associated with hematological disorders. Bone foramina put pressure on cranial nerves and lead to visual and hearing impairments and cranial nerve palsies. Among the other signs of this disease are failure to thrive, anemia, thrombocytopenia, hypokalemia, hepatosplenomegaly, esotropia, amblyopia, extramedullary hematopoiesis, and pathological fractures [Figure 3].
A number of patients present with neurological symptoms such as seizures, hypotonia, retinal atrophy with absent evoked visual potentials, neural sensory-based deafness, significantly delayed myelination, diffuse progressive cortical and subcortical atrophy.
Reports of ARO variants (neuropathic ARO) with structural brain anomalies included macrocephaly, hypertelorism, agenesis of the corpus callosum, hydrocephalus, and Dandy–Walker malformation. Classical ARO is caused by TCIRG1 mutations.
Pathologic bone remodeling, which causes greater mineral density and compressive strength, lacks the needed elasticity and as a result pathologic bone fracture develops which is the hall mark of osteopetrosis.[15,16,17]
Hematopoietic stem cell transplantation may reduce the difficult airway-related problems in subsequent anesthesia procedures, but this has not been confirmed yet.
Patients with severe pancytopenia may develop heart failure or sepsis. A forward flow theory due to splenomegaly is considered to explain the etiology of portal hypertension in osteopetrosis patients.(22) Although controversial captopril has been used for the treatment of portal hypertension in patients with low portal variceal velocity to prevent complications of variceal bleeding. Osteopetrotic patients may develop hypertension and left ventricular heart failure, as in our patient, for which captopril and digoxin are commonly administered.
Difficult airway management and failed intubation have been reported in 17.7% and 14.5% of cases, respectively. Moreover, the chance of intubation failure has been reported to be higher in osteopetrosis children than other children. In a report, the incidence of respiratory-related problems was 11% which included critical airway management and hypoxemia. However, the rate of respiratory problems was reported to be only 2% of children younger than 8 years among pediatric surgical patients.
Factors that are related to difficult airway management in osteopetrosis patients can be due to mandibular abnormalities with hypoplasia. The space between the tongue and the posterior pharyngeal wall can also be narrow. A high arched, narrow hard palate, an obliterated nasal passage due to congestion, wide lower hyperplasic jaw, restricted temporomandibular joint movement, and cervical spine fractures may cause difficult endotracheal intubation. Hepatosplenomegaly-induced abdominal distention may also lead to ventilation difficulty.
Equipment and methods (e.g., awake intubation) required for a difficult intubation and possibility of tracheal aspiration must be taken into account. Our particular patient did not pose any difficulty or adverse event during the anesthesia besides the administration of atropine may have suppressed the oral secretions. The child's conditions were favorable with face mask ventilation. Complete fasting conditions, short duration of the procedure, and no electrolyte abnormalities permitted a smooth course of anesthesia with no impending need for a more advanced airway management as the mask ventilation was adequate, and the patient's oxygenation and end tidal carbon dioxide levels were in normal range.
Despite the possibility of critical airway management in osteopetrosis patients who have premorbid conditions such as heart failure and central nervous system involvement, it can be handled less invasively under general anesthesia.
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There are no conflicts of interest.