Respiratory failure after scoliosis correction surgery in patients with Prader-Willi syndrome: Two case reports

Table 1 Demographics of two cases

	Case 1		Case 2
Birth age (wk)	NSVD, 35 + 2		NSVD, 41 + 1
Weight at birth (g)	2100		3100
Age of PWS diagnosis	5 mon		2 yr
Sex	Male		Male
Growth hormone therapy	Ongoing for 4 yr		Not applied
Scoliosis surgery	Before OP	Post OP (At respiratory failure)	Before OP	Post OP (At respiratory failure)
Scoliosis Cobb’s angle (°)	66.1	54	82.6	71.8
Height (cm)	134	137	141	143
Weight (kg)	53.5	57	79.5	87
BMI (kg/m2)	29.8	30.4	40.0	42.5
Age (yr)	12	12	13	13

BMI: Body mass index; OP: Scoliosis repair surgery; PWS: Prader-Willi syndrome; NSVD: Normal spontaneous vaginal delivery.

Table 2 Respiratory status before and after noninvasive ventilator apply

	Case 1				Case 2
	Post OP	Before NIV	After NIV	F/U (5 mo)	Post OP	Before NIV	After NIV	F/U (12 mo)
ABG test1
pH	7.55	7.3474	7.38	7.403	7.393	7.3754	7.3724	7.384
PaO2 (mmHg)	87	54.24	106.9	83.3	63.4	37.24	99.04	65.5
PaCO2 (mmHg)	42	55.24	47.7	36.0	56.3	53.44	48.94	48.9
SaO2 (%)	98	85.24	98.0	96.3	91.1	68.14	97.44	92.8
Transcutaneous monitoring
SaO2 min (%)	NT	504	904	86	NT	NT	744	863
SaO2 mean (%)	NT	894	984	96	NT	NT	964	983
TcCO2 mean (mmHg)	NT	62.24	52.24	40.5	NT	NT	42.94	41.73
TcCO2 max (mmHg)	NT	71.64	61.14	48.1	NT	NT	53.14	433
Pulmonary function test
FVC (L)	0.962	0.68	NT	0.42	1.092	0.89	0.84	0.98
FVC (%)	482	31	NT	18	472	35	34	39
Respiratory muscle strength
MIP (mmHg)	NT	17	NT	17	452	59	62	53
MIP (%)	NT	19.5	NT	19.5	47.42	54.9	56.9	45.8
MEP (mmHg)	NT	14	NT	20	982	76	85	59
MEP (%)	NT	13.9	NT	19.8	102.62	71.4	79.8	52.7

¹Measured in the morning (reflecting respiration values during sleep).

²Measured before surgery.

³Measured 6 months after NIV application.

⁴Measured value use of O₂. ABG: Arterial blood gas; F/U: Follow up; FVC: Forced vital capacity; MEP: Maximal expiratory pressure; MIP: Maximal inspiratory pressure; NIV: Noninvasive ventilation; NT: Not tested; PFT: Pulmonary function test; TcCO₂: Transcutaneous carbon dioxide pressure.

Table 3 Results of polysomnography

	Case 1	Case 2
Polysomnography	6 mon after surgery	7 mon after surgery
CAI (events/h)	0	0
Obstructive apnea (events/h)	10	1.4
Hypopnea (events/h)	82	32.5
AHI (events/h)	91.2	33.9
ODI	90.2	31.8
Total arousal index (events/h)	4	9.9
Mean sleep SaO2%	74.6	79.2
Minimal SaO2%	50	50
Neck circumference (cm)	39	39

AHI: Apnea-hypopnea index; CAI: Central apnea index; ODI: Oxygen desaturation index; SaO₂: Oxygen saturation.