Paediatric neuromuscular scoliosis and post-operative blood pressure targets: a retrospective analysis

Abstract

PURPOSE: This study investigates blood pressure variations and clinical outcomes in paediatric neuromuscular scoliosis patients after deformity correction surgery to mitigate the risk of ischaemic spinal cord injury (SCI). Hypotension is proposed as an aetiological mechanism for delayed SCI, but there is limited evidence regarding the frequency, severity, duration, and clinical effect of hypotension exposure in the immediate post-operative period. METHODS: This is a retrospective review of 94 patients with cerebral palsy or CP-like conditions, who underwent posterior spinal instrumentation at Queensland Children's Hospital. Post-operative mean arterial pressure (MAP) variations and associations with tissue perfusion markers were analysed. Hypotension was described using area under threshold (AUT) and time under threshold (TUT) for MAP thresholds of 40-80 mmHg. RESULTS: 14.9% of patients experienced an episode of hypotension under 60 mmHg lasting ≥ 60 min, compared to 62.4% at 70 mmHg. At the 60 mmHg threshold, mean TUT was 9.2%, 95% CI [6.55, 11.8], compared to 40.9%, 95% CI [35.1, 46.6] at 70 mmHg. Logistic regression revealed increased hypotension exposure under thresholds of 60 and 65 mmHg over a 60-min period was associated with increased risk of hyperlactataemia (AUT, 60 mmHg threshold β = 2.85, OR 17, p = 0.03, 95% CI [0.22-5.48]. Increased AUT exposure was associated with low urine output at thresholds ≥ 60 mmHg over 30 min. Haemoglobin ≤ 80 g/L was associated with elevated lactate. CONCLUSION: Periods of sustained hypotension were common and usually without neurologic sequalae; however, a MAP below 60 and 65 mmHg sustained for 60 min was associated with surrogate markers of global tissue hypoperfusion.