Abstract Body (Do not enter title and authors here): Introduction: Children with single-ventricle heart disease undergo a series of palliative surgeries that result in passive pulmonary blood flow. To maintain pulmonary blood flow, there is a necessary rise in superior vena cava (SVC) pressure, which exposes patients to a variety of complications. Longitudinal monitoring of SVC pressure may improve triage of high-risk patients, but it is hindered by the invasiveness of the measurement (e.g., cardiac catheterization). We have developed a non-invasive optical measure of cerebral critical closing pressure (CrCP) that is obtained with simple application of a fiberoptic sensor to the forehead (Fig. (A)). CrCP is the external pressure compressing the cerebral arterioles, which depends on intracranial pressure (ICP), and thus SVC pressure through back-propagation. Indeed, increased ICP is thought to be the cause of the postoperative irritability commonly seen in these patients immediately after the surgery to establish their superior cavopulmonary connection (SCPC).
Hypothesis: Optically measured CrCP correlates with invasive SVC pressure measurements and post-SCPC pain scores in single-ventricle patients.
Methods: We performed two prospective studies in children with single-ventricle heart defects. In one study, we measured CrCP in patients with SCPC physiology during cardiac catheterization procedures wherein SVC pressure was invasively measured for clinical care. In the second study, we measured CrCP before and after the SCPC operation. Specifically, a single preoperative measurement was performed within 24 hours of surgery, and episodic postoperative measurements, targeted to occur once daily, were performed during the first week after surgery. We averaged the postoperative measurements and the clinical postoperative FLACC pain scores to create single postoperative values for each patient.
Results: CrCP was positively correlated with invasive SVC pressure measurements in 15 patients (R=0.69, p=0.004; Fig. (B)). In the other study, we measured a significant preoperative to postoperative increase in CrCP across 16 patients (p<0.001; Fig. (C)), which demonstrates the sensitivity of CrCP to the acute increase in SVC pressure. The degree of increase was also correlated with the mean FLACC Pain Score across the postoperative measurement period (R=0.55, p=0.03; Fig. (D)).
Conclusion: CrCP is a promising non-invasive proxy of SVC pressure in patients with SCPC that can be deployed to the bedside and clinic.