Blood pressure goals: Is cerebral saturation the new mean arterial pressure?

Objective: To correlate hypotension and cerebral saturation from near-infrared spectroscopy (cNIRS) in neonates on dopamine. Study Design: Retrospective review of neonates receiving dopamine between August 2018-2019 was performed. Hypotension thresholds included mean arterial pressure (MAP) of postmenstrual age (PMA) ± 5mmHg, 30mmHg, and gestational age (GA) ± 5mmHg. Time below threshold MAP was compared to time with cerebral hypoxia (cNIRS <55%). Results: Hypotension occurred 6-33% of time on dopamine in 59 cases. Hypotension did not correlate with abnormal cNIRS overall, within PMA subgroups, or by outcomes. Hypotensive periods with MAP<GA had fewer corresponding percent time with abnormal cNIRS events (3.7±1.3%) compared to MAP <PMA (11.9±4.9%, p<0.003) or 30 mm Hg thresholds (12.2±4.7%, p<0.0001). In the most premature infants, mean cNIRS values during hypotension were still within normal range (57±6%). Conclusion: cNIRS may be a more clinically relevant measure than MAP for assessment of neonatal hypotension.

End-organ saturations correlate with aortic blood flow estimates by echocardiography in the extremely premature newborn – an observational cohort study

Background Near-infrared spectroscopy (NIRS) measures of cerebral saturation (Csat) and renal saturation (Rsat) in extreme premature newborns may be affected by systemic blood flow fluctuations. Despite increasing clinical use of NIRS to monitor tissue saturation in the premature infant, validation of NIRS measures as a correlate of blood flow is still needed. We compared echocardiography (ECHO) derived markers of ascending aorta (AscAo) and descending aorta (DesAo) blood flow with NIRS measurements obtained during the ECHO. Methods Newborns < 29 weeks’ gestation (2013–2017) underwent routine NIRS monitoring. Csat, Rsat and systemic saturation at the time of ECHO were retrospectively analyzed and compared with Doppler markers of aortic flow. Renal and cerebral fractional tissue oxygen extraction (rFTOE and cFTOE, respectively) were calculated. Mixed effects models evaluated the association between NIRS and Doppler markers. Results Forty-nine neonates with 75 Csat-ECHO and 62 Rsat-ECHO observations were studied. Mean post-menstrual age was 28.3 ± 3.8 weeks during the ECHO. Preductal measures including AscAo velocity time integral (VTI) and AscAo output were correlated with Csat or cFTOE, while postductal measures including DesAo VTI, DesAo peak systolic velocity, and estimated DesAo output were more closely correlated with Rsat or rFTOE. Conclusions NIRS measures are associated with aortic blood flow measurements by ECHO in the extremely premature population. NIRS is a tool to consider when following end organ perfusion in the preterm infant.

The Use of the Comma Sign and Tissue for Recognition, Reduction, and Stability During Arthroscopic Repair of Combined Anterosuperior Cuff Tears

Background: The comma sign is a useful marker for combined retracted supraspinatus and subscapularis tears. It was first described by the group of Burkhart as a “composite ligamentous structure” of the rotator interval attached to the retracted subscapularis. However, Neyton and coworkers suggested that the ruptured superior part of subscapularis is pulled upward by supraspinatus retraction. This video illustrates the value of “comma” recognition for reduction and repair stability. We feel that the comma tissue can be a composition of rotator interval ligaments with or without superior subscapularis contribution depending on an associated cleavage tear. Indications: Patients with retracted anterosuperior tears, unless muscle quality is poor (Goutallier classification ≥3). Understanding of the comma tissue is difficult but of crucial importance to assess complex anterosuperior cuff tears for reduction and repair with stability by maintaining and integrating this comma link into the repair construct. Technique Description: Arthroscopic setup includes beach chair position, armholder, cerebral saturation monitoring (target mean arterial blood pressure of about 70 mm Hg). Previously described circumferential portals were used for a repair with a double row construct (4 medial anchors: 2.5 for subscapularis; 1.5 for supraspinatus) and 2 lateral anchors. The superior boarder of subscapularis as well as the retracted capsular layer of supraspinatus was reduced and fixed using a lasso loop technique. Key stages are (1) tendon manipulation with 2 traction sutures; (2) tendon release; (3) comma reduction; (4) footprint preparation (burr, microfracture); (5) retrograde suture passing; (6) knot tying, knotless lateral row; and (7) a close surgeon to physiotherapist rehabilitation link (6 weeks passive to 90°, no resistance training for 3-6 months). Results: Senior author’s (S.B.) series: 32 anterosuperior tears over 4 years (mean age: 62 years, 48-73 years), minimum follow-up 1 year showed good results (mean SSV: 85% [preop. 35%], range: 40%-95%; mean Constant: 82 [preop. 30], range: 40-90). One major complication (cutibacterium infection; brick layer; workers compensation; invalidity demand; Constant/Subjective Shoulder Value both 40) and minor temporary stiffness at 3 months (8 patients; 22%). Conclusion: Adequate reduction and comma integration into a solid repair construct, as well as responsible rehabilitation surveillance, deliver successful results after technically intricate anterosuperior repairs.

Abstract 372: Regional Cerebral Saturation in a Swine Model of Goal-directed Resuscitation of Prolonged Ventricular Fibrillation Cardiac Arrest

Introduction: The characteristics and limitations of near-infrared spectroscopy (NIRS) measurement of regional cerebral saturation (rSO2) for reflecting key moment-to-moment physiological changes needed to guide cardiopulmonary resuscitation (CPR) have yet to be fully determined. Objective: Examine the impact of NIRS sensor placement and resuscitation process variation on rSO2 measurements during prolonged cardiac arrest. Methods: Thirty mixed-breed domestic pigs (mean weight: 25.0kg+/-2.0) were sedated (ketamine / xylazine), anesthetized (fentanyl), paralyzed (vecuronium) and mechanically ventilated. Micromanometer pressure transducers were placed in the aorta and right atrium via femoral cutdown to measure central pressures, including mean arterial pressure (MAP) and coronary perfusion pressure (CPP). Two NIRS sensors were placed on the cranium: one on the skin surface and one on the bare skull. Ventricular fibrillation was induced electrically and untreated for 8 minutes followed by CPR. Initial BLS phase: 4 minutes of CPR at 100 compressions per minute (CPM) and 2 inches depth with manual ventilations (30:2). Randomized ALS phase: CPR with a pressor-titrated (Group A) or a compression rate/depth-titrated (Group B) strategy targeting 25mmHg CPP. Group A animals received pressor doses q1min and fixed rate/depth CPR. Group B animals received increasing rates and depth of CPR with epinephrine q3min. Defibrillation was attempted at 6min CPR q2min. rSO2 was compared between skin and skull across phases of resuscitation with t-tests and generalized estimating equations (GEE). Results: Mean skin and skull rSO2 differed marginally overall (63.8 vs 62.0, p < 0.001), at baseline (69.9 vs 64.9, p < 0.001), during BLS CPR (56.9 vs 48.7, p < 0.001), during ALS CPR (59.5 vs 51.0, p < 0.001), and following ROSC (70.0 vs 60.5, p<0.001). rSO2 measured on either skull or skin both varied throughout phases of the experiment but not between CPR groups. In GEE models, rSO2 measured on skin or skull was not associated with MAP at baseline, but was directly associated during BLS (coef 0.13; p<0.001) & ALS CPR (coef 0.09; p<0.001), and after ROSC (coef 0.02; p=0.017). Conclusion: rSO2 measures differ between skin and skull though both correlate with MAP.

Combined Multimodal Cerebral Monitoring and Focused Hemodynamic Assessment in the First 72 h in Extremely Low Gestational Age Infants

<b><i>Background:</i></b> Characteristic changes in cerebral saturation (CrSO₂), amplitude-integrated electroencephalography (aEEG), and echocardiography (ECHO) may be associated with intraventricular hemorrhage (IVH); however, the feasibility of their combined application is not known. <b><i>Objective:</i></b> The aim of this work was to investigate the feasibility and safety of combined multimodal cerebral and hemodynamic monitoring in extremely low gestational age (ELGA) infants in the first 72 h after birth. <b><i>Methods:</i></b> In this prospective ­observational study of 50 infants born between 23 + 0 and 27 + 6 weeks gestation, we measured CrSO₂ and aEEG, starting &#x3c;8 h until 72 h of age. Sequential echocardiography and head ultrasound were performed at 4–8, 12–18, 24–30, and 48–60 h of age. The primary outcome was feasibility of multimodal monitoring, defined as &#x3e;75% of the subjects satisfying at least 3/4 criteria: (a) CrSO₂ and (b) aEEG monitoring each for &#x3e;75% of the time, and (c) at least 2 out of 4 ECHO and (d) head ultrasounds (at least one by age 24 h). Adverse reactions to sensors, desaturation, and bradycardia during ultrasound studies were recorded. <b><i>Results:</i></b> Fifty infants were enrolled over 14 months. Multimodal monitoring was feasible in 49 (98%) infants. Forty-one (82%) infants fulfilled all 4 criteria. Mild erythema below CrSO₂ sensors lasting 3–8 h without skin breakdown was noted in 8/50 subjects (16%). Desaturation was noted during 17/197 (8.6%) of the ultrasound studies. In total, 26/50 (52%) infants developed IVH (grade I/II, <i>n</i> = 22; grade III/IV, <i>n</i> = 4). <b><i>Conclusion:</i></b> Multimodal monitoring is feasible, safe, and well tolerated in ELGA infants in the first 72 h after birth.

Monitoring of cerebral oximetry in patients with postural orthostatic tachycardia syndrome

Aims Postural orthostatic tachycardia syndrome (POTS) is a disorder of unknown aetiology characterized by orthostatic intolerance and tachycardia with diverse other symptoms, including neurocognitive deficits. Cerebral oximetry non-invasively measures cerebral tissue saturation (SctO2) and has been shown to be informative in syncope evaluation. We aimed to assess SctO2 in POTS patients and those with normal response to orthostatic provocation, relative to haemodynamic parameters and symptoms. Methods and results Thirty-four patients with POTS (29.1 ± 9.5 years; 26 females) and 34 age-/sex-matched controls with normal head-up tilt tests (HUTs) were included. SctO2 at rest and during HUT were compared between POTS and controls. The relation between SctO2, systolic blood pressure (SBP), and heart rate (HR) during HUT was linearly assessed. SctO2 values were related to dizziness or syncope during HUT. The minimum SctO2-value during HUT was lower (65.4 ± 5.6 vs. 68.2 ± 4.2%, P = 0.023) and changes in SctO2 from supine to minimum HUT value were more pronounced in POTS patients (−5.7 ± 2.9% vs. −4.3 ± 2.1%, P = 0.028). Decrease in SBP from supine to minimum HUT value (P = 0.004) and increase in HR from supine to HUT value at 3 min (P = 0.022) correlated with more pronounced SctO2 decrease in POTS but not controls. SctO2 did not predict syncope or dizziness during HUT. Conclusion Postural orthostatic tachycardia syndrome patients have lower cerebral tissue saturation during orthostatic provocation compared with those subjects having normal haemodynamic response to tilt. Orthostatic decrease in cerebral saturation only weakly correlates with HR increase and does not predict vasovagal reflex in POTS. Other hitherto unknown factors may affect cerebral tissue saturation in POTS.