Current perspectives on treatment of perioperative hemodynamic instability and hypotension

Frequency domain analysis of photoplethysmographic and arterial pressure waveforms for assessing hemodynamics in children with congenital heart surgery

BACKGROUND

Time-domain parameters are less reliable in children due to increased arterial and chest wall compliance. We assessed the ability of indices derived from frequency analysis of photoplethysmography (PPG) and arterial blood pressure (ABP) waveforms to predict the hemodynamic state in children undergoing congenital heart surgery.

METHODS

We analyzed waveforms after cardiopulmonary bypass period in 76 children who underwent total repair of congenital heart disease. Amplitude density of baseline and amplitude modulation in PPG and ABP by respiratory frequency were obtained using fast Fourier transform analysis and normalized by cardiac pulse height (representing respiratory modulations in venous blood [PPG-DC%] and in amplitude [PPG-AC%] at respiratory frequency). The ratio of amplitude density of PPG at the cardiac frequency (CF) to ABP-CF was used to assess vascular compliance. We assessed volume replacement (ml/kg) and vasoactive inotropic score (VIS).

RESULTS

Children requiring volume replacement > 10 ml/kg (15.8%) showed higher PPG-DC% than those not requiring it (median: 52.4%, 95% CI [24.8, 295.1] vs. 36.7% [10.7, 125.7], P = 0.017). In addition, children with a VIS > 7 (22.4%) showed higher PPG-CF/ABP-CF (3.6 [0.91, 10.8] vs. 1.2 [0.27, 5.5], P = 0.008). On receiver operating characteristic curve analysis, PPG-DC% predicted a higher fluid requirement (area under the curve: 0.71, 95% CI [0.604, 0.816], P = 0.009), while PPG-CF/ABP-CF predicted a higher VIS (0.714, [0.599, 0.812], P = 0.004).

CONCLUSIONS

Frequency domain analysis of PPG and ABP may assess hemodynamic status requiring fluid or vasoactive inotropic therapy after congenital heart surgery.

Single centre analysis of factors influencing surgical treatment of splenic trauma in children

OBJECTIVE

This study aims to investigate determinants impacting the surgical management of splenic trauma in paediatric patients by scrutinizing age distribution, etiological factors and concomitant injuries. The analysis seeks to establish a foundation for delineating optimal operative timing.

METHODS

A cohort of 262 paediatric cases presenting with splenic trauma at our institution from January 2011 to December 2021 underwent categorization into either the conservative or operative group.

RESULTS

Significantly disparate attributes between the two groups included age, time of presentation, blood pressure, haemoglobin levels, blood transfusion requirements, thermal absorption, American Association for the Surgery of Trauma (AAST) classification and associated injuries. Logistic regression analysis revealed age, haemoglobin levels, AAST classification and blood transfusion as autonomous influencers of surgical intervention (OR = 1.024, 95% CI: 1.011-1.037; OR = 1.067, 95% CI: 1.01-1.127; OR = 0.2760, 95% CI: 0.087-0.875; OR = 7.873, 95% CI: 2.442-25.382; OR = 0.016, 95% CI: 0.002-0.153). The AAST type and age demonstrated areas under the receiver operating characteristic (ROC) curve of 0.782 and 0.618, respectively.

CONCLUSION

Age, haemoglobin levels, AAST classification and blood transfusion independently influence the decision for surgical intervention in paediatric patients with splenic trauma. Age and AAST classification emerge as viable parameters for assessing and prognosticating the likelihood of surgical intervention in this patient cohort.

A practical approach to cerebral near-infrared spectroscopy (NIRS) directed hemodynamic management in noncardiac pediatric anesthesia

Safeguarding cerebral function is of major importance during pediatric anesthesia. Premature, ex-premature, and full-term neonates can be vulnerable to physiological changes that occur during anesthesia and surgery. Data from studies performed during pediatric cardiac surgery and in neonatal/pediatric intensive care units have shown the benefits of near-infrared spectroscopy (NIRS) monitoring of regional cerebral oxygenation (c-rSO₂ ). However, NIRS monitoring is seldom used during noncardiac pediatric anesthesia. Despite compelling evidence that blood pressure does not reflect end-organ perfusion, it is still regarded as the most important determinant of cerebral perfusion and the most relevant hemodynamic management target parameter by most (pediatric) anesthetists. The principle of NIRS monitoring is not self-explanatory and sometimes seems even counterintuitive, which may explain why many anesthesiologists are reserved regarding its use. The first part of this paper is dedicated to a clinical introduction to NIRS monitoring. Despite scientific efforts, it has not yet been possible to define individual lower limit c-rSO₂ values and it is unlikely this will succeed in the near future. Nonetheless, published treatment algorithms usually specify c-rSO₂ values which may be associated with cerebral hypoxia. Our treatment guideline for maintaining sufficient cerebral oxygenation differs fundamentally from all previously published approaches. We define a baseline c-rSO₂ value, registered in the awake child prior to anesthesia induction, as the lowest acceptable limit during anesthesia and surgery. The cerebral rSO₂ is the single target parameter, while blood pressure, heart rate, P_a CO₂ , and SaO₂ are major parameters that determine the c-rSO2. Cerebral NIRS monitoring, interpreted together with its continuously available contributing parameters, may help avoid potentially harmful episodes of cerebral desaturation in anesthetized pediatric patients.