[Prognostic markers of mortality after congenital heart defect surgery]

Effect of preoperative pulse oximeter oxygen saturation on postoperative prolonged mechanical ventilation in patients with tetralogy of Fallot

Background

As an easily accessible and intervened clinical indicator, preoperative pulse oximeter oxygen saturation (SpO₂) is an important factor affecting the prognosis of patients with tetralogy of Fallot (TOF). However, whether SpO₂ is associated with postoperative mechanical ventilation (MV) time remains unknown. Therefore, this study aimed to investigate the impact of preoperative SpO₂ on postoperative prolonged mechanical ventilation (PMV) in children with TOF.

Materials and methods

The study included children younger than 18 years who underwent corrective operations for TOF between January 2016 and December 2018 in Fuwai Hospital, China. Univariate and multivariate logistic regression analyses were used to evaluate the influence of preoperative SpO₂ on postoperative PMV. After identifying SpO₂ as an independent risk factor for PMV, patients were further divided into two groups according to the cutoff value of SpO₂, and propensity score matching (PSM) analysis was used to eliminate the effect of confounding factors. The logistic regression was used to compare the outcomes between the two groups after PSM.

Results

A total of 617 patients were finally enrolled in this study. By the univariable and multivariate logistic analysis, four independent risk factors for PMV were determined, namely, SpO₂, surgical technique, aortic cross-clamp time, and intraoperative minimum temperature. According to the outcomes of 219 paired patients after PSM, the incidence of PMV was significantly higher in patients with lower preoperative SpO₂ (P = 0.022). Also, there was significant increase in mechanical ventilation time (P = 0.019), length of intensive care unit stay (P = 0.044), postoperative hospital stay (P = 0.006), hospital stay (P = 0.039), and hospitalization cost (P = 0.019) at the lower preoperative SpO₂ level.

Conclusion

Low preoperative SpO₂ represents an independent risk factor of postoperative PMV in children with TOF.

[Regional cerebral oxygen saturation as a marker of hemodynamic state following cardiac surgery]

INTRODUCTION

Regional cerebral oxygen saturation (rSO₂) is a measure of the general state of perfusion and oxygenation. We aim to analyze the relationship between this and various hemodynamic and respiratory parameters.

PATIENTS AND METHODS

Forty-three patients, operated on between October 2011 and July 2012, were included in this prospective observational descriptive study. The following parameters were measured: mean arterial pressure, both arterial and central venous oxygen saturation and partial pressures of oxygen and carbon dioxide, and lactate levels. From these parameters, the oxygenation index and the oxygen extraction ratio were calculated. These measurements were studied to evaluate whether rSO₂ correlated significantly with the other parameters.

RESULTS

The average age and weight of the patients were 27.3 months and 9.2 kg, respectively. The rSO₂ correlated positively with both central venous oxygen saturation (r=0.73, P<.01) and mean arterial pressure (r=0.59, P<.01), and negatively with the oxygen extraction ratio (r=-0.7, P<.01). No correlation was found with the respiratory parameters. Concordance analysis established an acceptable Kappa index (> 0.4) between the rSO₂ and central venous oxygen saturation, and between the rSO₂ and oxygen extraction ratio.

CONCLUSIONS

Regional cerebral oxygen saturation correlates well with hemodynamic parameters - mean arterial pressure, venous saturation, and the tissue oxygen extraction. However, it does not correlate with respiratory parameters.