Central venous-to-arterial CO2 difference as a biomarker of outcome in children who underwent surgery for congenital heart disease / Diferencia arteriovenosa de CO2 como biomarcador de desenlace en niños operados de cardiopatías congénitas

Abstract Background: In congenital heart surgery, low cardiac output syndrome (LCOS) is a major cause of morbidity in the immediate post-operative period. A decrease in cardiac output leads to an increase in tissue oxygen consumption. Several biomarkers such as venous oxygen saturation (SvO2), arteriovenous oxygen difference (DavO2), and lactate can assess tissue perfusion in the presence of LCOS. Recently, central venous to arterial CO2 difference (ΔCO2) has been proposed as a biomarker of tissue ischemia that could be used as a predictor of death in neonatal patients. This study aimed to analyze the relationship between ΔCO2 and immediate post-operative outcomes in pediatric patients undergoing congenital heart surgery and its correlation with DavO2, SvO2, and lactate. Methods: We conducted a longitudinal study of patients aged 0-18 years who underwent congenital heart surgery with or without cardiopulmonary bypass at the Instituto Nacional de Pediatría, from March 2019 to March 2021. Results: Eighty-two patients were included; the median age was 17 months. About 59% had a ΔCO2 ≥ 6 mmHg. Patients with ΔCO2 ≥ 6 mmHg had a vasoactive-inotropic score > 5 (p < 0.001), DavO2 > 5 mL/dL (p = 0.048), and lactate > 2 mmol/L (p = 0.027), as well as a longer hospital stay (p = 0.043). Patients with ΔCO2 > 6 mmHg and vasoactive-inotropic score ≥ 10 were 12.6 times more likely to die. Conclusion: ΔCO2 is a good marker of tissue hypoperfusion and outcome in the post-operative period of congenital heart surgery.

Resumen Introducción: En la cirugía cardiaca de malformaciones congénitas, el síndrome de bajo gasto cardiaco (SBGC) es una de las principales causas de morbilidad en el postoperatorio inmediato. La caída del gasto cardiaco aumenta el consumo de oxígeno en los tejidos. Varios biomarcadores, como la saturación venosa de oxígeno (SvO2), la diferencia arteriovenosa de oxígeno (DavO2) y el lactato han sido utilizados como indicadores hipoperfusión tisular en presencia de SBGC. Recientemente, la diferencia arteriovenosa de CO2 (ΔCO2) se ha propuesto como otro biomarcador de isquemia tisular que podría utilizarse como predictor de muerte en pacientes en edad neonatal. El objetivo de este estudio fue analizar la relación entre la ΔCO2 y la evolución postoperatoria de pacientes pediátricos operados de cardiopatías congénitas y correlacionarlo con la DavO2, SvO2 y lactato. Métodos: Se realizó un estudio longitudinal en pacientes de 0 a 18 años operados de corazón con empleo de bomba de circulación extracorpórea en el Instituto Nacional de Pediatría. Resultados: Se incluyeron 82 pacientes; la mediana de edad fue de 17 meses. El 59% presentó un ΔCO2 > 6 mmHg. Los pacientes con un ΔCO2 > 6 mmHg mostraron un puntaje de inotrópicos > 5 (p < 0.001), DavO2 > 5 mL/dL (p = 0.048) y lactato > 2 mmol/L (p = 0.027), así como mayor estancia hospitalaria (p = 0.043). Los pacientes con ΔCO2 > 6 mmHg y un puntaje de inotrópicos ≥ 10 presentaron una probabilidad de muerte 12.6 veces mayor. Conclusiones: El ΔCO2 en el periodo postoperatorio de una cirugía cardiaca congénita es un buen marcador de hipoperfusión tisular y de desenlace.

Using peripheral perfusion index and venous-to-arterial CO2difference/arterial-central venous O2 difference ratio to assess lactate clearance in septic patients after resuscitation / 中华内科杂志

Objective The relationship of venous-to-arterial CO2difference(Pv-aCO2)/ arterial-central venous O2difference (Ca-vO2) ratio, peripheral perfusion index(PI) and lactate clearance(LC) were investigated during resuscitation in septic patients. And, the meaning of the combination PI and Pv-aCO2/Ca-vO2ratio to interpret incoherence of lactate clear was explored. Methods The patients with sepsis were prospectively observed, who admitted to critically care medicine department of Peking Union Medical College Hospital. The hemodynamic parameters, simultaneous arterial and central venous blood gas analysis and PI were obtained at the enrollment (T0) and 8 hours (T8) during resuscitation. The lactate clearance was defined as 8h-LC≥10% and non-lactate clearance was defined as 8h-LC≤10%. Additionally, the patients were divided as three sub-groups according to the PI value at T8: the normalized PI group with PI≥1.4,the mild impaired PI with 1.4＜PI＜0.6 and severe impaired PI with PI≤0.6. Results A total of 84 patients were enrolled in this study. There was no significant difference in Pv-aCO2/Ca-vO2ratio in the three groups. However, the PI≤0.6 group had a significantly higher Pv-aCO2than other groups. Moreover, the patients with non-lactate clearance (13/32) had a higher Pv-aCO2/Ca-vO2ratio than the patients with lactate clearance in PI≥1.4 group (1.9±0.7 vs. 1.3±1.0, P=0.01). Multivariate analysis showed both Pv-aCO2/Ca-vO2ratio [Exp(B) 2.235,95% CI 1.232-4.055,P=0.008] and acute physiology and chronic health evaluation Ⅱ(APACHEⅡ) [Exp(B)1.087,95%CI 1.022-1.156,P=0.008] were independent risk factor of non-lactate clearance. 8h-PI was significantly negative correlated with the 8 h Pv-aCO2gap (r=-0.311, P=0.004), but not significantly with Pv-aCO2/Ca-vO2ratio (r=-0.094, P=0.385). Conclusions Both high Pv-aCO2/Ca-vO2 ratio and low PI were related to non-lactate clearance after resuscitation in sepsis. Combined PI and Pv-aCO2/Ca-vO2ratio could interpret incoherence of latacte clearance after resuscitation.

Influence of Intra-Operative Regional Cerebral Blood Flow and the Carbon Dioxide Partial Pressure Difference between Arterial and End-Tidal on the Neurologic Outcome

OBJECTIVE: End-tidal partial pressure of carbon dioxide(PETCO2) is often used as an estimate of arterial partial pressure of carbon dioxide(PaCO2), with the understanding that PaCO2 usually exceeds PETCO2. During craniotomies, because hyperventilation is used to therapeutically lower intracranial pressure, the difference between arterial and end-tidal partial pressure of carbon dioxide(P(a-ET)CO2) has therapeutic implications. To determine how much information concerning neurosurgical operation and clinical outcome is provided by the PETCO2, PaCO2 and P(a-ET)CO2 during surgery, we evaluated 81 patients who had neurosurgical operation. METHODS: There were 51 males and 30 females with a mean age of 50.3 years(range 7-85 years). After the induction of general anesthesia, body temperature was maintained in a normothermia, endtidal CO2 was maintained 28-34mmHg and the systolic blood pressure was kept 90-120mmHg. ETCO2, PaCO2 and regional cortical blood flow(rCoBF) were checked at the time of dura closure. Neurologic outcome was evaluated at 8 hours after operation to rule out other factors which may influence on the patient's long-term outcome. Data were collected and compared by student's t-test or chi-square analysis. RESULTS: The PaCO2 was 34.6+/-5.2mmHg(range, 24.9-54.8), PETCO2 was 29.9+/-4.1mmHg(range, 20.0-45.0) and P(a-ET)CO2 was 4.7+/-3.5mmHg(range, -1.1-18.6). The correlation between the PaCO2 and PETCO2 was statistically significant(PETCO2=13.3-0.57xPaCO2). But there was no correlation of rCoBF with PaCO2 and ETCO2. P(a-ET)CO2 values less than 8mmHg were correlated well with good neurologic outcome compared with higher P(a-ET)CO2 patients. PaCO2, rCoBF, mean arterial blood pressure, arterial pH and initial Glasgow coma scale showed statistically significant correlation with neurologic outcome(p<0.05). CONCLUSION: Based on our study, P(a-ET)CO2 value could be used as a good prognostic factor during the neurosurgical operation and anesthesiologist should be tried to decrease this value. And in patients who has a intact brain autoregulation, rCoBF was not influenced by PaCO2 and ETCO2, entirely.

End-tidal CO2 Measurement Via Nasal Cannula in Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Major respiratory problems during spinal anesthesia occur due to several causes, particulary, high spinal block, use of sedatives or opioids, and underlying cardiopulmonary diseases. Pulse oximetry has prevented most of these problems, but has not provided rapid and accurate information of the patient's ventilation. We measured end-tidal CO2 tension via the side-stream capnometer with a small rubber cannula and investigated its effectiveness in ventilatory monitoring under spinal anesthesia. METHODS: Nineteen patients were involved in this study. We performed spinal anesthesia with 0.5% heavy marcaine 12 mg (L3-4 interspace). After fixation of spinal sensory blockade level, 0.035 mg/kg of midazolam was administered intravenously to sedate the patient. A polyvinylchloride catheter with a rubber extending nasal cannula was used for sampling of respiratory gas. PETCO2 was measured at 15 minutes after spinal anesthetic injection (before sedation), and at 5 minutes after midazolam injection (after sadation). Arterial CO2 tension was also measured during PETCO2 measurement. RESULTS: There was no correlation of spinal maximal sensory blockade level with repiratory rate, PaCO2 and PETCO2. Linear regression analysis of arterial vs. end-tidal CO2 yielded a slope of 0.92, r=0.81 and p<0.001 (before sedation), and a slope of 0.98, r=0.79 and p<0.01 (after sedation). Arterial to end-tidal differences were 4.2+/-2.8 mmHg (before sedation) and 4.3+/-3.0 (after sedation), but there was no significant difference in comparing them with each other. Conclusions : We conclude that this form of PETCO2 measurement is useful in continuous, noninvasive monitoring of ventilation in patients under spinal anesthesia.