Mixed venous to arterial CO 2 gap as a marker to identify fluid responsiveness in septic shock patients / 中华急诊医学杂志

Objective:To investigate the value of the venous-to-arterial CO 2 gap (Δ CO 2 gap) before and after the fluid challenge (FC) in determining the fluid responsivenessin septic shock patients. Methods:A total of 104 septic shock patients admitted to the Medical Intensive Care Unit (MICU) of Peking Union Medical College Hospital were included in the retrospective study. All patients were monitored by Swan Ganz floating catheter during the FC. Hemodynamics and blood gas indices were collected before FC (T0) and immediately (T1), 10 min (T2), 30 min (T3) and 60 min (T4) after FC. Responders were defined as patients with a > 10% increase in cardiac output (CO) after FC. Spearman correlation analysis was used to evaluate the correlation between CO 2 gap and CO. The value of ΔCO2 gap were calculated by the area under the receiver operating characteristic (AUROC) curve in the whole population. Results:Among 104 patients, the effective rates of FC at T1, T2, T3 and T4 were 59% (61/104), 72% (75/104), 73% (76/104), and 77% (80/104), respectively. CO of patients in the reactive group was lower than that in the non-reactive group at T2 [6.0 (4.7, 7.5) vs. 7.2 (6.4, 8.5) L/min, P=0.019], and there was no significant difference in CO 2 gap between the two groups before FC. Spearman correlation analysis showed that CO 2 gap was negatively correlated with CO, and the correlations between CO 2 content gap and CO was -0.34, and -0.33 of CO 2 pressure gap and CO, respectively (both P <0.05). ROC curve analysis showed that the ΔCO 2 gap at T1 could weakly judge the reactivity at T2, T3 and T4, but could not judge the reactivity at T1. The AUROC at T2 was 0.669 of ΔCO 2 content gap and 0.684 of ΔCO 2 pressure gap (both P <0.05). Conclusions:The evaluate time judging the effect of FC should be appropriately extended. The change value of CO 2 gap before and immediately after volume expansion in septic shock patients can judge the fluid responsiveness within 10 min after FC.

The prognostic value of PI combined with Pv-aCO 2 /Ca-vO 2 in patients with septic shock / 中华急诊医学杂志

Objective:To explore the predictive value of peripheral perfusion index (PI) combined with central venous-arterial carbon dioxide tension to arterial-venous oxygen content ratio(Pv-aCO 2/Ca-vO 2)for prognosis after initial resuscitation of septic shock. Methods:A total of 76 cases of patients with septic shock from January 2019 to January 2021 in emergency intensive care unit (EICU) of Harrson international peace hospital affiliated to Hebei Medical University were enrolled. All recovered according to 2016 Severe Sepsis and Septic Shock Treatment International Guidelines 2016 (SSC 2016) , and PI was monitored, central vein and arterial blood gas analysis was performed, and the ratio of Pv-aCO 2/Ca-vO 2 was calculated.The PI and Pv-aCO 2/Ca-vO 2 at 3 h,hemodynamic variables,oxygen metabolism indexes,APACHEⅡ and SOFA score were recorded.Patients were divided into survival group and death group according to 28 d survival condition, the dfferences in demographics and clinical data were compared between two groups.The Kaplan-Meier urviving curve was created and the survival of the patients was analyzed by the Log-rank test. Risk factors associated with the prognosis were analyzed using the Cox regression analysis. The role of PI and Pv-aCO 2/Ca-vO 2 in prediting death was evaluated by receiver operating characteristic curves(ROC). Results:There were 37 cases in survival group and 39 cases in death group.Compared with death group, PI in survival group [(1.77±0.63) vs. (0.89±0.69)]was significantly higher,and Pv-aCO 2/Ca-vO 2[(1.52±0.52) vs. (2.57±0.86)] was significantly lower ( P<0.05). Kaplan-Meier survival curve showed that the median survival time in the high PI group [20.09 d (95% CI:16.95-23.24) vs.11.00d (95% CI:7.14-14.86)] was longer than that in the low PI group(χ 2=12.424, P=0.000),and that in low Pv-aCO 2/Ca-vO 2 group [23.74 d (95% CI:20.35-27.13) vs.12.85d (95% CI:9.75-15.95)] was longer than that in the high Pv-aCO 2/Ca-vO 2 group (χ 2=12.200, P=0.000) .Cox regression analysis showed that both PI ( RR=0.397, 95% CI: 0.230-0.687, P =0.001) and Pv-aCO 2/Ca-vO 2 ( RR=1.878, 95% CI: 1.169-3.019, P =0.009) were predictors of 28 d mortality.The area under the ROC curve of PI and Pv-aCO 2/Ca-vO 2 for predicting 28 d death in patients with septic shock were 0.828 (95% CI: 0.732-0.923) and 0.785 (95% CI: 0.6777-0.893)respectively. The optimal cutoff values were 0.52 (sensitivity 58.3% and specificity 94.4%) and 0.35 (sensitivity 88.9% and specificity 63.9%)respectively, and the AUC of the combined prediction of the two indicators was 0.903 (95% CI: 0.835-0.971). Conclusions:Combination of PI and Pv-aCO 2/Ca-vO 2 is better to predict the risk of adverse outcomes of septie shock patients,and may provide useful information for the resuscitation at early stage.

The Relationship between Arterial Carbon Dioxide Tension and Oxygenator Exhausted Carbon Dioxide Tension during Cardiopulmonary Bypass

BACKGROUND: The neurologic deficit is one of the most serious complications after cardiopulmonary bypass (CPB). This complication has reported to be closely associated with arterial partial pressure of carbon dioxide tension (PaCO2). The traditional way to measure PaCO2 is by intermittent arterial gas analysis during CPB. We tested the relationship between PaCO2 and CPB exhausted partial pressure of carbon dioxide tension (exPCO2) which can be monitored continuously during CPB. METHODS: The total 46 patients who underwent cardiac surgery under CPB were studied. Capnography sampling line was connected to CPB exhausted port to monitor exPCO2. We sampled arterial blood from CPB for gas analysis at cooling, stable hypothermia, and rewarming phase and recorded exPCO2 simultaneously at each phase. RESULTS: We found out that exPCO2 was associated with temperature corrected PaCO2 (cPaCO2) at all 3 phases(r = 0.73, 0.70, 0.84, P < 0.05) and with temperature uncorrected PaCO2 (ucPaCO2) at cooling (r = 0.64, P < 0.05) and rewarming phases (r = 0.81, P < 0.05). CONCLUSIONS: We concluded that exPCO2 could be used to monitor either ucPaCO2 or cPaCO2 at cooling and rewarming phase and cPaCO2 at hypothermia during CPB.

Monitoring of PETCO2 during High Frequency Jet Ventilation for Laryngomicrosurgery

In general, PETCO2 is well correlated with PaCO2 during spontaneous and conventional mechanical ventilation in normal lungs. However, it is known that during high frequency jet ventilation, PETCO2 may underestimate PaCO2 because of inadequate washout of the anatomical dead space by a small tidal volume and the relatively slow response time of infrared CO2 analyzers. The validity of PETCO2 as a reflection of PaCO2 was assessed during HFJV in 40 patients undergoing laryngeal microsurgery. HFJV was applied through an injector inserted into the trachea 6 cm below the vocal cord. PETCO2 was obtained from a sampling line placed 2 cm below the injector. Both PETCO2 and PaCO2 were measured simultaneously after decreasing the frequency from 100 beats per minute to 15 beats per minute 10 and 20 minutes after the commencement of HFJV. There was a strong correlation (r = 0.955, P < 0.001) and a good correspondence between the mean PETCO2 and PaCO2 values with an average difference of 1.93 +/- 1.21 mmHg and a limit of agreement from -0.49 to 4.35 mmHg. It is suggested that the PETCO2 obtained following a decrease in the jet frequency during HFJV could closely reflect PaCO2.

The Monitoring of PETCO2 via Nasal Cannula in Spontaneously Breathing Patients during Spinal Anesthesia / 대한마취과학회지

BACKGROUND: Monitoring of PETCO2 in the patients during regional anesthesia may be no less important than under general anesthesia, but will aid in early detection of potentially catastrophic events. However, the utility and accuracy of capnography in non-intubated patients has received little attention. We examined correlation between PETCO2 measured via nasal cannula and PaCO2 values in the sedated spontaneously breathing patients during spinal anesthesia. METHODS: Thirty adult patients who underwent elective surgery were administered optimal doses of tetracaine and epinephrine mixture in their site of operation, length, weight and age. Thereafter, we sampled expired gas by 175ml/min and administered oxygen by 3L/min using oxygen delivery CO2 sampling nasal cannula. End tidal carbon dioxide tension, heart rate, blood pressure and respiratory rate were measured before and 20 min after 0.02 mg/kg midazolam i.v.. And arterial blood gases were once measured 20 min after 0.02 mg/kg midazolam i.v.. RESULTS: The patients, sedation state was asleep or calm in awake. End tidal carbon dioxide tension was significantly increased after midazolam injection (p<0.01), but another values were not different after midazolam injection. Linear regression analysis of arterial carbon dioxide tension and end tidal carbon dioxide tension after midazolam injection yielded y = 0.77x + 4.82 and r2 = 0.76 (p<0.01). CONCLUSIONS: End tidal carbon dioxide tension using oxygen delivery CO2 sampling nasal cannula in the sedated spontaneously breathing patients with midazolam during spinal anesthesia were significantly related with arterial carbon dioxide tension. Therefore, we conclude that monitoring of PETCO2 via nasal cannula is a reliable means during spinal anesthesia.

Variation in Arterial to End - Tidal Carbon Dioxide Tension Differences by Duration of Anesthesia and Position during Anesthesia / 대한마취과학회지

BACKGROUND: The adquacy of ventilation can be monitored noninvasively, continuously, and in real time by using capnography. But the difference between arterial and end-tidal carbon dioxide tension was related to the presence or absence of lung disease, age, ASA class, systolic blood pressure and the other factors. The purpose of this study is to evaluate the effect of duration of anesthesia and position on the difference between arterial and end-tidal carbon dioxide tension. METHOD: 15 patients were selected for supine group(group 1) and 15 patients scheduled for spine surgery were selected for prone group(group 2). The anesthesia was induced by penthotal sodium(5mg/kg) and succinylcholine(2mg/kg). After intubation, anesthesia was maintained by demerol, midazolam, nitrous oxide and oxygen. The patients were ventilated mechanically with tidal volume 10mi/kg and respiration rate 12/min. Arterial and end-tidal carbon dioxide tension, heart rate, arterial blood pressure and esophageal temperature were estimated at 10min after induction of anesthesia. At 30min, 60min and 90min after placement in the position for operation and the end of the surgical procedure, these parameters were also measured. RESULT: 1) Arterial and end-tidal carbon dioxide tension decreased significantly at 30min, 60min and 90min after placement in the position for operation and the end of the surgical procedure in both group. 2) There was no statistically significantly difference in P(a-ET)CO2 between both group. But a gradual increase in mean P(a-ET)CO2 occured with maintenance of anesthesia in group 2. 3) No significant relationship was seen between mean P(a-ET)CO2 and heart rate, mean arterial pressure and temperature. CONCLUSION: We do not believe it is valid to assume that a constant arterial to end-tidal CO2 gradients exists when estimating PaCO2 from P(ET)CO2 when the patient is in the prone position for spine surgery.

Comparison of Arterial Carbon Dioxide Tension and End-tidal Carbon Dioxide Tension in Infants and Children / 대한마취과학회지

End-tidal PCO2 measurements are less accurate in neonates, infants, and small children than in adults. These in accuracies may by attributed in part to the dilution of end-tidal gas with fresh gas as a result of placing the sampling catheter between the endotracheal tube and a partial rebreathing circuit. To determine the most accurate catheter position for measurements of end-tidal gas tensions, end-tidal PCO2 was measured continuously from the distal and proximal end of the endotracheal tube and these data were compared with simultaneous arterial PCO2 The results were as follows: 1) In children weigthing above 15 kg ventilated with partial rebreathing circuit, both distal and proximal end-tidal PCO2 values approximated arterial PCO2 (p<0.05). 2) In infants and children weigthing below 15 kg ventilated with Ayre's T-piece breathing circuit(Jackson-Rees modification), only distal end-tidal PCO2 approximated arterial PCO2.

Comparison between End - Tidal Carbon Dioxide Tension and Arterial Carbon Dioxide Tension during Cardiopulmonary Bypass / 대한마취과학회지

The changes in arterial carbon dioxide tension (PaCO2) during cardiopulmonary bypass reflect changes of temperature and gas flow through an oxygenator. The changes in PaCO2 can be reduced through the frequent analysis of arterial blood gases and subsequent adjustment of total gas flow and CO2 concentration in the gas flow or both. Utilizing a capnometer (CAPNOMAC AGM-103. Datex), we compared end-tidal carbon dioxide tension (PetCO2) from the capnometer with temperature corrected PaCO2 during cardiopulmonary bypass. One end of the sampling port of the capnometer was incorporated into the prime port of the arterial reservoir in a bubbling type oxygenator (William-Harvey). When arterial reservoir temperatures of the oxygenator were 30 degrees C and 35 degrees C, PetCO2 from the capnometer was recorded and two arterial blood gas samplings were done at the same temperatures. The results were as follows: 1) The difference of PetCO2 and temperature corrected PaCO2 was below 3 mmHg in all cases. 2) The relationship between PetCO2 and temperature corrected PaCO2 was significantly linear. The results show that continuous monitoring of PetCO2, using a capnometer is useful to control the changes in PaCO2 during cardiopulmonary bypass.

Relationship between Arterial and End-tidal CO2 Tensions in Anesthetized Infants and Children / 대한마취과학회지

End-tidal (PETCO2) and arterial CO2, tensions (PaCO2) were measured in 66 anesthetized infants and children. 35 patients were under 7 year-old (group 1) and 31 patients were over 7 year-old (group 2). In both groups, differences between PETCO2, and PaCO2, were evaluated, and correlations between PETCO2, and PaCO2, were carried out. The children in group 1 had a PaCO2, (mean+/-S.D.) of 29.2+/-4.1mmHg and a PCO2, (mean+/-S,D.) of 29.2+4.1mmHg. The range of the PaCO2, and PETCO2 difference (P alpha-ETCO2) was from -1.0 to 1.2 mmHg. The children in group 2 had a PaCO2 (mean+/-S.D.) of 29.3+/-3.0 mmHg and a PETCO2 (mean+/-S.D.) of 29.3+/-4.0mmHg. The range of the P alpha-ETCO2 was from 1.9 to 2.5mmHg. The significant direct correlations between PaCO2 and PETCO2 in both groups (r=0.96,0.84, respec-tively) were defined. The difference between groups wasnt statistically significant. It is concluded that in normal infants and children during anesthesia, noninvasive measurement of PET CO2 can be used as a reliable estimate of PaCO2 and that PETCO2did not differ significantly from PaCO2.

Acute Respiratory Failure following Anesthesia / 대한마취과학회지

We define acute respiratory failure(ARF) as present whenever the ratio of arterial oxygen tension (PaO2) and inspired oxygen concentrarion(FiO2) is below the normal predicted range for the patient's age and/or the arterial carbon dioxide tension(PaCO2) is above 45 in the absence of respiratory compention for metabolic alkalosis. Adult respiratory distress syndrome(ARDS) which is associated with shock, trauma, infection, inhalation of toxic gas, aspiration of gastric content and drugs etc, first received wide-spread attention in 1967. ARDS is a descriptive term that is characterized by a combination of refractory hypoxemia and severly decreased lung compliance. Numerous specific incidents or illnesses may be complicated by, or associated with ARDS. Early diagnosis and improvement in physiological therapy including PEEP therapy have been successful in treating the early and mild episodes of ARDS. This report describes three cases of ARF following anesthesia and reviews the literature.

The Difference between End-tidal and Arterial PCO2 in Anesthetized Patients / 대한마취과학회지

The relationship between end-tidal carbon dioxide tension(PECO2) as measured by infrared analysis(Datascope Accucap, U.S.A.) and arterial carbon dioxide tension(PaCO2) during general anesthesia was systemically examined in fifty relatively healthy patients(ASA class 1). Body temperature was measured to determine the variation in PaCO2 minus PECO2. The results were as follows: 1) The mean PEzCO2 was 26.2+/-0.7 torr. 2) The mean PaCO2 was 31.6+/-0.8 torr. 3) The average of PaCO2 minus PECO2 was 5.1+/-0.6 torr. 4) PaCO2 was directly related to PECO2. An equation was obtained by simple regression analysis to predict PaCO2. PaCO2=0.899. PECO2+7.57(r=0.715; p<0.01). 5) Body temperature (between 34.3 degrees C and 37.9 degrees C) was not related to PaCO2 minus PECO2 (r=0.1). I thought that measurement of PECO2 is very simple and a guideline of ventilation of the patients in anesthesis and ICU.