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302 results on '"Arterial carbon dioxide tension"'

1. Lower Oxygen Tension and Intracranial Hemorrhage in Veno-venous Extracorporeal Membrane Oxygenation.

Author

Akbar, Armaan F., Shou, Benjamin L., Feng, Cheng-Yuan, Zhao, David X., Kim, Bo Soo, Whitman, Glenn, Bush, Errol L., Cho, Sung-Min, the HERALD Investigators, Keller, Steven, Alejo, Diane, Calligy, Kate, Anderson, Scott, Menta, Arjun, Sun, Philip, Kook Kang, Jin, Rando, Hannah, Chinedozi, Ifeanyi, Hwang, Jaeho, and Darby, Zachary

Subjects
*EXTRACORPOREAL membrane oxygenation, *INTRACRANIAL hemorrhage, *BRAIN injuries, *CARBON dioxide, *OXYGEN
Abstract

Introduction and Methods: We examined the relationship between 24-h pre- and post-cannulation arterial oxygen tension (PaO2) and arterial carbon dioxide tension (PaCO2) and subsequent acute brain injury (ABI) in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) with granular arterial blood gas (ABG) data and institutional standardized neuromonitoring. Results: Eighty-nine patients underwent VV-ECMO (median age = 50, 63% male). Twenty (22%) patients experienced ABI; intracranial hemorrhage (ICH) was the most common diagnosis (n = 14, 16%). Lower post-cannulation PaO2 levels were significantly associated with ICH (66 vs. 81 mmHg, p = 0.007) and a post-cannulation PaO2 level < 70 mmHg was more frequent in these patients (71% vs. 33%, p = 0.007). PaCO2 parameters were not associated with ABI. By multivariable logistic regression, hypoxemia post-cannulation increased the odds of ICH (OR = 5.06, 95% CI:1.41–18.17; p = 0.01). Conclusion: In summary, lower oxygen tension in the 24-h post-cannulation was associated with ICH development. The precise roles of peri-cannulation ABG changes deserve further investigation, as they may influence the management of VV-ECMO patients. [ABSTRACT FROM AUTHOR]

Published
2023
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2. Arterial carbon dioxide tension has a non-linear association with survival after out-of-hospital cardiac arrest: A multicentre observational study.

Author

Mckenzie, Nicole, Finn, Judith, Dobb, Geoffrey, Bailey, Paul, Arendts, Glenn, Celenza, Antonio, Fatovich, Daniel, Jenkins, Ian, Ball, Stephen, Bray, Janet, and Ho, Kwok M.

Subjects
*CARDIAC arrest, *CARBON dioxide, *INTENSIVE care units, *SPLINES, *ODDS ratio, *SCIENTIFIC observation
Abstract

Purpose: International guidelines recommend targeting normocapnia in mechanically ventilated out-of-hospital cardiac arrest (OHCA) survivors, but the optimal arterial carbon dioxide (PaCO2) target remains controversial. We hypothesised that the relationship between PaCO2 and survival is non-linear, and targeting an intermediate level of PaCO2 compared to a low or high PaCO2 in the first 24-h of ICU admission is associated with an improved survival to hospital discharge (STHD) and at 12-months.Methods: We conducted a retrospective multi-centre cohort study of adults with non-traumatic OHCA requiring admission to one of four tertiary hospital intensive care units for mechanical ventilation. A four-knot restricted cubic spline function was used to allow non-linearity between the mean PaCO2 within the first 24 h of ICU admission after OHCA and survival, and optimal PaCO2 cut-points were identified from the spline curve to generate corresponding odds ratios.Results: We analysed 3769 PaCO2 results within the first 24-h of ICU admission, from 493 patients. PaCO2 and survival had an inverted U-shape association; normocapnia was associated with significantly improved STHD compared to either hypocapnia (<35 mmHg) (adjusted odds ratio [aOR] 0.45, 95% confidence interval [CI] 0.24-0.83) or hypercapnia (>45 mmHg) (aOR 0.45, 95% CI 0.24-0.84). Of the twelve predictors assessed, PaCO2 was the third most important predictor, and explained >11% of the variability in survival. The survival benefits of normocapnia extended to 12-months.Conclusions: Normocapnia within the first 24-h of intensive care admission after OHCA was associated with an improved survival compared to patients with hypocapnia or hypercapnia. [ABSTRACT FROM AUTHOR]

Published
2021
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5. Association Between Arterial Carbon Dioxide Tension and Outcome in Patients Admitted to the Intensive Care Unit After Coronary Artery Bypass Surgery.

Author

Choi, Jeong-Hyun, Lee, Eun-Ho, Jang, Myung-Soo, Jeong, Dae-Hee, and Kim, Mi Kyeong

Abstract

Objectives The aim of this study was to determine the association between PaCO 2 and patient outcome in patients admitted to the intensive care unit (ICU) after coronary artery bypass grafting (CABG). Design A retrospective cohort study. Setting Single-institutional, university hospital. Participants All patients admitted to the ICU after CABG between January 2009 and December 2012. Interventions None. Measurements and Main Results Based on PaCO 2 status during the first 24 hours after CABG, 1,011 patients were classified into 4 groups: normocapnia, hypocapnia, hypercapnia, and dual hyper/hypocapnia. The 30-day mortality rate was 0.7% (n = 4) for normocapnia, 1.5% (n = 4) for hypocapnia, 2.2% (n = 3) for hypercapnia, and 7.5% (n = 4) for the dual-exposure group. The extubation times were 13.3±21.7 hours, 15.8±21.37 hours, 21.79±39.70 hours, and 42.29±75.35 hours, respectively. After adjusting for confounding variables, the dual hypocapnia and hypercapnia exposure group was associated with increased 30-day mortality (odds ratio [OR] = 8.08; 95% confidence interval [CI], 1.82-35.86; p = 0.006) and delayed extubation (OR = 2.40; 95% CI, 1.24-4.64; p = 0.010). Conclusions Exposure to both hypocapnia and hypercapnia within 24 hours after CABG was associated independently with increased risk of 30-day mortality and delayed extubation. Exposure to either hypocapnia or hypercapnia alone was not associated with patient outcome. [ABSTRACT FROM AUTHOR]

Published
2017
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8. Arterial carbon dioxide tension has a non-linear association with survival after out-of-hospital cardiac arrest: A multicentre observational study

Abstract

Purpose: International guidelines recommend targeting normocapnia in mechanically ventilated out-of-hospital cardiac arrest (OHCA) survivors, but the optimal arterial carbon dioxide (PaCO2) target remains controversial. We hypothesised that the relationship between PaCO2 and survival is non-linear, and targeting an intermediate level of PaCO2 compared to a low or high PaCO2 in the first 24-h of ICU admission is associated with an improved survival to hospital discharge (STHD) and at 12-months. Methods: We conducted a retrospective multi-centre cohort study of adults with non-traumatic OHCA requiring admission to one of four tertiary hospital intensive care units for mechanical ventilation. A four-knot restricted cubic spline function was used to allow non-linearity between the mean PaCO2 within the first 24 h of ICU admission after OHCA and survival, and optimal PaCO2 cut-points were identified from the spline curve to generate corresponding odds ratios. Results: We analysed 3769 PaCO2 results within the first 24-h of ICU admission, from 493 patients. PaCO2 and survival had an inverted U-shape association; normocapnia was associated with significantly improved STHD compared to either hypocapnia (<35 mmHg) (adjusted odds ratio [aOR] 0.45, 95% confidence interval [CI] 0.24−0.83) or hypercapnia (>45 mmHg) (aOR 0.45, 95% CI 0.24−0.84). Of the twelve predictors assessed, PaCO2 was the third most important predictor, and explained >11% of the variability in survival. The survival benefits of normocapnia extended to 12-months. Conclusions: Normocapnia within the first 24-h of intensive care admission after OHCA was associated with an improved survival compared to patients with hypocapnia or hypercapnia.

Published
2021

9. Incidence and management of metabolic acidosis with sodium bicarbonate in the ICU: An international observational study.

Abstract

BACKGROUND: Metabolic acidosis is a major complication of critical illness. However, its current epidemiology and its treatment with sodium bicarbonate given to correct metabolic acidosis in the ICU are poorly understood. METHOD(S): This was an international retrospective observational study in 18 ICUs in Australia, Japan, and Taiwan. Adult patients were consecutively screened, and those with early metabolic acidosis (pH<7.3 and a Base Excess<-4 mEq/L, within 24-h of ICU admission) were included. Screening continued until 10 patients who received and 10 patients who did not receive sodium bicarbonate in the first 24 h (early bicarbonate therapy) were included at each site. The primary outcome was ICU mortality, and the association between sodium bicarbonate and the clinical outcomes were assessed using regression analysis with generalized linear mixed model. RESULT(S): We screened 9437 patients. Of these, 1292 had early metabolic acidosis (14.0%). Early sodium bicarbonate was given to 18.0% (233/1292) of these patients. Dosing, physiological, and clinical outcome data were assessed in 360 patients. The median dose of sodium bicarbonate in the first 24 h was 110 mmol, which was not correlated with bodyweight or the severity of metabolic acidosis. Patients who received early sodium bicarbonate had higher APACHE III scores, lower pH, lower base excess, lower PaCO2, and a higher lactate and received higher doses of vasopressors. After adjusting for confounders, the early administration of sodium bicarbonate was associated with an adjusted odds ratio (aOR) of 0.85 (95% CI, 0.44 to 1.62) for ICU mortality. In patients with vasopressor dependency, early sodium bicarbonate was associated with higher mean arterial pressure at 6 h and an aOR of 0.52 (95% CI, 0.22 to 1.19) for ICU mortality. CONCLUSION(S): Early metabolic acidosis is common in critically ill patients. Early sodium bicarbonate is administered by clinicians to more severely ill patients but without correction fo

Published
2021

10. Incidence and management of metabolic acidosis with sodium bicarbonate in the ICU: An international observational study.

Abstract

BACKGROUND: Metabolic acidosis is a major complication of critical illness. However, its current epidemiology and its treatment with sodium bicarbonate given to correct metabolic acidosis in the ICU are poorly understood. METHOD(S): This was an international retrospective observational study in 18 ICUs in Australia, Japan, and Taiwan. Adult patients were consecutively screened, and those with early metabolic acidosis (pH<7.3 and a Base Excess<-4 mEq/L, within 24-h of ICU admission) were included. Screening continued until 10 patients who received and 10 patients who did not receive sodium bicarbonate in the first 24 h (early bicarbonate therapy) were included at each site. The primary outcome was ICU mortality, and the association between sodium bicarbonate and the clinical outcomes were assessed using regression analysis with generalized linear mixed model. RESULT(S): We screened 9437 patients. Of these, 1292 had early metabolic acidosis (14.0%). Early sodium bicarbonate was given to 18.0% (233/1292) of these patients. Dosing, physiological, and clinical outcome data were assessed in 360 patients. The median dose of sodium bicarbonate in the first 24 h was 110 mmol, which was not correlated with bodyweight or the severity of metabolic acidosis. Patients who received early sodium bicarbonate had higher APACHE III scores, lower pH, lower base excess, lower PaCO2, and a higher lactate and received higher doses of vasopressors. After adjusting for confounders, the early administration of sodium bicarbonate was associated with an adjusted odds ratio (aOR) of 0.85 (95% CI, 0.44 to 1.62) for ICU mortality. In patients with vasopressor dependency, early sodium bicarbonate was associated with higher mean arterial pressure at 6 h and an aOR of 0.52 (95% CI, 0.22 to 1.19) for ICU mortality. CONCLUSION(S): Early metabolic acidosis is common in critically ill patients. Early sodium bicarbonate is administered by clinicians to more severely ill patients but without correction fo

Published
2021

11. Cardiac Output and Cerebral Blood Flow: A Systematic Review of Cardio-Cerebral Coupling.

Abstract

Control of cerebral blood flow (CBF) is crucial to the management of neurocritically ill patients. Small studies which have examined the role of cardiac output (CO) as a determinant of CBF have inconsistently demonstrated evidence of cardio-cerebral coupling. Putative physiological mechanisms underpinning such coupling include changes in arterial blood pressure pulsatility, which would produce vasodilation through increased oscillatory wall-shear-stress and baroreceptor mediated reflex sympatholysis, and changes in venous backpressure which may improve cerebral perfusion pressure. We sought to summarize and contextualize the literature on the relationship between CO and CBF and discuss the implications of cardio-cerebral coupling for neurocritical care. A systematic review of the literature yielded 41 studies; all were of low-quality and at high-risk of bias. Results were heterogenous, with evidence for both corroboration and confutation of a relationship between CO and CBF in both normal and abnormal cerebrovascular states. Common limitations of studies were lack of instantaneous CBF measures with reliance on transcranial Doppler-derived blood flow velocity as a surrogate, inability to control for fluctuations in established determinants of CBF (eg, PaCO2), and direct effects on CBF by the interventions used to alter CO. Currently, the literature is insufficiently robust to confirm an independent relationship between CO and CBF. Hypothetically, the presence of cardio-cerebral coupling would have important implications for clinical practice. Manipulation of CBF could occur without the risks associated with extremes of arterial pressure, potentially improving therapy for those with cerebral ischemia of various etiologies. However, current literature is insufficiently robust to confirm an independent relationship between CO and CBF, and further studies with improved methodology are required before therapeutic interventions can be based on cardio-cerebral coupling.Copy

Published
2021

12. Cardiac Output and Cerebral Blood Flow: A Systematic Review of Cardio-Cerebral Coupling.

Abstract

Control of cerebral blood flow (CBF) is crucial to the management of neurocritically ill patients. Small studies which have examined the role of cardiac output (CO) as a determinant of CBF have inconsistently demonstrated evidence of cardio-cerebral coupling. Putative physiological mechanisms underpinning such coupling include changes in arterial blood pressure pulsatility, which would produce vasodilation through increased oscillatory wall-shear-stress and baroreceptor mediated reflex sympatholysis, and changes in venous backpressure which may improve cerebral perfusion pressure. We sought to summarize and contextualize the literature on the relationship between CO and CBF and discuss the implications of cardio-cerebral coupling for neurocritical care. A systematic review of the literature yielded 41 studies; all were of low-quality and at high-risk of bias. Results were heterogenous, with evidence for both corroboration and confutation of a relationship between CO and CBF in both normal and abnormal cerebrovascular states. Common limitations of studies were lack of instantaneous CBF measures with reliance on transcranial Doppler-derived blood flow velocity as a surrogate, inability to control for fluctuations in established determinants of CBF (eg, PaCO2), and direct effects on CBF by the interventions used to alter CO. Currently, the literature is insufficiently robust to confirm an independent relationship between CO and CBF. Hypothetically, the presence of cardio-cerebral coupling would have important implications for clinical practice. Manipulation of CBF could occur without the risks associated with extremes of arterial pressure, potentially improving therapy for those with cerebral ischemia of various etiologies. However, current literature is insufficiently robust to confirm an independent relationship between CO and CBF, and further studies with improved methodology are required before therapeutic interventions can be based on cardio-cerebral coupling.Copy

Published
2021

14. Changes in central venous-to-arterial carbon dioxide tension induced by fluid bolus in critically ill patients

Author

Dimitrios Velissaris, David De Bels, Charalampos Pierrakos, Daniel De Backer, Fabio Silvio Taccone, Jacques Devriendt, Thomas Nguyen, Patrick M. Honore, and Rachid Attou

Subjects
Physiology, Cardiac index, Psychologie appliquée, Hemodynamics, Blood Pressure, Vascular Medicine, Medicine and Health Sciences, Gas analysis, Prospective Studies, Cardiac Output, Fluid bolus, Materials, Aged, 80 and over, Fluids, Multidisciplinary, Physics, Respiration, Arterial carbon dioxide tension, Arteries, Middle Aged, Sciences bio-médicales et agricoles, Body Fluids, Chemistry, Positive response, Treatment Outcome, Blood, Area Under Curve, Physical Sciences, Cardiology, Medicine, Anatomy, Biologie, Research Article, Chemical Elements, medicine.medical_specialty, States of Matter, Critical Illness, Science, Materials Science, Sensitivity and Specificity, Veins, Oxygen Consumption, Internal medicine, medicine, Humans, Colloids, Aged, Critically ill, business.industry, Pulmonary Gas Exchange, Chemical Compounds, Biology and Life Sciences, Carbon Dioxide, Oxygen, Blood pressure, Mixtures, Fluid Therapy, Blood Gas Analysis, business, Physiological Processes
Abstract

Background In this prospective observational study, we evaluated the effects of fluid bolus (FB) on venous-to-arterial carbon dioxide tension (PvaCO2) in 42 adult critically ill patients with pre-infusion PvaCO2 > 6 mmHg. Results FB caused a decrease in PvaCO2, from 8.7 [7.6−10.9] mmHg to 6.9 [5.8−8.6] mmHg (p < 0.01). PvaCO2 decreased independently of pre-infusion cardiac index and PvaCO2 changes during FB were not correlated with changes in central venous oxygen saturation (ScvO2) whatever pre-infusion CI. Pre-infusion levels of PvaCO2 were inversely correlated with decreases in PvaCO2 during FB and a pre-infusion PvaCO2 value < 7.7 mmHg could exclude a decrease in PvaCO2 during FB (AUC: 0.79, 95%CI 0.64–0.93; Sensitivity, 91%; Specificity, 55%; p < 0.01). Conclusions Fluid bolus decreased abnormal PvaCO2 levels independently of pre-infusion CI. Low baseline PvaCO2 values suggest that a positive response to FB is unlikely., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2021

16. Relationship between end-tidal carbon dioxide and arterial carbon dioxide in critically ill patients on mechanical ventilation: A cross-sectional study

Author

Yajing Liu, Zhaobo Cui, Huimian Shang, Li Peng, Jinrong Wang, and Jianjun Zhang

Subjects
Male, medicine.medical_specialty, Correlation coefficient, Cross-sectional study, Oxygenation index, intensive care units, medicine.medical_treatment, Critical Illness, Partial Pressure, Observational Study, arterial carbon dioxide tension, invasive mechanically ventilation, chemistry.chemical_compound, end-expiratory carbon dioxide partial pressure, Internal medicine, medicine, Humans, Aged, Mechanical ventilation, business.industry, General Medicine, Oxygenation, Carbon Dioxide, medicine.disease, Respiration, Artificial, Oxygen, Pneumonia, Cross-Sectional Studies, chemistry, Breath Tests, Carbon dioxide, Breathing, Cardiology, Female, business, Research Article
Abstract

So far, only a few studies have examined and confirmed the correlation between end-expiratory carbon dioxide partial pressure (PETCO2) and arterial carbon dioxide tension (PaCO2) during invasive mechanical ventilation in critically ill patients. This study aimed to observe the correlation between PaCO2 and PETCO2 in patients on invasive mechanical ventilation. This was a cross-sectional study of adult patients on invasive mechanical ventilation enrolled between June 2018 and March 2019. Patients requiring invasive mechanical ventilation underwent one of the following mechanical ventilation modes: assisted/controlled ventilation, synchronized intermittent mandatory ventilation, and spontaneous breathing. Subsequently, the difference and correlation between PETCO2 and PaCO2 were analyzed. A total of 184 patients with 298 pairs of PETCO2-PaCO2 data were included in the analysis. Without distinguishing the ventilator mode, there was significant positive correlation between PETCO2 and PaCO2. In different ventilator modes, the correlation coefficient was 0.81 for synchronized intermittent mandatory ventilation, 0.47 for assisted/controlled ventilation, and 0.55 for spontaneous breathing, respectively. In patients with chronic obstructive pulmonary disease (r = 0.80), multiple trauma (r = 0.64), severe pneumonia (r = 0.60), gastrointestinal surgery (r = 0.57), and cerebrovascular diseases (r = 0.53), PETCO2 and PaCO2 were positively correlated. For oxygenation index

Published
2021

21. Venous–arterial CO2 difference in children with sepsis and its correlation with myocardial dysfunction

Author

P. Barrera, Rafael Orozco, Nathalie Gualdrón, Ana Maria Eraso Díaz Del Castillo, Joseph A. Carcillo, Jaime Fernández-Sarmiento, and María Angélica Nieto Rodríguez

Subjects
Continuous infusion, Male, Survival rate, Transthoracic echocardiography, Interquartile range, Observational study, Septic shock, Child, Prospective cohort study, Children, Pediatric intensive care unit, Clinical outcome, Steroid therapy, Lactic acid, General Medicine, Venous oxygen tension, Cardiology, Female, Lung infection, Cohort analysis, Human, Cohort study, medicine.medical_specialty, Adolescent, Tissue perfusion, Arterial carbon dioxide tension, Major clinical study, Article, Sepsis, Internal medicine, medicine, Prospective study, Mortality, Venous saturation, Steroid, Analytical research, business.industry, Pv-aco2, medicine.disease, Multiple organ failure, Myocardial disease, Myocardial dysfunction, Lactate blood level, Carbon dioxide, Transthoracic echocardiogram, business, Adrenal insufficiency
Abstract

Objective: This study aimed to determine the association between venous–arterial CO2 difference (Pv-aCO2) and clinical outcomes of interest in children with severe sepsis and septic shock. Design: An analytical observational study of a prospective cohort was conducted. Setting: The study was carried out from January 2015 to January 2018 in the pediatric intensive care unit of a referral hospital. Materials and methods: Of a total of 1159 patients who were admitted to pediatric critical care, 375 had severe sepsis and septic shock, of which 67 fulfilled the inclusion criteria. Arterial and venous gases were drawn simultaneously with a transthoracic echocardiogram, Pv-aCO2, and other measures of tissue perfusion such as arterial lactate, venous, and evolution to multiple organ failure. Measurements and main results: Half (53.7%) of the patients were under 24 months old, with a slight predominance of male patients. The main site of infection was the lungs in 56% of the cases, with a 91.2% survival rate. Patients who died had a higher venous lactate level (interquartile range 16.2–33.6, p = 0.02). However, there was no correlation between myocardial dysfunction seen on echocardiogram and a Pv-aCO2 greater than 6 mm Hg in children with severe sepsis and septic shock (r = 0.13). Pv-aCO2 and central venous saturation had low sensitivity to detect multiple organ failure and poor correlation with the number of compromised systems (r = 0.8). Conclusion: Pv-aCO2 was not associated with myocardial dysfunction, measured by echocardiogram, in children with severe sepsis and septic shock. It also did not correlate with the number of organs involved or mortality.

Published
2020

22. THAM administration reduces pulmonary carbon dioxide elimination in hypercapnia - an experimental porcine study

Author

Gaetano Perchiazzi, Rafael Kawati, Anders Larsson, and Staffan Höstman

Subjects
Swine, Hypercapnia, Excretion, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, medicine, Animals, 030212 general & internal medicine, Tromethamine, Lung, business.industry, Hemodynamics, 030208 emergency & critical care medicine, Arterial carbon dioxide tension, General Medicine, Carbon Dioxide, Hydrogen-Ion Concentration, Water-Electrolyte Balance, medicine.disease, Hypoventilation, Respiratory acidosis, Anesthesiology and Pain Medicine, chemistry, Hypercapnic Acidosis, Anesthesia, Carbon dioxide, medicine.symptom, business, Respiratory minute volume
Abstract

BACKGROUND In a previous study, we found a rebound of arterial carbon dioxide tension (PaCO2 ) after stopping THAM buffer administration. We hypothesized that this was due to reduced pulmonary CO2 elimination during THAM administration. The aim of this study was to investigate this hypothesis in an experimental porcine hypercapnic model. METHODS In seven, initially normoventilated, anesthetized pigs (22-27 kg) minute ventilation was reduced by 66% for 7 h. Two hours after commencing hypoventilation, THAM was infused IV for 3 h in a dose targeting a pH of 7.35 followed by a 2 h observation period. Acid-base status, blood-gas content and exhaled CO2 were measured. RESULTS THAM raised pH (7.07 ± 0.04 to 7.41 ± 0.04, P < 0.05) and lowered PaCO2 (15.2 ± 1.4 to 12.2 ± 1.1 kPa, P < 0.05). After the infusion, pH decreased and PaCO2 increased again. At the end of the observation period, pH and PaCO2 were 7.24 ± 0.03 and 16.6 ± 1.2 kPa, respectively (P < 0.05). Pulmonary CO2 excretion decreased from 109 ± 12 to 74 ± 12 ml/min (P < 0.05) during the THAM infusion but returned at the end of the observation period to 111 ± 15 ml/min (P < 0.05). The estimated reduction of pulmonary CO2 elimination during the infusion was 5800 ml. CONCLUSIONS In this respiratory acidosis model, THAM reduced PaCO2 , but seemed not to increase the total CO2 elimination due to decreased pulmonary CO2 excretion, suggesting only cautious use of THAM in hypercapnic acidosis.

Published
2018

25. Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia.

Abstract

OBJECTIVES: Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH). METHOD(S): DH was surgically induced at approximately 80days' gestation in 16 lamb fetuses (term in lambs is approximately 147days). From 105days' gestation, ewes received either sildenafil (0.21mg/kg/h intravenously) or saline infusion until delivery (n=8 fetuses in each group). At approximately 138days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs. RESULT(S): Lung-to-body-weight ratio (0.016+/-0.001 vs 0.013+/-0.001; P=0.06) and dynamic lung compliance (0.8+/-0.2 vs 0.7+/-0.2mL/cmH2 O; P=0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120min after cord clamping than in controls (0.6+/-0.1 vs 2.2+/-0.6mmHg/(mL/min); P=0.002). Pulmonary arterial pressure was also lower (46+/-2 vs 59+/-2mmHg; P=0.048) and pulmonary blood flow higher (25+/-3 vs 8+/-2mL/min/kg; P=0.02) in DH-sildenafil than in DH-saline lambs

Published
2019

26. Antenatal sildenafil treatment improves neonatal pulmonary hemodynamics and gas exchange in lambs with diaphragmatic hernia.

Abstract

OBJECTIVES: Infants with congenital diaphragmatic hernia (CDH) are predisposed to pulmonary hypertension after birth, owing to lung hypoplasia that impairs fetal pulmonary vascular development. Antenatal sildenafil treatment attenuates abnormal pulmonary vascular and alveolar development in rabbit and rodent CDH models, but whether this translates to functional improvements after birth remains unknown. We aimed to evaluate the effect of antenatal sildenafil on neonatal pulmonary hemodynamics and lung function in lambs with diaphragmatic hernia (DH). METHOD(S): DH was surgically induced at approximately 80days' gestation in 16 lamb fetuses (term in lambs is approximately 147days). From 105days' gestation, ewes received either sildenafil (0.21mg/kg/h intravenously) or saline infusion until delivery (n=8 fetuses in each group). At approximately 138days' gestation, all lambs were instrumented and then delivered via Cesarean section. The lambs were ventilated for 120min with continuous recording of physiological (pulmonary and carotid artery blood flow and pressure; cerebral oxygenation) and ventilatory parameters, and regular assessment of arterial blood gas tensions. Only lambs that survived until delivery and with a confirmed diaphragmatic defect at postmortem examination were included in the analysis; these comprised six DH-sildenafil lambs and six DH-saline control lambs. RESULT(S): Lung-to-body-weight ratio (0.016+/-0.001 vs 0.013+/-0.001; P=0.06) and dynamic lung compliance (0.8+/-0.2 vs 0.7+/-0.2mL/cmH2 O; P=0.72) were similar in DH-sildenafil lambs and controls. Pulmonary vascular resistance decreased following lung aeration to a greater degree in DH-sildenafil lambs, and was 4-fold lower by 120min after cord clamping than in controls (0.6+/-0.1 vs 2.2+/-0.6mmHg/(mL/min); P=0.002). Pulmonary arterial pressure was also lower (46+/-2 vs 59+/-2mmHg; P=0.048) and pulmonary blood flow higher (25+/-3 vs 8+/-2mL/min/kg; P=0.02) in DH-sildenafil than in DH-saline lambs

Published
2019

27. Differences Between Arterial and Expired Pump Carbon Dioxide During Robotic Cardiac Surgery.

Author

Song, Jun-Gol, Lee, Eun Ho, Choi, Dae Kee, Chin, Ji Hyun, and Choi, In Cheol

Subjects
PHYSIOLOGICAL effects of carbon dioxide, CARDIAC surgery patients, SURGICAL robots, CARDIAC catheterization, OXYGENATORS, CARDIOPULMONARY bypass
Abstract

Objective: To investigate whether expired pump carbon dioxide (PepCO2) is an effective arterial carbon dioxide (PaCO2) monitor during cardiopulmonary bypass (CPB) in patients undergoing robotic cardiac surgery compared with traditional cardiac surgery. Design: A prospective control study. Setting: A university, single-institutional setting. Participants: Sixty patients undergoing cardiac surgery. Interventions: PepCO2 was measured using a standard multigas analyzer with the monitoring catheter connected to the exhaust port of the oxygenator. The authors measured PaCO2 values of the arterial blood provided to the patient and PepCO2 from the oxygenator exhaust outlet during the cooling, stable hypothermia, and rewarming phases of CPB. Measurements and Main Results: There were significant differences between temperature-uncorrected PaCO2 (PaCO2tu) and PepCO2 measured during the cooling phase; between temperature-corrected PaCO2 (PaCO2tc) and PepCO2; and between PaCO2tu and PepCO2 measured during the stable hypothermia phase between the 2 groups (p < 0.001 for all). However, there were no significant differences between PaCO2tc and PepCO2 measured during the cooling phase or between PaCO2tc and PepCO2 or PaCO2tu and PepCO2 measured during the rewarming phase between the 2 groups (p = 0.453, p = 0.122, and p = 0.412, respectively). Conclusion: These results reveal that PepCO2 is not suitable for continuous monitoring of PaCO2 during CPB in patients undergoing robotic cardiac surgery. [ABSTRACT FROM AUTHOR]

Published
2011
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28. Facial immersion in cold water enhances cerebral blood velocity during breath-hold exercise in humans.

Author

Kjeld, Thomas, Pott, Frank C., and Secher, Niels H.

Subjects
BREATH holding, BRADYCARDIA, VASOCONSTRICTION, PERFUSION, WATER immersion, CARBON dioxide, BLOOD flow
Abstract

The diving response is initiated by apnea and facial immersion in cold water and includes, besides bradycardia, peripheral vasoconstriction, while cerebral perfusion may be enhanced. This study evaluated whether facial immersion in 10°C water has an independent influence on cerebral perfusion evaluated as the middle cerebral artery mean flow velocity (MCA Vmean) during exercise in nine male subjects. At rest, a breath hold of maximum duration increased the arterial carbon dioxide tension (PaCO2) from 4.2 to 6.7 kPa and MCA Vmean from 37 to 103 cm/s (mean; ∼178%; P < 0.001). Similarly, during 100-W exercise, a breath hold increased PaCO2 from 5.9 to 8.2 kPa (P < 0.001) and MCA Vmean from 55 to 113 cm/s (∼105%), and facial immersion further increased MCA Vmean to 122 cm/s (∼88%; both P < 0.001). MCA Vmean also increased during 180-W exercise (from 47 to 53 cmls), and this increment became larger with facial immersion (76 cm/s, ∼62%; P < 0.001), although PaCO2 did not significantly change. These results indicate that a breath hold diverts blood toward the brain with a >100% increase in MCA Vmean, largely because PaCO2 increases, but the increase in MCA Vmean becomes larger when combined with facial immersion in cold water independent of PaCO2. [ABSTRACT FROM AUTHOR]

Published
2009
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29. Enhanced cerebral CO2 reactivity during strenuous exercise in man.

Author

Rasmussen, P., Stie, H., Nielsen, B., and Nybo, L.

Subjects
*CEREBRAL circulation, *CARBON dioxide, *PHYSICAL fitness, *PHYSICAL education, *BLOOD circulation, *EXERCISE, *BLOOD flow measurement, *BODY temperature, *CEREBRAL arteries, *FEVER, *HEMODYNAMICS, *REGRESSION analysis, *RELAXATION for health, *TRANSCRANIAL Doppler ultrasonography, *HYPOCAPNIA
Abstract

Light and moderate exercise elevates the regional cerebral blood flow by approximately 20% as determined by ultrasound Doppler sonography (middle cerebral artery mean flow velocity; MCA V(mean)). However, strenuous exercise, especially in the heat, appears to reduce MCA V(mean) more than can be accounted for by the reduction in the arterial CO(2) tension (P(a)CO(2)). This study evaluated whether the apparently large reduction in MCA V(mean) at the end of exhaustive exercise relates to an enhanced cerebrovascular CO(2) reactivity. The CO(2) reactivity was evaluated in six young healthy male subjects by the administration of CO(2) as well as by voluntary hypo- and hyperventilation at rest and during exercise with and without hyperthermia. At rest, P(a)CO(2) was 5.1 +/- 0.2 kPa (mean +/- SEM) and MCA V(mean) 50.7 +/- 3.8 cm s(-1) and the relationship between MCA V(mean) and P(a)CO(2 )was linear (double-log slope 1.1 +/- 0.1). However, the relationship became curvilinear during exercise (slope 1.8 +/- 0.1; P < 0.01 vs. rest) and during exercise with hyperthermia (slope 2.3 +/- 0.3; P < 0.05 vs. control exercise). Accordingly, the cerebral CO(2) reactivity increased from 30.5 +/- 2.7% kPa(-1) at rest to 61.4 +/- 10.1% kPa(-1) during exercise with hyperthermia (P < 0.05). At exhaustion P(a)CO(2) decreased 1.1+/- 0.2 kPa during exercise with hyperthermia, which, with the determined cerebral CO(2) reactivity, accounted for the 28 +/- 10% decrease in MCA V(mean). The results suggest that during exercise changes in cerebral blood flow are dominated by the arterial carbon dioxide tension. [ABSTRACT FROM AUTHOR]

Published
2006
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30. Initial arterial carbon dioxide tension is associated with neurological outcome after resuscitation from cardiac arrest

Author

David F. Gaieski, Molly L. Tolins, Daniel J. Henning, Alison Jaworski, Nicholas J. Johnson, and Anne V. Grossestreuer

Subjects
Adult, Male, medicine.medical_specialty, Resuscitation, Databases, Factual, Partial Pressure, medicine.medical_treatment, 030204 cardiovascular system & hematology, Emergency Nursing, Return of spontaneous circulation, Sensitivity and Specificity, 03 medical and health sciences, 0302 clinical medicine, Outcome Assessment, Health Care, medicine, Hospital discharge, Humans, Cardiopulmonary resuscitation, Aged, Retrospective Studies, Chi-Square Distribution, business.industry, 030208 emergency & critical care medicine, Arterial carbon dioxide tension, Retrospective cohort study, Carbon Dioxide, Middle Aged, Respiration, Artificial, Cardiopulmonary Resuscitation, Heart Arrest, Surgery, Cerebrovascular Circulation, Anesthesia, Emergency Medicine, Female, Blood Gas Analysis, Cardiology and Cardiovascular Medicine, business, Chi-squared distribution, Respiratory minute volume
Abstract

Study objectives To determine the relationships between partial pressure of arterial carbon dioxide (PaCO 2 ), prescribed minute ventilation (MV), and neurologic outcome in patients resuscitated from cardiac arrest. Methods This was a retrospective cohort study utilizing a multicenter database of adult patients with return of spontaneous circulation (ROSC) after cardiac arrest. The primary outcome was neurologic status at hospital discharge, defined by Cerebral Performance Category (CPC) score: CPC 1–2 was favorable, CPC 3–5 was poor. We compared rates of initial normocarbia (PaCO 2 31–49mmHg) and mean sequential PaCO 2 measurements obtained over the first 24h. We also assessed the influence of MV on the PaCO 2 at initial, 6, 12, 18, and 24h after cardiac arrest using univariate linear regression. Results One hundred and fourteen patients from 3 institutions met inclusion criteria. Overall, 46/114 (40.4%, 95% CI: 31.4–49.4%) patients survived to hospital discharge, and 33/114 (28.9%, 20.6–37.2%) had CPC 1–2 at the time of discharge. A total of 38.9% (95% CI: 29.9–47.9%) of patients had initial normocarbia; 43.2% (28.6–57.8%) of these patients were discharged with CPC 1–2, compared with 20.3% (10.8–29.8%) of dyscarbic patients. By 6h, neurologic outcomes were not significantly associated with PaCO 2 . Prescribed MV was not associated with PaCO 2 at any time point with the exception of a weak correlation at hour 18. Conclusion Initial normocarbia was associated with favorable neurological outcome in patients resuscitated from cardiac arrest. This relationship was not seen at subsequent time points. There was no significant association between prescribed MV and PaCO 2 or neurologic outcome.

Published
2017

31. A systematic review and meta-analysis of the association between arterial carbon dioxide tension and outcomes after cardiac arrest

Author

Teresa A. Williams, Kwok M. Ho, Hideo Tohira, Nicole McKenzie, and Judith Finn

Subjects
medicine.medical_specialty, Resuscitation, business.industry, MEDLINE, 030208 emergency & critical care medicine, Arterial carbon dioxide tension, Arteries, Odds ratio, Carbon Dioxide, 030204 cardiovascular system & hematology, Emergency Nursing, Hypercarbia, Confidence interval, Heart Arrest, 03 medical and health sciences, Study heterogeneity, 0302 clinical medicine, Anesthesia, Meta-analysis, Emergency Medicine, medicine, Humans, Cardiology and Cardiovascular Medicine, Intensive care medicine, business
Abstract

Introduction Arterial carbon dioxide tension (PaCO 2 ) abnormalities are common after cardiac arrest (CA). Maintaining a normal PaCO 2 makes physiological sense and is recommended as a therapeutic target after CA, but few studies have examined the association between PaCO 2 and patient outcomes. This systematic review and meta-analysis aimed to assess the effect of a low or high PaCO 2 on patient outcomes after CA. Methods We searched MEDLINE, EMBASE, CINAHL and Cochrane CENTRAL, for studies that evaluated the association between PaCO 2 and outcomes after CA. The primary outcome was hospital survival. Secondary outcomes included neurological status at the end of each study's follow up period, hospital discharge destination and 30-day survival. Meta-analysis was conducted if statistical heterogeneity was low. Results The systematic review included nine studies; eight provided sufficient quantitative data for meta-analysis. Using PaCO 2 cut-points of 45mmHg to define hypo- and hypercarbia, normocarbia was associated with increased hospital survival (odds ratio [OR] 1.30, 95% confidence interval [CI] 1.23, 1.38). Normocarbia was also associated with a good neurological outcome (cerebral performance category score 1 or 2) compared to hypercarbia (OR 1.69, 95% CI 1.13, 2.51) when the analysis also included an additional study with a slightly different definition for normocarbia (PaCO 2 30–50mmHg). Conclusions From the limited data it appears PaCO 2 has an important U-shape association with survival and outcomes after CA, consistent with international resuscitation guidelines' recommendation that normocarbia be targeted during post-resuscitation care.

Published
2017

32. Relationship between arterial and end-tidal carbon dioxide pressures during anesthesia using a laryngeal tube.

Author

Lee, J. S., Nam, S. B., Chang, C. H., Han, D. W., Lee, Y. W., and Shin, C. S.

Subjects
*ANESTHESIA, *CARBON dioxide, *CARBON compounds, *TRACHEA, *PAIN medicine, *ANESTHESIOLOGY
Abstract

The Laryngeal Tube® (LT), (VBM Medizintechnik, Sulz, Germany) is a relatively new supraglottic device for controlling the airway. Arterial carbon dioxide tension (PaCO2) can be estimated by monitoring the end-tidal tension of carbon dioxide (PETCO2). The relationship between PETCO2 and PaCO2 during controlled ventilation via the LT has not been reported. During general anesthesia, 45 patients were mechanically ventilated using an LT. PETCO2 and PaCO2 were measured once PETCO2 had reached a steady state. The LT was then removed and the trachea intubated using an endotracheal tube (ETT), and the identical ventilatory variables were resumed. Following stabilization, PETCO2 was again determined and PaCO2 estimated. The mean PETCO2 and PaCO2 values were 4.43 ± 0.26 kPa and 4.67 ± 0.32 kPa, respectively, during LT ventilation, and 4.36 ± 0.23 kPa and 4.61 ± 0.26 kPa, respectively, during ETT ventilation. Analysis of differences between the PETCO2 and PaCO2 values using the Bland and Altman method revealed a bias ± precision of 0.24 ± 0.15 kPa for LT and 0.27 ± 0.15 kPa for ETT. The root mean square error was 0.28 for the LT and 0.30 for the ETT. This study suggests that for healthy adult patients mechanically ventilated via the LT, the PETCO2 value reflects the PaCO2 value as closely as when patients are ETT ventilated, allowing capnometry to be used to evaluate the adequacy of ventilation. [ABSTRACT FROM AUTHOR]

Published
2005
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33. Accuracy of an indirect carbon dioxide Fick method in determination of the cardiac output in critically ill mechanically ventilated patients.

Author

Blanch, L., Fernández, R., Benito, S., Mancebo, J., Calaf, N., Net, A., and Fernández, R

Abstract

We evaluated the accuracy of an indirect CO2 Fick method for measuring cardiac output in 30 critically ill mechanically ventilated patients. When the Fick principle was applied to CO2 using estimated PaCO2, the cardiac output obtained underestimated the thermodilution technique showing a lack of accuracy. However, there was a significant correlation between thermodilution and CO2 rebreathing methods using measured (r = 0.92; p less than 0.001) and estimated (r = 0.60; p less than 0.01) arterial PCO2. The regression equation using measured arterial PCO2 was y = 0.59 + 0.91x, and for estimated arterial PCO2 was y = 1.7 + 0.33x. The results suggest that the CO2 rebreathing method using measured arterial PCO2 may be useful to determine cardiac output in those seriously ill patients on artificial ventilation not requiring right heart catheterization. [ABSTRACT FROM AUTHOR]

Published
1988
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34. Secondary Response to Chronic Respiratory Acidosis in Humans: A Prospective Study

Author

Horacio J. Adrogué, Guillermo A. Raimondi, Nicolaos E. Madias, Guillermo Menga, Hocine Tighiouart, and Silvia Gonzalez

Subjects
Chronic respiratory acidosis, inorganic chemicals, medicine.medical_specialty, 030232 urology & nephrology, hypercapnic respiratory failure, Hypoxemia, 03 medical and health sciences, 0302 clinical medicine, Clinical Research, Internal medicine, medicine, 030212 general & internal medicine, renal acidification, Prospective cohort study, hypoxemia, business.industry, Arterial carbon dioxide tension, Plasma bicarbonate, medicine.disease, CO2 retention, Respiratory acidosis, Nephrology, Cardiology, plasma bicarbonate concentration, Arterial blood, medicine.symptom, respiratory acidosis, business, Hypercapnia
Abstract

Introduction The magnitude of the secondary response to chronic respiratory acidosis, that is, change in plasma bicarbonate concentration ([HCO3−]) per mm Hg change in arterial carbon dioxide tension (PaCO2), remains uncertain. Retrospective observations yielded Δ[HCO3−]/ΔPaCO2 slopes of 0.35 to 0.51 mEq/l per mm Hg, but all studies have methodologic flaws. Methods We studied prospectively 28 stable outpatients with steady-state chronic hypercapnia. Patients did not have other disorders and were not taking medications that could affect acid−base status. We obtained 2 measurements of arterial blood gases and plasma chemistries within a 10-day period. Results Steady-state PaCO2 ranged from 44.2 to 68.8 mm Hg. For the entire cohort, mean (± SD) steady-state plasma acid−base values were as follows: PaCO2, 52.8 ± 6.0 mm Hg; [HCO3−], 29.9 ± 3.0 mEq/l, and pH, 7.37 ± 0.02. Least-squares regression for steady-state [HCO3−] versus PaCO2 had a slope of 0.476 mEq/l per mm Hg (95% CI = 0.414–0.538, P < 0.01; r = 0.95) and that for steady-state pH versus PaCO2 had a slope of −0.0012 units per mm Hg (95% CI = −0.0021 to −0.0003, P = 0.01; r = −0.47). These data allowed estimation of the 95% prediction intervals for plasma [HCO3−] and pH at different levels of PaCO2 applicable to patients with steady-state chronic hypercapnia. Conclusion In steady-state chronic hypercapnia up to 70 mm Hg, the Δ[HCO3−]/ΔPaCO2 slope equaled 0.48 mEq/l per mm Hg, sufficient to maintain systemic acidity between the mid-normal range and mild acidemia. The estimated 95% prediction intervals enable differentiation between simple chronic respiratory acidosis and hypercapnia coexisting with additional acid−base disorders.

Published
2018

35. High blood carbon dioxide variability and adverse outcomes in neonatal hypoxic ischemic encephalopathy

Author

Jeff K. Vallance, Ganesh Srinivasan, Michael Narvey, Nasser Al Shafouri, and Gregory Hansen

Subjects
Male, Pediatrics, medicine.medical_specialty, Adverse outcomes, 03 medical and health sciences, Child Development, 0302 clinical medicine, Hypothermia, Induced, 030225 pediatrics, medicine, Humans, Blood carbon dioxide, Retrospective Studies, Asphyxia, Retrospective review, Hypocapnia, business.industry, Infant, Newborn, Obstetrics and Gynecology, Arterial carbon dioxide tension, Carbon Dioxide, Hypothermia, Neonatal Hypoxic Ischemic Encephalopathy, Child, Preschool, Anesthesia, Hypoxia-Ischemia, Brain, Pediatrics, Perinatology and Child Health, Arterial blood, Female, medicine.symptom, business, 030217 neurology & neurosurgery, Follow-Up Studies
Abstract

Hypocarbia during the first 12 h of life is associated with mortality and disability in neonatal hypoxic ischemic encephalopathy (HIE). Notable variation in arterial carbon dioxide tension (PaCO2) during the first 4 d of life is related to severe intraventricular hemorrhages in preterm infants. We examined the association between PaCO2 during 72 h of whole-body therapeutic hypothermia for neonatal HIE and 2-year neurodevelopmental outcomes.A retrospective review of 23 term neonates treated with whole-body hypothermia documented clinical, demographic and arterial blood gas data. Comparisons were made across good and severe neurodevelopmental outcome groups at 2 years of age.Severe neurodevelopmental outcomes were documented in 8 of 23 toddlers. There were no significant differences between outcome groups with regard to the number of patients with hypocarbic means or measurements. There were also no significant differences with mean PaCO2, PaO2, pH, time-weighted cumulative hypocarbia, and PaCO2 range. The severe neurodevelopmental outcomes group had a significantly higher mean PaCO2 standard deviation (p = 0.04; 95% CI, -5.46 to -0.39).Severe neurodevelopmental outcomes were significantly associated with high PaCO2 variability over 72 h in whole-body-cooled HIE neonates. Mitigating these fluctuations may be a potential management strategy.

Published
2015

36. Impact of hypercapnia on neurovascular coupling in the fetal sheep and Newborn lamb.

Abstract

Background: Neurovascular coupling (NVC) leads to increased cerebral blood flow (CBF) and cerebral oxygenation upon increased neural activity. Hypercapnia (HC) increases baseline CBF and attenuates NVC-induced CBF response in the adult brain. HC is common in preterm infants undergoing intensive care, but effects of HC on NVC in the immature brain remain unknown. We examined the impact of HC on NVC in the fetal sheep and neonatal lamb, using somatosensory evoked potential (SEP) after median nerve stimulation measured by EEG as an index of increased cortical activity, and cerebral oxy- and deoxyhaemoglobin (oxyHb and deoxyHb) measured by near infrared spectroscopy (NIRS). Method(s): Under isoflurane anaesthesia, EEG and NIRS electrodes were positioned bilaterally over the somatosensory cortex of fetal sheep (128-132 days gestation; n = 6) and 4-8 day old neonatal lambs (n = 6). Trains of median nerve electrical stimuli evoked a SEP, and oxyHb and deoxyHb were recorded before, during and after HC. Result(s): PaCO2 [mean (SD)] before, during and after HC was 48.2(5.6), 69.6(5.5) and 52.7(6.9)mmHg, respectively, in fetal sheep, and 39.5(3.2), 64.6(6.3) and 41.6(4.4)mmHg, respectively, in newborn lambs. During HC, 5 of the 6 fetal sheep showed higher oxyHb in the contralateral cortex after median nerve stimulation compared to before HC [mean oxyHb (During HC-before HC): 21.0 muM.cm]. Four of the 6 newborn lambs showed higher oxyHb in contralateral cortex [mean oxyHb (During HC-before HC): 10.5 muM.cm]. Conclusion(s): Cerebral oxygenation after somatosensory stimulation is increased with HC in fetal sheep and newborn lambs, in contrast to previous studies in the adult brain.

Published
2017

37. Monitoring variables affecting positron emission tomography measurements of cerebral blood flow in anaesthetized pigs

Author

Ole Lajord Munk, Nora E. Zois, Aage Kristian Olsen Alstrup, and Mette Kildevæld Simonsen

Subjects
medicine.medical_specialty, Positron emission tomography, Time Factors, 040301 veterinary sciences, High body temperature, Swine, (O)-water, Sus scrofa, Brain research, Positron-Emission Tomography/standards, Body Temperature, 0403 veterinary science, 03 medical and health sciences, 0302 clinical medicine, Arterial oxygen tension, Internal medicine, medicine, Animals, Anesthesia, ( O)-water, lcsh:Veterinary medicine, General Veterinary, medicine.diagnostic_test, business.industry, Animal, Research, Arterial carbon dioxide tension, 04 agricultural and veterinary sciences, General Medicine, Pet imaging, Carbon Dioxide, [15O]-water, nervous system, High heart rate, Cerebral blood flow, Cerebrovascular Circulation, Positron-Emission Tomography, Physiological monitoring, Cardiology, lcsh:SF600-1100, Female, CBF, business, 030217 neurology & neurosurgery, circulatory and respiratory physiology
Abstract

Background: Positron emission tomography (PET) imaging of anaesthetized pig brains is a useful tool in neuroscience. Stable cerebral blood flow (CBF) is essential for PET, since variations can affect the distribution of several radiotracers. However, the effect of physiological factors regulating CBF is unresolved and therefore knowledge of optimal anaesthesia and monitoring of pigs in PET studies is sparse. The aim of this study was therefore to determine if and how physiological variables and the duration of anaesthesia affected CBF as measured by PET using (15O)-water in isoflurane-N2O anaesthetized domestic female pigs. First, we examined how physiological monitoring parameters were associated with CBF, and which parameters should be monitored and if possible kept constant, during studies where a stable CBF is important. Secondly, we examined how the duration of anaesthesia affected CBF and the monitoring parameters. Results: No significant statistical correlations were found between CBF and the nine monitoring variables. However, we found that arterial carbon dioxide tension (PaCO2) and body temperature were important predictors of CBF that should be observed and kept constant. In addition, we found that long-duration anaesthesia was significantly correlated with high heart rate, low arterial oxygen tension, and high body temperature, but not with CBF. Conclusions: The findings indicate that PaCO2 and body temperature are crucial for maintaining stable levels of CBF and thus optimizing PET imaging of molecular mechanisms in the brain of anaesthetized pigs. Therefore, as a minimum these two variables should be monitored and kept constant. Furthermore, the duration of anaesthesia should be kept constant to avoid variations in monitoring variables.

Published
2017

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