End-tidal Carbon Dioxide Tension Research Articles

Anesthesia experience in an adult Silver-Russell syndrome: a case report

BackgroundThere are no reports of anesthesia use in adult patients with Silver-Russell syndrome (SRS). Here, we report our experience with anesthesia in an adult patient with SRS complicated by chronic respiratory failure.Case presentationA 33-year-old woman was clinically diagnosed with SRS. She had severe chronic respiratory failure, complicated by superior mesenteric artery syndrome. Percutaneous gastrostomy was scheduled for nutritional management under epidural anesthesia; however, soon after esophagogastroduodenoscopy was started, she lost consciousness and spontaneous respiration. The patient was urgently intubated and converted to general anesthesia. The end-tidal carbon dioxide tension was > 90 mmHg at intubation.ConclusionsAdult SRS patients with chronic respiratory failure have a risk of CO2 narcosis. SRS also requires preparation for difficult airway management during the perioperative period.

Better Respiratory Function in Heart Failure Patients With Use of Central-Acting Therapeutics

BackgroundDiaphragm atrophy can contribute to dyspnea in patients with heart failure (HF) with its link to central neurohormonal overactivation. HF medications that cross the blood-brain barrier could act centrally and improve respiratory function, potentially alleviating diaphragmatic atrophy. Therefore, we compared the benefit of central- vs peripheral-acting HF drugs on respiratory function, as assessed by a single cardiopulmonary exercise test (CPET) and outcomes in HF patients. MethodsA retrospective study was conducted of 624 ambulatory adult HF patients (80% male) with reduced left ventricular ejection fraction ≤ 40% and a complete CPET, followed at a single institution between 2001 and 2017. CPET parameters, and the outcomes all-cause death, a composite endpoint (all-cause death, need for left ventricular assist device, heart transplantation), and all-cause and/or HF hospitalizations, were compared in patients receiving central-acting (n = 550) vs peripheral-acting (n = 74) drugs. ResultsCompared to patients who receive peripheral-acting drugs, patients who receive central-acting drugs had better respiratory function (peak breath-by breath oxygen uptake [VO2], P = 0.020; forced expiratory volume in 1 second [FEV1], P = 0.007), and ventilatory efficiency (minute ventilation / carbon dioxide production [VE/VCO2], P < 0.001; end-tidal carbon dioxide tension [PETCO2], P = 0.015; and trend for forced vital capacity [FVC], P = 0.056). Many of the associations between the CPET parameters and drug type remained significant after multivariate adjustment. Moreover, patients receiving central-acting drugs had fewer composite events (P = 0.023), and HF hospitalizations (P = 0.044), although significance after multivariant correction was not achieved, despite the hazard ratio being 0.664 and 0.757, respectively. ConclusionsCentral-acting drugs were associated with better respiratory function as measured by CPET parameters in HF patients. This could extend to clinically meaningful composite outcomes and hospitalizations but required more power to be definitive in linking to drug effect. Central-acting HF drugs show a role in mitigating diaphragm weakness.

The effects of subconcussive head impacts on cerebral vascular reactivity

Purpose: One bout of repetitive subconcussive head impacts (SHI) can increase biomarkers of neurological injury, decrease neurovascular coupling, and alter cerebral autoregulation. It is unclear whether a bout of repetitive SHI alters cerebral vascular reactivity to carbon dioxide (CVR). We tested the hypotheses that CVR to hypercapnia (CVRhyper) and hypocapnia (CVRhypo) will decrease after a bout of repetitive SHI in healthy participants. Methods: Eight healthy participants (age: 20±2 y; BMI: 23±3 kg/m2; 2 women) completed four CVR tests: one prior to a bout of SHI (PRE), and three follow-up tests at 2 h, 24 h, and 72 h after the SHI. SHI were induced by 20 soccer headers projected from a soccer JUGS machine (1 header/30 s at 40 km/h and from 12.2 m). Mean arterial pressure (MAP), heart rate (HR), end tidal carbon dioxide tension (PETCO2), middle cerebral artery blood velocity (MCAV) and posterior cerebral artery blood velocity (PCAV) were measured prior to and during each CVR test. MCA conductance (MCAcon) and PCA conductance (PCAcon) were calculated as the quotient of MCAv and PCAv to MAP, respectively. During the CVRhyper test, participants inhaled 6% CO2, 21% O2, 73% N2 gas for 2 min or until PETCO2 was 10 mmHg greater than baseline. 3 min after the CVRhyper test, participants hyperventilated until PETCO2 was 10 mmHg less than baseline for 2 min (CVRhypo). PETCO2 values were plotted against MCAV, PCAV, MCAcon, and PCAcon at baseline and the last 10 s of each CVR test. The slopes of these linear regression lines were calculated for each variable and for both CVR tests. Data are presented as mean±SD. Results: There were no differences from PRE to post SHI for resting HR, PETCO2, MCAV, PCAV, MCAcon, or PCAcon (all p&gt;0.13). A time effect was found for resting MAP (PRE: 90±10; 2 h: 101±8; 24 h: 86±4; 72 h: 88±10 mmHg; p=0.02). There were no differences from PRE to post SHI for the CVRhyper test for MCAV (PRE: 0.10±0.20; 2 h: 0.27±0.17; 24 h: 0.24±0.31; 72 h: 0.24±0.31 cm/s/mmHg; p=0.13), MCAcon (PRE: -0.0009±0.0014; 2 h: -0.0001±0.0023; 24 h: -0.0002±0.0017; 72 h: -0.0011±0.0017 cm/s/mmHg/mmHg; p=0.36), PCAV (PRE: 0.02±0.13; 2 h: 0.07±0.07; 24 h: 0.12±0.18; 72 h: 0.14±0.13 cm/s/mmHg; p=0.26), or PCAcon (PRE: 0.0018±0.0011; 2 h: 0.0014±0.0007; 24 h: 0.0033±0.0033; 72 h: 0.0012±0.0007 cm/s/mmHg/mmHg; p=0.18). There were also no differences from PRE to post SHI for the CVRhypo test for MCAV (PRE: 0.10±0.20; 2 h: 0.27±0.17; 24 h: 0.24±0.31; 72 h: 0.24±0.31 cm/s/mmHg; p=0.13), MCAcon (PRE: 0.0006±0.0019; 2 h: 0.0019±0.0011; 24 h: 0.004±0.0049; 72 h: 0.0025±0.0016 cm/s/mmHg/mmHg; p=0.10), PCAV (PRE: 0.02±0.13; 2 h: 0.07±0.07; 24 h: 0.12±0.18; 72 h: 0.14±0.13 cm/s/mmHg; p=0.26), or PCAcon (PRE: 0.0018±0.0016; 2 h: 0.0019±0.0007; 24 h: 0.004±0.0033; 72 h: 0.0037±0.0014; p=0.09). Conclusion: These preliminary data indicate that a bout of soccer headings does not change CVR to carbon dioxide in the MCA or PCA in healthy adults. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cerebral vascular function in young, healthy non-Hispanic Black and White females

Non-Hispanic Black (BL) individuals are ~2-times more likely to suffer from conditions including cognitive dysfunction and Alzheimer’s disease and related dementias (ADRD) – conditions which are among the fastest growing causes of morbidity and mortality in the US. The prevalence of ADRD is expected to double by 2060 with a more rapid increase in the BL (and Hispanic) population. Importantly, reduced vascular function, particularly in the cerebral circulation, contributes to elevated risk for and prevalence of ADRD. While previous research has provided valuable insight into mechanisms of cerebral vascular dysfunction, this work has been primarily conducted in males and has largely not included socioeconomic/racial discrimination measurements, which are critical to understanding race/ethnicity-related disparities in cerebral vascular health. To our knowledge no studies have specifically examined cerebral vascular function in young, healthy BL females relative to WH females. Therefore, we tested the hypothesis that cerebral vascular function would be blunted in BL relative to WH females. METHODS: Eleven healthy WH (age: 26±7 yr; BMI: 26±3 kg/m2) and 17 healthy (age: 21±2 yr; BMI: 26±4 kg/m2) BL females participated. Beat-to-beat blood pressure, end-tidal carbon dioxide tension, and middle cerebral artery mean blood velocity (MCAVmean) were continuously collected. Transfer function analysis (i.e. gain, phase, and coherence) of blood pressure and MCAVmean were calculated in the very-low, low, and high-frequency ranges to assess cerebral autoregulation. Cerebral vascular function was also assessed as the % increase in MCA vascular conductance (CVCi = MCAVmean/mean arterial pressure) during administration of a hypercapnic gas (6% CO2 gas). Socioeconomic background and psychosocial stress exposures were assessed as: 1) parental education level; 2) adverse childhood experiences (ACEs); and 3) perceived ethnic discrimination (PEDQ). RESULTS: Transfer function analysis of gain, phase, and coherence was similar across all frequency ranges ( P&gt;0.05 for all) and the % increase in CVCi ( P=0.71) during hypercapnia was similar between BL and WH females. Although perceived ethnic discrimination was greater in BL relative to WH females ( P&lt;0.001), there were no group differences in parental education level nor ACEs ( P&gt;0.05 for both). CONCLUSION: These preliminary data suggest that cerebral vascular function is not different between young, healthy BL and WH females of similar socioeconomic background. Future studies should continue to examine these relationships but expand inclusion to a wider age group with a greater diversity in socioeconomic background. Funding: NIH R15 (HL156128, RMB) &amp; AHA Predoctoral Fellowship (915133, ZTM) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

End-tidal carbon dioxide tension is a reliable surrogate of arterial carbon dioxide tension across different oxygen, carbon dioxide and barometric pressures.

End-tidal CO2 tension provides an accurate estimation of P aCO2 in healthy awake individuals over an extensive range of CO2 pressures induced by 17 environmental conditions combining different O2, CO2 and barometric pressures https://bit.ly/3YuKPAY.

Effects of Retroperitoneal or Transperitoneal Pneumoperitoneum on Inferior Vena Cava Hemodynamics and Cardiopulmonary Function: A Prospective Real-Time Comparison.

Objective: To evaluate the effects of CO2 pneumoperitoneum on venous hemodynamics and cardiopulmonary function during transperitoneal or retroperitoneal laparoscopic surgery. Materials and Methods: A single-institution prospective study. Forty-three patients with renal-cell carcinoma undergoing retroperitoneal (22) or transperitoneal (21) laparoscopic partial nephrectomy were enrolled. Hemodynamic functions were monitored by minimally invasive FloTrac/Vigileo system. Transesophageal echocardiography was used to measure the diameter and blood flow of the inferior vena cava (IVC). Measured parameters were recorded at baseline, 10, 30, 60 minutes following insufflation to 14 mm Hg and 10 minutes following desufflation. Results: For hemodynamic changes in the transperitoneal laparoscopic surgery (TPL) and retroperitoneal laparoscopic surgery (RPL), transperitoneal CO2 insufflation resulted in a rapid parallel increase in central intravenous pressure (CVP), peak airway pressure (AWP), and IVC blood flow velocity after the first 30 minutes of pneumoperitoneum (p < 0.05). In contrast, CVP, AWP, and IVC blood flow velocity increased progressively in RPL. The variation of those parameters was significantly lower than that of TRL (p < 0.001; p = 0.002; p = 0.004). The mean maximum CVP in the two groups was 20 and 16 mm Hg, respectively. The IVC diameter at the cavoatrial junction was significantly reduced in TPL after 10 minutes of insufflation, but it remained unchanged in RPL throughout the surgery. For cardiopulmonary function changes, heart output decreased after a short period of pneumoperitoneum, but no statistical differences were observed between the two groups. The increments of partial pressure of arterial carbon dioxide and end-tidal carbon dioxide tension were significantly higher in RPL than TPL (p < 0.001; p < 0.001). Conclusions: Compared with retroperitoneal pneumoperitoneum, transperitoneal pneumoperitoneum has significant effects on IVC hemodynamics. Elevated intra-abdominal pressure (IAP) causes higher AWP and venous return resistance, which lead to the significant increase of CVP during transperitoneal approach. Adjusting the balance between IAP and CVP might be an effective way to control intravenous bleeding. Clinical Trial Registry: Registration number: ChiCTR2000038291.

Cardiopulmonary Exercise Performance and Endothelial Function in Convalescent COVID-19 Patients.

Background: Endothelial dysfunction has been proposed as the common pathogenic background of most manifestations of coronavirus disease 2019 (COVID-19). Among these, some authors also reported an impaired exercise response during cardiopulmonary exercise testing (CPET). We aimed to explore the potential association between endothelial dysfunction and the reduced CPET performance in COVID-19 survivors. Methods: 36 consecutive COVID-19 survivors underwent symptom-limited incremental CPET and assessment of endothelium-dependent flow-mediate dilation (FMD) according to standardized protocols. Results: A significantly higher FMD was documented in patients with a preserved, as compared to those with a reduced, exercise capacity (4.11% ± 2.08 vs. 2.54% ± 1.85, p = 0.048), confirmed in a multivariate analysis (β = 0.899, p = 0.038). In the overall study population, FMD values showed a significant Pearson’s correlation with two primary CPET parameters, namely ventilation/carbon dioxide production (VE/VCO2) slope (r = −0.371, p = 0.026) and end-tidal carbon dioxide tension (PETCO2) at peak (r = 0.439, p = 0.007). In multiple linear regressions, FMD was the only independent predictor of VE/VCO2 slope (β = −1.308, p = 0.029) and peak PETCO2 values (β = 0.779, p = 0.021). Accordingly, when stratifying our study population based on their ventilatory efficiency, patients with a ventilatory class III-IV (VE/VCO2 slope ≥ 36) exhibited significantly lower FMD values as compared to those with a ventilatory class I-II. Conclusions: The alteration of endothelial barrier properties in systemic and pulmonary circulation may represent a key pathogenic mechanism of the reduced CPET performance in COVID-19 survivors. Personalized pharmacological and rehabilitation strategies targeting endothelial function may represent an attractive therapeutic option.

Effects of intravenous ethyl pyruvate on cardiopulmonary variables and quality of recovery from anesthesia in horses

ObjectiveTo determine the effects of intravenous ethyl pyruvate, an anti-inflammatory with putative benefits in horses with endotoxemia, on cardiopulmonary variables during anesthesia and the quality of anesthetic recovery. Study designRandomized, crossover, blinded experimental design. AnimalsA total of six healthy Standardbred geldings, aged 13 ± 3 years and weighing 507 ± 66 kg (mean ± standard deviation). MethodsHorses were anesthetized for approximately 90 minutes on two occasions with a minimum of 2 weeks apart using xylazine for sedation, ketamine and diazepam for induction, and isoflurane in oxygen for maintenance. Lactated Ringer’s solution (LRS; 10 mL kg–1 hour–1) was administered during anesthesia. Treatments were randomized and administered starting approximately 30 minutes after induction of anesthesia and infused over 60 minutes: LRS (1 L) or ethyl pyruvate (150 mg kg–1 in 1 L LRS). Invasive arterial pressures, heart rate, respiratory rate and end-tidal carbon dioxide tensions were recorded every 5 minutes for the duration of anesthesia. Arterial blood gases, glucose and lactate concentrations were measured every 20 minutes. Anesthetic recovery was video recorded, stored, and subsequently rated by two individuals blinded to treatments. Total recovery time, time to extubation, number of attempts and time to sternal recumbency, number of attempts to stand and time to stand were recorded. Quality of recovery was analyzed. Data between treatments and within a treatment were assessed using two-way repeated-measures anova and a Pearson correlation coefficient, significant at p < 0.05. ResultsAll horses completed the study. No significant differences were detected between the ethyl pyruvate and LRS treatments for either the cardiopulmonary variables or quality of recovery from anesthesia. Conclusions and clinical relevanceThe results suggest that intravenous ethyl pyruvate can be administered to healthy anesthetized horses with minimal impact on the cardiopulmonary variables studied or the quality of recovery from anesthesia.

Effect of 15° Reverse Trendelenburg Position on Arterial Oxygen Tension during Isoflurane Anesthesia in Horses.

Simple SummaryHorses commonly develop low blood oxygen levels during anesthesia, especially when they are placed on their backs. This study investigated whether a 15° head-up tilt, in a homogenous group of anesthetized horses positioned on their backs, would result in better blood oxygen levels as compared to no tilt. The results showed significantly greater blood oxygen levels with tilt compared to no tilt in five out of six horses tested. In one horse the effect was the opposite. The concurrent effect on cardiovascular function remains to be tested in detail. Further studies are needed to confirm these findings in a larger group of horses and to determine the effects on blood pressure and treatment options.Lower than expected arterial oxygen tension (PaO2) continues to be an unresolved problem in equine anesthesia. The aim of this randomized, crossover, and prospective study using six adult horses is to determine if a 15° reverse Trendelenburg position (RTP) increases PaO2 during inhalation anesthesia. Under constant-dose isoflurane anesthesia, dorsally recumbent horses were positioned either horizontally (HP) or in a 15° RTP for 2 h. Lungs were mechanically ventilated (15 mL/kg, 6 breaths/min). Arterial carbon dioxide tension (PaCO2), PaO2, inspired oxygen fraction (FiO2), and end-tidal carbon dioxide tension (EtCO2) were determined every 30 min during anesthesia. Indices of dead-space ventilation (Vd/Vt), oxygenation (P–F ratio), and perfusion (F–shunt) were calculated. Dobutamine and phenylephrine were used to support mean arterial pressure (MAP). Data are presented as median and range. In one horse, which was deemed an outlier due to its thoracic dimensions and body conformation, indices of oxygenation worsened in RTP compared to HP (median PaO2 438 vs. 568 mmHg; P–F ratio 454 vs. 586 mmHg, and F–shunt 13.0 vs. 5.7 mmHg). This horse was excluded from calculations. In the remaining five horses they were significantly better with RTP compared to HP. Results in remaining five horses showed that PaO2 (502, 467–575 vs. 437, 395–445 mmHg), P-F ratio (518, 484–598 vs. 455, 407–458 mmHg), and F-shunt (10.1, 4.2–11.7 vs. 14.2, 13.8–16.0 mmHg) were significantly different between RTP and HP (p = 0.03). Other variables were not significantly different. In conclusion, the 15° RTP resulted in better oxygenation than HP in dorsally recumbent, isoflurane-anesthetized horses, although worsening of oxygenation may occur in individual horses. A study detailing the cardiovascular consequences of RTP is necessary before it can be recommended for clinical practice.

Hemodynamic efficacy of a motor-driven automatic device performing simultaneous sternothoracic cardiopulmonary resuscitation compared to standard cardiopulmonary resuscitation in an animal model of cardiac arrest

The aim of this study was to investigate hemodynamic effects and resuscitation outcomes of simultaneous sternothoracic cardiopulmonary resuscitation (SST-CPR) with a prototype of a motor-driven automatic device, comparing to manual standard CPR (S-CPR), in an animal model of ventricular fibrillation (VF). 20 male pigs were randomized to receive standard CPR (S-CPR group) or CPR with an automatic SST-CPR device (A-CPR group) after 5 minutes of VF. Five minutes of basic life support CPR was performed, followed by 10 minutes of advanced life support CPR. Hemodynamic variables including systolic blood pressure (SBP), diastolic blood pressure (DBP), coronary perfusion pressure (CPP), and end-tidal carbon dioxide tension (ETCO2), and resuscitation outcomes including rate of restoration of spontaneous circulation (ROSC) and 2-hour survival were compared between two groups. Ten animals among the A-CPR group and 8 animals among the S-CPR group were included in the final analysis. SBP was higher in the A-CPR group than in the S-CPR group during CPR (p = 0.046). The DBP, CPP and ETCO2 were not different between two groups (p = 0.412, 0.585, and 0.243, respectively). ROSC rate was 38% in the S-CPR group and 10% in the A-CPR group (p = 0.275). The 2-hour survival rate was 25% in the S-CPR group and 0% in the A-CPR group (p = 0.183). In a swine model of cardiac arrest, CPR with a prototype of a motor-driven automatic SST-CPR device, compared with standard CPR, produced higher systolic blood pressure, but there was no difference in diastolic pressure, coronary perfusion pressure, ROSC rate and 2-hour survival rate.

Comparison of Intra and Post-operative Sedation Efficacy of Dexmedetomidinemidazolam and Dexmedetomidine-propofol for Major Abdominal Surgery.

The effectiveness and side effects of dexmedetomidine (DEX) in combination with midazolam and propofol have not been comparatively studied in a single clinical trial as sedative agents to general anesthesia before. The objective of this study is to compare intra and post-operative sedation between DEX-Midazolam and DEX-Propofol in patients who underwent major abdominal surgery on the duration of general anesthesia, hemodynamic and sedation effect. This prospective, randomized, double-blinded clinical trial included 50 patients who were 20 to 60 years of age and admitted for major abdominal surgery. The patients were randomly assigned by a computer-generated random numbers table to sedation with DEX plus midazolam (DM group) (n=25) or DEX plus propofol (DP group) (n=25). In the DM group, patients received a bolus dose of 0.1 mg/kg of midazolam and immediately initiated the intravenous (i.v.) infusion of DEX 1 μg/kg over a 10 min and 0.5 μg/kg/hr by continuous i.v. infusion within operation period. In the DP group, patients received pre-anesthetic i.v. DEX 1 μg/kg over 15 min before anesthesia induction and 0.2-1 μg/kg/hr by continuous i.v. infusion during the operative period. After preoxygenation for at least 2 min, during the surgery, patients received propofol infusion dose of 250 μg/kg/min for 15 min then a basal infusion dose of 50 μg/kg/min. The bispectral index (BIS) value, as well as mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), oxygen saturation (SaO2), percutaneous arterial oxygen saturation (SpO2) and end-tidal carbon dioxide tension (ETCO2) were recorded before anesthesia (T0), during anesthesia (at 15-min intervals throughout the surgical procedure), by a blinded observer. Evidence of apnea, hypotension, hypertension and hypoxemia were recorded during surgery. The hemodynamic changes, including HR, MAP, BIS, VT, SaO2, and RR had a downward tendency with time, but no significant difference was observed between the groups (P>0.05). However, the two groups showed no significant differences in ETCO2 and SPO2 values in any of the assessed interval (P>0.05). In this study, the two groups showed no significant differences in the incidence of nausea, vomiting, coughing, apnea, hypotension, hypertension, bradycardia and hypoxemia (P>0.05). Respiratory depression and serious adverse events were not reported in either group. Extubation time after surgery was respectively 6.3 ± 1.7 and 5.8 ± 1.4 hr. in the DM and DP groups and the difference was not statistically significant (P= 0.46). Our study showed no significant differences between the groups in hemodynamic and respiratory changes in each of the time intervals. There were also no significant differences between the two groups in the incidence of complication intra and post-operative. Further investigations are required to specify the optimum doses of using drugs which provide safety in cardiovascular and respiratory system without adverse disturbance during surgery.

Comparison of direct laryngoscopy and video-assisted laryngoscopy in pediatric intensive care unit

Our objective was to compare video-assisted laryngoscopy (VAL) with direct laryngoscopy (DL) for glottic visualization in a pediatric intensive care unit in terms of the success rate in first attempts. Our study included patients aged from 1 month to 18 years who were admitted to the pediatric intensive care unit. We excluded patients with limited neck extension (C-spine immobilization, congenital abnormality), congenital anomalies (e.g., Pierre Robin syndrome, micrognathia, macroglossia), and recent airway surgery. Patients were premedicated before intubation. The time to intubation was defined as the time between the start of anesthesia and completion of intubation. The start of anesthetic induction was defined as the time the sedative was first administered. Completion of intubation was defined as the time that the end-tidal carbon dioxide tension was detected. We evaluated 120 of 135 intubations that met our inclusion criteria; 15 were excluded because in eight cases (53%) non-pediatric intensive care physicians made the initial attempts, and in seven cases (47%) the recorded intubation times were erroneous. We detected significantly higher POGO scores in the VAL group (p<0.001). VAL provided a fuller view of the glottis (Cormack and Lehane grade 1) than DL (p<0.001). Although the intubation attempts in the DL group were significantly higher (two or more attempts), no intubation failures occurred in either group.

Effects of changes in end-tidal carbon dioxide tension on oral tissue blood flow and tissue oxygen tension during remifentanil infusion in rabbits.

The aim of this study was to investigate the effects of end-tidal carbon dioxide tension (ETCO2) changes during remifentanil infusion on mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO2) and masseter muscle tissue oxygen tension (PmO2) in rabbits. Ten male tracheotomized Japan White rabbits were anesthetized and ventilated with sevoflurane. ETCO2 was adjusted to 30mmHg. After baseline measurement, CO2 was added to the inhaled air, and ETCO2 was increased to 40 and 60mmHg. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), BBF, MBF, PbO2, and PmO2 were recorded with and without remifentanil infusion at 0.4µg/kg/min. Two-way repeated measures analysis of variance showed no interaction between ETCO2 and remifentanil in all variables. Remifentanil infusion produced decreases in HR, SBP, MAP, BBF and MBF compared with those without remifentanil infusion, while it did not affect DBP, PbO2 and PmO2. Elevation of ETCO2 from 30 to 60mmHg produced decreases in HR and MBF, and increases in SBP, DBP, MAP and BBF, while it did not affect PbO2 and PmO2. PbO2 and PmO2 remained unchanged despite changes in BBF and MBF during ETCO2 change with or without remifentanil infusion.

Respiratory Changes under Spinal Anaesthesia for Laparoscopic Gynaecological Procedures- a comparison with General Anaesthesia

Background: Laparoscopic surgery has become a frequently applied technique for a wide field ofindications. The procedure has become the gold standard for many procedures, with some of the mostcommon being gynecological procedures and appendectomy. Laparoscopic procedures that are widelyused in gynecological surgery are commonly applied under general anesthesia (GA). Now a days spinalanaesthesia (SAB) has become a routine technique for healthy patients. It is currently presumed thatspinal anaesthesia can compromise respiratory muscle function during carbon dioxide (CO2)pneumoperitoneum and causes some respiratory changes. Objective: This study was designed to compare the respiratory effects of CO2 pneumoperitoneumunder spinal anaesthesia with general anaesthesia for short duration (&lt;1hr) laparoscopicgynaecological procedures. Methods: A total number of sixty female patients, thirty in each group of ASA grade I &amp; II wereenrolled for the study. Group I patients received lumber SAB with 15 mg heavy bupivacaine and 25mcg fentanyl. Group II patients received standard general anaesthesia with propofol, halothane andfentanyl. Baseline heart rate, blood pressure, respiratory rate, ETCO2 &amp; SPO2 were noted in allpatients. Arterial blood gas analysis was done at time 0, 20 and 40 min after initiation ofpneumoperitoneum. Continuous ECG, pulse oximetry, noninvasive blood pressure, and ETCO2 weremonitored during the procedure. Any per operative and post-operative side effects were recorded andmanaged. Results: There were no observed changes in the respiratory rate. In group I, ETCO2 increased in astepwise manner over the first 10 min and reached a plateau between 15th and 30th min and declinedafter deflation of pneumoperitoneum. Arterial CO2 tension also increased at 20 min with significantchanges (p=0.000) in arterial to end tidal carbon dioxide tension. ETCO2 and arterial carbon dioxidetension changes were almost similar in both groups. Conclusion: Arterial and end-tidal CO2 tension changes during lower abdominal laparoscopicsurgery under SAB remain within physiological limits and comparable to the CO2 tension under GA.SAB may be adopted in ASA physical status I and II patients with proper preoperative counseling.Hence it is a safe alternative to GA with minimum respiratory alterations. JBSA 2021; 34 (2) : 10-15

Evidence of a double anaerobic threshold in healthy subjects.

The anaerobic threshold (AT) is an important cardiopulmonary exercise test (CPET) parameter both in healthy and in patients. It is normally determined with three approaches: V-slope method, ventilatory equivalent method, and end-tidal method. The finding of different AT values with these methods is only anecdotic. We defined the presence of a double threshold (DT) when a ΔVO2 > 15 mL/min was observed between the V-slope method (met AT) and the other two methods (vent AT). The aim was to identify whether there is a DT in healthy subjects. We retrospectively analysed 476 healthy subjects who performed CPET in our laboratory between 2009 and 2018. We identified 51 subjects with a DT (11% of cases). Cardiopulmonary exercise test data at rest and during the exercise were not different in subjects with DT compared to those without. Met AT always preceded vent AT. Compared to subjects without DT, those with DT showed at met AT lower carbon dioxide output (VCO2), end-tidal carbon dioxide tension (PetCO2) and respiratory exchange ratio (RER), and higher ventilatory equivalent for carbon dioxide (VE/VCO2). Compared to met AT, vent AT showed a higher oxygen uptake (VO2), VCO2, ventilation, respiratory rate, RER, work rate, and PetCO2 but a lower VE/VCO2 and end-tidal oxygen tension. Finally, subjects with DT showed a higher VO2 increase during the isocapnic buffering period. Double threshold was present in healthy subjects. The presence of DT does not influence peak exercise performance, but it is associated with a delayed before acidosis-induced hyperventilation.

Exercise Capacity, Ventilatory Response, and Gas Exchange in COPD Patients With Mild to Severe Obstruction Residing at High Altitude.

BackgroundExercise intolerance, desaturation, and dyspnea are common features in patients with chronic obstructive pulmonary disease (COPD). At altitude, the barometric pressure (BP) decreases, and therefore the inspired oxygen pressure and the partial pressure of arterial oxygen (PaO2) also decrease in healthy subjects and even more in patients with COPD. Most of the studies evaluating ventilation and arterial blood gas (ABG) during exercise in COPD patients have been conducted at sea level and in small populations of people ascending to high altitudes. Our objective was to compare exercise capacity, gas exchange, ventilatory alterations, and symptoms in COPD patients at the altitude of Bogotá (2,640 m), of all degrees of severity.MethodsMeasurement during a cardiopulmonary exercise test of oxygen consumption (VO2), minute ventilation (VE), tidal volume (VT), heart rate (HR), ventilatory equivalents of CO2 (VE/VCO2), inspiratory capacity (IC), end-tidal carbon dioxide tension (PETCO2), and ABG. For the comparison of the variables between the control subjects and the patients according to the GOLD stages, the non-parametric Kruskal–Wallis test or the one-way analysis of variance test was used.ResultsEighty-one controls and 525 patients with COPD aged 67.5 ± 9.1 years were included. Compared with controls, COPD patients had lower VO2 and VE (p < 0.001) and higher VE/VCO2 (p = 0.001), A-aPO2, and VD/VT (p < 0.001). In COPD patients, PaO2 and saturation decreased, and delta IC (p = 0.004) and VT/IC increased (p = 0.002). These alterations were also seen in mild COPD and progressed with increasing severity of the obstruction.ConclusionThe main findings of this study in COPD patients residing at high altitude were a progressive decrease in exercise capacity, increased dyspnea, dynamic hyperinflation, restrictive mechanical constraints, and gas exchange abnormalities during exercise, across GOLD stages 1–4. In patients with mild COPD, there were also lower exercise capacity and gas exchange alterations, with significant differences from controls. Compared with studies at sea level, because of the lower inspired oxygen pressure and the compensatory increase in ventilation, hypoxemia at rest and during exercise was more severe; PaCO2 and PETCO2 were lower; and VE/VO2 was higher.

Availability of portable capnometers in children with tracheostomy.

A capnometer is a noninvasive monitor that is used to assess patients' respiratory status. This study was performed to evaluate the availability of a portable capnometer in children with tracheostomy. This retrospective study included children with tracheostomy who were treated at the Osaka Women's and Children's Hospital Osaka, Japan, from 1 September 2018 to 31 October 2019. We assessed the correlation between the partial pressure of venous carbon dioxide (PvCO2 ) and end-tidal carbon dioxide tension (EtCO2 ) using a portable capnometer (EMMA; Masimo, Irvine, CA, USA). Nine infants and 43 simultaneous PvCO2 -EtCO2 pairs were analyzed. The correlation coefficient of these pairs was 0.87 (95% confidence interval, 0.77-0.93; P < 0.001). The Bland-Altman plot showed that EtCO2 was on average 10.0mmHg lower than its paired PvCO2 value (95% limits of agreement, 1.0-19.1). The difference between PvCO2 and EtCO2 was significantly greater in patients on ventilators. The portable capnometer evaluated in this study (EMMA) was readily available and useful for assessment of the respiratory condition in children with tracheostomy.

Cerebral Oxygenation and Metabolism in Patients Undergoing Clipping of Cerebral Aneurysm: A Comparative Study between Propofol-based total intravenous anesthesia and Sevoflurane-based inhalational anesthesia.

ABSTRACT Background: Sevoflurane unfortunately increases the cranial blood flow, blood volume, and pressure changes cope with cerebral aneurysmal neuroanesthesia goals. Propofol decreases the brain metabolism, blood flow, preserve cerebral reactivity to carbon dioxide, creates neuroprotective effect during cerebral ischemia. Hypothesis: Propofol-based total intravenous anesthesia would be more appropriate than sevoflurane-based inhalational technique during surgical clipping of cerebral aneurysm. Methods: A prospective, randomized, comparative study on 50 patients subjected for elective clipping of cerebral aneurysm, randomly allocated into two equal groups of 25 patients each: propofol-dormicum total intravenous only group and sevoflurane based inhalational group. Results: Jugular oxygen saturation (primary outcome), cerebral blood flow equivalent, heart rate, mean arterial blood pressure, and end tidal carbon dioxide tension were statistically significantly decreased in propofol group compared to sevoflurane group at basal, just after dura opening, at 1,2,3 hours later, and after scalp closure. Arterio-Jugular oxygen content difference, cerebral extraction ratio of O2, estimated cerebral metabolic rate for O2, serum lactate (mg/dl) showed significant increase in propofol group compared to sevoflurane group at basal, 1, 2, 3 h, and after scalp closure. Duration of surgery, time of recovery, blood loss, blood transfusion, intraoperative complications, urine output, total midazolam consumption, surgeon satisfaction, intensive care unit stay time, and Ramsay sedation scale difference was not significant in between both studied groups during the early postoperative period. Conclusion: Propofol based total intravenous anesthesia has better cerebral oxygenation and neuro anesthesia profile compared to sevoflurane-based inhalational anesthesia during cerebral aneurysm clipping surgery with systemic hemodynamic stability.

Could we suspect pulmonary veno-oclussive disease with a cardiopulmonary exercise test?

Abstract Background Cardiopulmonary exercise test (CPET) provides information about the pathophysiology of the exercise limitation. CPET parameters in pulmonary arterial hypertension (PAH) exhibit distinctive features, such as low peak oxygen uptake (pVO2), low end tidal carbon dioxide tension (PetCO2) and high ventilation-carbon dioxide slope (VE/VCO2).Pulmonary veno-oclussive disease (PVOD) is a PAH subgroup with particular underlying physiology, difficult diagnosis and poor prognosis. Purpose We hypothesized that different CPET patterns could be identified in PAH subgroups, and this may contribute to their diagnosis workup. Methods CPETs performed on the following PAH subgroups between September 2019 and January 2020 were prospectively included: Idiopathic PAH (IPAH), Heritable PAH (HPAH), and PAH responders to calcium channel blockers (CCB-R). Due to its low prevalence and its clinical relevance, CPET data on PVOD patients was retrospectively included. Results 57 CPET were included: 20 IPAH (35%); 13 HPAH (22.8%); 9 CCB-R (15.8%),15 PVOD (26.3%). All patients presented impaired functional capacity with reduced peakVO2 and increased VE/VCO2). Remarkably, PVOD patients,in spite of a younger age, exhibit the worst functional capacity and ventilatory efficiency even showing downward PetCO2 kinetics. CCB-R group achieved the highest peakVO2 and had better ventilatory parameters.(Table 1) Conclusion CPET is a useful tool to classify patients by PAH subgroups. Very low PetCO2 at rest and a downward PetCO2 kinetic strongly suggest PVOD, which has significant implications on treatment. Funding Acknowledgement Type of funding source: None

Severe hypercapnia associated with a chemodectoma causing profound tracheal narrowing in a cat

An 11-year-old, domestic short-haired cat presented out-of-hours with a 1-day history of dyspnoea and open-mouthed breathing. Ninety minutes after arrival, the cat acutely deteriorated. Butorphanol (0.2 mg/kg) was administered intravenously...