Unilateral pulmonary artery agenesis: An unusual cause of unilateral ARDS.

Unilateral pulmonary artery agenesis (UPAA) is a rare malformation that can present as an isolated anomaly or may be associated with certain congenital cardiac anomalies, such as tetralogy of Fallot, atrial septal defect, coarctation of aorta, right aortic arch, truncus arteriosus and pulmonary atresia. Clinical presentation is non-specific which makes the diagnosis elusive; chronic dyspnea, hemoptysis or recurrent infections are the most common manifestations. Patients may remain asymptomatic until adulthood. There is no definitive treatment for patients with UPAA. Acute respiratory distress syndrome (ARDS) is usually a bilateral disease, unilateral ARDS has been described after lung resection or trauma. We present a case of a 39 year-old woman who developed unilateral ARDS and was later diagnosed with isolated UPAA.

Use of 'ideal' alveolar air equations and corrected end-tidal PCO2 to estimate arterial PCO2 and physiological dead space during exercise in patients with heart failure.

BACKGROUND: Arterial CO2 tension (PaCO2) and physiological dead space (VD) are not routinely measured during clinical cardiopulmonary exercise testing (CPET). Abnormal changes in PaCO2 accompanied by increased VD directly contribute to impaired exercise ventilatory function in heart failure (HF). Because arterial catheterization is not standard practice during CPET, this study tested the construct validity of PaCO2 and VD prediction models using 'ideal' alveolar air equations and basic ventilation and gas-exchangegas exchange measurements during CPET in HF. METHODS: Forty-seven NYHA class II/III HF (LVEF=21±7%; age=55±9years; male=89%; BMI=28±5kg/m2) performed step-wise cycle ergometry CPET to volitional fatigue. Breath-by-breath ventilation and gas exchange were measured continuously. Steady-state PaCO2 was measured at rest and peak exercise via radial arterial catheterization. Criterion VD was calculated via 'ideal' alveolar equations, whereas PaCO2 or VD models were based on end-tidal CO2 tension (PETCO2), tidal volume (VT), and/or weight. RESULTS: Criterion measurements of PaCO2 (38±5 vs. 33±5mmHg, P<0.01) and VD (0.26±0.07 vs. 0.41±0.15L, P<0.01) differed at rest vs. peak exercise, respectively. The equation, 5.5+0.90×PETCO2-0.0021×VT, was the strongest predictor of PaCO2 at rest and peak exercise (bias±95%LOA=-3.24±6.63 and -0.98±5.76mmHg; R2=0.57 and 0.75, P<0.001, respectively). This equation closely predicted VD at rest and peak exercise (bias±95%LOA=-0.03±0.06 and -0.02±0.13L; R2=0.86 and 0.83, P<0.001, respectively). CONCLUSIONS: These data suggest predicted PaCO2 and VD based on breath-by-breath gas exchange and ventilatory responses demonstrate acceptable agreement with criterion measurements at peak exercise in HF patients. Routine assessment of PaCO2 and VD can be used to improve interpretability of exercise ventilatory responses in HF.

The Effect of Pneumoperitoneum and Trendelenburg position on respiratory mechanics under general anesthesia during gynecological laparoscopic surgery / Монголын Анагаах Ухаан

Background@#Gynecological laparoscopic surgery requires pneumoperitoneum(PP) with CO₂ gas insufflation and Trendelenburg position. Pneumoperitoneum and Trendelenburg position may impact intraoperative respiratory mechanics in anesthetic management.The goal of this study was to evaluate the influence of Pneumoperitoneum and Trendelenburg position on respiratory mechanics and ventilation. @*Methods@#Twenty one patients scheduled for elective gynecological laparoscopy were evaluated. The patients had no preexisting lung and heart disease or pathologic lung function. Conventional general anesthesia with thiopental sodium, fentanyl, аtracrium and isoflurane was administered. The peak inspiratory pressure, plateau pressure, and end-tidal CO₂ were compared before after creation of pneumoperitoneum with an intraabdominal pressure of 15 mmH₂O, then after PP10, PP20, PP30 minutes in the 20° Trendelenburg position, and after deflation of pneumoperitoneum. The dynamic lung compliance was calculated.@*Results@#During of pneumoperitoneum, there were a significant increase in peak inspiratory pressure by 6 cmH₂O, plateau pressure by 5 cmH₂O, while dynamic lung compliance decreased by 11 ml/cmH₂O. General, the Trendelenburg position induced no significant hemodynamic and pulmonary changes.@*Conclusion@#The effects of pneumoperitoneum significantly reduced dynamic lung compliance and increased peak inspiratory and plateau pressures. The Tredelenburg position did not change these parameters. The end-tidal CO₂ significantly increased after pneumoperitoneum and CO₂ deflation.

A systematic evaluation of intraoperative white matter tract shift in pediatric epilepsy surgery using high-field MRI and probabilistic high angular resolution diffusion imaging tractography.

OBJECTIVE Characterization of intraoperative white matter tract (WMT) shift has the potential to compensate for neuronavigation inaccuracies using preoperative brain imaging. This study aimed to quantify and characterize intraoperative WMT shift from the global hemispheric to the regional tract-based scale and to investigate the impact of intraoperative factors (IOFs). METHODS High angular resolution diffusion imaging (HARDI) diffusion-weighted data were acquired over 5 consecutive perioperative time points (MR1 to MR5) in 16 epilepsy patients (8 male; mean age 9.8 years, range 3.8-15.8 years) using diagnostic and intraoperative 3-T MRI scanners. MR1 was the preoperative planning scan. MR2 was the first intraoperative scan acquired with the patient's head fixed in the surgical position. MR3 was the second intraoperative scan acquired following craniotomy and durotomy, prior to lesion resection. MR4 was the last intraoperative scan acquired following lesion resection, prior to wound closure. MR5 was a postoperative scan acquired at the 3-month follow-up visit. Ten association WMT/WMT segments and 1 projection WMT were generated via a probabilistic tractography algorithm from each MRI scan. Image registration was performed through pairwise MRI alignments using the skull segmentation. The MR1 and MR2 pairing represented the first surgical stage. The MR2 and MR3 pairing represented the second surgical stage. The MR3 and MR4 (or MR5) pairing represented the third surgical stage. The WMT shift was quantified by measuring displacements between a pair of WMT centerlines. Linear mixed-effects regression analyses were carried out for 6 IOFs: head rotation, craniotomy size, durotomy size, resected lesion volume, presence of brain edema, and CSF loss via ventricular penetration. RESULTS The average WMT shift in the operative hemisphere was 2.37 mm (range 1.92-3.03 mm) during the first surgical stage, 2.19 mm (range 1.90-3.65 mm) during the second surgical stage, and 2.92 mm (range 2.19-4.32 mm) during the third surgical stage. Greater WMT shift occurred in the operative than the nonoperative hemisphere, in the WMTs adjacent to the surgical lesion rather than those remote to it, and in the superficial rather than the deep segment of the pyramidal tract. Durotomy size and resection size were significant, independent IOFs affecting WMT shift. The presence of brain edema was a marginally significant IOF. Craniotomy size, degree of head rotation, and ventricular penetration were not significant IOFs affecting WMT shift. CONCLUSIONS WMT shift occurs noticeably in tracts adjacent to the surgical lesions, and those motor tracts superficially placed in the operative hemisphere. Intraoperative probabilistic HARDI tractography following craniotomy, durotomy, and lesion resection may compensate for intraoperative WMT shift and improve neuronavigation accuracy.

Comparison of arterial-to-end-tidal carbon dioxide tension difference during cardiac surgery in children with cyanotic or acyanotic congenital heart disease / 临床麻醉学杂志

Objective To estimate the arterial-to-end-tidal carbon dioxide tension difference (Pa-ET CO 2 )in children with cyanotic or acyanotic congenital heart diseases;evaluate whether hyper-ventilation can reduce the tension difference or not;analyze the effect of sevofleurane on Pa-ET CO 2 . Methods One hundred and twenty patients (male 60 cases,female 60 cases,aged 1 month-6 years, ASA class Ⅱ or Ⅲ)undergoing selective cardiac surgery were randomly divided into 6 groups (n =20 each)based on right-to-left or left-to-right intracardic shunts:group A1,cyanotic with sevoflurane of 0.5 MAC;group A2,cyanotic with sevoflurane of 1.0 MAC;group B1,acyanotic with sevoflurane of 0.5 MAC;group B2,acyanotic with sevoflurane of 1.0 MAC;group C1,cyanotic with no inter-vention factors;group C2,acyanotic with no intervention factors.All the children received general an-aesthesia after placing an intravenous and arterial catheter.The value of PET CO 2 ,SpO 2 ,PaCO 2 , SaO 2 ,Hct and temperature(nasopharyngeal temperature and rectal temperature)were obtained before operation,after hyperventilation(the control groups without hyperventilation)and five minutes before surture sternum.Results The values of Pa-ET CO 2 were more than the normal one in six groups before operation.The value of Pa-ET CO 2 in group B1 was less than that in group A1,that in group B2 was less than that in group A2 and that in group C2 was less than that in group C1 before operation (P <0.01).Compared with the time point before operation,the values of Pa-ET CO 2 in groups A1,A2,B1 and B2 decreased significantly after hyperventilation (P < 0.05 or P < 0.01 ).Moreover, this reduction was more significant in groups B1 and B2.Compared with the time point before operation, the values of Pa-ET CO 2 in groups B1,B2,C2 increased significantly (P <0.01)and that in groups A1, A2,C1 decreased significantly (P <0.05)at 5 minutes before surture sternum.There was no statisti-cal difference at three different time points between group A1 and A2,B1 and B2.Conclusion The value of Pa-ET CO 2 in cyanotic children increased more significantly than that in acyanotic children.Hy-perventilation can reduce the value of Pa-ET CO 2 especially in acynanotic children with pulmonary con-gestion.The concentration (from 0.5 MAC to 1.0 MAC)of sevoflurane had little effect on the value of Pa-ET CO 2 .

Volumetric capnography in infants with bronchopulmonary dysplasia.

OBJECTIVES: To assess the feasibility of using volumetric capnography in spontaneously breathing small infants and its ability to discriminate between infants with and without bronchopulmonary dysplasia (BPD). STUDY DESIGN: Lung function variables for 231 infants (102 term, 52 healthy preterm, 77 BPD), matched for post-conceptional age of 44 weeks, were collected. BPD was defined as supplemental oxygen requirement at 36 weeks post-menstrual age. Tidal breath-by-breath volume capnograms were obtained by mainstream capnography. The capnographic slope of phase II (SII) and slope of phase III (SIII) were calculated and compared between study groups. The effect of BPD, tidal volume (VT), respiratory rate (RR), and prematurity on the magnitude of the slopes was assessed. RESULTS: SII was steeper in infants with BPD (100 ± 28/L) compared with healthy preterm (88 ± 22/L; P = .007) and term infants (79 ± 18/L; P < .001), but this finding was attributed to differences in VT, RR, and gestational age. SIII was steeper in the BPD group (26.8 ± 14.1/L) compared with healthy preterm (16.2 ± 6.2/L; P < .001) and term controls (14.8 ± 5.4/L; P < .001). BPD was a significant predictor of SIII independently of VT, RR, and gestational age. The ability of SIII to discriminate between BPD and controls was significantly higher compared with lung clearance index (area under the curve 0.83 vs 0.56; P < .001). CONCLUSIONS: Volumetric capnography may provide valuable information regarding functional lung alterations related to BPD and might be considered as an alternative to more involved lung function techniques for monitoring chronic lung disease during early infancy.

Phrenic motoneuron discharge patterns following chronic cervical spinal cord injury.

Cervical spinal cord injury (SCI) dramatically disrupts synaptic inputs and triggers biochemical, as well as morphological, plasticity in relation to the phrenic motor neuron (PhMN) pool. Accordingly, our primary purpose was to determine if chronic SCI induces fundamental changes in the recruitment profile and discharge patterns of PhMNs. Individual PhMN action potentials were recorded from the phrenic nerve ipsilateral to lateral cervical (C2) hemisection injury (C2Hx) in anesthetized adult male rats at 2, 4 or 8 wks post-injury and in uninjured controls. PhMNs were phenotypically classified as early (Early-I) or late inspiratory (Late-I), or silent according to discharge patterns. Following C2Hx, the distribution of PhMNs was dominated by Late-I and silent cells. Late-I burst parameters (e.g., spikes per breath, burst frequency and duration) were initially reduced but returned towards control values by 8wks post-injury. In addition, a unique PhMN burst pattern emerged after C2Hx in which Early-I cells burst tonically during hypocapnic inspiratory apnea. We also quantified the impact of gradual reductions in end-tidal CO2 partial pressure (PETCO2) on bilateral phrenic nerve activity. Compared to control rats, as PETCO2 declined, the C2Hx animals had greater inspiratory frequencies (breaths∗min(-1)) and more substantial decreases in ipsilateral phrenic burst amplitude. We conclude that the primary physiological impact of C2Hx on ipsilateral PhMN burst patterns is a persistent delay in burst onset, transient reductions in burst frequency, and the emergence of tonic burst patterns. The inspiratory frequency data suggest that plasticity in brainstem networks is likely to play an important role in phrenic motor output after cervical SCI.

End-tidal CO2: an important parameter for a correct interpretation in functional brain studies using speech tasks.

The aim was to investigate the effect of different speech tasks, i.e. recitation of prose (PR), alliteration (AR) and hexameter (HR) verses and a control task (mental arithmetic (MA) with voicing of the result on end-tidal CO2 (PETCO2), cerebral hemodynamics and oxygenation. CO2 levels in the blood are known to strongly affect cerebral blood flow. Speech changes breathing pattern and may affect CO2 levels. Measurements were performed on 24 healthy adult volunteers during the performance of the 4 tasks. Tissue oxygen saturation (StO2) and absolute concentrations of oxyhemoglobin ([O2Hb]), deoxyhemoglobin ([HHb]) and total hemoglobin ([tHb]) were measured by functional near-infrared spectroscopy (fNIRS) and PETCO2 by a gas analyzer. Statistical analysis was applied to the difference between baseline before the task, 2 recitation and 5 baseline periods after the task. The 2 brain hemispheres and 4 tasks were tested separately. A significant decrease in PETCO2 was found during all 4 tasks with the smallest decrease during the MA task. During the recitation tasks (PR, AR and HR) a statistically significant (p<0.05) decrease occurred for StO2 during PR and AR in the right prefrontal cortex (PFC) and during AR and HR in the left PFC. [O2Hb] decreased significantly during PR, AR and HR in both hemispheres. [HHb] increased significantly during the AR task in the right PFC. [tHb] decreased significantly during HR in the right PFC and during PR, AR and HR in the left PFC. During the MA task, StO2 increased and [HHb] decreased significantly during the MA task. We conclude that changes in breathing (hyperventilation) during the tasks led to lower CO2 pressure in the blood (hypocapnia), predominantly responsible for the measured changes in cerebral hemodynamics and oxygenation. In conclusion, our findings demonstrate that PETCO2 should be monitored during functional brain studies investigating speech using neuroimaging modalities, such as fNIRS, fMRI to ensure a correct interpretation of changes in hemodynamics and oxygenation.

Effect of PaCO2, PETCO2, P(a-ET)CO2 and Regional Cortical Blood Flow on the Prognosis of Craniotomy Patients / 대한마취과학회지

BACKGROUND: Carbon dioxide is a potent cerebral vasodilator. The change of carbon dioxide partial pressure may influence the intracranial pressure and the patients' neurological outcome. There are few reports about the influence of end-tidal CO2 (ETCO2), arterial CO2 (PaCO2) and its pressure difference P(a-ET)CO2 during a craniotomy on the Glasgow coma scale (GCS) score for evaluation of neurological status. In this study, authors tried to discover the influence of PaCO2, PETCO2, and P(a-ET)CO2 on neurological outcome. METHODS: The data of PaCO2 and PETCO2 and P(a-ET)CO2 during a craniotomy was saved. The correlations between each parameter, the GCS score and rCoBF were analyzed. To prevent a direct effect on carbon dioxide tension, blood pressure and body temperature were maintained within a normal range. At the same time, we inserted a probe of the thermal diffusion flowmetry monitor in the subdural space to monitor the regional cortical cerebral blood flow (rCoBF). All the data was saved simultaneously, at the moment of dura closure. RESULTS: There was a fair correlation between the PaCO2 and PETCO2. A low PaCO2 level correlated well with a good GCS score but, not with PETCO2. The mean P(a-ET)CO2 value was 4.4 +/- 3.1 mmHg. The high P(a-ET)CO2 level correlated well with a poor GCS score. High rCoBF correlated well with a good GCS score. However, the changes of PaCO2 and PETCO2 showed no correlations with the rCoBF. CONCLUSIONS: As a result, if we decrease the PaCO2 level by hyperventilation and increase the rCoBF level through proper management during anesthesia, we can improve the patients' neurological outcome.

Correlation between PaCO2 and PETCO2 during Laparoscopic Cholecystectomy / 대한마취과학회지

During the laparoscopic cholecystectomy, the ventilatory and hemodynamic changes could occur due to the peritoneal insufflation of CO2 as well as the position change. Various sults of the relationship between arterial and end-tidal PCO2 in different conditions have been reported. The authars studied to determine how closely end-tidal PCO2 reflects arterial PCO2 before, during, and after laparoscopic cholecystectomy. Peak inspiratory airway pressures, arterial blood pressures and heart rates were also measured simultaneously. Peritoneal insufflation of CO2 resulted in significant increase in peak inspiratory airway pressure and arterial blood pressure, but there were no significant changes in heart rates. Arterial and end-tidal PCO2 increased during laproscopy and, although there was no statistical significance in P(a-ET)CO2, P(a-ET)CO2 increased during laparoscopy and retumed to perinsufflation level after deflation of CO2. There was positive correlation between arterial and end-tidal PCO2 before CO2 insufflation, 10 minutes after CO2 insufflation and 10 minutes after deflation of CO2. However there was no correlation at 30 and 50 minutes after CO2 insufflation. These results suggested that the arterial PCO2 could not reflect end-tidal PCO2 exactly, and intermittent arterial blood gas studies should be warranted during laparoscopic cholecystectomy.

End Tidal CO2 Monitoring with Salter Divided Nasal Cannula in Post-extubated Spontaneous Breathing Patients / 대한마취과학회지

For the evaluation of the correlation between the ETCO2 and the PaCO2 in post-extubated spontaneously breathing patients, we tested 30 patients in recovery room with Salter Divided Nasal Cannula, which have permanent bamer in the face piece and a dual tubing set that allows end tidal sampling from one nare and oxygen delivery to the other. When the wave form of capnogram looked regular and normal, the value of ETCO2 was recorded and the arterial blood was taken from the radial artery to analize blood gas immediately. The results were as following; 1. The mean value of PaCO2 was 42.0+/-4.8 mmHg. 2. The mean value of P(ET)CO2 was 39.3+/-5.1 mmHg. 3. The value of P(ET)CO2 acquired with Salter Divided Nasal Cannula hase close positive correlation with the values of the PaCO2. (PaCO2=0.75 x P(ET)CO2+/-12.64, r=0.79, p<0.001)