...being the possibility to “charge” oxygen limited by the hemoglobin concentration and its saturation in the venous blood, the oxygen transfer to the membrane lung is primarily function of the ...extracorporeal blood flow. ...the same PaO2/FIO2 threshold below 100 may encompass different shunt fractions depending on several factors 29. ...it is not surprising (and luckily it is the best solution) that, in clinical practice, are the attending physicians, usually in team, to decide if that particular hypoxemia in a given patient is such as to require the membrane lung application, considering its values together with a myriad of other anamnestic and pathological information. ...the PO2 in the pulmonary capillaries, perfusing the open lung units, only depends on FIO2, barometric pressure, and respiratory quotient. ...the drive for the oxygen transfer in the natural lung is the difference between PAO2 (equal to the pulmonary capillary partial pressure) and the PVO2/saturation of the blood entering the venous side. ...the increased oxygen content in the venous side increases the hemoglobin oxygen saturation in the pulmonary artery and decreases the hypoxic vasoconstriction, which, although dampened, is well-presented and effective in ARDS patients 30.
Benefits and risks of the P/F approach Gattinoni, L.; Vassalli, F.; Romitti, F.
Intensive care medicine,
12/2018, Letnik:
44, Številka:
12
Journal Article
The term THRIVE refers to the delivery of 100% heated and humidified oxygen via a nasal cannula to maintain viable gas exchange during prolonged apnea. There are no reports of its application for ...Operative Hysteroscopy (OH) under general anesthesia (GA). The aim of the study is to investigate the success rate of THRIVE as unique airway management technique in this setting. The results will support the development of a randomized controlled trial (RCT) to demonstrate the non-inferiority of THRIVE compared to traditional techniques.
Twenty consecutive ASA I-II women presenting for OH were enrolled. Standard anesthesia, as well as transcutaneous carbon dioxide (tcCO2) monitoring, was performed. After preoxygenation with 30 L∙min-1, GA was induced with propofol and fentanyl, then oxygen flow was increased to 70 L∙min-1 and anesthesia maintained with propofol infusion. The primary outcome was success rate of THRIVE defined as SpO2 > 94%, tcCO2 < 60 mmHg and no need for rescue airway intervention.
Mean age was 47 ± 12 years. Mean duration of the procedure was 25 ± 9 minutes, and the success rate of the technique was 100%. Median SpO2 during the procedure was 100 (IQR 99-100) %. Mean maximum tcCO2 level was 51 ± 7 mmHg while mean tcCO2 level during the procedure was 45 ± 7 mmHg. At the end of the procedure, mean tcCO2 was 44 ± 5 mmHg.
THRIVE allowed adequate gas exchange during OH under GA, without additional rescue airway interventions. The application of THRIVE in this setting may allow minimal airway manipulation and optimal comfort for the patient with low failure rate. We calculated the sample size for the planned non-inferiority RCT investigating the effectiveness of THRIVE versus laryngeal mask ventilation in OH: 82 is the minimal number of patients per group to test a non-inferiority limit of 10%.
sPHENIX is a new experiment under construction for the Relativistic Heavy Ion Collider at Brookhaven National Laboratory which will study the quark-gluon plasma to further the understanding of ...quantum chromodynamics (QCP) matter and interactions. A prototype of the sPHENIX electromagnetic calorimeter (EMCal) was tested at the Fermilab Test Beam Facility in Spring 2018 as experiment T-1044. The EMCal prototype corresponds to a solid angle of <inline-formula> <tex-math notation="LaTeX">\Delta \eta \times \Delta \phi = 0.2 \times 0.2 </tex-math></inline-formula> centered at pseudo-rapidity <inline-formula> <tex-math notation="LaTeX">\eta = 1 </tex-math></inline-formula>. The prototype consists of scintillating fibers embedded in a mix of tungsten powder and epoxy. The fibers project back approximately to the center of the sPHENIX detector, giving 2-D projectivity. The energy response of the EMCal prototype was studied as a function of position and input energy. The energy resolution of the EMCal prototype was obtained after applying a position-dependent energy correction and a beam profile correction. Two separate position-dependent corrections were considered. The EMCal energy resolution was found to be <inline-formula> <tex-math notation="LaTeX">\sigma (E)/\langle E\rangle = 3.5(0.1) \oplus 13.3(0.2)/\sqrt {E} </tex-math></inline-formula> based on the hodoscope position-dependent correction, and <inline-formula> <tex-math notation="LaTeX">\sigma (E)/\langle E\rangle = 3.0(0.1) \oplus 15.4(0.3)/\sqrt {E} </tex-math></inline-formula> based on the cluster position-dependent correction. These energy resolution results meet the requirements of the sPHENIX physics program.
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•Sacral sparing is a common cause of neuraxial labor analgesia failure.•27-gauge dural puncture epidural technique improved sacral block in the first hour.•Analgesia and sacral block ...at delivery were similar to an epidural technique.
The dural puncture epidural (DPE) technique has been associated with better sacral analgesia compared with a traditional epidural (EPL) technique in laboring parturients. The aim of this study was to investigate whether DPE with a 27-gauge pencil-point needle compared with a traditional EPL technique produces more rapid bilateral sacral blockade in nulliparous parturients.
Patients were randomized to a DPE or EPL technique. Epidural analgesia in both groups was initiated with ropivacaine 0.1% and sufentanil 0.5 μg/mL (15 mL) and maintained via programmed intermittent epidural boluses. Analgesic blockade was tested bilaterally beginning 10 min after initiation, and then at predefined intervals until delivery. The presence of an S2 blockade at 20 min was the primary outcome.
Among 108 (54 per group) patients enrolled, bilateral sacral (S2) blockade at 20 min was significantly more common in the DPE than in the EPL group 47 (87%) vs. 23 (43%), absolute risk reduction (ARR) 44%, 95% CI 28 to 60; P < 0.001. Time to a numeric pain rating scale score (0–10 scale) ≤ 3 (20 20,30 min in both groups, HR 1.15, 95% CI 0.77 to 1.15; P = 0.50), number of rescue doses 0 (0, 1) vs 0 (0, 1); P 0.08, and presence of bilateral S2 blockade at delivery were not significantly different between groups.
The DPE technique with a 27-gauge pencil-point spinal needle more often provides bilateral sacral blockade at 20 min following block initiation compared with the EPL technique. The time to adequate analgesia and need for supplemental analgesia did not appear to differ between techniques.
We tested the hypothesis that carbon monoxide might participate in the modulation of hypoxic pulmonary vasoconstriction (HPV) by prostacyclin (PGI2) and nitric oxide.
Prospective, interventional ...study.
University laboratory.
Nineteen intact anesthetized mongrel dogs.
Right heart catheterization for the measurements of mean pulmonary artery pressure (Ppa), left atrial pressure estimated from occluded Ppa (Ppao), pulmonary capillary pressure (Pcp) calculated from the Ppa decay curve after balloon occlusion, and cardiac output (Q); inferior vena cava balloon for the control of Q by manipulation of venous return; ventilation in hyperoxia (fraction of inspired O2, 0.4) or in hypoxia (Fio2, 0.1); inhibition of cyclooxygenase by indomethacin (Indo); inhibition of nitric oxide synthase by NG-nitro-l-arginine (L-NA); inhibition of heme oxygenase by mesoporphyrin IX (SnMP); inhalation of nitric oxide (20 ppm); and inhalation of carbon monoxide (100 ppm).
The first seven dogs were weak responders to hypoxia as assessed by a hypoxia-induced increase in the gradient between Ppa and Ppao, measured at one level of Q kept constant, by an average of only 2 mm Hg (p = NS). This HPV was markedly increased by the combined administration of Indo and L-NA. A further enhancement of HPV was observed after the addition of SnMP, leading to severe pulmonary hypertension with an average increase in Ppa to 39 mm Hg. Inhaled nitric oxide inhibited HPV only after the combined administration of Indo, L-NA, and SnMP. Inhaled carbon monoxide had no effect. The next 12 dogs were stronger responders to hypoxia, as assessed by a hypoxia-induced increase in the gradient between Ppa and Ppao, measured at several levels of Q, by an average of 3 mm Hg (p <.05). This HPV was of the same magnitude after administration of placebo (n = 6) or SnMP (n = 6). Addition of Indo enhanced HPV to the same extent in the placebo and in the SnMP groups. Addition of L-NA induced a further enhancement of HPV, which was, however, greater in the SnMP group. There was a slight increase in the capillary-venous segment relative to the arterial segment in hypoxic conditions, but the partitioning of pulmonary vascular resistance was otherwise unaffected by nitric oxide, carbon monoxide, or PGI2.
Endogenous carbon monoxide modulates canine HPV only in the absence of nitric oxide. The vasodilation mediated by nitric oxide, PGI2, or carbon monoxide is essentially distributed between proximal and distal sites proportionally to the degree of constriction produced during hypoxia.
Right ventricular (RV) adaptation is an important prognostic factor in acute and chronic pulmonary hypertension. Pulmonary vascular basal tone and hypoxic reactivity are known to vary widely between ...species. We investigated how RV adaptation to acute pulmonary hypertension is preserved in species with low, intermediate, and high pulmonary vascular resistance and reactivity. Acute pulmonary hypertension was induced by hypoxia, distal embolism, and proximal constriction in anesthetized dogs (n = 10), goats (n = 8), and pigs (n = 8). Pulmonary vessels were assessed by flow-pressure curves and by impedance to quantify distal resistance, proximal elastance, and wave reflections. RV function was assessed by pressure-volume curves to quantify afterload, contractility, and ventricular-arterial coupling efficiency. First, hypoxia was associated with a progressive increase of resistance, elastance, and wave reflection from dogs to goats and from goats to pigs. RV contractility increased proportionally to RV afterload, and optimal coupling was preserved in all species. Second, embolism increased resistance and wave reflection but not elastance. The increase in RV contractility matched the increase in RV afterload and optimal coupling was preserved. Finally, proximal pulmonary artery constriction increased resistance, increased and accelerated wave reflection, and markedly increased elastance. RV contractility increased markedly and coupling showed a nonsignificant trend to decrease. We conclude that optimal or near-optimal ventricular-arterial coupling is maintained in acute pulmonary hypertension, whether in absence or presence of chronic species-induced pulmonary hypertension.
To develop a deep learning-based decision tree for the primary care setting, to stratify adult patients with confirmed and unconfirmed coronavirus disease 2019 (COVID-19), and to predict the need for ...hospitalization or home monitoring.
We performed a retrospective cohort study on data from patients admitted to a COVID hospital in Rome, Italy, between 5 March 2020 and 5 June 2020. A confirmed case was defined as a patient with a positive nasopharyngeal RT-PCR test result, while an unconfirmed case had negative results on repeated swabs. Patients' medical history and clinical, laboratory and radiological findings were collected, and the dataset was used to train a predictive model for COVID-19 severity.
Data of 198 patients were included in the study. Twenty-eight (14.14%) had mild disease, 62 (31.31%) had moderate disease, 64 (32.32%) had severe disease, and 44 (22.22%) had critical disease. The G2 value assessed the contribution of each collected value to decision tree building. On this basis, SpO2 (%) with a cut point at 92 was chosen for the optimal first split. Therefore, the decision tree was built using values maximizing G2 and LogWorth. After the tree was built, the correspondence between inputs and outcomes was validated.
We developed a machine learning-based tool that is easy to understand and apply. It provides good discrimination in stratifying confirmed and unconfirmed COVID-19 patients with different prognoses in every context. Our tool might allow general practitioners visiting patients at home to decide whether the patient needs to be hospitalized.
The clinical significance of coronary flow reserve (CFR) was evaluated after pharmacological (papaverine) and physiological (exercise) vasodilation in patients with coronary artery disease (CAD).
CFR ...was determined using parametric imaging in 10 patients with normal coronary arteries (group 1) and in 10 with CAD (group 2). Contrast density and mean appearance time were measured (region of interest = 249 pixels) in the perfusion beds of the left circumflex and the left anterior descending coronary arteries at rest, 45 s after 10 mg intracoronary papaverine, and during supine bicycle exercise. CFR was calculated from coronary perfusion after papaverine divided by perfusion at rest and coronary perfusion during exercise divided by perfusion at rest. Perfusion zones in patients with CAD were subdivided into regions supplied by a non-stenosed (group 2a) and a stenosed (group 2b) coronary artery.
In control patients, heart rate increased from 75 beats/min at rest to 125 beats/min during exercise, and in patients with CAD from 63 to 107 beats/min, respectively. Mean aortic pressure showed a significant increase during exercise in both groups. Mean pulmonary artery pressure increased significantly during exercise from 19 to 28 mmHg in control patients and from 22 to 42 mmHg in the CAD group (P < 0.001). Coronary driving pressure (mean aortic minus diastolic pulmonary artery pressure) tended to increase during exercise in the control group (from 90 to 101 mmHg, NS) and remained nearly unchanged in patients with CAD (from 92 to 94 mmHg, NS). In the control group, CFR was significantly higher during exercise than after papaverine (4.0 versus 3.5, respectively; P < 0.01). However, coronary resistance (coronary driving pressure divided by coronary flow index) was similar after papaverine and during exercise. In patients with CAD, papaverine-dependent CFR was significantly reduced in the perfusion zone of the stenosed (2.1) but not of the non-stenosed coronary artery (3.0). In contrast, CFR during exercise was significantly decreased in both perfusion zones (2.5 in non-stenosed arteries and 1.5 in stenosed vessels).
In control patients, CFR is slightly but significantly larger during exercise than after papaverine because of the exercise-induced increase in coronary driving pressure. In contrast, CFR is smaller during exercise than after papaverine in patients with CAD, most probably as a result of secondary mechanisms such as exercise-induced narrowing of stenosed vessels or an increase in extravascular resistance. Thus, CFR based on papaverine appears to be of limited value for assessing the functional significance of a stenotic lesion.
Coronary vasomotion and coronary blood flow are important determinants of myocardial perfusion in patients with coronary artery disease. New digital angiographic techniques allow to study, not only ...the dimensions of a stenotic lesion (quantitative coronary arteriography), but also coronary flow reserve (parametric imaging). In a preliminary study both techniques were combined and coronary dimensions, as well as coronary flow reserve were determined in 15 patients (seven normals and eight patients with coronary artery disease) at rest, 45 s after 10 mg i.c. papaverine, during two levels of supine bicycle exercise, as well as 5 min after 1.6 mg sublingual nitroglycerin. Our results show that with modern digital subtraction techniques, not only stenosis geometry, but also coronary flow reserve can be determined at rest and during exercise conditions.
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