Changes in lung mechanics and ventilation-perfusion match: comparison of pulmonary air- and thromboembolism in rats.

BACKGROUND: Pulmonary air embolism (AE) and thromboembolism lead to severe ventilation-perfusion defects. The spatial distribution of pulmonary perfusion dysfunctions differs substantially in the two pulmonary embolism pathologies, and the effects on respiratory mechanics, gas exchange, and ventilation-perfusion match have not been compared within a study. Therefore, we compared changes in indices reflecting airway and respiratory tissue mechanics, gas exchange, and capnography when pulmonary embolism was induced by venous injection of air as a model of gas embolism or by clamping the main pulmonary artery to mimic severe thromboembolism. METHODS: Anesthetized and mechanically ventilated rats (n = 9) were measured under baseline conditions after inducing pulmonary AE by injecting 0.1 mL air into the femoral vein and after occluding the left pulmonary artery (LPAO). Changes in mechanical parameters were assessed by forced oscillations to measure airway resistance, lung tissue damping, and elastance. The arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were determined by blood gas analyses. Gas exchange indices were also assessed by measuring end-tidal CO2 concentration (ETCO2), shape factors, and dead space parameters by volumetric capnography. RESULTS: In the presence of a uniform decrease in ETCO2 in the two embolism models, marked elevations in the bronchial tone and compromised lung tissue mechanics were noted after LPAO, whereas AE did not affect lung mechanics. Conversely, only AE deteriorated PaO2, and PaCO2, while LPAO did not affect these outcomes. Neither AE nor LPAO caused changes in the anatomical or physiological dead space, while both embolism models resulted in elevated alveolar dead space indices incorporating intrapulmonary shunting. CONCLUSIONS: Our findings indicate that severe focal hypocapnia following LPAO triggers bronchoconstriction redirecting airflow to well-perfused lung areas, thereby maintaining normal oxygenation, and the CO2 elimination ability of the lungs. However, hypocapnia in diffuse pulmonary perfusion after AE may not reach the threshold level to induce lung mechanical changes; thus, the compensatory mechanisms to match ventilation to perfusion are activated less effectively.

Venovenous extracorporeal membrane oxygenation for COVID-19 associated severe respiratory failure: Case series from a Hungarian tertiary centre.

INTRODUCTION: Venovenous extracorporeal membrane oxygenation (V-V ECMO) is recommended for the support of patients with severe COVID-19 associated severe respiratory failure (SRF). We report the characteristics and outcome of COVID-19 patients supported with V-V ECMO in a Hungarian centre. METHODS: We retrospectively collected data on all patients admitted with proven SARS CoV-2 infection who received V-V ECMO support between March 2021 and May 2022. RESULTS: Eighteen patients were placed on ECMO during this period, (5 women, age (mean ± SD) 44 ± 10 years, APACHE II score (median (interquartile range)) 12 (10-14.5)). Before ECMO support, they had been hospitalised for 6 (4-11) days. Fifteen patients received noninvasive ventilation for 4 (2-8) days, two patients had high flow nasal oxygen therapy, for one day each. They had already been intubated for 2.5 (1-6) days. Prone position was applied in 15 cases. On the day before ECMO initiation the Lung Injury Score was 3.25 (3-3.26), the PaO2/FiO2 ratio was 71 ± 19 mmHg. The duration of V-V ECMO support was 26 ± 20 days, and the longest run lasted 70 days. Patients were mechanically ventilated for 34 ± 23 days. The intensive care unit (ICU) and the hospital length of stay were 40 ± 28 days and 45 ± 31 days, respectively. Eleven patients were successfully weaned from ECMO. The ICU survival rate was 56%, the in-hospital survival was 50%. All patients who were discharged from hospital reported a good health-related quality of life Rankin score (0-2) at the 5-16 months follow-up. CONCLUSIONS: During the last three waves of the COVID-19 pandemic, we achieved a 56% ICU and a 50% hospital survival rate at our low volume centre.

Expiratory high-frequency percussive ventilation: a novel concept for improving gas exchange.

BACKGROUND: Although high-frequency percussive ventilation (HFPV) improves gas exchange, concerns remain about tissue overdistension caused by the oscillations and consequent lung damage. We compared a modified percussive ventilation modality created by superimposing high-frequency oscillations to the conventional ventilation waveform during expiration only (eHFPV) with conventional mechanical ventilation (CMV) and standard HFPV. METHODS: Hypoxia and hypercapnia were induced by decreasing the frequency of CMV in New Zealand White rabbits (n = 10). Following steady-state CMV periods, percussive modalities with oscillations randomly introduced to the entire breathing cycle (HFPV) or to the expiratory phase alone (eHFPV) with varying amplitudes (2 or 4 cmH2O) and frequencies were used (5 or 10 Hz). The arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were determined. Volumetric capnography was used to evaluate the ventilation dead space fraction, phase 2 slope, and minute elimination of CO2. Respiratory mechanics were characterized by forced oscillations. RESULTS: The use of eHFPV with 5 Hz superimposed oscillation frequency and an amplitude of 4 cmH2O enhanced gas exchange similar to those observed after HFPV. These improvements in PaO2 (47.3 ± 5.5 vs. 58.6 ± 7.2 mmHg) and PaCO2 (54.7 ± 2.3 vs. 50.1 ± 2.9 mmHg) were associated with lower ventilation dead space and capnogram phase 2 slope, as well as enhanced minute CO2 elimination without altering respiratory mechanics. CONCLUSIONS: These findings demonstrated improved gas exchange using eHFPV as a novel mechanical ventilation modality that combines the benefits of conventional and small-amplitude high-frequency oscillatory ventilation, owing to improved longitudinal gas transport rather than increased lung surface area available for gas exchange.

Dopamine Reverses Lung Function Deterioration After Cardiopulmonary Bypass Without Affecting Gas Exchange.

OBJECTIVE: To investigate the effects of dopamine on the adverse pulmonary changes after cardiopulmonary bypass. DESIGN: A prospective, nonrandomized clinical investigation. SETTING: A university hospital. PARTICIPANTS: One hundred fifty-seven patients who underwent elective cardiac surgery that required cardiopulmonary bypass. INTERVENTIONS: Fifty-two patients were administered intravenous infusion of dopamine (3 µg/kg/min) for five minutes after weaning from cardiopulmonary bypass; no intervention was applied in the other 105 patients. MEASUREMENTS AND MAIN RESULTS: Measurements were performed under general anesthesia and mechanical ventilation before cardiopulmonary bypass, after cardiopulmonary bypass, and after the intervention. In each protocol stage, forced oscillatory lung impedance was measured to assess airway and tissue mechanical changes. Mainstream capnography was performed to assess ventilation- and/or perfusion-matching by calculating the normalized phase-3 slopes of the time and volumetric capnograms and the physiologic deadspace. Arterial and central venous blood samples were analyzed to characterize lung oxygenation and intrapulmonary shunt. After cardiopulmonary bypass, dopamineinduced marked improvements in airway resistance and tissue damping, with relatively small decreases in lung tissue elastance. These changes were associated with decreases in the normalized phase-3 slopes of the time and volumetric capnograms. The inotrope had no effect on physiologic deadspace, intrapulmonary shunt, or lung oxygenation. CONCLUSION: Dopamine reversed the complex detrimental lung mechanical changes induced by cardiopulmonary bypass and alleviated ventilation heterogeneities without affecting the physiologic deadspace or intrapulmonary shunt. Therefore, dopamine has a potential benefit on the gas exchange abnormalities after weaning from cardiopulmonary bypass.

Obesity and diabetes: similar respiratory mechanical but different gas exchange defects.

Diabetes mellitus increases smooth muscle tone and causes tissue remodeling, affecting elastin and collagen. Although the lung is dominated by these elements, diabetes is expected to modify the airway function and respiratory tissue mechanics. Therefore, we characterized the respiratory function in patients with diabetes with and without associated obesity. Mechanically ventilated patients with normal body shapes were divided into the control nondiabetic (n = 73) and diabetic (n = 31) groups. The other two groups included obese patients without diabetes (n = 43) or with diabetes (n = 30). The mechanical properties of the respiratory system were determined by forced oscillation technique. Airway resistance (Raw), tissue damping (G), and tissue elastance (H) were assessed by forced oscillation. Capnography was applied to determine phase 3 slopes and dead space indices. The intrapulmonary shunt fraction (Qs/Qt) and the lung oxygenation index (PaO2/FIO2) were estimated from arterial and central venous blood samples. Compared with the corresponding control groups, diabetes alone increased the Raw (7.6 ± 6 cmH2O.s/l vs. 3.1 ± 1.9 cmH2O.s/l), G (11.7 ± 5.5 cmH2O/l vs. 6.5 ± 2.8 cmH2O/l), and H (31.5 ± 11.8 cmH2O/l vs. 24.2 ± 7.2 cmH2O/l (P < 0.001 for all). Diabetes increased the capnographic phase 3 slope, whereas PaO2/FIO2 or Qs/Qt was not affected. Obesity alone caused similar detrimental changes in respiratory mechanics and alveolar heterogeneity, but these alterations also compromised gas exchange. We conclude that diabetes-induced intrinsic mechanical abnormalities are counterbalanced by hypoxic pulmonary vasoconstriction, which maintained intrapulmonary shunt fraction and oxygenation ability of the lungs.

Comparison of the Previous and Current Trauma-Related Shock Classifications: A Retrospective Cohort Study from a Level I Trauma Center.

PURPOSE: The aim was to examine the predictive value of the hypovolemic shock classification currently accepted by the Advanced Trauma Life Support (ATLS) program over the previous one, which used only vital signs (VS) for patient allocation. The primary outcome was 30-day mortality; as secondary outcome, heart rate (HR), systolic blood pressure (SBP), Glasgow Coma Scale (GCS) and base deficit (BD) data were compared and investigated in terms of mortality prediction. METHODS: Retrospective analysis at a level I trauma center between 2014 and 2019. Adult patients treated by trauma teams were allocated into severity classes (I-IV) based on the criteria of the current and previous ATLS classifications, respectively. The prognostic values for the classifications were determined with Fisher's exact test and χ2 test for independence, and compared with the 2-proportion Z test. The individual variables were analyzed with receiver-operating characteristic (ROC) analyses. RESULTS: A total of 156 patients met the inclusion criteria. Mortality was effectively predicted by both classifications, and there was no statistically significant difference between the predictive performances. According to ROC analyses, GCS, BD and SBP had significant prognostic values while HR change was ineffective in this regard. CONCLUSIONS: The currently used ATLS shock classification does not appear to be superior to the VS-based previous classification. GCS, BD and SBP are useful parameters to predict the prognosis. Changes in HR do not reflect the clinical course accurately; thus, further studies will be needed to determine the value of this parameter in trauma-associated hypovolemic-hemorrhagic shock conditions.

Lung volume dependence of respiratory function in rodent models of diabetes mellitus.

BACKGROUND: Diabetes mellitus causes the deterioration of smooth muscle cells and interstitial matrix proteins, including collagen. Collagen and smooth muscle cells are abundant in the lungs, but the effect of diabetes on airway function and viscoelastic respiratory tissue mechanics has not been characterized. This study investigated the impact of diabetes on respiratory function, bronchial responsiveness, and gas exchange parameters. METHODS: Rats were allocated randomly to three groups: a model of type 1 diabetes that received a high dose of streptozotocin (DM1, n = 13); a model of type 2 diabetes that received a low dose of streptozotocin with a high-fat diet (DM2, n = 14); and a control group with no treatment (C, n = 14). Forced oscillations were applied to assess airway resistance (Raw), respiratory tissue damping (G), and elastance (H). The arterial partial pressure of oxygen to the inspired oxygen fraction (PaO2/FiO2) and intrapulmonary shunt fraction (Qs/Qt) were determined from blood gas samples at positive end-expiratory pressures (PEEPs) of 0, 3, and 6 cmH2O. Lung responsiveness to methacholine was also assessed. Collagen fibers in lung tissue were quantified by histology. RESULTS: The rats in groups DM1 and DM2 exhibited elevated Raw, G, H, and Qs/Qt, compromised PaO2/FiO2, and diminished airway responsiveness. The severity of adverse tissue mechanical change correlated with excessive lung collagen expression. Increased PEEP normalized the respiratory mechanics, but the gas exchange abnormalities remained. CONCLUSIONS: These findings indicate that diabetes reduces airway and lung tissue viscoelasticity, resulting in alveolar collapsibility that can be compensated by increasing PEEP. Diabetes also induces persistent alveolo-capillary dysfunction and abnormal adaptation ability of the airways to exogenous constrictor stimuli.

Infective endocarditis complicated with coronary artery septic embolization: is it worth to be mentioned? Case presentation and review of the literature.

Coronary artery septic embolization is a rare, but severe complication of infective endocarditis involving the leftside of the valves. The first case mentioned in the literature was a postmortem finding of a left anterior descending coronary artery occlusion by a vegetation fragment. Since this case, there have been several therapeutic strategies published with this clinical setting including medical treatment, percutaneous coronary angioplasty addressing coronary occlusion, surgical intervention for both the infected valve and coronary embolization, and hybrid procedures with transcatheter septic embolus aspiration followed by surgical valvular interventions. Out of the three interventions mentioned, the latter provided the best results and was in concordance with results observed in a case of mitral valve infected endocarditis complicated with acute occlusion of the left anterior descending coronary artery in patient whose comorbidities included hypertrophic obstructive cardiomyopathy. A transcatheter left anterior descending coronary artery embolus aspiration was performed , followed by a surgical mitral valve replacement and septal myectomy with an uneventful postoperative course. Although rare, this severe complication of infective endocarditis has a specific clinical course and therapeutic strategy, and in our opinion, it could be mentioned as a separate entity among embolic complications of infective endocarditis in future guidelines. Previously published cases suggest that the hybrid intervention might be the therapy of choice for this clinical setting; however, larger studies are necessary for confirmation.

Reversing Cholinergic Bronchoconstriction by Common Inotropic Agents: A Randomized Experimental Trial on Isolated Perfused Rat Lungs.

BACKGROUND: The ability of inotropic agents to alter airway reactivity and lung tissue mechanics has not been compared in a well-controlled experimental model. Therefore, we compared the potential to alter lung tissue viscoelasticity and bronchodilator effects of commonly used inotropic agents in an isolated perfused rat lung model. METHODS: After achieving steady state lung perfusion, sustained bronchoconstriction was induced by acetylcholine (ACh). Isolated rat lungs were then randomly allocated to 6 groups treated with either saline vehicle (n = 8) or incremental concentrations of inotropes (adrenaline, n = 8; dopamine, n = 7; dobutamine, n = 7; milrinone, n = 8; or levosimendan, n = 6) added to the whole-blood perfusate. Airway resistance (Raw), lung tissue damping (G), and elastance were measured under baseline conditions, during steady-state ACh-induced constriction and for each inotrope dose. RESULTS: No change in Raw was observed after addition of the saline vehicle. Raw was significantly lower after addition of dopamine (maximum difference [95% CI] of 29 [12-46]% relative to the saline control, P = .004), levosimendan (58 [39-77]%, P < .001), and adrenaline (37 [21-53]%, P < .001), whereas no significant differences were observed at any dose of milrinone (5 [-12 to 22]%) and dobutamine (4 [-13 to 21]%). Lung tissue damping (G) was lower in animals receiving the highest doses of adrenaline (difference: 22 [7-37]%, P = .015), dobutamine (20 [5-35]%, P = .024), milrinone (20 [6-34]%, P = .026), and levosimendan (36 [19-53]%, P < .001) than in controls. CONCLUSIONS: Although dobutamine and milrinone did not reduce cholinergic bronchoconstriction, they reversed the ACh-induced elevations in lung tissue resistance. In contrast, adrenaline, dopamine, and levosimendan exhibited both potent bronchodilatory action against ACh and diminished lung tissue damping. Further work is needed to determine whether these effects are clinically relevant in humans.

Optimal crystalloid volume ratio for blood replacement for maintaining hemodynamic stability and lung function: an experimental randomized controlled study.

BACKGROUND: Crystalloids are first line in fluid resuscitation therapy, however there is a lack of evidence-based recommendations on the volume to be administered. Therefore, we aimed at comparing the systemic hemodynamic and respiratory effects of volume replacement therapy with a 1:1 ratio to the historical 1:3 ratio. METHODS: Anesthetized, ventilated rats randomly included in 3 groups: blood withdrawal and replacement with crystalloid in 1:1 ratio (Group 1, n = 11), traditional 1:3 ratio (Group 3, n = 12) and a control group with no interventions (Group C, n = 9). Arterial blood of 5% of the total blood volume was withdrawn 7 times, and replaced stepwise with different volume rations of Ringer's acetate, according to group assignments. Airway resistance (Raw), respiratory tissue damping (G) and tissue elastance (H), mean arterial pressure (MAP) and heart rate (HR) were assessed following each step of fluid replacement with a crystalloid (CR1-CR6). Lung edema index was measured from histological samples. RESULTS: Raw decreased in Groups 1 and 3 following CR3 (p < 0.02) without differences between the groups. H elevated in all groups (p < 0.02), with significantly higher changes in Group 3 compared to Groups C and 1 (both p = 0.03). No differences in MAP or HR were present between Groups 1 and 3. Lung edema was noted in Group 3 (p < 0.05). CONCLUSIONS: Fluid resuscitation therapy by administering a 1:1 blood replacement ratio revealed adequate compensation capacity and physiological homeostasis similar with no lung stiffening and pulmonary edema. Therefore, considering this ratio promotes the restrictive fluid administration in the presence of continuous and occult bleeding.

[Diabetes mellitus: endothelial dysfunction and changes in hemostasis]. / Diabetes mellitus: endotheldiszfunkció és haemostasiselváltozások.

Diabetes mellitus involves a group of chronic metabolic disorders with elevated blood glucose concentrations. Since this disease needs lifelong treatment and care, the medical and social aspects present major public health concerns and pose a global challenge for health care providers. The number of aged patients with degenerative diseases undergoing surgical procedures is continuously increasing, resulting in an overwhelming dominance of diabetes in the perioperative care. There is a particular need for an increased awareness of diabetic patients in cardiovascular units, where the incidence of this disease reaches as high as 30-40%. The main hallmarks of the pathologic metabolic milieu of diabetes are hyperglycaemia, insulin resistance and pathologic lipid metabolism. The biochemical, cellular and organ-level pathophysiological changes lead to endothelial dysfunction including a low-grade prothrombotic balance, inflammatory state and, as a consequence, impaired micro- and macrocirculation. Diabetes is also followed by platelet dysfunction resulting from intracellular hyperglycaemia, because thrombocytes have insulin-independent glucose transporters in their cell membrane. The levels of the coagulation factors of the plasma are increased, and these factors are also modified by oxidation and glycation. Diabetes mellitus is a prothrombotic condition resulting from direct and indirect tendencies of the endothelial platelet and the plasma coagulation factors. The basic "bench to clinical basics" knowledge of the endothelial dysfunction and prothrombotic balance in diabetes may contribute to the better understanding of the clinical focuses in the perioperative care of patients with diabetes mellitus. Orv Hetil. 2018; 159(33): 1335-1345.

[Perioperative use of levosimendan in cardiac surgery. Hungarian recommendation]. / A levoszimendán perioperatív alkalmazása a szívsebészetben. Magyar ajánlás.

Low output syndrome significantly increases morbidity and mortality of cardiac surgery and lengthens the durations of intensive care unit and hospital stays. Its treatment by catecholamines can lead to undesirable systemic and cardiac complications. Levosimendan is a calcium sensitiser and adenosine triphosphate (ATP)-sensitive potassium channel (IK,ATP) opener agent. Due to these effects, it improves myocardium performance, does not influence adversely the balance between O2 supply and demand, and possesses cardioprotective and organ protective properties as well. Based on the scientific literature and experts' opinions, a European recommendation was published on the perioperative use of levosimendan in cardiac surgery in 2015. Along this line, and also taking into consideration cardiac surgeon, anaesthesiologist and cardiologist representatives of the seven Hungarian heart centres and the children heart centre, the Hungarian recommendation has been formulated that is based on two pillars: literature evidence and Hungarian expert opinions. The reviewed fields are: coronary and valvular surgery, assist device implantation, heart transplantation both in adult and pediatric cardiologic practice. Orv Hetil. 2018; 159(22): 870-877.

Levosimendan prevents bronchoconstriction and adverse respiratory tissue mechanical changes in rabbits.

Levosimendan has a calcium-sensitizing effect in the myocardium and opens ATP-sensitive potassium channels (KATP) in vascular smooth muscle. Because airway smooth muscle also expresses KATP, we characterized the protective potential of levosimendan against increased airway and respiratory tissue resistances. Animals were administered levosimendan alone (group L), levosimendan after pretreatment with a KATP channel blocker (glibenclamide, group LG), glibenclamide only (group G), or solvent alone (dextrose, group C). Airway resistance (Raw), tissue damping, and elastance were determined by forced oscillations under baseline conditions and following provocation tests with intravenous methacholine (MCh). Cardiac output (CO) was assessed by transpulmonary thermodilution. The same sequence of measurements was then repeated during intravenous infusion of levosimendan in groups L and LG or glucose in groups G and C Sham treatments in groups C and G had no effect on lung responsiveness. However, levosimendan treatment in group L elevated CO and inhibited the MCh-induced airway responses [Raw changes of 87.8 ± 83% (SD) vs. 24.4 ± 16% at 4 µg·kg-1·min-1 MCh, P < 0.001], and in G (35.2 ± 12.7 vs. 25.2 ± 12.9%, P < 0.05). The preventive affect of levosimendan against lung constriction vanished in the LG group. Levosimendan exerts a KATP-mediated potential to prevent bronchoconstriction and may prohibit adverse lung peripheral changes both in the small bronchi and the pulmonary parenchyma. The identification of a further pleiotropic property of levosimendan that is related to the pulmonary system is of particular importance for patients with decreased cardiorespiratory reserves for which simultaneous circulatory support is complemented with prevention of adverse respiratory events.

Sevoflurane Relieves Lung Function Deterioration After Cardiopulmonary Bypass.

OBJECTIVE: To investigate sevoflurane's potential to alleviate the detrimental pulmonary changes after cardiopulmonary bypass (CPB). DESIGN: Prospective, randomized clinical investigation. SETTING: University hospital. PARTICIPANTS: One hundred ninety patients undergoing elective cardiac surgery. INTERVENTIONS: Ninety-nine patients under intravenous anesthesia were administered 1 minimal alveolar concentration of sevoflurane for 5 minutes after being weaned from CPB (group SEV); intravenous anesthesia was maintained in the other 91 patients (group CTRL). MEASUREMENTS AND MAIN RESULTS: Measurements were performed with open chest: before CPB, after CPB, and after intervention. The lungs' mechanical impedance and capnogram traces were recorded, arterial and central venous blood samples were analyzed, and lung compliance was documented. Airway resistance, tissue damping, and elastance were obtained from the impedance spectra. The capnogram phase III slope was determined using linear regression. The partial pressure of oxygen in the arterial blood/fraction of inspired oxygen ratio and shunt fraction were calculated from blood gas parameters. After CPB, sevoflurane induced bronchodilation, reflected in marked drops in airway resistance and smaller improvements in lung tissue viscoelasticity indicated by decreases in tissue damping and elastance. These changes were reflected in a decreased capnogram phase III slope and shunt fraction and increased partial pressure of oxygen in the arterial blood/fraction of inspired oxygen ratio and lung compliance. The more severe deteriorations that occurred after CPB, the greater improvements by sevoflurane were observed. CONCLUSIONS: Sevoflurane can alleviate CPB-induced bronchoconstriction, compromised lung tissue mechanics, and enhanced intrapulmonary shunt. This benefit has particular importance in patients with severe CPB-induced lung function deterioration.

[Multivalve redo surgery in adult patient with complex pulmonary artesia]. / Több-billentyus redomutét felnott betegen komplex pulmonalis atresiában.

30-year-old adult with complex pulmonary atresia (previous surgical procedures: in infancy: exploration, at age of 10: ventricular septal defect closing, unifocalization, homograft implantation between right ventricular outflow tract and pulmonary artery) has biventricular dysfunction because of aortic valve regurgitation, ascending aortic aneurysm, and homograft insufficienty. Multivalve surgery: aortic valve plasty, pulmonary homograft changes for homograft and ascending aortic reconstruction by graft were carried out successfully. In Hungary this was the first case of this type of surgery. Management of special problems (follow-up, correct diagnostics (echocardiography, MR, CT), indication and necessity of reoperation, optimal age) in adult patients with complex congenital heart defects produces excellent early and late surgical results. Orv. Hetil., 2017, 158(14), 546-549.

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics.

BACKGROUND: Although the mechanical status of the lungs affects the shape of the capnogram, the relations between the capnographic parameters and those reflecting the airway and lung tissue mechanics have not been established in mechanically ventilated patients. We, therefore, set out to characterize how the mechanical properties of the airways and lung tissues modify the indices obtained from the different phases of the time and volumetric capnograms and how the lung mechanical changes are reflected in the altered capnographic parameters after a cardiopulmonary bypass (CPB). METHODS: Anesthetized, mechanically ventilated patients (n = 101) undergoing heart surgery were studied in a prospective consecutive cross-sectional study under the open-chest condition before and 5 minutes after CPB. Forced oscillation technique was applied to measure airway resistance (Raw), tissue damping (G), and elastance (H). Time and volumetric capnography were performed to assess parameters reflecting the phase II (SII) and phase III slopes (SIII), their transition (D2min), the dead-space indices according to Fowler, Bohr, and Enghoff and the intrapulmonary shunt. RESULTS: Before CPB, SII and D2min exhibited the closest (P = 0.006) associations with H (0.65 and -0.57; P < 0.0001, respectively), whereas SIII correlated most strongly (P < 0.0001) with Raw (r = 0.63; P < 0.0001). CPB induced significant elevations in Raw and G and H (P < 0.0001). These adverse mechanical changes were reflected consistently in SII, SIII, and D2min, with weaker correlations with the dead-space indices (P < 0.0001). The intrapulmonary shunt expressed as the difference between the Enghoff and Bohr dead-space parameters was increased after CPB (95% ± 5% [SEM] vs 143% ± 6%; P < 0.001). CONCLUSIONS: In mechanically ventilated patients, the capnographic parameters from the early phase of expiration (SII and D2min) are linked to the pulmonary elastic recoil, whereas the effect of airway patency on SIII dominates over the lung tissue stiffness. However, severe deterioration in lung resistance or elastance affects both capnogram slopes.

Fluid replacement and respiratory function: comparison of whole blood with colloid and crystalloid: A randomised animal study.

BACKGROUND: Fluid replacement with blood products, colloids and crystalloids is associated with morbidity and mortality. Despite this, the consequences of fluid administration on airway and respiratory tissue properties are not fully understood. OBJECTIVE: Comparison of respiratory effects of fluid replacement with autologous blood (Group B), colloid (HES 6% 130/0.4, Group CO) or crystalloid solution (NaCl 0.9%, Group CR) after haemorrhage with separate assessments of airway resistance and respiratory tissue mechanics. DESIGN: A randomised study. SETTING: An experimental model of surgical haemorrhage and fluid replacement in rats. PARTICIPANTS: Anaesthetised, ventilated rats randomly allocated into three groups (Group B: n = 8, Group CO: n = 8, Group CR: n = 9). INTERVENTION: Animals were bled in six sequential steps, each manoeuvre targeting a loss of 5% of total blood volume. The blood loss was then replaced stepwise in a 1 : 1 ratio with one of the three fluids. MAIN OUTCOME MEASURE: After each step, airway resistance (Raw), tissue damping and elastance (H) were determined by forced oscillations. Oedema indices from lung weights and histology were also measured. RESULTS: Raw (mean ±â€ŠSD) decreased in all groups following blood loss (-20.3 ±â€Š9.5% vs. baseline, P < 0.05), and remained low following blood replacement (-21.7 ±â€Š14.5% vs. baseline, P < 0.05), but was normalised by colloid (5.5 ±â€Š10.7%, NS). Crystalloid administration exhibited an intermediate reversal effect (-8.4 ±â€Š14.7%, NS). Tissue viscoelasticity increased following both blood loss and replacement, with no evidence of a significant difference in H between Groups CO and CR. More severe oedema was observed in Groups CR and CO than in Group B (P < 0.05), with no difference between the colloid and crystalloid solutions. CONCLUSION: This model, which mimics surgical haemorrhage, yields no evidence of a difference between colloids and crystalloids with regard to the pulmonary consequences of blood volume restoration. Functional changes in the lung should not be a key concern when choosing fluid replacement therapy with these solutions.

[Surgical management of congenital heart defects beyond the age of 60]. / Veleszületett szívhibák sebészi kezelése 60 éves kor felett.

INTRODUCTION: The population with congenital heart disease is increasing and ageing. AIM: The aim of the authors was to examine the outcome of surgical management of congenital heart diseases beyond the age of 60 years. METHOD: Between 2013 and 2015, 77 adults were operated (36 younger, and 41 older than forty years, including 12 patients aged over 60 years. The numbers of procedures were as follows (in brackets the number of operations in the three age groups): Ross surgery 5 (3, 2, 0); aortic valve replacement 19 (12, 1, 6); subaortic membrane resection 1 (0, 0, 1); Bentall/ascending aortic plasty 8 (4, 3, 1); myectomy with or without mitral valve replacement in left ventricular outflow obstruction 5 (0, 3, 2); aortic coarctation 1 (1, 0, 0); ligation of ductus arteriosus 2 (1, 1, 0); reconstruction of right ventricular outflow tract with biological valve 4 (0, 3, 1); homograft 5 (5, 0, 0); BioValsalva graft 1 (0, 1, 0); primary reconstruction of complete atrioventricular septum defect 3 (1, 2, 0); valve replacement 2 (1, 1, 0); ventricular septum defect 10 (4, 6, 0); atrial septum defect closure 5 (2, 3, 0); total cavopulmonal anastomosis 1 (1, 0, 0); valve replacement in congenital transposition of great arteries 1 (0, 1, 0), Ebstein operation with valve plasty 2 (0, 1, 1); valve replacement 2 (1, 0, 1). RESULTS: There was no operative mortality, while early mortality occurred in one patient with total cavopulmonal anastomosis due to multiorgan failure. CONCLUSIONS: Congenital heart defects can be operated beyond the age of 60 years with good results in a tertiary heart centre having great experience in the management of congenital and acquired heart disease.

[Perspectives in the management of congenital heart defects in adult patients]. / Perspektívák a veleszületett szívhibák felnottkori sebészi kezelésében.

Due to improving results in congenital heart surgery, the number of adult patients with congenital heart defect is increasing. The question is: what kind of problems can be managed in this patient-group? The authors review the different problems of management of congenital heart defects in adults based on national and international literature data. Simple defects recognised in adults, postoperative residual problems, changing of small grafts and valves, correction of primary or operated coarctation aortae can be usually managed without problems. A very close follow-up is necessary to establish the correct period for heart transplantation in patients with transposition of great arteries with Senning/Mustard operation, and univentricular heart corrected with "Fontan-circulation" type surgical procedure. The authors conclude that although the number of patients increases, only a few congenital heart diseases may cause problems. It seems important (1) to monitor asymptomatic patient who underwent operation (Fallot-IV, Ross procedure, etc.), (2) follow up regularly patients who underwent Senning/Mustard procedure (magnetic resonance imaging, echocardiography, brain natriuretic peptide measurement), (3) define the proper period of preparation for heart transplantation of patients with a univentricular heart, with special attention to the possibility of multiorgan (lung, liver, etc.) failure. Due to the improvement of foetal diagnosis of congenital heart defects, the number of patients with complex congenital heart defects is decreasing. The standard management of these patients could be primary heart transplantation in infancy.