Significant Decrease In Cardiac Index Research Articles

Autonomic support of central hemodynamics and physical working capacity in female swimmers and runners in a one-year training cycle

The aim of the work is to assess dynamic changes in heart rate variability (HRV), central hemodynamics and physical performance in female swimmers at a distance of 50–200 meters and female runners at a distance of 400 meters in the preparatory and competitive periods of the training process. Materials and methods. At the beginning of the preparatory period and at the end of the competitive period, 11 female swimmers were examined, including 1 athlete – Master of Sports of Ukraine (MSU), 7 athletes – Candidate Masters of Sports (CMS), 1 – first-class athlete, 2 – second-class athletes, and 22 female runners, including 1 athlete – Master of Sports of Ukraine of International Class (MSUIC), 3 athletes – Candidate Masters of Sports, 7 first-class athletes, 8 – second-class athletes and 3 – third-class athletes. Time- and frequency domain methods of HRV analysis were used to assess the mechanisms of heart neurohumoral regulation. Central hemodynamic parameters were examined by an automated tetrapolar rheography according to W. Kubiček et al. (1970) modified by Yu. T. Pushkar et al. (1970). Physical working capacity (PWC) was measured using a submaximal PWC170 test. The functional state index (FSI) was calculated according to the formula that we had proposed and patented. Results. Analysis of HRV indices in female swimmers revealed the prevalence of parasympathetic influences in the competitive period. There was a central hemodynamics-related significant decrease in cardiac index (CI) in the competitive period, although its value corresponded to the eukinetic circulatory type (CT). The ratio of CTs was 18.2 %: 81.8 %: 0.0 %, hypokinetic, eukinetic and hyperkinetic CT, respectively, indicating a tendency towards eukinetic CT prevalence over hypokinetic one (P = 0.075) and the absence of athletes with physiologically unfavorable hyperkinetic CT. The PWC170/kg value increased by an average of 12.44 %, from 12.860 ± 0.732 kgm·min-1·kg-1 to 14.460 ± 0.823 kgm·min-1·kg-1 (P = 0.002), and FSI – of 22.21 % (P = 0.0005) and corresponding to “below average” score. In the competitive period, 2 CMS female athletes qualified for MSU, 1 first-class athlete qualified for CMS, and 2 second-class athletes achieved the first-class sport qualification. Conclusions. Female swimmers demonstrated the significant prevalence of parasympathetic effects of the ANS, the tendency towards the eukinetic CT predominance and the absence of hyperkinetic CT, significantly increased PWC170/kg value by 12.44 % and FSI – by 22.21 % in the competitive period as compared with the preparatory period. The correlation analysis to assess both periods revealed the important relationship between heart rate (HR) and autonomic rhythm index (ARI), HR and indicator of the adequacy of regulation processes (IARP), indicating that training-induced bradycardia shifted the autonomic balance towards the predominance of the parasympathetic arm of the ANS. Decreased ARI caused the decrease in СI, resulting in the transformation of hyperkinetic CT into eukinetic one and the absence of physiologically unfavorable hyperkinetic CT in the athletes. The increased functional state of female swimmers in the competitive period helped to achieve improvements in their athletic performance.

Esmolol response in septic shock patients in relation to vascular waterfall phenomenon measured by critical closure pressure and mean systemic filling pressure: a prospective observational study

BackgroundBedside measurements of critical closure pressure (Pcc) and mean systemic circulation filling pressure (Pmsf) were utilized to evaluate the response to esmolol in septic shock patients, in relation to the vascular waterfall phenomenon and body oxygen supply and demand.MethodsThis prospective observational self-controlled study included patients with septic shock, newly admitted to the intensive care unit, between August 2019 and January 2021. Pcc and Pmsf, along with the heart rate and other hemodynamic indicators were observed and compared before and 1 h after esmolol IV infusion.ResultsAfter 24 h of initial hemodynamic optimization, 56 patients were finally enrolled. After start of esmolol infusion, patients had a significant decrease in cardiac index (CI) (4.0 vs. 3.3 L/min/m2, P < 0.001), a significant increase in stroke index (SI) (34.1 vs. 36.6 mL/m2, P < 0.01), and a significant decrease in heart rate (HR) (116.8 vs. 90.6 beats/min, P < 0.001). After 1 h of treatment with esmolol, patients had a significant increase in Pcc (31.4 vs. 36.7 mmHg, P < 0.01). The difference between Pcc and Pmsf before and after treatment was statistically different (4.0 vs. 10.0 mmHg, P < 0.01). After heart rate control with esmolol, the patients had a significant increase in the body circulation vascular resistance indices (RIs) (15.14 vs. 18.25 mmHg/min/m2/L, P < 0.001). There was an increase in ScvO2 in patients after treatment with esmolol, but the difference was not statistically significant (68.4% vs. 69.8%, P > 0.05), while Pcv-aCO2 was significantly lower (6.3 vs. 4.9 mmHg, P < 0.001) and patients had a significant decrease in blood lactate levels (4.0 vs. 3.6 mmol/L, P < 0.05).ConclusionPatients with septic shock whose heart rate is greater than 95 beats/min after hemodynamic optimization were treated with esmolol, which could effectively control heart rate and reduce CI, as well as improve Pcc and increase the difference between Pcc and Pmsf (known as “vascular waterfall” phenomenon), without affecting MAP, CVP, Pmsf and arteriovenous vascular resistance, and improve the balance of oxygen supply and demand in the body.

Comparison the Effect of Etomidate vs. Thiopentone on Left Ventricular Strain and Strain Rate at the Time of Anesthesia Induction in Patients Undergoing Elective Coronary Artery Bypass Surgery: A Randomized Double Blind Controlled Trial

AbstractMyocardial strain imaging with speckle tracking echocardiography (STE) is getting popularity because it does not depends on insonation angle and has shown good correlation with intraoperative and postoperative ventricular function in patients with coronary artery disease. The impact of thiopentone and etomidate induction on myocardial function was studied and compared on sixty patients undergoing elective coronary artery bypass grafting. Three loops for each views (apical 4 chamber, apical 2 chamber, and apical long axis ) were acquired at base line (T0) and 1 minute (T1) after induction for offline analysis. In Group T, significant increase in HR from the base line values (67.8 ± 13.8 vs 79.2 ± 15.6, p = 0.001) occurred post induction, where as in Group E it remain near to the base line (71.7 ± 8.3 vs 70.1± 8.9, p = 0.345). A reduction in mean arterial pressure (MAP) was noted in both the groups after the injection of the allocated drug. There was no significant difference in the index of contractility (ICON) (T0 vs T1: 48.7 ± 10.6 vs 47.0 ± 11.7, p = 0.120) in Group E where as in Group T there was a reduction in the ICON value (T0 vs T1: 45.0 ± 10.7 vs 41.0 ± 8.4, p = 0.005). A similar picture was also noted in systemic vascular resistance index. A significant decrease in cardiac index (CI) was seen in Group E (T0 vs T1: 2.7 ± 0.4 vs 2.5 ± 0.4, p = 0.027), however it remain near to the base line in Group T. There occurred no changes in stroke index (SI) in Group E (T0 vs T1: 38.7 ± 6 vs 37.0± 5.3, p = 0.134), where as a significant decrease was noted after injection of thiopental (T0 vs T1: 38.0 ± 6.2 vs 36.1± 4.9, p = 0.049). A significant decline in cardiac performance index (CPI) was also recorded in Group E (T0 vs T1: 0.57 ± 0.15 vs 0.52 ± 0.12, p = 0.032), and not in Group T. There was decrease in left ventricular ejection fraction (LVEF) after the injection of both the drugs (Group E, T0 vs T1: 57 ± 3.7 vs 54± 3.7, p= 0.001; and Group T, T0 vs T1: 57 ± 3.7 vs 54± 3.7, p = 0.001). In Group E, global longitudinal peak systolic strain (GLPSS) showed no change after the injection of the drug (T0 vs T1: −13.2 ± 2.2 vs −13.1± 2.3, p = 0.631). However, a significant decrease in GLPSS (T0 vs T1: −13.5 ± 1.5 vs – 10 ± 1.8, p = 0.001) after injection of thiopental. Longitudinal peak systolic strain rate (LPSSR) was significantly decreased in all echocardiographic views after the injection of respective drugs. However, the decrease in LPSSR was significantly less in Group E in comparison to Group T.To conclude, STE provides accurate and reliable real time quantitative regional and global LV assessment. Use of thiopentone for anesthesia induction is associated with more profound impairment of LV function in comparison to etomidate as assessed by a decreased longitudinal peak systolic strain rate and global longitudinal peak systolic strain. Further studies are warranted to understand the exact clinical impact, which may influence the choice of intravenous induction agent based upon preoperative patient characteristics.

Cardiopulmonary effects of an intravenous infusion of fentanyl in cats during isoflurane anesthesia and with concurrent acepromazine or dexmedetomidine administration during anesthetic recovery.

To determine the cardiopulmonary effects of IV administration of fentanyl to cats anesthetized with isoflurane and during anesthetic recovery with concurrent administration of acepromazine or dexmedetomidine. 6 healthy adult cats. Cats received an IV bolus (5 μg/kg) followed by an IV infusion (5 μg/kg/h) of fentanyl for 120 minutes during isoflurane anesthesia and for 30 minutes after discontinuing isoflurane. Cats were randomly assigned in a crossover study to receive acepromazine (0.05 mg/kg) or dexmedetomidine (2.5 μg/kg), IV, when isoflurane was discontinued. Cardiopulmonary data were obtained during anesthesia and for 30 minutes during the anesthetic recovery period. The administration of fentanyl during isoflurane anesthesia resulted in a transient increase in arterial blood pressure, mean pulmonary artery pressure, and oxygen delivery. Compared with values during isoflurane anesthesia, administration of dexmedetomidine during anesthetic recovery resulted in significant decreases in cardiac index, stroke index, and oxygen delivery and significant increases in arterial, central venous, and mean pulmonary artery pressures; systemic vascular resistance index; and oxygen extraction ratio. Administration of acepromazine resulted in increases in heart rate, cardiac index, oxygen uptake, and oxygen extraction ratio. Oxygen extraction ratio did not differ between acepromazine and dexmedetomidine. Fentanyl transiently improved indices of cardiopulmonary performance when administered to healthy cats anesthetized with isoflurane. The cardiovascular effects of acepromazine and dexmedetomidine in healthy cats receiving fentanyl during recovery from isoflurane anesthesia differed, but measured cardiopulmonary parameters remained within acceptable limits.

Application of dexmedetomidine for lung injury in elderly patients undergoing one-lung ventilation.

This study aimed to evaluate the effects of dexmedetomidine (DEX) on lung injury, the oxygenation index and perioperative pulmonary complications in elderly patients who underwent thoracotomy with one-lung ventilation (OLV). A total of 120 elderly patients with lung cancer were included in the present study. According to the random number table method, these patients were randomly divided into two groups: group D and group C. Patients in group D were intravenously pumped with 0.5 μg/kg/h of DEX before anesthesia. The infusion was completed within 15 min, and anesthesia was induced by venous injection. Patients in group C were pumped with equal volumes of normal saline. At T2 and T3, compared with group C, group D had a significant decrease in cardiac index, mean arterial pressure and central venous pressure (p < 0.05). At T2, T3 and T4, compared with group C, group D had a significant increase in pH and PaO2 (p < 0.05). At T2, T3 and T4, compared with group C, group D had a significant decrease in Qs/Qt (p < 0.05). At T6, compared with group C, group D had a significant decrease in the supernatant of bronchoalveolar lavage fluid of tumor necrosis factor-α and interleukin 6 (p < 0.05). At T5, compared with group C, group D had a significant decrease in Visual Analogue Scale score (p < 0.05), and a significant increase in Ramsay Sedation Scale score (p < 0.05), and the number of respiratory and cardiovascular events also decreased (p < 0.05). In elderly patients, dexmedetomidine can reduce Qs/Qt and increase PaO2 during OLV in surgery. It can reduce lung injury. Moreover, DEX reduced respiratory and cardiovascular complications in the perioperative period.

Hemodynamic effects of dexmedetomidine, with and without MK-467, following intramuscular administration in cats anesthetized with isoflurane

ObjectiveTo characterize the hemodynamic effects of dexmedetomidine, with or without MK-467, following intramuscular (IM) administration in cats. Study designRandomized, crossover, experimental study. AnimalsSix healthy adult male castrated purpose-bred cats. MethodsCats were anesthetized with isoflurane in oxygen and instrumented. Cats were administered dexmedetomidine (25 μg kg−1), with (DM) or without (D) MK-467 (600 μg kg−1), IM in the epaxial muscles. Cardiovascular variables, respiratory variables, temperature, and arterial and mixed-venous pH, blood gases and electrolytes were measured prior to drug administration and at various time points for 6 hours thereafter, during anesthesia with isoflurane. Additional variables were calculated from the measurements, using standard equations. Results were analyzed with a two-way repeated-measures analysis of variance, followed by Dunnett’s and paired t tests where appropriate. ResultsDexmedetomidine resulted in a significant decrease in cardiac index (CI) and significant increases in mean arterial pressure (MAP) and systemic vascular resistance index (SVRI). The addition of MK-467 failed to prevent most of the early cardiovascular effects of dexmedetomidine, but the duration of systemic vasoconstriction was shorter and CI did not decrease. The lowest and highest post-treatment values in each treatment were 0.1 ± 0.03 and 0.13 ± 0.03 L minute−1 BW−0.67 (D) versus 0.14 ± 0.01 and 0.19 ± 0.03 L minute−1 BW−0.67 (DM) for CI, 87 ± 13 and 181 ± 21 mmHg (D) versus 70 ± 11 and 153 ± 18 mmHg (DM) for MAP and 58,948 ± 17,754 and 119,432 ± 40,423 dynes second cm−5 BW−0.67 (D) versus 25,870 ± 3782 and 76,498 ± 17,258 dynes second cm−5 BW−0.67 (DM) for SVRI, respectively. Conclusion and clinical relevanceIM coadministration of MK-467 and dexmedetomidine in isoflurane-anesthetized cats shortened dexmedetomidine-induced cardiovascular effects. This drug combination may be useful in cats in which longer-lasting hypertension and hemodynamic depression is of concern.

Faster rate of blood volume change in pediatric hemodialysis patients impairs cardiac index.

Intradialytic hypotension and myocardial stunning are proposed as contributing to the pathogenesis of increased cardiovascular disease burden and death in patients receiving maintenance hemodialysis (HD). Noninvasive cardiac output measurements provide a dynamic, real-time assessment of hemodynamic parameters. We investigated intradialytic changes in hemodynamic parameters in pediatric outpatients receiving chronic HD and determined patient and treatment risk factors associated with such intradialytic changes. Hemodialysis was performed using linear fluid removal over 4h with polysulfone dialyzers. Continuous wave Doppler ultrasound was used to measure hemodynamic parameters prior, 2h into, and after the mid-week HD treatment session. Pulse wave tonometry was performed at the same time. The percentage change in blood volume was measured by noninvasive hematocrit monitoring during HD. Twenty-two patients fit the inclusion criteria, of whom 16 (73%) were male. The mean age of the patients was 17 ± 3.8years, and the dialysis vintage was 47.8 ± 33.7months. The cardiac index decreased significantly midway through the HD treatment session and remained low until the end of treatment. A significant decline in cardiac index without hypotension occurred in 12 (54 %) patients. Expected increase in systemic vascular resistance index to preserve the cardiac index was not observed. Weight, percentage fluid overload, dialysis vintage, and adequacy did not correlate with the observed decline in the cardiac index. The decrease in blood volume at the 2h (R = 0.43, p = 0.045) and 4h (R = 0.56, p = 0.007) time points was the only factor associated with cardiac index decline. The cardiac index and stroke volume decreased significantly during the HD session. Patients with larger blood volume changes during the first 2h of HD and at 4 h showed a significant decrease in cardiac index that did not recover at the completion of the HD treatment. Rate of fluid removal was the only significant risk factor for compromised cardiac index during HD. Conventional methods currently used for assisting fluid removal in HD are inadequate to assess hemodynamic changes.

Cardiac remodeling after reduction of high-flow arteriovenous fistulas in end-stage renal disease.

In patients with end-stage renal disease, excessive blood flow through an arteriovenous fistula (AVF) may lead to volume overload-induced cardiac remodeling and heart failure. It is unclear which patients with hyperfunctional AVF may benefit from AVF reduction or ligation. The indication for the procedure is often based on AVF flow. Because cardiac remodeling is driven by increased venous return, which is equivalent to cardiac output, we hypothesized that an elevated cardiac index (CI) might better identify subjects with reverse remodeling after AVF reduction. Thirty patients (age 52±12 years, 73% male) with AVF flow ⩾1.5 l min(-1) underwent comprehensive echocardiographic evaluations before and after AVF reduction. At baseline, 16 patients had a normal CI (2.5-3.8 l min(-1) m(-2)) and 14 had a high CI (4.0-6.0 l min(-1) m(-2)). A left ventricular end-diastolic diameter decrease after operation was predicted by elevated baseline CI (P<0.01), but not elevated AVF flow (P=0.07). There was a significant decrease in CI, left ventricular mass, left atrial and right ventricular diameter and pulmonary systolic pressure in the high CI group but not in the normal CI group. After AVF reduction, systemic vascular resistance decreased in the normal CI group, whereas it did not change in the high CI group. In conclusion, reduction of high-flow AVF leads to reverse cardiac remodeling but only in patients with elevated CI. The variability of the response of systemic vascular resistance to AVF flow may explain this observation. Increased CI but not increased AVF flow may better determine candidates for AVF reduction.

The cardiopulmonary effects of dexmedetomidine infusions in dogs during isoflurane anesthesia

ObjectiveTo determine the cardiopulmonary changes associated with intravenous (IV) infusions of dexmedetomidine at equipotent isoflurane-dexmedetomidine concentrations compared with isoflurane alone. Study designProspective, randomized, crossover experiment. AnimalsSix adult intact female mixed-breed dogs weighing (mean ± SD [range]) 23.3 ± 3.8 (17.8–29.4) kg. MethodsAnesthesia was induced and maintained with isoflurane in oxygen. Measurements of respiratory rate (fR), heart rate (HR), systemic and pulmonary arterial pressures (SAP, DAP, MAP, MPAP), central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), cardiac index (CI), left and right ventricular stroke work index (LVSWI, RVSWI), systemic and pulmonary vascular resistance index (SVRI, PVRI), arteriovenous shunt ( Q˙s/Q˙t), oxygen delivery ( D˙O2), oxygen extraction ratio (O2ER), oxygen consumption, arterial and mixed venous blood gases, and arterial packed cell volume (PCV) were obtained 30 minutes after instrumentation at an end-tidal isoflurane concentration (Fe’Iso) of 1.73 ± 0.02% (1.3 MAC). Dexmedetomidine was administered IV at 0.5 or 3 μg kg−1 over 6 minutes followed by an infusion at 0.5 (LD) or 3 μg kg−1 hour−1 (HD), respectively, with Fe’Iso at 1.41 ± 0.02 (LD) or 0.72 ± 0.09% (HD). Measurements were taken at 10, 30, 60, 90, 120, 150 and 180 minutes after the start of the infusion. ResultsThe low dose produced significant decreases in HR, increases in SAP, DAP, CVP, MPAP, PAOP and LVSWI, but no change in CI. HD produced significant increases in SAP, MAP, DAP, CVP, PAOP, SVRI, LVSWI, O2ER and PCV and significant decreases in CI and D˙O2. There were significant differences between treatments in HR, MAP, DAP, CVP, MPAP, PAOP, CI, SVRI, HCO3-, SBE, D˙O2, O2ER and Q˙s/Q˙t. Conclusions and clinical relevanceCardiopulmonary changes associated with LD were within clinically accepted normal ranges whereas HD produced clinically significant changes. The LD may be useful as an anesthetic adjunct in healthy dogs.

The effects of propofol and dexmedetomidine infusion on fluid responsiveness in critically ill patients

BackgroundWe studied the effects of propofol or dexmedetomidine on preload dependency and fluid responsiveness in critically ill patients. MethodsIn the study, we included 91 patients with acute circulatory failure (70 ± 15 y) who received propofol (n = 45 patients, PROP group) or dexmedetomidine (n = 46 patients, DEX group). An initial passive leg-raising (PLR 1) test was performed in all patients to evaluate preload dependency at baseline. Propofol and dexmedetomidine were infused and titrated according to the Richmond Agitation Sedation Scale; the results ranged from −2 to −1, and the bispectral index values ranged from 60–75. A second PLR test (PLR 2) was performed before administration of a 250-mL normal saline fluid challenge over a 5-min period. We obtained central venous pressure and cardiac index (CI) measurements before and after the two PLR tests and volume expansion. An increase of ≥10% in CI during PLR was considered to be a positive test finding that was indicative of preload dependency, whereas an increase of <10% in CI during PLR was considered to be a negative test finding. ResultsAt baseline, 22 of 45 patients had negative PLR 1 in the PROP group, whereas 20 of 46 patients had negative PLR 1 in the DEX group. After propofol or dexmedetomidine sedation, there were significant decreases in CI (−9.5% [±6.6%] versus −16.4% [±8.5%], P < 0.001) in the PROP and DEX groups, respectively. In the PROP group, there were significant increases in CI (+18.4% [±9.5%] versus +10.7% [±12.3%], P < 0.05) induced by PLR 2 compared with that induced by PLR 1. In the DEX group, there were no significant increases in CI (+13.2% [±14.9%] versus +12.8% [±17.7%]) induced by PLR 2 compared with that induced by PLR 1. Although the mean arterial pressure values increased comparably with the volume expansion observed in both groups, the volume expansion resulted in a significantly higher increase in CI compared with the baseline values in the PROP group (3.2 ± 0.8 versus 3.2 ± 0.7 L/min/m2) but not in the DEX group (2.9 ± 0.7 versus 3.1 ± 0.8 L/min/m2, P < 0.05). ConclusionsWe observed that propofol infusion, but not dexmedetomidine infusion, can increase preload dependency and fluid responsiveness in patients with circulatory failure.

Cardiovascular and microvascular responses to mild hypothermia in an ovine model

AimsHypothermia is used for brain protection after resuscitation from cardiac arrest and other forms of brain injury, but its impact on systemic and tissue perfusion has not been well defined. The aim of this study was to evaluate the cardiovascular and microvascular responses to mild therapeutic hypothermia (MTH) in an ovine model. MethodsSeven anaesthetised, mechanically ventilated, invasively monitored sheep were cooled from a baseline temperature of 39–40°C to 34°C using cold intravenous fluids, ice packs and transnasal cooling. After 6h of MTH, sheep were progressively re-warmed to baseline temperature. Positive fluid balance was maintained during the entire study period to avoid hypovolemia. In addition to standard haemodynamic assessment, the sublingual microcirculation was evaluated using sidestream dark-field (SDF) videomicroscopy. ResultsMTH was associated with significant decreases in cardiac index and left (LVSWI) and right (RVSWI) ventricular stroke work indexes. There was a downward shift in the relationship between LVSWI and pulmonary artery occlusion pressure during MTH, indicating myocardial depression. During MTH, mixed venous oxygen saturation increased, in association with reduced oxygen consumption, but blood lactate concentrations increased significantly. There was a significant decrease in the proportion and density of small perfused vessels. All variables returned to baseline levels during the re-warming phase. ConclusionIn this large animal model, MTH was associated with decreased ventricular function, oxygen extraction and microvascular flow compared to normothermia. These changes were associated with increased blood lactate levels. These observations suggest that MTH may impair tissue oxygen delivery through maldistribution of capillary flow.

Comparison of the therapeutic effectiveness of a dantrolene sodium solution and a novel nanocrystalline suspension of dantrolene sodium in malignant hyperthermia normal and susceptible pigs

Stopping trigger agents and prompt administration of dantrolene are the cornerstones of treatment of malignant hyperthermia. However, significant time is lost in treatment of the condition because of the cumbersome preparation and administration of the commercially available dantrolene sodium for injection. A potential improvement has become available in the form of a novel nanocrystalline dantrolene sodium suspension (DSS), which is 150 times more concentrated (50 mg ml(-1)) than the standard dantrolene sodium solution (0.33 mg ml(-1)). The aims of this study were to measure the effects of DSS on clinical and laboratory variables in malignant hyperthermia normal pigs and to compare the therapeutic management and clinical effectiveness of DSS with standard dantrolene sodium in a fulminant malignant hyperthermia crisis in susceptible pigs. The pig model is a well accepted method of studying the malignant hyperthermia crisis and is an ideal way to evaluate the variables of interest in this study. Seven malignant hyperthermia normal and 10 malignant hyperthermia susceptible pigs were studied. Malignant hyperthermia susceptible pigs (body weight approximately 24 kg) were allocated to a dantrolene sodium group or a DSS group. After induction of anaesthesia, a 22-gauge catheter was placed in an ear vein and trigger-free anaesthesia was performed. After achieving stable conditions, administration of halothane was started with 0.1% and then 0.15%. Halothane was discontinued after the administration of 0.2% (malignant hyperthermia normal pigs) or when a fulminant malignant hyperthermia crisis was achieved (malignant hyperthermia susceptible pigs). After halothane was discontinued, FIO2 was set to 1.0, respiratory minute volume was doubled and sodium bicarbonate 2 mmol kg(-1) was administered. The time required to prepare and administer each formulation was measured. To simulate the administration of the substances under typical clinical conditions for a child weighing approximately 24 kg, dantrolene sodium (5 mg kg(-1)) or DSS (5 mg kg(-1)) was prepared and injected via the intravenous 22-gauge cannula. Bolus administrations of dantrolene sodium or DSS were repeated after 24 min. Arterial pH, arterial pCO2, mean arterial pressure and arterial lactate concentration remained stable during the experiment with DSS in malignant hyperthermia normal pigs. A significant decrease in cardiac index and increases in systemic vascular resistance and serum potassium concentration occurred after administration of DSS. In all malignant hyperthermia susceptible animals, the inhaled administration of halothane 0.15% led to a fulminant malignant hyperthermia crisis. The therapeutic regimens with administration of dantrolene sodium or DSS were successful in treating the malignant hyperthermia crisis in all animals. The course of the malignant hyperthermia crisis and the therapeutic effects of dantrolene sodium or DSS were comparable in the two groups. The time needed to prepare DSS for administration was significantly shorter (51 ± 9 s) compared to dantrolene sodium (860 ± 202 s). The time taken to inject DSS (4 ± 2 s) was significantly shorter than for dantrolene sodium (472 ± 51 s). The therapeutic action of DSS in a malignant hyperthermia crisis in pigs was effective and comparable to that of standard dantrolene sodium. However, preparation and administration of DSS were significantly faster, which may offer a clinically significant advantage in the treatment of a fulminant malignant hyperthermia crisis and may result in a reduction in stress for the anaesthesia team.

The Hemodynamic Effect of Total Liquid Ventilation in Piglets With Reduced Cardiac Function After Cardiopulmonary Bypass

Total liquid ventilation (TLV) is a promising treatment for severe lung injury and heart resuscitation. We aim to investigate the hemodynamic effect of TLV in piglets with preexisting cardiac dysfunction. After onset of cardiopulmonary dysfunction induced by cardiopulmonary bypass (CPB), piglets were randomly treated with TLV (n = 6) or conventional gas ventilation (n = 6) for 240 min. Hemodynamics was monitored before and at a 30-min interval after CPB. CPB with cardiac arrest resulted in significant decrease in cardiac index (CI) (96.19 ± 6.74 vs. 48.58 ± 3.96 mL/min/kg, P < 0.001) and increase of pulmonary vascular resistance (PVR) (1123.38 ± 198.97 vs. 8180.62 ± 1041.35 dyne·s/cm(5), P < 0.001). Compared with conventional gas ventilation, there was no further significant decrease of CI or increase of PVR during TLV throughout the experiment. No significant difference was observed on other hemodynamic variables including heart rate, mean arterial pressure, mean pulmonary arterial pressure, and central venous pressure between both groups. The fluctuation of mean arterial blood pressure was 3.95 ± 1.68 mm Hg during TLV. No evidence of fluorothorax or cardiac tamponade was observed in either group. We conclude that TLV does not further impair hemodynamics in piglets with preexisting cardiac dysfunction immediately after CPB.

Effect of Body Positions on Hemodynamics and Gas Exchange in Anesthetized Pigs Shortly After Pneumonectomy

Positional changes are thought to affect hemodynamics, respiratory mechanics, and gas exchange after pneumonectomy. The objective of this study was to compare hemodynamic and respiratory parameters and gas exchange in different positions before and after pneumonectomy. Twenty pigs were anesthetized and mechanically ventilated. Seven received right-side pneumonectomy, seven received left-side pneumonectomy, and six were anesthetized but did not receive surgery and served as controls. Hemodynamic and respiratory parameters and blood gas values were measured in different positions (supine and right and left lateral decubitus). Minute mechanical ventilation was controlled throughout. Pneumonectomy resulted in significant reductions in MAP, accompanied by significant decreases in cardiac index, stroke volume index, global ejection fraction, and global end-diastolic volume index. Mean pulmonary arterial pressure and pulmonary vascular resistance index increased. PaCO2, airway resistance, and peak airway pressure increased, whereas PaO2 and lung compliance decreased. Hemodynamic and respiratory parameters and gas exchange were also significantly affected by changes in position with pneumonectomy. Mean arterial pressure, cardiac index, stroke volume index, global ejection fraction, and global end-diastolic volume index were significantly lower in the supine than in the right or left lateral decubitus position. PaO2 was significantly higher in a lateral position, with the remaining lung uppermost. Our findings suggest that avoiding the supine positioning after pneumonectomy may facilitate improvements in hemodynamics and a decreased risk of hypoxemia. The optimal position for gas exchange after pneumonectomy is a lateral position, with the remaining lung in the uppermost position.

Global and right ventricular end‐diastolic volumes correlate better with preload after correction for ejection fraction

Volumetric monitoring with right ventricular end-diastolic volume indexed (RVEDVi) and global end-diastolic volume indexed (GEDVi) is increasingly being suggested as a superior preload indicator compared with the filling pressures central venous pressure (CVP) or the pulmonary capillary wedge pressure (PCWP). However, static monitoring of these volumetric parameters has not consistently been shown to be able to predict changes in cardiac index (CI). The aim of this study was to evaluate whether a correction of RVEDVi and GEDVi with a measure of the individual contractile reserve, assessed by right ventricular ejection fraction (RVEF) and global ejection fraction, improves the ability of RVEDVi and GEDVi to monitor changes in preload over time in critically ill patients. Hemodynamic measurements, both by pulmonary artery and by transcardiopulmonary thermodilution, were performed in 11 mechanically ventilated medical ICU patients. Correction of volumes was achieved by normalization to EF deviation from normal EF values in an exponential fashion. Data before and after fluid administration were obtained in eight patients, while data before and after diuretics were obtained in seven patients. No correlation was found between the change in cardiac filling pressures (DeltaCVP, DeltaPCWP) and DeltaCI (R(2) 0.01 and 0.00, respectively). Further, no correlation was found between DeltaRVEDVi or DeltaGEDVi and DeltaCI (R(2) 0.10 and 0.13, respectively). In contrast, a significant correlation was found between DeltaRVEDVi corrected to RVEF (DeltacRVEDVi) and DeltaCI (R(2) 0.64), as well as between DeltacGEDVi and DeltaCI (R(2) 0.59). An increase in the net fluid balance with +844 + or - 495 ml/m(2) resulted in a significant increase in CI of 0.5 + or - 0.3 l/min/m(2); however, only DeltacRVEDVi (R(2) 0.58) and DeltacGEDVi (R(2) 0.36) correlated significantly with DeltaCI. Administration of diuretics resulting in a net fluid balance of -942 + or - 658 ml/m(2) caused a significant decrease in CI with 0.7 + or - 0.5 l/min/m(2); however, only DeltacRVEDVi (R(2) 0.80) and DeltacGEDVi (R(2) 0.61) correlated significantly with DeltaCI. Correction of volumetric preload parameters by measures of ejection fraction improved the ability of these parameters to assess changes in preload over time in this heterogeneous group of critically ill patients.

Impact of acute hypercapnia and augmented positive end-expiratory pressure on right ventricle function in severe acute respiratory distress syndrome

To evaluate the effects of acute hypercapnia induced by positive end-expiratory pressure (PEEP) variations at constant plateau pressure (P (plat)) in patients with severe acute respiratory distress syndrome (ARDS) on right ventricular (RV) function. Prospective observational study in two academic intensive care units enrolling 11 adults with severe ARDS (PaO(2)/FiO(2) <150 mmHg at PEEP >5 cmH(2)O). We compared three ventilatory strategies, each used for 1 h, with P (plat) at 22 (20-25) cmH(2)O: low PEEP (5.4 cmH(2)O) or high PEEP (11.0 cmH(2)O) with compensation of the tidal volume reduction by either a high respiratory rate (high PEEP/high rate) or instrumental dead space decrease (high PEEP/low rate). We assessed RV function (transesophageal echocardiography), alveolar dead space (expired CO(2)), and alveolar recruitment (pressure-volume curves). Compared to low PEEP, PaO(2)/FiO(2) ratio and alveolar recruitment were increased with high PEEP. Alveolar dead space remained unchanged. Both high-PEEP strategies induced higher PaCO(2) levels [71 (60-94) and 75 (53-84), vs. 52 (43-68) mmHg] and lower pH values [7.17 (7.12-7.23) and 7.20 (7.16-7.25) vs. 7.30 (7.24-7.35)], as well as RV dilatation, LV deformation and a significant decrease in cardiac index. The decrease in stroke index tended to be negatively correlated to the increase in alveolar recruitment with high PEEP. Acidosis and hypercapnia induced by tidal volume reduction and increase in PEEP at constant P (plat) were associated with impaired RV function and hemodynamics despite positive effects on oxygenation and alveolar recruitment ( ClinicalTrials.gov #NCT00236262).

Trendelenburg positioning does not prevent a decrease in cardiac output after induction of anaesthesia with propofol in children

Induction of anaesthesia may cause decreased cardiac output and blood pressure. Head-down tilt is often the first clinical step to treat hypotension. The objective of this randomized single centre study was to determine, with the use of impedance cardiography (ICG), whether Trendelenburg positioning modifies the haemodynamic response to propofol/fentanyl induction of anaesthesia in ASA I children. Thirty ASA I children aged between 7 and 16 years scheduled for elective minor orthopaedic surgery were included. After intravenous induction with propofol and fentanyl in the head-down group (HDG, n = 15), 5 min of 20 degrees head-down tilt was applied. In the supine group (SG, n = 15), no change in the supine position was made. Heart rate (HR), mean arterial blood pressure (MABP), end-tidal carbon dioxide (ETCO(2)), stroke volume index (SVI), cardiac index (CI), systemic vascular resistance index (SVRI) and Heather index (HI) were recorded before (B), at 3 (A(3)), 5 (A(5)) and 8 (A(8)) minutes after induction in each group. After induction, a significant decrease in CI, MABP, HR and HI was recorded in both groups. In the study group, significantly lower values of HR (66 vs. 78 beat/min) and higher values of SVI (42.9 vs. 40.6 ml/min/m(2)) were measured at A(3) compared with the control group. After induction, no difference in CI and SVRI was found between the two groups. The present study shows that cardiac performance is not improved by Trendelenburg positioning after propofol/fentanyl induction of anaesthesia in children.

Hemodynamic Characteristics of Vasopressin in Dogs with Severe Hemorrhagic Shock

The effect of vasopressin was compared with that of the established vasopressor epinephrine in experimentally induced hemorrhagic shock. After rapid crystalloid resuscitation in a ratio of three volumes of 0.9% saline to one volume of blood (3:1 crystalloid resuscitation), six dogs were given 0.4 IU/kg vasopressin and another six dogs were given 0.1 mg/kg epinephrine. Five dogs in the control group were given fluid resuscitation in the same manner as above without administration of any drugs. Administration of vasopressin increased diastolic arterial pressure (DAP) from 45.0 +/- 4.9 to 91.2 +/- 9.6 mmHg within 5 min, compared with epinephrine from 46 +/- 4.0 to 51.8 +/- 7.7, and control from 47.3 +/- 7.5 to 46.3 +/- 7.3. Systolic arterial pressure (SAP) did not increase significantly following vasopressin compared with epinephrine and control group. Results of DAP and systemic vascular resistance index (SVRI) suggested that vasopressin administration was vasoconstrictive after fluid resuscitation in decompensatory hemorrhagic shock in dogs, whereas epinephrine did not compared with control. In addition, epinephrine did not affect the cardiac index (CI) and SVRI, while a significant decrease in CI and increase in SVRI were observed in vasopressin group. The pressor effect of epinephrine in the vascular system was abrupt and only lasted a short period of time (within 5 min), while that of vasopressin was steady and lasted for more than 1 hr, especially regard to in DAP. When compared with epinephrine, vasopressin can be a more effective and safer choice in patients with severe hemorrhagic shock.

Hemolysis-Endothelial Dysfunction Syndrome: A Novel Paradigm of Disease Mechanism.

Background: Normal vasomotor tone is maintained by the production of nitric oxide (NO) from endothelial-derived nitric oxide synthase in excess of consumption of NO within the vasculature by intra-erythrocytic hemoglobin. NO reacts up to 600-fold less rapidly when hemoglobin is compartmentalized within the erythrocyte rather than in a cell free form (i.e. cell-free plasma hemoglobin). This implies that during intravascular hemolysis, NO consumption by hemoglobin would be greatly increased. We have proposed that NO consumption and loss of normal vasomotor tone contributes to the pathogenesis of sickle cell disease. However, the increased reactivity of cell-free plasma hemoglobin, released during hemolysis, compared to intra-erythrocytic hemoglobin and the physiologic consequences of hemolysis on nitric oxide consumption have not been definitively proven in vivo.Methods: We have developed a canine model of free water induced intravascular hemolysis to test this mechanism and to examine whether inhaled NO can selectively oxidize the cell free plasma hemoglobin and thus attenuate any associated physiologic changes. Paired experiments were performed in each animal which included a 6-hour control infusion of 5% Dextrose (D5W) followed one week later by a 6-hour infusion of either D5W or free water with or without 80 ppm inhaled NO (full factorial design). Based on pilot experiments, infusions of free water or D5W (control) were administered at a rate of 16 ml/kg/hr. At the end of each experiment, an escalating sodium nitroprusside infusion, a direct NO donor (1 to 27 mcg/kg/min), was administered to evaluate the vascular responsiveness to NO in the presence and absence of hemolysis. In this model, total intravascular hemoglobin concentration remains constant, whereas the ratio of plasma to intracellular hemoglobin concentration increases with hemolysis.Results: In comparison to D5W, free water infusion caused linear increases in plasma hemoglobin (25–50 mM/h) which remained ferrous (FeII) and correlated with increased plasma nitric oxide consumption (R = 0.95; p<0.001). This free water induced intravascular hemolysis caused significant increases in mean systemic arterial pressure (MAP; p=0.0003) and systemic vascular resistance index (SVRI; p=0.0003) and a significant decrease in cardiac index (CI; p=0.02) compared to an equivalent infusion of D5W. In the setting of hemolysis, concurrent inhalation of nitric oxide gas converted the cell free plasma hemoglobin to methemoglobin (50–90% of total plasma hemoglobin), inhibited NO consumption by plasma (methemoglobin does not oxidize NO to nitrate), and normalized hemodynamic parameters. Furthermore, free water induced hemolysis led to blunted hemodynamic effects of sodium nitroprusside on MAP, CI, and SVRI, which were restored with inhaled nitric oxide therapy (p=0.01, p=0.09, and p=0.003 respectively). This further supports the thesis that cell-free plasma hemoglobin consumes NO in the vasculature.Conclusion: These data support the hypothesis that NO scavenging by cell-free plasma hemoglobin disrupts endothelial NO-dependent vasomotor function producing systemic physiologic changes which are attenuated by inhaled nitric oxide therapy. These biochemical and physiological studies support the existence of a hemolysis-endothelial dysfunction syndrome, which may contribute to the vasculopathy of hereditary, acquired and iatrogenic hemolytic states.

Age-related difference in myocardial function and inflammation in a rat model of myocardial ischemia-reperfusion.

Aging is associated with a reduced tolerance to myocardial ischemia reperfusion injury when compared to the young adult. However, there is very little information in the literature regarding age-related changes in myocardial function and inflammation during myocardial ischemia-reperfusion (MI/R) in vivo. We examined age-related differences in myocyte apoptosis and the inflammatory response in a rat model of myocardial ischemia-reperfusion (MI/R). The aged (19 months) and young (4 months) male F344 BN rats were subjected to 30 min of myocardial ischemia by ligating the left main coronary artery, followed by release of the ligature and 4 h of reperfusion. Four experimental groups, e.g. young sham control, aged sham control, young rats subjected to MI/R, and aged rats subjected to MI/R, were studied. MI/R induced a 78% increase in circulating leukocytes and a 30% increase in superoxide generation in the ischemic region of the heart of young rats, when compared to aged rats. Moreover, the arrhythmia scores were higher in young rats than in aged rats (P=0.058) following MI/R. There was no difference in hemodynamics between young sham and aged sham rats. However, the cardiac index was decreased by 34% at 3 h of reperfusion and by 33% at 4 h of reperfusion in aged rats, when compared to young rats following MI/R. Furthermore, stroke volume index was decreased by 54, 56, and 65% at 2, 3, and 4 h of reperfusion in aged rats, respectively, when compared that of young rats subjected to MI/R. There was an enhanced myocyte apoptosis, as indicated by ELISA and TUNEL staining in the myocardium of aged rats compared to young rats following MI/R. Interestingly, RT-PCR analysis indicated that MI/R significantly increased the ratio of Bax mRNA to Bcl-2 mRNA in aged rats compared to that of young rats (3.51 vs. 0.74). MI/R is associated with an increase in circulating leukocytes and generation of superoxide in the peri-ischemic areas of the heart of young rats, compared to aged rats. However, MI/R induces a significant decrease in cardiac index and stroke volume index in aged rats, when compared to young rats following MI/R. Furthermore, aged rats exhibit an increase in the ratio of Bax mRNA to Bcl-2 mRNA and cardiomyocyte apoptosis following MI/R, which may explain, at least in part, the enhanced myocardial dysfunction.