Differences In Hemodynamic Parameters Research Articles

Hemodynamic determinants and ventriculo-arterial coupling are sex-associated in heart failure patients.

End-systolic volume (ESV) and end-diastolic volume (EDV) are key parameters in the analysis of left ventricular (LV) function, and the study of cardiac remodeling. The volume regulation graph (VRG) relates these fundamental determinants, and permits convenient stratification for clinically relevant covariates. This contribution analyzes sex-associated differences in hemodynamic parameters for 197 heart failure (HF) patients, evaluated by biplane ventriculography, in combination with arterial pressure. We calculated LV parameters such as stroke volume (SV), cardiac output (CO), ESV, EDV, ejection fraction (EF), end-systolic elastance (Emax), besides arterial parameters: effective arterial elastance (Ea), elastance ratio (the coupling index k), peripheral resistance (Rs), pulse pressure (PP), and arterial compliance (C), all normalized for body surface area when appropriate. Average values for heart rate, SV, CO, Ea, C, Rs are similar between the sexes, as are the VRG regression lines. However, ESV and EDV are significantly (P<;0.034 and P<;0.016, respectively) smaller in women (N=67), whereas EF, Emax, mean arterial pressure, PP, and k are higher (P<;0.008 or less). We conclude that the various sex-associated differences observed in these HF patients are striking, and thus require due attention when evaluating the clinical status of HF patients. Formulation of distinct cut-off values for male and female patients with HF seems warranted, when considering specific HF phenotypes.

Half dose protamine sulphate, does it work in valvular replacement cardiac surgery? A prospective, double-blinded randomized study

IntroductionCardiac surgery of valvular replacement carries multiple complications, the commonest of which is bleeding. Effective anti-coagulation during valvular replacement is necessary to prevent excessive activation of the hemostatic system; protamine sulfate is used to neutralize the effect of circulating heparin. The Aim of the work was to determine the effectiveness of half dose Protamine in reversing the action of heparin in valvular replacement cardiac surgery without the appearance the side effect of protamine.Method40 patients undergoing valvular replacement divided into two groups. Group A: received 1mg of protamine per 100 unit heparin (common ratio 1:1, protamine: heparin). Group B: received 0.5 mg of protamine per100 unit of heparin (our ratio 1:2, protamine: heparin). Following data were detected in each patients (1) blood loss, 2 Activated clotting Time, (3) Hemoglobin, (4) unites of FFP requirements, (5) Clotting Time, and Maximum Clot Firmness (MCF) test.ResultsWe found that the administration of half (1/2) of Total Calculated Dose of protamine sulphate was always able to reverse the anticoagulant effect of heparin .with insignificant difference in hemodynamic parameters, and in the amount of blood loss and insignificant difference in unites of FFP requirement, on other hand there was mild significant results in MCF test between both groups.DiscussionOur present study suggests that the commonly applied ratio equal to 1:1 (ratio of protamine to heparin) could be higher than needed with potential and hazardous impacts and lowering it to be 1:2 ratio is similarly effective. Our results are in line with the findings obtained by Salvatore et al., who observed that reversal of heparin administered in patients undergoing cardiac surgery could be effectively achieved with 2/3 of the usual dose of Protamine and that the additional administration of protamine seems to induce an elongation of the clotting time with no impact on clot firmness. (1) While the impact of a high protamine to heparin ratio was even studied by Kahn et al., who studied blood samples of 46 patients undergoing cardiac surgery using CABG and found a significant worsening of the coagulation parameters using protamine to heparin ratio of more than 2:12.

Characteristic analysis of hemodynamics for trunk aneurysm of posterior communicating artery

Objective To study the hemodynamic characteristics of the difference between the trunk aneurysm of posterior communicating artery (PCoA) and the internal carotid artery (ICA)-PCoA aneurysm. Methods A total of 15 patients with trunk aneurysm of PCoA (11 ruptured aneurysms, 4 unruptured aneurysms, for short PCoA trunk group) treated at the Department of Interventional Neuroradiology, Beijing Tiantan Hospital, Capital Medical University from January 2014 to June 2015 were studied retrospectively. The 15 patients with ICA-PCoA aneurysm with approximately the same size and the same rupture state at the same time were used as a matched control group. A numerical simulation analysis was conducted for individual three-dimensional digital subtraction angiography (DSA) images of the patients using the method of computational fluid dynamics. The differences of hemodynamic parameters of the aneurysms were compared between the 2 groups. Results The PCoA trunk aneurysms were in accordance with the blood flow pattern of the lateral aneurysms, and the ICA-PCoA aneurysms were in accordance with the flow blood pattern of the aneurysms at the bifurcations. The hemodynamic parameters in the PCoA trunk group vs. the control group: The wall shear stress (WSS) of the PCoA trunk group and the control group was 0.48±0.08 and 0.63±0.07 respectively. The percentage of the low WSS area (LSA) was 23.20±6.94% and 4.50±2.29% respectively. There were significant differences (P=0.022, P=0.008). The oscillatory shear index (OSI) of the two groups was 0.0233±0.0071 and 0.0158±0.0044 respectively. There was no significant difference (P=0.411). The WSS of the ruptured group (n=22) and the unruptured group (n=8) was 0.45±0.05 and 0.84±0.08 respectively, and LSA was 18.22±5.11% and 1.84±1.76% respectively. There was significant difference (P<0.001, P=0.006). The OSI of the two groups was 0.0234±0.0054 and 0.0091±0.0027 respectively. There was no significant difference (P=0.132). Conclusion The low WSS may be one of the reasons for the high risk of PCoA trunk aneurysm rupture. Key words: Intracranial aneurysms; Aneurysm, ruptured; Hemodynamics; Posterior communicating artery; Computational fluid dynamics

The hemodynamic characteristics of septic shock and relationship with syndrome types of traditional Chinese medicine

To observe hemodynamic characteristics and the correlation with syndrome types of traditional Chinese medicine (TCM) in patients with septic shock, so as to direct the treatment based on syndrome differentiation. A prospective observation was conducted. Sixty-eight patients with septic shock admitted to the Department of Critical Care Medicine of Dade Road General Hospital of Guangdong Hospital of TCM from January 2013 to July 2015 were enrolled. Pulse indicating continuous cardiac output (PiCCO) was used to monitor the hemodynamic changes, including heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), cardiac index (CI), global end diastolic volume index (GEDVI), extravascular lung water index (EVLWI), maximum rate of the increase in pressure (dPmax) and systemic vascular resistance index (SVRI), for assessment of hemodynamics. According to the CI, the patients were divided into two groups , i.e. high CI group (CI ≥ 50.0 mL×s(-1)×m(-2), n = 34) and low CI group (CI < 50.0 mL×s(-1)×m(-2), n = 34), and the clinical and hemodynamic characteristics of two groups were investigated. The TCM differentiation was conducted with "four syndromes and four methods", and the hemodynamic characteristics of different syndrome types were investigated, the correlation between the TCM syndrome factors and hemodynamic parameters was analyzed. The patients were divided into survival group and death group, and clinical parameters and hemodynamic characteristics were compared between two groups. The acute physiology and chronic health evaluation II (APACHEII) score and blood glucose of low CI group were higher than those of high CI group [APACHEII score: 24.4±7.2 vs. 19.8±7.4, t = -2.279, P = 0.023; blood glucose (mmol/L): 9.7 (7.7, 14.6) vs. 6.7 (5.6, 10.0), Z = -2.257, P = 0.024], CI and GEDVI were lowered [CI (mL×s(-1)×m(-2)): 36.7±8.3 vs. 68.4±16.7, t = 10.285, P = 0.000; GEDVI (mL/m(2)): 689.0 (566.0, 883.8) vs. 838.5 (692.8, 1?247.3), Z = -2.711, P = 0.007], while SVRI was increased [kPa×s×L(-1)×m(-2): 248.7 (202.1, 324.5) vs. 143.4 (102.7, 171.4), Z = -5.336, P = 0.000]. Accompanied symptoms were found to occur more commonly in septic shock patients, and the most common syndrome elements were Qi deficiency syndrome (n = 45), blood stasis syndrome (n = 40), heat-toxin syndrome (n = 37), Fushi syndrome (n = 24) and Yin deficiency syndrome (n = 10), respectively. There was no significant difference in hemodynamic parameters among patients with five types of syndrome (all P > 0.05). However, only the CI of those with Qi deficiency syndrome was significantly lower than that of heat-toxin syndrome (mL×s(-1)×m(-2): 48.3±18.3 vs. 53.3±21.7, P < 0.05). While the results after removing the effect of accompanied symptoms showed that CI of Qi deficiency syndrome was significantly lower than that of non-Qi deficiency syndrome (mL×s(-1)×m(-2): 48.3±18.3 vs. 61.7±21.7, t = -2.783, P = 0.007), CI of heat-toxin syndrome was significantly higher than that of non-heat-toxin syndrome (mL×s(-1)×m(-2): 58.3±21.7 vs. 48.3±16.7, t = 2.133, P = 0.037), EVLWI of blood stasis syndrome was significantly lower than that of non-blood stasis syndrome [mL/kg: 10.0 (7.0, 15.1) vs. 14.9 (8.5, 26.8), Z = -2.075, P = 0.038]. Compared with survival group (n = 38), APACHEII score in death group (n = 30) was increased (25.8±8.4 vs. 19.1±5.4, t = -3.940, P = 0.000), the proportion of continuous renal replacement therapy (CRRT) was increased [60.0% (18/30) vs. 31.6% (12/38), χ (2) = 5.493, P = 0.019], HR was increased (bpm: 118.5±20.5 vs. 98.1±19.9, t = -4.157, P = 0.000), and the proportion of Qi deficiency syndrome was increased [86.7% (26/30) vs. 50.0% (19/38), χ (2) = 10.070, P = 0.002]. Patients with sepsis shock may be divided into high-output and low-resistance and low-output and high-resistance groups according to hemodynamics, with respective hemodynamic characteristics. Hemodynamic performance differed among different syndrome types, and there was a certain relationship. Hemodynamic monitoring with PiCCO was a useful supplement of TCM, which was good for the evidence-based medicine.

The Protective Effect of Low-Dose Ethanol on Myocardial Fibrosis through Downregulating the JNK Signaling Pathway in Diabetic Rats.

Objective. To investigate the effects of low dose ethanol feeding in diabetic rats and analyze its underlying mechanisms. Methods. Male Sprague-Dawley rats were divided into 4 groups: control (Con), diabetes at 4 weeks (DM4W), diabetes at 8 weeks (DM8W), and EtOH + DM8W. After 8 weeks, hemodynamic parameters were recorded and heart weight/body weight (H/B) and hydroxyproline (Hp) content in myocardium were measured. Morphology of collagen in myocardial tissue was observed with Masson's trichrome staining method and collagen volume fraction (CVF) was analysed. The mRNA expression of ALDH2 was assessed with Real-Time PCR. The protein expressions of p-JNK and JNK were evaluated using western blot. Results. In contrast to Con group, there was no difference in hemodynamic parameters in DM4W group, but mean arterial pressure and heart rate were decreased in DM8W group, and the ratios of H/B, Hp, and CVF were markedly increased. ALDH2 mRNA expression was decreased, while the ratio of p-JNK/JNK were increased. Compared with DM8W group, the above indexes were improved in EtOH + DM8W group. Conclusion. With low dose ethanol intervention, enhanced ALDH2 expression can antagonize the happening of myocardial fibrosis in diabetic rats, which may be relevant with downregulating the JNK pathway.

Effect of glucose-insulin-potassium on hyperlactataemia in patients undergoing valvular heart surgery: A randomised controlled study.

Hyperlactataemia represents oxygen imbalance in the tissues and its occurrence during cardiac surgery is associated with adverse outcomes. Glucose-insulin-potassium (GIK) infusion confers myocardial protection against ischaemia-reperfusion injury and has the potential to reduce lactate release while improving its clearance. The objective of this study is to compare the effect of GIK on the incidence of hyperlactataemia in patients undergoing valvular heart surgery. A randomised controlled study. Single university teaching hospital. One hundred and six patients scheduled for elective valvular heart surgery with at least two of the known risk factors for hyperlactataemia. Patients were randomly allocated to receive either GIK solution (insulin 0.1 IU kg(-1) h(-1) and an infusion of 30% dextrose and 80 mmol l(-1) potassium at 0.5 ml kg(-1) h(-1)) or 0.9% saline (control) throughout surgery. The primary outcome was the incidence of hyperlactataemia (lactate ≥ 4 mmol l(-1)) during the operation and until 24 h after the operation. Secondary outcomes included haemodynamic parameters, use of vasopressor or inotropic drugs, and fluid balance until 24 h postoperatively. Postoperative morbidity endpoints were also assessed. The incidences of hyperlactataemia were similar in the groups (32/53 patients in each of the control and GIK groups, P > 0.999). There were no intergroup differences in haemodynamic parameters, use of vasopressor and inotropic drugs, or fluid balance. The incidences of postoperative morbidity endpoints were similar in both groups. Despite its theoretical advantage, GIK did not provide beneficial effects in terms of the incidence of hyperlactataemia or outcome in patients undergoing valvular heart surgery. Clinicaltrials.gov identifier: NCT01825720.

Differences in maternal temperature during labour with remifentanil patient-controlled analgesia or epidural analgesia: a randomised controlled trial

BackgroundEpidural analgesia and remifentanil patient-controlled analgesia are two popular techniques for the treatment of labour pain, each with its own efficacy and toxicity. MethodsParturients requesting analgesia were randomly assigned to either patient-controlled intravenous remifentanil or epidural analgesia. Control patients consisted of parturients not requesting pain medication. The primary objective was to compare the incidence of maternal fever (temperature ⩾38°C); secondary outcomes included the incidence of low oxygen saturation, pain scores, nausea and vomiting, sedation scores, pruritus and neonatal outcome. ResultsData from 140 parturients were analysed: 49 received remifentanil analgesia, 49 epidural analgesia and 42 no analgesia (controls). Fever (temperature ⩾38°C) developed in 10% of remifentanil patients compared to 37% of epidural patients and 7% of control patients (P<0.001). One or more hypoxaemic events (oxygen saturation <90% for at least 1min) occurred in 48% of patients on remifentanil versus 15% of patients on epidural analgesia and 20% of control patients (P=0.003). Although pain intensity scores differed significantly between the two groups in favour of the epidural, mean satisfaction scores were similar in both analgesia groups (remifentanil 8.1±1.2 vs. epidural 8.4±1.2). Remifentanil analgesia was associated with a higher incidence of nausea and deeper levels of sedation. The differences in haemodynamic parameters between groups were small and clinically insignificant. ConclusionsDuring treatment of labour pain, epidural analgesia is associated with a higher incidence of maternal fever, while remifentanil analgesia results in more frequent and deeper hypoxaemic events.

Hemodynamic alterations in unilateral chronic middle cerebral artery stenosis patients and the effect of percutaneous transluminal angioplasty and stenting: a perfusion-computed tomography study.

The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial indicated that most patients with symptomatic intracranial atherosclerosis are not good candidates for percutaneous transluminal angioplasty and stenting (PTAS) because of a higher complication risk than with conservative treatment. However, enrollment of SAMMPRIS patients was based on lesion severity only, without functional imaging. To determine whether perfusion computed tomography (PCT) can effectively evaluate hemodynamic compromise in unilateral chronic middle cerebral artery stenosis and the alterations of hemodynamics after PTAS. In this prospective study, 89 patients with unilateral middle cerebral artery (MCA) stenosis/occlusion were enrolled and classified into four groups according to the degree of stenosis. Cerebral hemodynamics was evaluated by measuring cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) in the ipsilateral and contralateral hemispheres by PCT before and after intervention with PTAS. Differences in hemodynamic parameters before and after intervention were analyzed. Three different hemodynamic patterns were observed in these patients. Patients with severe MCA stenosis (70-99%) or MCA occlusion demonstrated a significant increase of ipsilateral CBV and TTP, indicating hemodynamic compromise. Ten severe stenosis patients with recurrent ischemic symptoms despite of maximal conservative therapy were selected for PTAS. PTAS induced a rapid recovery of cerebral hemodynamics (especially TTP) at 1 week post intervention. PCT appears to be a valuable noninvasive technique to evaluate hemodynamic compromise in unilateral chronic MCA stenosis and the improvements after PTAS.

Customized Cutting Blocks Reduce Surgical Time for Total Knee Arthroplasty

This randomized trial was designed to compare outcomes in patients undergoing total knee arthroplasty using either a customized cutting block or conventional instrumentation. There was no difference in hemodynamic parameters or knee stability using either approach, but surgical time was significantly reduced using a customized cutting block.

Non-Invasive Measurement of Systemic Haemodynamics by Finometry in Patients with Cirrhosis

Background and Aim: Cirrhosis and portal hypertension are characterised by a hyperdynamic circulation, which is independently associated with portal pressure and variceal size. Measurement is invasive and performed in limited centres; non-invasive techniques are available. We assessed whether non-invasive measurement of systemic haemodynamics can identify the hyperdynamic circulation and its associations with portal pressure and variceal size. Methods: We studied 29 cirrhotic patients. Systemic haemodynamics were studied non-invasively using the Finometer® (cardiac output/index CO/CI, heart rate HR, peripheral vascular resistance PVR). Gastroscopy assessed variceal presence, size and bleeding risk. Portal pressure was assessed by hepatic venous pressure gradient (HVPG). Results: A significant negative correlation was seen between CO and PVR (r= -0.95, p<0.001). Significant positive correlations were seen between CI, HR, HVPG and ChildPugh score (r=0.36, r=0.37 and r=0.58 respectively). HVPG correlated positively with HR and CI (r=0.62, p<0.001 and r=0.53, p=0.05 respectively). Significant differences in haemodynamic parameters were seen according to variceal size.

Role of OCT in a case of VF arrest

Myocardial reperfusion injury can be ameliorated by prior transient limb ischaemia, which induces remote ischaemic preconditioning (RIPC) and contributes to reduced infarct size. The mechanisms by which RIPC causes cardioprotection are unclear, but likely involve neural and/or humoral mechanisms. The aim of this study was to determine the role of vagal innervation in the cardioprotective effect of RIPC. Anaesthetised sheep were randomly allocated into 4 groups, (1) Sham conditioning (n=6), (2) RIPC (n=6), 3) Proximal vagal denervation + RIPC (n=6) and (4) Distal vagal denervation + RIPC (n=6). RIPC involved 3x5 min occlusions of the iliac artery. Subsequently, the animalsunderwent 1h coronary ischaemia followed by 3h reperfusion. Haemodynamic parameters were measured throughout the protocol. At the end of 3h of reperfusion the heartwas excised and infarct size was measured. There were no clinically relevant significant differences in haemodynamic parameters among the 4 treatment groups. Compared with Sham animals, RIPC significantly reduced infarct size following IR (infarct size/area-at-risk, 82±5% vs. 49±7%, respectively, P<0.05). Distal vagotomy enhanced RIPC protection (31±7% infarct size) compared with proximal denervation (69 ±8% infarct size, P<0.05). These data confirm the potential clinical benefits of limb RIPC against myocardial IR injury. Furthermore, they indicate that bilateral resection of the vagus nerves distal to theheart enhanced thecardioprotectiveeffect ofRIPC against reperfusion injury. This finding adds complexity to previous studies indicating that parasympathetic blockade with ganglion blockers inhibited the cardioprotective effect of RIPC against reperfusion injury.

A comparative study of intranasal midazolam spray and oral midazolam syrup as premedication in pediatric patients

Background: Preoperative preparation of children to alleviate the stress and anxiety related to surgery is an important aspect of balanced anesthesia care, it can not only affect the smoothness of induction and emergence from anesthesia but also the emotional and psychological make-up of the child, considering the pharmacological profile, midazolam is widely considered to be the ideal premedicant. The purpose of our prospective randomized observer-blinded study is to compare the effect of midazolam through oral and intranasal routes and determine the safer, more effective, and acceptable route by children. Subjects and Methods: Sixty patients aged 2–8 years, belonging to the American Society of Anesthesiologist I and II undergoing various surgeries were randomized into two groups of 30 each. Group O received 0.5 mg/kg of oral midazolam syrup, and Group N received 0.2 mg/kg of midazolam intranasal spray. Hemodynamic variables, sedation scores, ease of parental separation, and mask acceptance at the time of induction were studied. Results: Onset of sedation was shorter and the sedation scores were higher in intranasal group, separation from parents and acceptance to mask were satisfactory but statistically insignificant in both the groups. There was no statistical difference in hemodynamic parameters, and no major adverse effects were seen in either group. Conclusion: Both oral and intranasal midazolam are safe and effective as sedative premedication in children.

Clinical trial for the effectiveness of Unilateral Paravertebral Block Versus Unilateral Subarachnoid Block in Unilateral inguinal hernia for Herniorrhaphy

Background: Inguinal Herniorrhaphy is most commonly performed surgical procedurein male. Till now inguinal hernia repair was performed under general, regional, and peripheral nerve blocks. So the concept of paravertebral blocks which provided an excellent alternative anaesthesia technique for hernia repair. Aim: To study the effectiveness of unilateral paravertebral block versus unilateral subarachnoid block in unilateral inguinal hernias repair. Materials and Methods: 100 patients of unilateral inguinal hernia where enrolled in the study and randomized into two groups each of 50 patients. Group S (50) receiving subarachnoid block, group P (50) receiving paravertebral block. Time for procedure and onset of action, intraoperative hemodynamics, post-operative analgesia, and ambulation time were compared. Results: Significant difference was observed in time to perform and onset of action with group P (13.08± 1.31) & (15.94± 1.21) and group S (1.35±0.61) & (5.14±0.76) respectively. No significant difference in hemodynamic parameters and post op analgesia lasted for (324.00±52.84min) in group P and (182.67±40.13min) in group S. Conclusion: Paravertebral block provides excellent anesthesia with unilateral motor, sympathetic, and prolonged sensory blockade, provide excellent postoperative analgesia, and encourages early ambulation. Key words: Inguinal hernia, subarachnoid block, paravertebral block, post-operative analgesia

The role of mitochondrial ATP-sensitive potassium channels on cardiovascular effects of thiopental and ketamine in rats.

We aimed to investigate whether mitochondrial ATP-sensitive potassium (mitoKATP) channels play any role on cardiovascular effects of thiopental (TP) or ketamine (K) anesthesia in rats. mitoKATP channels are the end-effectors of cardioprotection induced by some anesthetics. TP and K are the most frequently used anesthetics with their own cardiovascular effects in experimental studies. To the best of our knowledge, there is no study investigating the cardiovascular effects of TP and K associated with mitoKATP channels. The experimental groups: TP control, K/Xylazine (X) control, TP+5-hydroxydecanoate (5-HD; mitoKATP channel blocker) and K/X+5-HD. Mean arterial blood pressure (MABP), heart rate (HR) and standard limb lead II ECG were recorded and arrhythmia parameters were evaluated. Blockage of mitoKATP channels by 5-HD increased MABP and decreased HR in the TP+5-HD and K/X+5-HD groups, respectively. 5-HD caused an increase in ventricular ectopic beat (VEB) incidence. Moreover, VEB incidence was significantly different in TP+5-HD (100%) than K/X+5-HDgroup (66.6%) and ventricular tachycardia was only seen in TP+5-HD (incidence was 88.3%). mitoKATP channels play different roles in influencing cardiovascular effects of K/X and TP anesthesia in rats. The differences in hemodynamic parameters and arrhythmia scores of these anesthetics should be considered when they are used in an experimental study associated with mitoKATP channels (Fig. 3, Ref. 35).

Abstract 2: Sodium Nitroprusside--Enhanced Cardiopulmonary Resuscitation Facilitates Intra-arrest Cerebral Therapeutic Hypothermia in a Porcine Model of Prolonged Ventricular Fibrillation

Introduction: Intra-arrest cooling has been shown to improve survival and neurologic outcome in animal models. The aim of this study was to assess the effect of Sodium Nitroprusside enhanced Cardiopulmonary Resuscitation (SNPeCPR) on heat exchange during surface cooling. We hypothesized that SNPeCPR would decrease the time to reach brain temperature to &lt;35°C compared to Active Compression Decompression plus Impedance Threshold Device (ACD+ITD) CPR alone, when surface cooling starts during CPR. Further, addition of epinephrine during SNPeCPR would mitigate heat exchange. Methods: After 10 minutes of untreated ventricular fibrillation, 26 animals were randomized to 3 different protocols: SNPeCPR (n=6), SNPeCPR plus epinephrine (SNP+EPI, n=10) and ACD+ITD alone (Control, n=10). All animals received surface cooling with ice bags at the initiation of CPR. SNPeCPR included ACD+ITD plus abdominal binding, 2mg of SNP every 4min, and no epinephrine during CPR. Control and SNP+EPI groups included 0.5mg of epinephrine every 4min during CPR. Defibrillation occurred after 10 minutes of CPR. After ROSC, an Arctic Sun® at maximum cooling was used on all animals. The primary endpoint was the time to reach brain temperature &lt;35°C. Hemodynamic parameters were recorded continuously. Data are presented as mean ± SEM. ANOVA or Kruskal Wallis test were used to compare continuous variables. Results: Time to reach brain temperature of 35°C was decreased with SNPeCPR vs. Control or SNP+EPI (18 ± 6 min, 53 ± 8 min and 40 ± 9 min, respectively, p=0.03). All animals survived 2h in the SNPeCPR group and 9/10 in the two other groups. Carotid blood flow was higher during CPR in the SNPeCPR group (96 ± 16 ml/min versus 26 ± 7 and 35 ± 5 in the Control and SNP+EPI group, respectively p=0.04). There were no other differences in hemodynamic parameters. Conclusion: This study demonstrates that SNPeCPR facilitates intra-CPR hypothermia, with the brain reaching target temperature (35°C) in less than half of the time of controls without impairing hemodynamics. The addition of epinephrine to SNPeCPR during CPR attenuated its effect on heat exchange.

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naïve patients undergoing colon surgery when nitrous oxide is used - a randomized study

Background: The analgesic properties of ketamine are associated with its non-competitive antagonism of the N-methyl-D-aspartate receptor; these receptors exhibit an excitatory function on pain transmission and this binding seems to inhibit or reverse the central sensitization of pain. In the literature, the value of this anesthetic for preemptive analgesia in the control of postoperative pain is uncertain. The objective of this study was to ascertain whether preoperative low-dose ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery. Methods: In a double-blind, randomized trial, 48 patients were studied. Patients in the ketamine group received 0.5 mg/kg intravenous ketamine before surgical incision, while the control group received normal saline. The postoperative analgesia was achieved with a continuous infusion of morphine at 0.015 mg∙kgˉ¹∙hˉ¹ with the possibility of 0.02 mg/kg bolus every 10 min. Pain was assessed using the Visual Analog Scale (VAS), morphine consumption, and hemodynamic parameters at 0, 1, 2, 4, 8, 12, 16, and 24 hours postoperatively. We quantified times to rescue analgesic (Paracetamol), adverse effects and patient satisfaction. Results: No significant differences were observed in VAS scores between groups (P>0.05), except at 4 hours postoperatively (P=0.040). There were no differences in cumulative consumption of morphine at any time point (P>0.05). We found no significant differences in incremental postoperative doses of morphine consumption in bolus, except at 12 h (P =0.013) and 24 h (P =0.002). The time to first required rescue analgesia was 70 ± 15.491 min in the ketamine group and 44 ± 19.494 min in the control (P>0.05). There were no differences in hemodynamic parameters or patient satisfaction (P>0.05). Conclusions: Preoperative low-dose-ketamine did not show a preemptive analgesic effect or efficacy as an adjuvant for decreasing opioid requirements for postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naïve patients undergoing colon surgery when nitrous oxide is used - a randomized study.

The analgesic properties of ketamine are associated with its non-competitive antagonism of the N-methyl-D-aspartate receptor; these receptors exhibit an excitatory function on pain transmission and this binding seems to inhibit or reverse the central sensitization of pain. In the literature, the value of this anesthetic for preemptive analgesia in the control of postoperative pain is uncertain. The objective of this study was to ascertain whether preoperative low-dose ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery. In a double-blind, randomized trial, 48 patients were studied. Patients in the ketamine group received 0.5 mg/kg intravenous ketamine before surgical incision, while the control group received normal saline. The postoperative analgesia was achieved with a continuous infusion of morphine at 0.015 mg∙kg-¹∙h-¹ with the possibility of 0.02 mg/kg bolus every 10 min. Pain was assessed using the Visual Analog Scale (VAS), morphine consumption, and hemodynamic parameters at 0, 1, 2, 4, 8, 12, 16, and 24 hours postoperatively. We quantified times to rescue analgesic (Paracetamol), adverse effects and patient satisfaction. No significant differences were observed in VAS scores between groups (P>0.05), except at 4 hours postoperatively (P=0.040). There were no differences in cumulative consumption of morphine at any time point (P>0.05). We found no significant differences in incremental postoperative doses of morphine consumption in bolus, except at 12 h (P =0.013) and 24 h (P =0.002). The time to first required rescue analgesia was 70 ± 15.491 min in the ketamine group and 44 ± 19.494 min in the control (P>0.05). There were no differences in hemodynamic parameters or patient satisfaction (P>0.05). Preoperative low-dose-ketamine did not show a preemptive analgesic effect or efficacy as an adjuvant for decreasing opioid requirements for postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

Effects of high-frequency oscillatory ventilation and conventional mechanical ventilation on oxygen metabolism and tissue perfusion in sheep models of acute respiratory distress syndrome

High-frequency oscillatory ventilation (HFOV) allows for small tidal volumes at mean airway pressures (mPaw) above that of conventional mechanical ventilation (CMV), but the effect of HFOV on hemodynamics, oxygen metabolism, and tissue perfusion in acute respiratory distress syndrome (ARDS) remains unclear. We investigated the effects of HFOV and CMV in sheep models with ARDS. After inducing ARDS by repeated lavage, twelve adult sheep were randomly divided into a HFOV or CMV group. After stabilization, standard lung recruitments (40 cmH2O × 40 seconds) were performed. The optimal mPaw or positive end-expiratory pressure was obtained by lung recruitment and decremental positive end-expiratory pressure titration. The animals were then ventilated for 4 hours. The hemodynamics, tissue perfusion (superior mesenteric artery blood flow, pHi, and Pg-aCO2), oxygen metabolism and respiratory mechanics were examined at baseline before saline lavage, in the ARDS model, after model stabilization, and during hourly mechanical ventilation for up to 4 hours. A two-way repeated measures analysis of variance was applied to evaluate differences between the groups. The titrated mPaw was higher and the tidal volumes lower in the HFOV group than the positive end-expiratory pressure in the CMV group. There was no significant difference in hemodynamic parameters between the HFOV and CMV groups. There was no difference in the mean alveolar pressure between the two groups. After lung recruitment, both groups showed an improvement in the oxygenation, oxygen delivery, and DO2. Lactate levels increased in both groups after inducing the ARDS model. Compared with the CMV group, the superior mesenteric artery blood flow and pHi were significantly higher in the HFOV group, but the Pg-aCO2 decreased in the HFOV group. Compared with CMV, HFOV with optimal mPaw has no significant side effect on hemodynamics or oxygen metabolism, and increases gastric tissue blood perfusion.

Effect of unilateral lung recruitment maneuver on hemodynamics and dead space ratio in pigs with unilateral acute respiratory distress syndrome

To compare unilateral lung and traditional lung recruitment maneuver (RM) in animals with unilateral acute respiratory distress syndrome (ARDS) by implementing independent lung ventilation, and to explore the rational mechanical ventilation strategy for unilateral lung lesions. Healthy hybrid pigs were used as experimental animals, and they were divided into two groups according to random number table method (sealed concealed envelope). There were 20 pigs in each group. According to different methods of lung RM, the conventional mechanical ventilation (i.e. implementing ventilation for both lung by using a ventilator) was performed as control group; the individual lung ventilation (that was, implementing ventilation for both lung individually by using two ventilators) as independent lung ventilation group. The model of left lung ARDS was reproduced, and the respective RM was implemented according to respective method of the two groups. The differences in hemodynamic parameters and dead space ratio (VD/VT) between two groups under the RM pressure of 20, 40, 60 cmH₂O (1 cmH₂O=0.098 kPa) were observed. (1) Hemodynamics parameters changes: with the increase in RM pressure, the heart rate (HR) in control group showed a tendency of gradual increase, and the level at 60 cmH₂O was significantly higher than that at 20 cmH₂O (192.65 ± 22.99 bpm vs. 178.20 ± 18.25 bpm, P<0.05). Mean arterial pressure (MAP) showed a tendency of gradual decrease, and that at 60 cmH₂O was lower significantly than that at 20 cmH₂O and 40 cmH₂O (78.55±25.77 mmHg (1 mmHg=0.133 kPa) vs. 112.40 ± 10.84 mmHg, 106.15 ± 13.54 mmHg, both P<0.01). Cardiac output (CO) gradually lowered, and the differences at 20, 40, 60 cmH₂O were logistically significant (11.14 ± 2.65 L/min, 9.56 ± 2.17 L/min, 6.01 ± 1.39 L/min, P<0.05 or P<0.01). With an increase in RM pressure, the difference in HR, MAP, CO in independent lung ventilation group were not significant, and the HR at 60 cmH₂O was significantly lower than that of the control group (178.20 ± 18.26 bpm vs. 192.65 ± 22.99 bpm, P<0.05), and MAP and CO were significantly higher than those of the control group (MAP: 110.80 ± 11.60 mmHg vs. 78.55 ± 25.77 mmHg, CO: 9.68 ± 2.08 L/min vs. 6.01 ± 1.39 L/min, both P<0.01). (2) VD/VT changes: with an increase in RM pressure, the oxygenation index (PaO₂/FiO₂) in control group showed a tendency of gradual decrease, and the level at 60 cmH₂O was significantly lower than that at 20 cmH₂O and 40 cmH₂O (126.40 ± 37.55 mmHg vs. 187.40 ± 21.66 mmHg, 175.20 ± 23.00 mmHg, both P<0.01). On the right side, VD/VT showed a tendency of gradual increase, and there was statistical significance in paired comparison among 20, 40, 60 cmH₂O (0.52 ± 0.12, 0.60 ± 0.15, 0.72 ± 0.12, P<0.05 or P<0.01). There was no obvious change on the left side. Along with the increase in RM pressure, the PaO₂/FiO₂ of independent lung ventilation group showed a tendency of gradual increase, and that at 40 cmH₂O and 60 cmH₂O were significantly higher than that at 20 cmH₂O (244.45 ± 53.93 mmHg, 270.05 ± 53.42 mmHg vs. 205.65 ± 31.33 mmHg, P<0.05 and P<0.01), and the level at 20, 40, 60 cmH₂O was higher than that of the control group (205.65±31.33 vs. 187.40 ± 21.66, P<0.05; 244.45 ± 53.93 vs. 175.20 ± 23.00, P<0.01; 270.05 ± 53.42 vs. 126.40 ± 37.55, P<0.01). There were no changes in VD/VT on both sides, and VD/VT on the right side was significantly lower than that of the control group when the inflation pressure was 20, 40, 60 cmH₂O (0.38 ± 0.14 vs. 0.52 ± 0.12, 0.43 ± 0.11 vs. 0.60 ± 0.15, 0.50 ± 0.13 vs. 0.72 ± 0.12, all P<0.01). For severe ARDS caused by single lung injury, implementation of independent lung RM on the basis of independent lung mechanical ventilation for individual lung was significantly superior to the traditional lung RM for the improvement of hemodynamic parameters and VD/VT.

A prospective comparison of the efficacy and safety of fully closed-loop control ventilation (Intellivent-ASV) with conventional ASV and SIMV modes

Background. Intellivent-adaptive support ventilation (ASV) is a closed-loop, fully automatic method of mechanical ventilation. This advanced mode of ventilation adjusts ventilation and oxygenation parameters according to patient weight, lung function (as assessed by the ventilator) and continuous input of end-tidal carbon dioxide and oxygen saturation. Our study compares the efficacy of this new mode with ASV and synchronised intermittent mandatory ventilation (SIMV) modes. Methods. We conducted a within-group comparison of three modes of ventilation, ASV, Intellivent-ASV and SIMV, using a Hamilton S1 ventilator (Hamilton Medical, Switzerland). Subjects were ventilated for 2 hours on each mode, and at the end of each 2-hour period, parameters of ventilation and haemodynamics were measured. Results. Twenty subjects participated in this study. Their mean age was 67.3 years (range 22 - 82 years). The most common diagnosis at resentation was pneumonia (55%), followed by chronic obstructive pulmonary disease (16%) and acute respiratory distress syndrome (11%). Mean (standard deviation) levels of positive end-expiratory pressure (PEEP) were significantly higher in the Intellivent-ASV group (7.6 (5) v. 5.1 (2) and 5.2 (2) cm H2O in the ASV and SIMV groups, respectively ( p &lt;0.005). Fractional inspired concentration of oxygen (FiO2) was significantly lower in the Intellivent-ASV group (0.35 (0.7)) v. 0.41 (0.6) and 0.41 (0.6) for the ASV and SIMV groups, respectively ( p &lt;0.005). The mean spontaneous breathing rate in the Intellivent-ASV group was 8.6 (7.5) breaths per minute (b/min), significantly higher than in the ASV group (2.9 (5.7) b/min) and the SIMV group (2.4 (4.5) b/min) ( p =0.002), while there was no difference in the total respiratory rate between the groups. There was no significant difference in haemodynamic parameters between the different ventilation modes. ASV tended to produce lower partial pressure of carbon dioxide (PCO2) levels than SIMV and Intellivent-ASV ( p &lt;0.05). Conclusions. Intellivent-ASV provided a significant reduction in the FiO 2 with higher PEEP levels, but without haemodynamic detriment. Intellivent-ASV encouraged significantly more spontaneous breathing, which may translate to faster weaning. Further studies to examine this effect are warranted.