Central Venous Blood Pressure Research Articles

Evaluation of a Nurse-Driven Fluid Management Protocol to Improve Outcomes in Critically Ill Patients.

This article reports results of a nurse-driven fluid management protocol in a medical-surgical intensive care unit (ICU). Use of static measures such as central venous pressure monitoring, heart rate, blood pressure, and urine output is poor predictors of fluid responsiveness and can result in inappropriate fluid administration. Indiscriminate administration of fluid can result in prolonged mechanical ventilation time, increased vasopressor requirements, increased length of stay, and greater costs. Use of dynamic preload parameters such as stroke volume variation (SVV), pulse pressure variation, or changes in stroke volume with a passive leg raise has been shown to be more accurate predictors of fluid responsiveness. Improved patient outcomes including decreased length of hospital stay, reduction in kidney injury, decreased mechanical ventilation time and requirements, and reduced vasopressor requirements have been demonstrated by using dynamic preload parameters. ICU nurses were educated on cardiac output and dynamic preload parameters and a nurse-driven fluid replacement protocol was established. Knowledge scores, confidence scores, and patient outcomes were measured pre- and post-implementation. The results indicated that there was no change in knowledge scores between pre- and postimplementation groups (mean = 80%). There was a statistically significant increase in nurse confidence in using SVV (P = .003); however, this change is not clinically significant. There was no statistically significant difference in other confidence categories. The study indicated that ICU nurses were resistant to adoption of a nurse-driven fluid management protocol. While anesthesia clinicians are familiar with technologies to evaluate fluid responsiveness in the perioperative setting, the new technology posed challenges to ICU confidence. This project demonstrates that traditional methods of nursing education did not provide the support needed for implementation of a novel approach to fluid management, and that there is a need for further improvement in educational strategies.

Flow-controlled expiration reduces positive end-expiratory pressure requirement in dorsally recumbent, anesthetized horses.

Equine peri-anesthetic mortality is higher than that for other commonly anesthetized veterinary species. Unique equine pulmonary pathophysiologic aspects are believed to contribute to this mortality due to impairment of gas exchange and subsequent hypoxemia. No consistently reliable solution for the treatment of peri-anesthetic gas exchange impairment is available. Flow-controlled expiration (FLEX) is a ventilatory mode that linearizes gas flow throughout the expiratory phase, reducing the rate of lung emptying and alveolar collapse. FLEX has been shown to improve gas exchange and pulmonary mechanics in anesthetized horses. This study further evaluated FLEX ventilation in anesthetized horses positioned in dorsal recumbency, hypothesizing that after alveolar recruitment, horses ventilated using FLEX would require a lower positive end-expiratory pressure (PEEP) to prevent alveolar closure than horses conventionally ventilated. Twelve adult horses were used in this prospective, randomized study. Horses were assigned either to conventional volume-controlled ventilation (VCV) or to FLEX. Following induction of general anesthesia, horses were placed in dorsal recumbency mechanically ventilated for a total of approximately 6.5 hours. Thirty-minutes after starting ventilation with VCV or FLEX, a PEEP-titration alveolar recruitment maneuver was performed at the end of which the PEEP was reduced in decrements of 3 cmH2O until the alveolar closure pressure was determined. The PEEP was then increased to the previous level and maintained for additional three hours. During this time, the mean arterial blood pressure, pulmonary arterial pressure, central venous blood pressure, cardiac output (CO), dynamic respiratory system compliance and arterial blood gas values were measured. The alveolar closure pressure was significantly lower (6.5 ± 1.2 vs 11.0 ± 1.5 cmH2O) and significantly less PEEP was required to prevent alveolar closure (9.5 ± 1.2 vs 14.0 ± 1.5 cmH2O) for horses ventilated using FLEX compared with VCV. The CO was significantly higher in the horses ventilated with FLEX (37.5 ± 4 vs 30 ± 6 l/min). We concluded that FLEX ventilation was associated with a lower PEEP requirement due to a more homogenous distribution of ventilation in the lungs during expiration. This lower PEEP requirement led to more stable and improved cardiovascular conditions in horses ventilated with FLEX.

Discussion on the zero-calibration and the zero line in the measurement of central venous pressure and invasive arterial blood pressure

To figure out the timing of zeroing and the location of the zero line in the central venous pressure (CVP) monitoring and invasive arterial blood pressure (IBP) monitoring, and to provide scientific and accurate data for patients management. The liquid vessel models were used to simulate the pressure measurement process of the continuous pressure monitoring system. Based on the theory of fluid mechanics and the knowledge of blood pressure physiology and cardiovascular anatomy, the composition and influencing factors of the pressure in the fluid-filled catheter system during the zeroing and placing the transducer in the zero line of CVP and IBP, were analyzed. The pressure in the liquid-filled catheter system was composed of atmospheric pressure, the pressure of pumping bag, the gravity of the water column (the vertical distance between the liquid level of Murphy's dropper and pressure transducer, ΔH), and the resistance of tube wall. This pressure value is set as a pressure of 0 mmHg (1 mmHg ≈ 0.133 kPa). In the process of pressure measurement, when the pressure transducer was placed at a horizontal position of 10 cm below the highest liquid level of the vessel, the pressure measured at different catheter tip positions was all 10 cmH2O (1 cmH2O ≈ 0.098 kPa); When the pressure transducer was placed at the horizontal position of the highest liquid level of the vessel, the measured pressure is 0 mmHg. Zeroing should repeatedly be performed only when one or more conditions (atmospheric pressure, pressure of pumping bag, gravity of ΔH water column and resistance of tube wall) are changed. In the measurement process, the pressure transducer should be placed at the zero line position at any time to eliminate the influence of hydrostatic pressure and to ensure the objective and accurate value.

Anaesthetic Management of a Patient with Advanced Abdominal Pregnancy, Intrauterine Foetal Death and Celiac Disease

Abdominal pregnancy is a rare form of ectopic pregnancy where implantation of fertilised ovum occurs in the abdominal cavity. If diagnosed late maternal and foetal mortality is very high. The major cause of death in abdominal pregnancy is haemorrhage. The case report is about a 31-year-old gravida two with 36 weeks of gestation period with Intrauterine Foetal Death (IUFD) and celiac disease. Celiac disease is a chronic malabsorptive disease of the small intestine occurring due to hypersensitivity to gluten ingestion. Due to chronic malabsorption, the patient presented with calcium deficiency. She also had lesions of dermatitis herpetiformis over the whole body sparing only the face. It is a rare case of advanced abdominal pregnancy with the IUFD, with celiac disease. The patient was managed successfully under general anaesthesia with preparedness for difficult airway management, securing wide bore peripheral cannulas, central venous cannulation and invasive blood pressure monitoring. Massive haemorrhage intraoperatively was managed with crystalloids, colloids, blood products and tranexamic acid. The intraoperative period was uneventful. The patient was extubated at the end of the surgery, and followed-up in a high dependency unit.

Echocardiogram Unmasked Hemodynamic Advantage of Atrial Pacing in Securing Ventricular Preload in a Fontan Patient with Junctional Rhythm

While the advancement of perioperative management has expanded Fontan candidacy, not all patients have a successful postoperative course. Our case was a right isomerism patient who could not leave the ICU due to high central venous pressure and low output syndrome. Initial observation of the monitor ECG showed his rhythm to be supraventricular, however, an echocardiogram indicated simultaneous contraction of the atrium and ventricle, implying a junctional rhythm. While neither central venous pressure nor blood pressure improved with temporary pacing, better central venous and pulmonary venous blood flow patterns during pacing unraveled its positive impact. The patient successfully left the ICU after permanent pacing implantation. Hemodynamic study revealed a beneficial impact of atrial pacing in securing cardiac output and ventricular preload, lowering central venous pressure, and shortening blood transit time, which is partly attributed to the optimization of the fenestration function in reservation of the preload. Our case emphasizes the significant advantage of atrial pacing in a failing Fontan patient with junctional rhythm by reducing venous congestion and maximizing the benefit of fenestration.

P1316PREDICTORS OF ARTERIO-VENOUS FISTULA FAILURE: A POST-HOC ANALYSIS OF THE FAVOURED STUDY

Abstract Background and Aims An autologous arteriovenous fistula (AVF) is the preferred haemodialysis vascular access but successful creation is hampered by high rates of AVF failure. This study aimed to evaluate patient and surgical factors associated with AVF failure to improve vascular access selection and outcomes. Method This is a post-hoc analysis of all participants of FAVOURED, a multi-centre, double-blind, multinational, randomized placebo-controlled trial evaluating the effect of fish oil and/or aspirin in preventing AVF failure in patients receiving haemodialysis. The primary outcome of AVF failure was a composite of fistula thrombosis and/or abandonment and/or cannulation failure at 12 months post AVF creation and secondary outcomes included individual outcome components. Patient data (demographics, comorbidities, medications and laboratory data) and surgical factors (surgical expertise, anaesthetic, intraoperative heparin use) were examined using multivariable logistic regression analyses to evaluate associations with AVF failure. Results Of 536 participants, 253 patients (47%) experienced AVF failure during the study period. The mean age was 55 ± 14.4 years, 64% were male, 45% were diabetic and 4% had peripheral vascular disease. Factors associated with AVF failure included female sex (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.20-2.67), lower diastolic blood pressure (DBP; OR for higher DBP 0.98, 95% CI 0.97-0.99), presence of central venous catheter (OR 1.50, 95% CI 1.02-2.20, p=0.04) and aspirin requirement (OR 1.61, 95% CI 1.01-2.57). Conclusion Female sex, requirement for aspirin therapy, requiring haemodialysis via a central venous catheter and lower diastolic blood pressure were factors associated with higher odds of AVF failure. These associations have potential implications for vascular access planning and warrant further studies.

The Physiological Effects of Percutaneous Right Ventricular Assist Device

Purpose The dual lumen cannula connected to a centrifugal extracorporeal pump has been used as a percutaneous right ventricular assist device (RVAD) for RV failure. We describe the physiological changes and outcomes associated with this continuous-flow percutaneous RVAD. Methods We included 7 patients underwent percutaneous RVAD from September 2015-June 2018: post-LVAD (n=6), post-heart transplant (n=1), after excluding 2 patients converted from/to peripheral VA-ECMO and 2 with oxygenator use with the RVAD. Baseline and 3-hour post-insertion arterial blood gases, end-tidal carbon dioxide (ETCO2) and hemodynamic parameters were compared. There were no changes in ventilator parameters during this period of assessment. Results The median duration of support was 10 days (minimum 1 day, maximum 29 days). There were 2 deaths of the 7 patients at less than 90 days (both post-LVAD). Percutaneous RVAD resulted in a drop in central venous pressure (CVP 16.4±2.1 to 12.8±2.7mmHg, p=0.024) and blood pressure increase (64.5±4.1 to 75.1±9.9mmHg, p=0.030) with no significant change in inotropic/vasopressor use. There was a rise in arterial CO2 without significant changes in ETCO2, which resulted in an increase in the arterial-ETCO2 gradient [FIGURE]. The modest change in arterial pH (7.35±0.06 to 7.33±0.05, p=0.646) reflected the increase in arterial CO2, as there were reductions in base deficits (-4.5±2.9 to -2.7±1.7, p=0.259) and lactate levels (5.0±2.2 to 2.2±0.5IU, p=0.027). There was no significant change in oxygenation (PaO2 12.2±2.9 to 12.6±1.4kPa, p=0.838). None of the patients required extracorporeal CO2 removal. Conclusion Continuous flow percutaneous RVAD improves hemodynamics but transiently worsens the arterial-ETCO2 gradient without affecting oxygenation in some patients with RV failure.

Interpretation of Noninvasive and Invasive Information

Traditional, static measures of resuscitation, such as vital signs, central venous pressure, and pulmonary arterial pressure, provide momentary glimpses evolving hemodynamic states. In patients with shock, these measures of resuscitation are poor indicators of response to therapy. As a result, dynamic assessments of cardiovascular status are now used in critically ill patients to facilitate resuscitation. Some of these approaches focus on fluid responsiveness. These assessments allow care to be tailored to each patient’s response to interventions. An evolving aspect of hemodynamic monitoring is evaluation of the adequacy of tissue perfusion and oxygen delivery. In this review, we consider the use of arterial, central venous, and pulmonary arterial blood pressure monitoring; echocardiography; transesophageal Doppler technology; pulse contour analysis; bioimpedance and bioreactance; and partial rebreathing monitoring modalities to assess hemodynamic status in critically ill patients. This review contains 22 figures, 5 tables, and 38 references. Key words: echocardiography, esophageal Doppler technology, invasive and noninvasive hemodynamic monitoring, pulse contour analysis, shock

Application of modified disinfection posture in coronary artery bypass grafting

Objective To explore the application effect of modified disinfection posture in coronary artery bypass grafting (CABG) . Methods A total of 50 patients who would undergo CABG were recruited in this study by purposive sampling method in Xuzhou Central Hospital from January 2014 to December 2015. They were divided into the control group (25 cases, conventional disinfection posture) and the observation group (25 cases, modified disinfection posture) according to the random number table. The central venous pressure (CVP) , blood pressure (BP) and heart rate (HR) were monitored between two groups before and after placing disinfection position with leg-raising immediately and after restoring horizontal position immediately. The comfort of body, the convenience of operation, the time of placing position and disinfection were investigated or recorded during the process of disinfection. Results There was no statistically significant difference in the time of placing position and disinfection during surgery between two groups (P>0.05) . There was also no statistically significant difference in the comfort and satisfaction degree of doctors during surgery between two groups (P>0.05) . The hemodynamic variables had no significant difference in two groups before leg-raising immediately (P>0.05) . After leg-raising immediately, the systolic pressure, diastolic pressure, CVP and HR in the control group [ (121.313±4.116) , (70.423±3.291) , (8.524±0.283) mmHg, (84.193±3.682) times/min] were higher than those in the observation group [ (116.323±6.242) , (66.191±11.468) , (7.254±0.989) mmHg, (67.524±3.193) times/min] with significant differences (t=2.013, 2.316, 5.913, 16.205; P<0.05) . After restoring horizontal position immediately, the systolic pressure, diastolic pressure, CVP and HR in the control group [ (109.267±6.167) , (60.766±5.233) , (4.063±0.572) mmHg, (86.524±4.254) times/min] were higher than those in the observation group [ (101.274±9.156) , (65.352±3.254) , (3.544±0.623) mmHg, (69.933±7.424) times/min] with significant differences (t=3.450, 2.025, 2.705, 9.266; P<0.05) . Conclusions The application of modified disinfection posture in patients with general anesthesia and CABG has no effect on the comfort of body, the convenience of the operation, and it will not increase the time of placing position and disinfection. The modified disinfection posture can effectively avoid the impact of conventional disinfection posture on the hemodynamic variables and can improve the quality of nursing care. Key words: Disinfection; Posture; Coronary artery bypass, off-pump; Hemodynamics

Plasma concentration and cardiovascular effects of intramuscular medetomidine combined with three doses of the peripheral alpha2-antagonist MK-467 in dogs

ObjectiveWe investigated the plasma concentrations and cardiovascular effects of intramuscularly (IM) administered medetomidine, administered alone or with three different doses of MK-467. Study designProspective, randomized, open, crossover trial. AnimalsEight purpose-bred healthy Beagle dogs. MethodsEach dog was administered four treatments: medetomidine 20 μg kg–1 IM alone or mixed in the same syringe with MK-467 (200 μg kg–1, 400 μg kg–1 or 600 μg kg–1). Instrumentation was performed under standardized anaesthesia. The dogs were allowed to recover before measurement of baseline values. Composite sedation scores, cardiovascular variables, i.e., heart rate (HR), cardiac output (CO), mean arterial and central venous blood pressures (MAP and CVP) and arterial blood gases were recorded at baseline and for 60 minutes after treatment. Drug concentrations in venous plasma were analysed. Generalized linear mixed models for repeated measures with post hoc Bonferroni correction were used with statistical significance level set at α=0.05. ResultsAll treatments initially demonstrated the effects of medetomidine: HR and CO decreased and CVP increased. MAP transiently increased and then significantly decreased from baseline with the two highest MK-467 doses. The cardiovascular effects of medetomidine disappeared more rapidly with MK-467 than with medetomidine alone. With medetomidine alone, sedation scores remained high until the end of the 60 minute follow-up. Maximum concentrations of medetomidine were more rapidly achieved and were higher with MK-467. Conclusions and clinical relevanceInitial haemodynamic effects of medetomidine were not prevented by MK-467, but these effects were attenuated and their duration shortened by MK-467, independently of dose. Absorption of medetomidine was accelerated by MK-467, when administered concomitantly IM, resulting in faster sedation; addition of MK-467 shortened the sedative effect of medetomidine.

The importance of albumin infusion rate for plasma volume expansion following major abdominal surgery - AIR: study protocol for a randomised controlled trial.

BackgroundAdministration of fluids to restore normovolaemia is one of the most common therapeutic interventions performed peri-operatively and in the critically ill, but no study has evaluated the importance of infusion rate for the plasma volume-expanding effect of a resuscitation fluid. The present study is designed to test the hypothesis that a slow infusion of resuscitation fluid results in better plasma volume expansion than a rapid infusion.Methods/designThe study is a single-centre, assessor-blinded, parallel-group, randomised prospective study. Patients over 40 years of age admitted to the post-operative care unit after a Whipple procedure or major gynaecological surgery and presenting with signs of hypovolaemia are eligible for inclusion. Patients are randomised in a 1:1 fashion with no stratification to either rapid (30 minutes) or slow (180 minutes) infusion of 5% albumin at a dose of 10 ml/kg ideal body weight. Plasma volume is measured using 125I human serum albumin at baseline (prior to albumin infusion) as well as at 30 minutes and 180 minutes after infusion start. The primary endpoint is change in plasma volume from baseline to 180 minutes after the start of 5% albumin infusion. Secondary endpoints include the integral of plasma volume over time from baseline to 180 minutes after the start of the infusion and transcapillary escape rate of albumin (%/h) from 180 minutes to 240 minutes after the start of albumin infusion. In addition, diuresis, change in central venous oxygen saturation, lactate and blood pressure will be evaluated. A total of 70 patients will be included in the study, and the study has 80% power to detect a difference of 4 ml/kg in plasma volume expansion between the two groups.DiscussionThe present study is the first clinical investigation of the importance of infusion rate for the plasma volume-expanding effect of a resuscitation fluid.Trial registrationEudraCT identifier: 2013-004446-42. Registration date: 20 December 2013.ClinicalTrials.gov identifier: NCT02728921. Registration date: 31 March 2016.Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-016-1714-5) contains supplementary material, which is available to authorized users.

Reduction in central venous pressure enhances erythropoietin synthesis: role of volume-regulating hormones.

Erythropoiesis is a tightly controlled biological event, but its regulation under non-hypoxic conditions, however, remains unresolved. We examined whether acute changes in central venous blood pressure (CVP) elicited by whole-body tilting affect erythropoietin (EPO) concentration according to volume-regulating hormones. Plasma EPO, angiotensin II (ANGII), aldosterone, pro-atrial natriuretic peptide (proANP) and copeptin concentrations were measured at supine rest and up to 3h during 30° head-up (HUT) and head-down tilt (HDT) in ten healthy male volunteers. Plasma albumin concentration was used to correct for changes in plasma volume and CVP was estimated through the internal jugular vein (IJV) aspect ratio with ultrasonography. From supine rest, the IJV aspect ratio was decreased and increased throughout HUT and HDT respectively. Plasma EPO concentration increased during HUT (13%; P=0.001, P for linear component=0.017), independent of changes in albumin concentration. Moreover, ANGII and copeptin concentrations increased during HUT, while proANP decreased. The increase in EPO concentration during HUT disappeared when adjusted for changes in copeptin. During HDT, EPO, ANGII and copeptin concentrations remained unaffected while proANP increased. In regression analyses, EPO was positively associated with copeptin (β=0.55; 95% CI=0.18, 0.93; P=0.004) irrespective of changes in other hormones and albumin concentration. Reduction in CVP prompts an increase in plasma EPO concentration independent of hemoconcentration and hence suggests CVP per se as an acute regulator of EPO synthesis. This effect may be explained by changes in volume-regulating hormones.

Low-Volume Intense Exercise Elicits Post-exercise Hypotension and Subsequent Hypervolemia, Irrespective of Which Limbs Are Exercised.

Introduction: Exercise reduces arterial and central venous blood pressures during recovery, which contributes to its valuable anti-hypertensive effects and to facilitating hypervolemia. Repeated sprint exercise potently improves metabolic function, but its cardiovascular effects (esp. hematological) are less well-characterized, as are effects of exercising upper versus lower limbs. The purposes of this study were to identify the acute (<24 h) profiles of arterial blood pressure and blood volume for (i) sprint intervals versus endurance exercise, and (ii) sprint intervals using arms versus legs.Methods: Twelve untrained males completed three cycling exercise trials; 50-min endurance (legs), and 5*30-s intervals using legs or arms, in randomized and counterbalanced sequence, at a standardized time of day with at least 8 days between trials. Arterial pressure, hemoglobin concentration and hematocrit were measured before, during and across 22 h after exercise, the first 3 h of which were seated rest.Results: The post-exercise hypotensive response was larger after leg intervals than endurance (AUC: 7540 ± 3853 vs. 3897 ± 2757 mm Hg·min, p = 0.049, 95% CI: 20 to 6764), whereas exercising different limbs elicited similar hypotension (arms: 6420 ± 3947 mm Hg·min, p = 0.48, CI: −1261 to 3896). In contrast, arterial pressure at 22 h was reduced after endurance but not after leg intervals (−8 ± 8 vs. 0 ± 7 mm Hg, p = 0.04, CI: 7 ± 7) or reliably after arm intervals (−4 ± 8 mm Hg, p = 0.18 vs. leg intervals). Regardless, plasma volume expansion at 22 h was similar between leg intervals and endurance (both +5 ± 5%; CI: −5 to 5%) and between leg and arm intervals (arms: +5 ± 7%, CI: −8 to 5%).Conclusions: These results emphasize the relative importance of central and/or systemic factors in post-exercise hypotension, and indicate that markedly diverse exercise profiles can induce substantive hypotension and subsequent hypervolemia. At least for endurance exercise, this hypervolemia may not depend on the volume of post-exercise hypotension. Finally, endurance exercise led to reduced blood pressure the following day, but sprint interval exercise did not.

Clinical practice in perioperative monitoring in adult cardiac surgery: is there a standard of care? Results from an national survey.

This study was to investigate and define what is considered as a current clinical practice in hemodynamic monitoring and vasoactive medication use after cardiac surgery in Italy. A 33-item questionnaire was sent to all intensive care units (ICUs) admitting patients after cardiac surgery. 71 out of 92 identified centers (77.2%) returned a completed questionnaire. Electrocardiogram, invasive blood pressure, central venous pressure, pulse oximetry, diuresis, body temperature and blood gas analysis were identified as routinely used hemodynamic monitoring, whereas advanced monitoring was performed with pulmonary artery catheter or echocardiography. Crystalloids were the fluids of choice for volume replacement (86.8% of Centers). To guide volume management, central venous pressure (26.7%) and invasive blood pressure (19.7%) were the most frequently used parameters. Dobutamine was the first choice for treatment of left heart dysfunction (40%) and epinephrine was the first choice for right heart dysfunction (26.8%). Half of the Centers had an internal protocol for vasoactive drugs administration. Intra-aortic balloon pump and extra-corporeal membrane oxygenation were widely available among Cardiothoracic ICUs. Angiotensin-converting enzyme inhibitors were suspended in 28% of the Centers. The survey shows what is considered as standard monitoring in Italian Cardiac ICUs. Standard, routinely used monitoring consists of ECG, SpO2, etCO2, invasive BP, CVP, diuresis, body temperature, and BGA. It also shows that there is large variability among the various Centers regarding hemodynamic monitoring of fluid therapy and inotropes administration. Further research is required to better standardize and define the indicators to improve the standards of intensive care after cardiac surgery among Italian cardiac ICUs.

Stroke volume optimization: the new hemodynamic algorithm.

Critical care practices have evolved to rely more on physical assessments for monitoring cardiac output and evaluating fluid volume status because these assessments are less invasive and more convenient to use than is a pulmonary artery catheter. Despite this trend, level of consciousness, central venous pressure, urine output, heart rate, and blood pressure remain assessments that are slow to be changed, potentially misleading, and often manifested as late indications of decreased cardiac output. The hemodynamic optimization strategy called stroke volume optimization might provide a proactive guide for clinicians to optimize a patient's status before late indications of a worsening condition occur. The evidence supporting use of the stroke volume optimization algorithm to treat hypovolemia is increasing. Many of the cardiac output monitor technologies today measure stroke volume, as well as the parameters that comprise stroke volume: preload, afterload, and contractility.

Hemodynamic changes in child acute respiratory distress syndrome with airway pressure release ventilation: a case series.

Airway pressure release ventilation (APRV) is widely used in adult critical care settings. However, information on the use of APRV in the pediatric population is limited. All patients admitted to the medical-surgical pediatric intensive care unit with a diagnosis of acute respiratory distress syndrome (ARDS) who received APRV for at least 12 h between 2007 and 2009 were reviewed. Thirteen patients with a variety of etiologies of ARDS were included, with a mean weight of 18.2 ± 15.0 kg, a mean age of 68 ± 57 months and a predicted mortality (based on Pediatric Index of Mortality version 2) of 23.9 ± 13.8%. Patients were placed on APRV for a median of 4 days (range 1-10 days). There was no change in blood gas parameters after 1 h or 12 h of APRV when compared with pre-APRV. There was no statistical difference in hemodynamic parameters, including mean arterial blood pressure, central venous blood pressure and heart rate, while the patients were on APRV. APRV could be safely used in pediatric ARDS patients, without significant hemodynamic compromise or side effects.

Haemodynamic variables and functional outcome in hypothermic patients following out-of-hospital cardiac arrest

Aim of the studyTo evaluate the association between haemodynamic variables during the first 24h after intensive care unit (ICU) admission and neurological outcome in out-of-hospital cardiac arrest (OHCA) victims undergoing therapeutic hypothermia. MethodsIn a multi-disciplinary ICU, records were reviewed for comatose OHCA patients undergoing therapeutic hypothermia. The hourly variable time integral of haemodynamic variables during the first 24h after admission was calculated. Neurologic outcome was assessed at day 28 and graded as favourable or adverse based on the Cerebral Performance Category of 1–2 and 3–5. Bi- and multivariate regression models adjusted for confounding variables were used to evaluate the association between haemodynamic variables and functional outcome. Results67/134 patients (50%) were classified as having favourable outcome. Patients with adverse outcome had a higher mean heart rate (73 [62–86] vs. 66 [60–78]bpm; p=0.04) and received noradrenaline more frequently (n=17 [25.4%] vs. n=9 [6%]; p=0.02) and at a higher dosage (128 [56–1004] vs. 13 [2–162] μgh−1; p=0.03) than patients with favourable outcome. The mean perfusion pressure (mean arterial blood pressure minus central venous blood pressure) (OR=1.001, 95% CI =1–1.003; p=0.04) and cardiac index time integral (OR=1.055, 95% CI=1.003–1.109; p=0.04) were independently associated with adverse outcome at day 28. ConclusionMean perfusion pressure and cardiac index during the first 24h after ICU admission were weakly associated with neurological outcome in an OHCA population undergoing therapeutic hypothermia. Further studies need to elucidate whether norepinephrine-induced increases in perfusion pressure and cardiac index may contribute to adverse neurologic outcome following OHCA.

Cardiac output monitoring to guide fluid replacement in head and neck microvascular free flap surgery—what is current practice in the UK?

Appropriate fluid balance is an important factor in the survival of free flaps, and recently there has been a shift towards more conservative fluid regimens. Several surgical specialties have made extensive use of the relatively non-invasive method of measuring cardiac output (CO) to optimise fluid balance during and after surgery, which has resulted in a shorter hospital stay, but little has been published in head and neck surgery. To ascertain its use in the head and neck we sent a postal questionnaire to the anaesthetic departments of 40 major head and neck units identified from the 2010 database of the British Association of Oral and Maxillofacial Surgeons (BAOMS). Questions were asked about the number of free flaps done in the unit each year, the monitoring of central venous and arterial blood pressure (and inotrope protocols), optimal target variables, and whether CO was monitored (with type of device). Thirty-two units responded (80%). While 26 units (81%) routinely monitored central venous pressure (CVP), CO was monitored in only 3 units (9%). There was a wide range of responses in relation to optimal variables and use of inotropes. As with other specialties, it is likely that CO monitoring will become widely used in head and neck reconstructive surgery. Not only does it enhance fluid optimisation, but it may also reduce hospital stay and morbidity. Appropriate clinical studies are urgently needed to evaluate its use in our specialty.

Effects of intravenous administration of lactated Ringer's solution on hematologic, serum biochemical, rheological, hemodynamic, and renal measurements in healthy isoflurane-anesthetized dogs

To determine the hematologic, serum biochemical, rheological, hemodynamic, and renal effects of IV administration of lactated Ringer's solution (LRS) to healthy anesthetized dogs. 4-period, 4-treatment cross-over study. 8 healthy mixed-breed dogs. Each dog was anesthetized, mechanically ventilated, instrumented, and randomly assigned to receive LRS (0, 10, 20, or 30 mL/kg/h [0, 4.5, 9.1, or 13.6 mL/lb/h]), IV, on 4 occasions separated by at least 7 days. Blood hemoglobin concentration and serum total protein, albumin, lactate, and electrolyte concentrations; PCV; colloid osmotic pressure; arterial and venous pH and blood gases (Po2; Pco2); whole blood and plasma viscosity; arterial and venous blood pressures; cardiac output; results of urinalysis; urine production; glomerular filtration rate; and anesthetic recovery times were monitored. Oxygen delivery, vascular resistance, stroke volume, pulse pressure, and blood and plasma volume were calculated. Increasing rates of LRS administration resulted in dose-dependent decreases in PCV; blood hemoglobin concentration and serum total protein and albumin concentrations; colloid osmotic pressure; and whole blood viscosity. Plasma viscosity; serum electrolyte concentrations; data from arterial and venous blood gas analysis; glomerular filtration rate; urine production; heart rate; pulse, central venous, and arterial blood pressures; pulmonary vascular resistance; and oxygen delivery did not change. Pulmonary artery pressure, stroke volume, and cardiac output increased, and systemic vascular resistance decreased. Conventional IV infusion rates of LRS to isoflurane-anesthetized dogs decreased colligative blood components; increased plasma volume, pulmonary artery pressure, and cardiac output; and did not change urine production or oxygen delivery to tissues.

Transpulmonary Thermodilution in Neonates Undergoing Arterial Switch Surgery

Measurement of the global end-diastolic volume index (GEDI) by transpulmonary thermodilution (TPTD) has become a useful technique for measuring preload in adults. This study aimed to investigate the hemodynamic changes in neonates during the postoperative period after arterial switch surgery. Over a 13-month period, the postoperative data of 12 neonates with transposition of the great arteries were retrospectively investigated. Arterial and central venous blood pressures were monitored, Cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index (SVRI), GEDI, and extravascular lung water index (ELWI) were measured by thermodilution. The CI was significantly correlated with the SVRI only in the closed chest condition (r = -0.92; P < 0.001). The CI and SVI values were significantly lower and the ELWI and SVRI values significantly higher in both the open and closed chest conditions than the postextubation values. The relationship between change in GEDI and change in CI was stronger in the open chest condition (r = 0.93; P < 0.006) than in the closed chest condition (r = 0.75; P = 0.055). However, the latter just missed statistical significance. According to the findings, TPTD seems to be a useful tool for assessing cardiac function after neonatal arterial switch surgery. Establishment of normal values will be essential for proper guidance of therapy for this population using volumetric parameters.