Showing papers on "Hypovolemia published in 2009"

Does perioperative hemodynamic optimization protect renal function in surgical patients? A meta-analytic study

Abstract: Objective:Postoperative acute deterioration in renal function, producing oliguria and/or increase in serum creatinine, is one of the most serious complication in surgical patients. Most cases are due to renal hypoperfusion as a consequence of systemic hypotension, hypovolemia, and cardiac dysfunctio

Crystalloid or colloid fluid loading and pulmonary permeability, edema, and injury in septic and nonseptic critically ill patients with hypovolemia*

Abstract: OBJECTIVE: To compare crystalloid and colloid fluids in their effect on pulmonary edema in hypovolemic septic and nonseptic patients with or at risk for acute lung injury/acute respiratory distress syndrome. We hypothesized that 1) crystalloid loading results in more edema formation than colloid loading and 2) the differences among the types of fluid decreases at high permeability. DESIGN, SETTING, AND PATIENTS: Prospective randomized clinical trial on the effect of fluids in 24 septic and 24 nonseptic mechanically ventilated patients with clinical hypovolemia. INTERVENTIONS: Patients were assigned to NaCl 0.9%, gelatin 4%, hydroxyethyl starch 6%, or albumin 5% loading for 90 minutes according to changes in filling pressures. MEASUREMENTS AND MAIN RESULTS: Twenty-three septic and 10 nonseptic patients had acute lung injury/acute respiratory distress syndrome (p < 0.001). Septic patients had greater pulmonary capillary permeability, edema, and severity of lung injury than nonseptic patients (p < 0.01), as measured by the pulmonary leak index (PLI) for Gallium-labeled transferrin, extravascular lung water (EVLW), and lung injury score (LIS), respectively. Colloids increased plasma volume, cardiac index, and central venous pressure (CVP) more than crystalloids (p < 0.05), although more crystalloids were infused (p < 0.05). Colloid osmotic pressure (COP) increased in colloid and decreased in crystalloid groups (p < 0.001). Irrespective of fluid type or underlying disease, the pulmonary leak index increased by median 5% (p < 0.05). Regardless of fluid type or underlying disease, EVLW and LIS did not change during fluid loading and EVLW related to COP-CVP (rs = -.40, p < 0.01). CONCLUSIONS: Pulmonary edema and LIS are not affected by the type of fluid loading in the steep part of the cardiac function curve in both septic and nonseptic patients. Then, pulmonary capillary permeability may be a smaller determinant of pulmonary edema than COP and CVP. Safety factors may have prevented edema during a small filtration pressure-induced rise in pulmonary protein and thus fluid transport.

Changes in stroke volume induced by passive leg raising in spontaneously breathing patients: comparison between echocardiography and Vigileo™/FloTrac™ device

Abstract: Passive leg raising (PLR) is a simple reversible maneuver that mimics rapid fluid loading and increases cardiac preload. The effects of this endogenous volume expansion on stroke volume enable the testing of fluid responsiveness with accuracy in spontaneously breathing patients. However, this maneuver requires the determination of stroke volume with a fast-response device, because the hemodynamic changes may be transient. The Vigileo™ monitor (Vigileo™; Flotrac™; Edwards Lifesciences, Irvine, CA, USA) analyzes systemic arterial pressure wave and allows continuous stroke volume monitoring. The aims of this study were (i) to compare changes in stroke volume induced by passive leg raising measured with the Vigileo™ device and with transthoracic echocardiography and (ii) to compare their ability to predict fluid responsiveness. Thirty-four patients with spontaneous breathing activity and considered for volume expansion were included. Measurements of stroke volume were obtained with transthoracic echocardiography (SV-TTE) and with the Vigileo™ (SV-Flotrac) in a semi-recumbent position, during PLR and after volume expansion (500 ml saline). Patients were responders to volume expansion if SV-TTE increased ≥ 15%. Four patients were excluded. No patients received vasoactive drugs. Seven patients presented septic hypovolemia. PLR-induced changes in SV-TTE and in SV-Flotrac were correlated (r2 = 0.56, P < 0.0001). An increase in SV-TTE ≥ 13% during PLR was predictive of response to volume expansion with a sensitivity of 100% and a specificity of 80%. An increase in SV-Flotrac ≥16% during PLR was predictive of response to volume expansion with a sensitivity of 85% and a specificity of 90%. There was no difference between the area under the ROC curve for PLR-induced changes in SV-TTE (AUC = 0.96 ± 0.03) or SV-Flotrac (AUC = 0.92 ± 0.05). Volume expansion-induced changes in SV-TTE correlated with volume expansion-induced changes in SV-Flotrac (r2 = 0.77, P < 0.0001). In all patients, the highest plateau value of SV-TTE recorded during PLR was obtained within the first 90 s following leg elevation, whereas it was 120 s for SV-Flotrac. PLR-induced changes in SV-Flotrac are able to predict the response to volume expansion in spontaneously breathing patients without vasoactive support.

A Model Analysis of Arterial Oxygen Desaturation during Apnea in Preterm Infants

Abstract: Rapid arterial O2 desaturation during apnea in the preterm infant has obvious clinical implications but to date no adequate explanation for why it exists. Understanding the factors influencing the rate of arterial O2 desaturation during apnea () is complicated by the non-linear O2 dissociation curve, falling pulmonary O2 uptake, and by the fact that O2 desaturation is biphasic, exhibiting a rapid phase (stage 1) followed by a slower phase when severe desaturation develops (stage 2). Using a mathematical model incorporating pulmonary uptake dynamics, we found that elevated metabolic O2 consumption accelerates throughout the entire desaturation process. By contrast, the remaining factors have a restricted temporal influence: low pre-apneic alveolar causes an early onset of desaturation, but thereafter has little impact; reduced lung volume, hemoglobin content or cardiac output, accelerates during stage 1, and finally, total blood O2 capacity (blood volume and hemoglobin content) alone determines during stage 2. Preterm infants with elevated metabolic rate, respiratory depression, low lung volume, impaired cardiac reserve, anemia, or hypovolemia, are at risk for rapid and profound apneic hypoxemia. Our insights provide a basic physiological framework that may guide clinical interpretation and design of interventions for preventing sudden apneic hypoxemia.

Crystalloids versus colloids for goal-directed fluid therapy in major surgery.

Abstract: Perioperative hypovolemia arises frequently and contributes to intestinal hypoperfusion and subsequent postoperative complications. Goal-directed fluid therapy might reduce these complications. The aim of this study was to compare the effects of goal-directed administration of crystalloids and colloids on the distribution of systemic, hepatosplanchnic, and microcirculatory (small intestine) blood flow after major abdominal surgery in a clinically relevant pig model. Twenty-seven pigs were anesthetized and mechanically ventilated and underwent open laparotomy. They were randomly assigned to one of three treatment groups: the restricted Ringer lactate (R-RL) group (n = 9) received 3 mL/kg per hour of RL, the goal-directed RL (GD-RL) group (n = 9) received 3 mL/kg per hour of RL and intermittent boluses of 250 mL of RL, and the goal-directed colloid (GD-C) group (n = 9) received 3 mL/kg per hour of RL and boluses of 250 mL of 6% hydroxyethyl starch (130/0.4). The latter two groups received a bolus infusion when mixed venous oxygen saturation was below 60% ('lockout' time of 30 minutes). Regional blood flow was measured in the superior mesenteric artery and the celiac trunk. In the small bowel, microcirculatory blood flow was measured using laser Doppler flowmetry. Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes. After 4 hours of treatment, arterial blood pressure, cardiac output, mesenteric artery flow, and mixed oxygen saturation were significantly higher in the GD-C and GD-RL groups than in the R-RL group. Microcirculatory flow in the intestinal mucosa increased by 50% in the GD-C group but remained unchanged in the other two groups. Likewise, tissue oxygen tension in the intestine increased by 30% in the GD-C group but remained unchanged in the GD-RL group and decreased by 18% in the R-RL group. Mesenteric venous glucose concentrations were higher and lactate levels were lower in the GD-C group compared with the two crystalloid groups. Goal-directed colloid administration markedly increased microcirculatory blood flow in the small intestine and intestinal tissue oxygen tension after abdominal surgery. In contrast, goal-directed crystalloid and restricted crystalloid administrations had no such effects. Additionally, mesenteric venous glucose and lactate concentrations suggest that intestinal cellular substrate levels were higher in the colloid-treated than in the crystalloid-treated animals. These results support the notion that perioperative goal-directed therapy with colloids might be beneficial during major abdominal surgery.

Anesthesia for free vascularized tissue transfer

Abstract: Anesthesia may be an important factor in maximizing the success of microsurgery by controlling the hemodynamics and the regional blood flow. The intraanesthetic basic goal is to maintain an optimal blood flow for the vascularized free flap by: increasing the circulatory blood flow, maintaining a normal body temperature to avoid peripheral vasoconstriction, reducing vasoconstriction resulted from pain, anxiety, hyperventilation, or some drugs, treating hypotension caused by extensive sympathetic block and low cardiac output. A hyperdynamic circulation can be obtained by hypervolemic or normovolemic hemodilution and by decrease of systemic vascular resistance. The importance of proper volume replacement has been widely accepted, but the optimal strategy is still open to debate. General anesthesia combined with various types of regional anesthesia is largely preferred for microvascular surgery. Maintenance of homeostasis through avoidance of hyperoxia, hypocapnia, and hypovolemia (all factors that can decrease cardiac output and induce local vasoconstriction) is a well-established perioperative goal. As the ischemia-reperfusion injury could occur, inhalatory anesthetics as sevoflurane (that attenuate the consequences of this process) seem to be the anesthetics of choice.

CT Hypotension Complex (Shock Bowel) Is Not Always Due to Traumatic Hypovolemic Shock

Abstract: OBJECTIVE. The purpose of our study was to review the clinical and CT findings in a substantial series of 41 patients with the shock bowel sign to determine if there is an association between shock bowel (and other CT signs of hypotension) and conditions other than post-traumatic hypovolemic shock.CONCLUSION. The shock bowel sign and the CT hypotension complex are frequently associated with hypotension from causes other than trauma-induced hypovolemic shock, such as severe head or spine injury, cardiac arrest, septic shock, bacterial endocarditis, and diabetic ketoacidosis. Other elements of the CT hypotension complex such as flattening of the inferior vena cava and aorta, abnormal pancreatic enhancement and peripancreatic fluid, and hypoperfusion of the spleen and liver are variably associated with shock bowel whether due to posttraumatic hypovolemia or other causes of hypotension. The CT hypotension complex (shock bowel) has important prognostic and therapeutic implications and can probably be distingui...

Stroke volume variation as a predictor of intravascular volume depression and possible hypotension during the early postoperative period after esophagectomy.

Abstract: Perioperative hypotension during esophagectomy results from hypovolemia caused by a shift of extracellular fluid from the intravascular to the extravascular compartment. Fluid management is often difficult to gauge during major surgery because there are no reliable indicators of fluid status, and some patients still experience cardiorespiratory instability. In this retrospective study, we evaluated stroke volume variation (SVV), calculated by using a new arterial pressure-based cardiac output measurement device, as a predictor for fluid responsiveness after esophageal surgery. Eighteen patients undergoing esophagectomy with extended radical lymphadenectomy were monitored by the FloTrac sensor/Vigileo monitor system during the perioperative and immediate postoperative period. Fluid responsiveness was assessed and compared with concurrent SVV and central venous pressure (CVP) values, and routine hemodynamic variables. Eleven of 18 patients needed additional volume loading within the first 10 postoperative hours as a result of hypotension. The maximum SVV value of fluid resuscitated patients was >15% in all cases, whereas six of seven patients without postoperative hypotension had maximum SVV values of 0.05). We conclude that SVV, as displayed on the Vigileo monitor, is an accurate predictor of intravascular hypovolemia and is a useful indicator for assessing the appropriateness and timing of applying fluid for improving circulatory stability during the perioperative period after esophagectomy.

Blood Volume Measurement to Guide Fluid Therapy After Aneurysmal Subarachnoid Hemorrhage. A Prospective Controlled Study

Abstract: Background and Purpose— Conventional parameters used to guide fluid therapy after aneurysmal subarachnoid hemorrhage (SAH) are poorly related to blood volume. In a prospective controlled study we assessed whether fluid management guided by daily measurements of blood volume (BV) reduces the incidence of severe hypovolemia compared to conventional fluid balance guided fluid therapy. Methods— We used Pulse Dye Densitometry to measure BV daily in 102 patients during the first 10 days after SAH. Fluid management was based on BV-measurements in the intervention group (n=54) and on fluid balance in the control group (n=48). Severe hypovolemia was defined as BV <50 mL/kg. Results— In the intervention group 6.7% of BV measurements were in the severe hypovolemic range and in the control group 17.1% (mean weighted difference 7.7%; 95% CI: 1.4 to 13.9%). In the intervention group 21 patients (39%) had 1 or more measurements with severe hypovolemia versus 26 (54%) of the controls (RR 0.7; 95% CI: 0.5 to 1.1). Conclus...

Hyperventilation in response to progressive reduction in central blood volume to near syncope

Abstract: Introduction: There is little evidence to support the usefulness in monitoring respiration during casualty triage and transport as an early indicator of hemorrhage severity and trauma patient outcome. We, therefore, tested the hypothesis that hyperventilation can be elicited by progressive reductions in central blood volume independent of metabolic stimuli. Methods: Progressive central hypovolemia was induced in 10 healthy subjects (5 men, 5 women) by applying lower body negative pressure (LBNP). The LBNP protocol consisted of a 5-min controlled rest period (0% LBNP) followed by progressive 5-min chamber decompressions until the onset of hemodynamic decompensation (LBNP max ). During each LBNP stage, total minute ventilation volume (V E ), tidal volume (V T ), respiratory rate, oxygen uptake (Vo 2 ), end-tidal CO 2 (E T co 2 ), arterial oxygen saturation (S p o 2 ), and venous blood pH and lactate were measured. Results: Compared with baseline, Vo 2 , S p o 2 , Po 2 , Pco 2 , pH, and lactate were unaltered throughout LBNP. V E was unaltered through 80% of LBNP tolerance, but increased by 54% during LBNP max as a result primari.ly of elevated V T , while E T co 2 was reduced. Conclusions: Increased V E at LBNP max combined with reduced E T co 2 in the absence of changes in blood and systemic metabolic stimuli support the hypothesis that severe reductions in central blood volume drive hyperventilation. The endogenous "respiratory pump" may be a protective strategy to optimize cardiac filling in conditions of central hypovolemic hypotension, but its late appearance indicates that respiratory parameters may not be useful as a clinical metric for early prediction of patient outcome during hemorrhage.

Hydrochlorothiazide in the treatment of hypertension. The effects on blood volume, exchangeable sodium and blood pressure.

Abstract: Eleven patients with essential hypertension were treated with hydrochlorothiazide/KCl for three months. A significant fall in total blood volume, exchangeable sodium and blood pressure could be demonstrated both after one to two weeks and after three months of treatment, while a fall in serum sodium and body weight was only significant after one to two weeks of treatment. Thus, hypovolemia may, perhaps, be the explanation for the antipressor effect of thiazide even after three months of treatment.

Retraction Note: The influence of a balanced volume replacement concept on inflammation, endothelial activation, and kidney integrity in elderly cardiac surgery patients

Abstract: A balanced fluid replacement strategy appears to be promising for correcting hypovolemia. The benefits of a balanced fluid replacement regimen were studied in elderly cardiac surgery patients. In a randomized clinical trial, 50 patients aged >75 years undergoing cardiac surgery received a balanced 6% HES 130/0.42 plus a balanced crystalloid solution (n = 25) or a non-balanced HES in saline plus saline solution (n = 25) to keep pulmonary capillary wedge pressure/central venous pressure between 12–14 mmHg. Acid-base status, inflammation, endothelial activation (soluble intercellular adhesion molecule-1, kidney integrity (kidney-specific proteins glutathione transferase-alpha; neutrophil gelatinase-associated lipocalin) were studied after induction of anesthesia, 5 h after surgery, 1 and 2 days thereafter. Serum creatinine (sCr) was measured approximately 60 days after discharge. A total of 2,750 ± 640 mL of balanced and 2,820 ± 550 mL of unbalanced HES were given until the second POD. Base excess (BE) was significantly reduced in the unbalanced (from +1.21 ± 0.3 to −4.39 ± 1.0 mmol L−1 5 h after surgery; P < 0.001) and remained unchanged in the balanced group (from 1.04 ± 0.3 to −0.81 ± 0.3 mmol L−1 5 h after surgery). Evolution of the BE was significantly different. Inflammatory response and endothelial activation were significantly less pronounced in the balanced than the unbalanced group. Concentrations of kidney-specific proteins after surgery indicated less alterations of kidney integrity in the balanced than in the unbalanced group. A total balanced volume replacement strategy including a balanced HES and a balanced crystalloid solution resulted in moderate beneficial effects on acid-base status, inflammation, endothelial activation, and kidney integrity compared to a conventional unbalanced volume replacement regimen.

Simultaneous multi-depth assessment of tissue oxygen saturation in thenar and forearm using near-infrared spectroscopy during a simple cardiovascular challenge

Abstract: Introduction: Hypovolemia and hypovolemic shock are lifethreatening conditions that occur in numerous clinical scenarios. Near-infrared spectroscopy (NIRS) has been widely explored, successfully and unsuccessfully, in an attempt to use it as an early detector of hypovolemia by measuring tissue oxygen saturation (StO 2 ). In order to investigate the measurement site dependence and probe dependence of NIRS in response to hemodynamic changes, such as hypovolemia, we applied a simple cardiovascular challenge: a posture change from supine to upright, causing a decrease in stroke volume (as in hypovolemia) and a heart rate increase in combination with peripheral vasoconstriction to maintain adequate blood pressure. Methods: Multi-depth NIRS was used in nine healthy volunteers to assess changes in StO2 in the thenar and forearm in response to the hemodynamic changes associated with a posture change from supine to upright. Results: A posture change from supine to upright resulted in a significant increase (P <0.001) in heart rate. Thenar StO2 did not respond to the hemodynamic changes following the posture change, whereas forearm StO2 did. Forearm StO2 was significantly lower (P <0.001) in the upright position compared to supine for all probing depths. Conclusion: The primary findings in this study were that forearm StO2 is a more sensitive parameter to hemodynamic changes than thenar StO2 and that the depth at which StO2 is measured is of minor influence. Our data support the use of forearm StO2 as a sensitive parameter for the detection of central hypovolemia and hypovolemic shock in (trauma) patients.

Hyponatremia in Severe Malaria: Evidence for an Appropriate Anti-diuretic Hormone Response to Hypovolemia

Abstract: Although hyponatremia occurs in most patients with severe malaria, its pathogenesis, prognostic signifi- cance, and optimal management have not been established. Clinical and biochemical data were prospectively collected from 171 consecutive Bangladeshi adults with severe malaria. On admission, 57% of patients were hyponatremic. Plasma sodium and Glasgow Coma Score were inversely related (r s = �0.36, P < 0.0001). Plasma antidiuretic hormone concentrations were similar in hyponatremic and normonatremic patients (median, range: 6.1, 2.3-85.3 versus 32.7, 3.0-56.4 pmol/L; P = 0.19). Mortality was lower in hyponatremic than normonatremic patients (31.6% versus 51.4%; odds ratio (95% confidence interval): 0.44 (0.23-0.82); P = 0.01 by univariate analysis). Plasma sodium normalized with crystalloid rehydration from (median, range) 127 (123-140) mmol/L on admission to 136 (128-149) mmol/L at 24 hours (P = 0.01). Hyponatremia in adults with severe malaria is common and associated with preserved consciousness and decreased mortality. It likely reflects continued oral hypotonic fluid intake in the setting of hypovolemia and requires no therapy beyond rehydration.

Using an expiratory resistor, arterial pulse pressure variations predict fluid responsiveness during spontaneous breathing: an experimental porcine study

Abstract: Fluid responsiveness prediction is difficult in spontaneously breathing patients Because the swings in intrathoracic pressure are minor during spontaneous breathing, dynamic parameters like pulse pressure variation (PPV) and systolic pressure variation (SPV) are usually small We hypothesized that during spontaneous breathing, inspiratory and/or expiratory resistors could induce high arterial pressure variations at hypovolemia and low variations at normovolemia and hypervolemia Furthermore, we hypothesized that SPV and PPV could predict fluid responsiveness under these conditions Eight prone, anesthetized and spontaneously breathing pigs (20 to 25 kg) were subjected to a sequence of 30% hypovolemia, normovolemia, and 20% and 40% hypervolemia At each volemic level, the pigs breathed in a randomized order either through an inspiratory and/or an expiratory threshold resistor (75 cmH2O) or only through the tracheal tube without any resistor Hemodynamic and respiratory variables were measured during the breathing modes Fluid responsiveness was defined as a 15% increase in stroke volume (ΔSV) following fluid loading Stroke volume was significantly lower at hypovolemia compared with normovolemia, but no differences were found between normovolemia and 20% or 40% hypervolemia Compared with breathing through no resistor, SPV was magnified by all resistors at hypovolemia whereas there were no changes at normovolemia and hypervolemia PPV was magnified by the inspiratory resistor and the combined inspiratory and expiratory resistor Regression analysis of SPV or PPV versus ΔSV showed the highest R2 (083 for SPV and 052 for PPV) when the expiratory resistor was applied The corresponding sensitivity and specificity for prediction of fluid responsiveness were 100% and 100%, respectively, for SPV and 100% and 81%, respectively, for PPV Inspiratory and/or expiratory threshold resistors magnified SPV and PPV in spontaneously breathing pigs during hypovolemia Using the expiratory resistor SPV and PPV predicted fluid responsiveness with good sensitivity and specificity

Influence of ventilatory settings on static and functional haemodynamic parameters during experimental hypovolaemia

Abstract: Background and objectiveThe influence of ventilatory settings on static and functional haemodynamic parameters during mechanical ventilation is not completely known. The purpose of this study was to evaluate the effect of positive end-expiratory pressure, tidal volume and inspiratory to expiratory t

Endogenous and exogenous vasopressin during hemodialysis.

Abstract: Intradialytic hypotension likely results from hypovolemia as well as patient and dialysis-specific factors. An impaired vasoconstrictive response to volume loss during hemodialysis has been demonstrated and increasing evidence suggests that deficiency in the hormone arginine vasopressin may be a contributing factor. Although vasopressin is widely recognized for its role in the regulation of serum osmolality, vasopressin is also an important regulator of blood pressure in health and in various disease states. That vasopressin deficiency contributes to the pathogenesis of intradialytic hypotension is suggested by several observations. First, vasopressin levels typically fall during hemodialysis when a rise might be expected as a result of volume loss. Second, therapies that prevent a fall in osmolality during dialysis, including dialysis against a high sodium bath and isolated ultrafiltration, have been shown to improve intradialytic blood pressure stability. Finally, and perhaps most importantly, the administration of low-dose exogenous vasopressin during dialysis has been shown to support blood pressure and improve volume removal. Further research is needed to determine the effect of chronic vasopressin (or selective V1a agonist) administration during dialysis on volume removal, inter- and intradialytic blood pressure control, and, ultimately, clinical outcomes in end-stage renal disease patients on dialysis.

Effects of epidural anesthesia on intrathoracic blood volume and extravascular lung water during on-pump cardiac surgery

Abstract: Background: The most important side effect of epidural anesthesia is hypotension with functional hypovolemia. Aggressive infusion therapy can reduce the hypotension effect. However, in conjunction with cardiopulmonary bypass, it can increase acute lung injury. We hypothesized that epidural anesthesia, by reducing cardiac sympathetic tonus, with subsequent better pulmonary flow, does not increase lung interstitial fluids.Methods: Sixty patients undergoing coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) were randomized to combined general anesthesia with epidural anesthesia / analgesia, (EA) group, and to general anesthesia with i/v opiate analgesia, (GA) group. Patients in the EA group received a high thoracic epidural, preoperatively. Intraoperatively, 0.25% bupivacaine 8 mL/h was infused and general anesthesia with sevoflurane was followed by bupivacaine infusion for 48 hours postoperatively. General anesthesia in the GA group was with sevoflurane and fentanyl 10 - 12 µg/kg ...

Measurement of systolic pressure variation during graded volume loss using simple tools on Datex Ohmeda S/5 monitor.

Abstract: Direct invasive arterial monitoring is performed routinely for all major neurosurgical procedures. Systolic pressure variation (SPV) used, independently or in combination with central venous pressure (CVP) allows optimal fluid management in hypovolemia and hemorrhage. This study aims to quantify SPV during graded hypovolemia using the simple technique described by Gouvea and Gouvea using Datex Ohmeda S/5, and to compare its reliability relative to other hemodynamic indicators of hypovolemia. Twenty anesthetized neurosurgical patients of ASA grade I and II patients were administered furosemide 0.5 mg/kg intravenously to obtain graded volume loss in the form of urine output. Invasive arterial pressure from radial artery and CVP were monitored using Datex OhmedaS/5 (Finland). Invasive arterial pressure label was changed to pulmonary artery label with the scale appropriate for arterial pressure. The trace was frozen in the wedge mode to reduce the sweep speed and the cursor was used to measure SPV and pulse pressure variation (PPV). Heart rate, systolic blood pressure, diastolic blood pressure, CVP at zero end-expiratory pressure, SPV and PPV are measured at baseline, and after a urine output of 200 and 500 mL. There was a significant correlation between volume loss and CVP, SPV, and PPV. The area under the curve of receiver operating characteristic analysis was >0.75 for CVP, SPV, and PPV. SPV of 7.5 mm Hg and a change of SPV by 4.5 mm Hg, a PPV of 4.5 and change in PPV by 2.5 mm Hg were the best cut-off values that corresponded to a volume change of 500 mL. This simple method enabled calculation of SPV without the computerized modules, and detected volume loss comparable to CVP.

Approach to the critically ill camelid.

Abstract: The estimation of fluid deficits in camelids is challenging. However, early recognition and treatment of shock and hypovolemia is instrumental to improve morbidity and mortality of critically ill camelids. Early goal-directed fluid therapy requires specific knowledge of clinical indicators of hypovolemia and assessment of resuscitation endpoints, but may significantly enhance the understanding, monitoring, and safety of intravenous fluid therapy in South American camelids (SAC). It is important to recognize that over-aggressive fluid resuscitation is just as detrimental as under resuscitation. Nonetheless, a protocol of conservative fluid management is often indicated in the treatment of camelids with pulmonary inflammation, to counteract edema formation. The early recognition of lung dysfunction is often based on advanced diagnostic techniques, including arterial blood gas analysis, diagnostic imaging, and noninvasive pulmonary function testing.

Hypovolemia-induced obesity and diabetes.

Abstract: The article by Saiki and colleagues [1] published in the Metabolism entitled “Circulating angiotensin II is associated with body fat accumulation and insulin resistance in obese subjects with type 2 diabetes mellitus” is very interesting in that it points out clearly the association between circulating angiotensin levels and the pathophysiology of obesity and diabetes. At first glance, this is rather unusual, as why would a hormone intimately implicated in cardiovascular and water balance functions be involved with fat accumulation and insulin resistance. However, these “unusual” associations have given rise to a series of reports, all independent at the time, which now taken together make sense [2-4]. It would appear that the common feature in the origin not only of hypertension but also of obesity and diabetes is hypovolemia. This is a physiologic state that comes about through reduced fluid intake and has as primary signal the release of renin that generates angiotensin II in the blood. Interestingly, neurochemical changes characteristic of extracellular dehydration have been found in the brain of obese Zucker rats, a model of obesity and type 2 diabetes [5]. Moreover, in animal studies on obesity, inhibition of the reninangiotensin system produces an increased fluid intake that has been suggested to lead to lipolysis and subsequent weight loss [3]. In other studies, it has been noted that inhibition of the renin-angiotensin system allows cells to restore membrane glucose transport and to increase insulin sensitivity [4]. It was thus proposed that this would restore to normal cellular carbohydrate and fat metabolism [4]. However, insulin signaling is linked also to cell volume regulation [6]; and cell volume regulation would be dependent on body hydration state. We thus come back to the regulation of hypovolemia. It is thus not surprising to find that circulating angiotensin levels are elevated in conditions of obese subjects with type 2 diabetes mellitus [1], and it would be interesting to propose that increased water intake be encouraged along with renin-angiotensin system blockade in cases of obesity and diabetes.

The blood volume in pheochromocytoma patients before and during treatment with phenoxybenzamine

Abstract: Total blood volume (TBV), red cell volume (RCV) and plasma volume (PV) were determined in 15 pheochromocytoma patients (9 males and 6 females) prior to and during preoperative treatment with phenoxybenzamine. Seventeen healthy male volunteers served as controls. Untreated male patients did not differ from the controls with respect to TBV, RCV or PV. In the total group of pheochromocytoma patients, phenoxybenzamine, in a dose of 145.6 +/- 45.2 (SD) mg/day over 14.3 +/- 5.7 (SD) days, induced significant increases in TBV (+9.4%) and PV (+14.5%), whereas RCV remained unchanged. During phenoxybenzamine, the mean PV in male patients significantly exceeded the control mean. We conclude that pheochromocytoma patients adapt their TBV to excessive catecholamine production and that they rarely present with profound hypovolemia. Moderate but higher doses of phenoxybenzamine than previously recommended induced marked increases in TBV secondary to PV expansion. Phenoxybenzamine counteracts the development of hypovolemia most effectively, thereby constituting one of several important measures for successful surgical management of pheochromocytoma patients.

Hemodynamic effects of norepinephrine in severe hypnotic drug poisoning with arterial hypotension

Abstract: The hemodynamic response to infusion of norepinephrine (NE) has been measured in 12 patients with severe hypnotic drug poisoning. All patients had a mean arterial blood pressure (B.P.) of 70 mmHg or less initially. As evaluated from central venous pressure no marked hypovolemia was present. Cardiac output (C.O.) was determined by the dye dilution method and right heart catheterization by a “floating” catheter technique. Following infusion of NE the arterial B.P. and C.O. increased. The increase in C.O. resulted from increases in stroke volume and to a less extent also in heart rate (HR). There was no significant change of peripheral vascular resistance index (PVRI), in contrast to the NE effect in cardiogenic, hemorrhagic and septic shock states. The increase in arterial B.P. was accompanied by an increase in HR, which implies a disturbed function of the high pressure baroreceptor system. The rise in B.P. is primarily due to the increase in C.O. No adverse effects were noted during the NE infusion. It is concluded that NE is beneficial in the treatment of severe hypnotic drug poisoning complicated by hypotension.

Peripheral blood stem cell recovery following early termination of apheresis due to hypotension in a 4.8‐kg infant

Abstract: We report a case in which peripheral blood stem cells (PBSC) were successfully recovered following early termination of a collection procedure due to hypotension in a 7-month-old patient. The patient was diagnosed at 4 months of age with neuroblastoma stage IV-S with favorable Shimada histology. She had completed two cycles of chemotherapy before the PBSC collection (PSCC). The procedure was performed on the Cobe Spectra in manual mode, and terminated after 35 min due to severe hypotension. Etiologies considered for the hypotensive episode included a transfusion reaction to the unit of red blood cells (RBC) used for priming the Spectra, citrate reaction, and hypovolemia due to blood drawn for laboratory testing and fluid shifts at the beginning of the procedure. Hypovolemia was ultimately determined to be the most likely etiology. A rinseback was performed into a transfer bag, and the cells were sent to the laboratory for analysis of CD34+ cell yield, volume reduction, and cryopreservation. An adequate number of PBSC were recovered to permit successful autologous transplantation. The ability to recover PBSC from the Spectra white blood cell collection set allowed the patient to avoid undergoing another PSCC. In procedures involving small children, the blood volume drawn for preprocedure testing should be limited to less than 10% of the patient's total blood volume, and the RBC prime should at a minimum replace the entire extracorporeal volume. If the procedure must be terminated early, sufficient PBSC may be recoverable from the blood in the apheresis instrument.

Volume replacement in trauma.

Abstract: We aimed to compare different fluids indicated in volume replacement in multiple trauma patients, enlightening the indications, mechanisms of action and side effects. An extensive review of references (indexed journals) between 1997 and 2008 was performed. There is not yet a consensus about which fluids should be used in trauma patients. The systematic reviews available did not show a benefit of colloid solutions over crystalloid fluids. Crystalloids intensify physiological internal dilution, furthered by water migration from interstitial and intracellular spaces into intravascular space due to hypovolemia. The most recent hypertonic solutions used in resuscitation have a large role in expanding blood volume and making blood pressure rise. The hyperoncotic effect of dextran solution produces an initial expansion of intravascular volume that is bigger than the administered volume. Gelatins are no longer used in developed countries due to their insignificant ability regarding volume expansion when compared to crystalloids and the potential risks of anaphylactic reactions. The crystalloids are used more in trauma, even if some authors prefer the use of colloids, which can produce a quicker restoration of the intravascular volume. No convincing evidence shows a clear superiority of colloids over crystalloids for restoration of the volume depletion.