Balagangadhar R. Totapally

Low Intensity Shear Stress Increases Endothelial ELR+ CXC Chemokine Production via a Focal Adhesion Kinase-p38β MAPK-NF-κB Pathway

CXC chemokines with a glutamate-leucine-arginine (ELR) tripeptide motif (ELR+ CXC chemokines) play an important role in leukocyte trafficking into the tissues. For reasons that are not well elucidated, circulating leukocytes are recruited into the tissues mainly in small vessels such as capillaries and venules. Because ELR+ CXC chemokines are important mediators of endothelial-leukocyte interaction, we compared chemokine expression by microvascular and aortic endothelium to investigate whether differences in chemokine expression by various endothelial types could, at least partially, explain the microvascular localization of endothelial-leukocyte interaction. Both in vitro and in vivo models indicate that ELR+ CXC chemokine expression is higher in microvascular endothelium than in aortic endothelial cells. These differences can be explained on the basis of the preferential activation of endothelial chemokine production by low intensity shear stress. Low shear activated endothelial ELR+ CXC chemokine production via cell surface heparan sulfates, β3-integrins, focal adhesion kinase, the mitogen-activated protein kinase p38β, mitogen- and stress-associated protein kinase-1, and the transcription factor.

Incidence and risk factors associated with venous thrombotic events in pediatric intensive care unit patients.

Objective: To evaluate the incidence and risk factors associated with venous thromboembolism (VTE) in children admitted to pediatric intensive care units (PICUs). Design: Prospective observational study. Setting: Eleven tertiary care PICUs in the United States. Patients: Children who were admitted to PICUs and had radiographically confirmed VTE over a rolling 6-month period were enrolled in the study. Demographic, patient-related, and outcomes data were collected and compared with all children admitted during the same period. Interventions: None. Results: Sixty-six symptomatic VTE were documented in sixty-two patients among 6653 patients admitted to 11 PICUs. Thirteen (19.7%) of the thrombi were present on admission. The incidence rate was 0.74% (range, 0–2.7% per PICU) with a point prevalence of 0.93%. Doppler ultrasound was most frequently used to diagnose or confirm a suspected VTE. Variables associated with unadjusted risk for VTE include: younger age (3.8 months for patients with VTE vs. 51 months for non-VTE patients, p < .001), cardiac diagnosis (41% in VTE cases vs. 15% in non-VTE, p < .001), pre-/post-operative status (63% in VTE cases vs. 40% in non-VTE, p = .001), presence of central venous catheter (88% in VTE case vs. 17% in non-VTE, p < .001), or mechanical ventilation (85% in VTE cases vs. 30% non-VTE, p < .001). Multivariate analysis showed increased risk of VTE with CVC (odds ratio 6.9; confidence interval 2.7–17.5) and mechanical ventilation (odds ratio 2.8; confidence interval 0.98–7.93). Children with VTE were sicker (Pediatric Index of Mortality 2 score risk of mortality of 3.0% vs. 0.9%; p<0.0001), stayed longer in the ICU (21.2 days vs. 1.6 days; p < .0001) and had increased mortality (10.2% vs. 2.6; p < .0001). Conclusions: Children admitted to the PICU have an increased risk of VTE. The presence of a CVC is the strongest risk factor for VTE in this PICU population. Children with VTE were younger, sicker, stayed longer in PICU, and had a higher mortality rate.

Validation of a Modified Pediatric Early Warning System Score A Retrospective Case–Control Study

The Pediatric Early Warning System (PEWS) score may be useful for detection of deterioration in clinical condition. In this retrospective study, the cases were patients transferred to the pediatric intensive care unit (PICU), and controls were those not transferred to the PICU. The maximum PEWS score in both groups were analyzed using Mann–Whitney U test and receiver operating characteristic curve (ROC). The study population included 100 cases and 250 controls. There was no difference in the age of cases and controls (6.3 vs 6.3 years). The length of hospital stay (18.09 ± 32 vs 3.93 ± 2.9 days; P < .001) and the maximum PEWS score (2.95 ± 1.5 vs 1.4 ± 0.8) were significantly higher for the cases (P < .0001). The PEWS score area under the ROC was 0.81 (95% confidence interval = 0.75-0.86). The sensitivity and specificity for a score 2.5 were 62% and 89%, respectively. The use of the modified PEWS score can help identify patients on wards who are at risk for deterioration.

Effect of hypothermia on ventilation in anesthetized, spontaneously breathing rats: theoretical implications for mechanical ventilation

Objective: To test if hypothermia, induced by a sustained pentobarbital anesthesia, in rats can reduce ventilatory demands without compromising pulmonary gas-exchange efficiency. Design: Prospective study. Setting: Research laboratory in a hospital. Subjects: One group of 11 female Sprague Dawley rats. Interventions: The rats were anesthetized with 45 mg/kg pentobarbital, tracheostomized and intubated; their femoral veins and arteries were cannulated. After surgery, anesthesia and fluid balance were maintained (10 mg/kg per h pentobarbital, and 5 ml/kg per h saline, i. v.). Rectal temperature, mean arterial blood pressure (MAP), and heart rate (HR) were continuously monitored. The respiratory variables and gas-exchange profiles were determined at 38 °C (normothermia), and during stepwise hypothermia at 37, 35, 33, 31 and 29 °C. The arterial pressure of carbon dioxide (PaCO2), pH and arterial pressure of oxygen (PaO2) during hypothermia were corrected at body temperature. Measurements and results: Graded systemic hypothermia, with maintained anesthesia, produced a strong correlation between reduction in the respiratory frequency and rectal temperature (r2 = 0.55; p < 0.0001; n = 66). The minute volume was significantly reduced, starting at 35 °C, without significant changes in the tidal volume (repeated measures of analyses of variance followed by Dunnett multiple comparisons test). No significant changes occurred in the PaCO2, pH, PaO2, hemoglobin oxygen saturation, the calculated arterial oxygen content and estimated alveolar-arterial oxygen difference during mild hypothermia (37–33 °C). The PaO2, however, was significantly reduced below 31 °C. The MAP remained stable at different levels of hypothermia, whereas HR was significantly reduced below 33 °C. Conclusions: Mild hypothermia in rats, induced by a sustained pentobarbital anesthesia, reduces ventilation without compromising arterial oxygenation or acid-base balance, as measured at body temperature. Theoretically, our observations in spontaneously breathing rats imply that a combination of mild hypothermia with anesthesia could be safely utilized to maintain adequate ventilation, using relatively low minute ventilation. We speculate that such a maneuver, if applied during mechanical ventilation, may prevent secondary pulmonary damage by allowing the use of lower ventilator volume-pressure settings.

Effects of arteriovenous extracorporeal therapy on hemodynamic stability, ventilation, and oxygenation in normal lambs.

ObjectiveTo evaluate hemodynamic stability and gas exchange in a neonatal animal model of pumpless arteriovenous extracorporeal membrane oxygenation (AV-ECMO) with extracorporeal shunt flow of up to 15% of cardiac output during variable ventilation and oxygenation. DesignProspective study. SettingResearch laboratory in a hospital. SubjectsSeven lambs (5.5 ± 0.6 kg, mean ± sd). InterventionsThe lambs initially were anesthetized by 50 mg/kg ketamine intravenously. After tracheostomy, the lambs were mechanically ventilated and paralyzed by using 1 mg/kg vecuronium bromide followed by 0.1 mg·kg−1·hr−1. One femoral vein was cannulated with a pulmonary artery flotation catheter and used for cardiac output and pulmonary artery pressure measurements. A femoral artery was cannulated for measuring mean arterial blood pressure, measuring heart rate, and blood sampling for gas exchange analyses. Finally, the right internal jugular vein and carotid artery were cannulated and used for the AV-ECMO. Normothermia (38 ± 0.5°C), fluid balance (5 mL·kg−1·hr−1 normal saline), and anesthesia (5 mg·kg−1·hr−1, intravenous ketamine) were maintained. Ventilator settings were adjusted to establish a baseline Paco2 (25–35 mm Hg) at an Fio2 of 0.4. The AV-ECMO circuit was established by using a hollow fiber oxygenator, primed with maternal sheep blood (150–200 mL). Measurements and Main Results The physiologic effects of the AV-ECMO shunt were evaluated at 15, 25, and 40 mL·kg−1·hr−1 ECMO flow, corresponding roughly to 4%, 8%, and 15% of the cardiac output values. The baseline minute volume was maintained during stepwise increases in arteriovenous shunt. A significant increase in endogenous cardiac output occurred at arteriovenous shunt of 25 and 40 mL·kg−1·hr−1 (analysis of variance followed by Tukey-Kramer multiple comparisons test), which was attributed to a significant increase of 30% in the heart rate. Effective cardiac output (difference between the thermodilution value and the AV-ECMO flow rate) and mean arterial blood pressure were not significantly changed. CO2 removal, measured at 15% arteriovenous shunt, was significantly increased with decreasing ventilation to 25% and 50% of the baseline (analysis of variance and Tukey-Kramer test). Oxygenation through the membrane was measured after reducing inspired Fio2 from 0.4 to 0.21, 0.15, and 0.10 with 15% arteriovenous shunt and baseline minute ventilation. Oxygen delivery by the oxygenator was significantly increased at Fio2 of 0.10, providing a maximum of 19.5% of the total oxygen consumption at an arterial hemoglobin-oxygen saturation of 60%. ConclusionsHealthy lambs are capable of maintaining effective cardiac output in the presence of moderate arteriovenous shunts (15%). AV-ECMO may provide efficient ventilatory support in the neonatal population with hypercapnia. The amount of oxygen delivery with AV-ECMO depends on arterial desaturation.

Therapeutic hypercapnia enhances the inflammatory response to endotoxin in the lung of spontaneously breathing rats

Objective: To test the hypothesis that therapeutic hypercapnia enhances the proinflammatory responses to endotoxemia in the lung and spleen of rats. Design: Prospective randomized study. Settings: Hospital research institute. Subjects: Forty-eight adult male rats. Interventions: Rats were randomly assigned for a 24-hr period to four breathing groups (n = 11/group), including air (controls), normoxic air with 5% CO2 (therapeutic hypercapnia), air and endotoxemia (5 mg/kg endotoxin), and therapeutic hypercapnia with endotoxemia. After euthanasia, the lung and spleen were removed for pro- and anti-inflammatory cytokine analyses and pulmonary histology evaluation. Four additional rats were used to examine changes in gas exchange and acid-base balance during exposure to therapeutic hypercapnia with and without endotoxemia before and at 4, 12, and 24 hrs into the study, using a permanently catheterized femoral artery. Measurements and Main Results: The ratios of proinflammatory cytokines (interleukin-1&bgr; [IL-1&bgr;] and IL-6) and an anti-inflammatory cytokine (IL-10) in the lungs and spleen were used as indices of inflammatory status. The wet-weight to dry-weight ratios, histologic changes in lung interstitial inflammation, and alveolar structures were used as indices of endotoxin-induced acute lung injury. IL-1&bgr; and IL-6 expression was significantly high in the lung of therapeutic hypercapnia-treated endotoxemic rats compared to the lung of rats subjected to only endotoxemia (p < .05 and p < .001, respectively). In the spleen, therapeutic hypercapnia-treated endotoxemic rats had low expression of IL-1&bgr; and IL-6 compared to rats subjected to only endotoxemia (p > .05 and p < .001). Therapeutic hypercapnia following endotoxemic challenge was associated with a proinflammatory response in the lung and an anti-inflammatory response in spleen, as assessed by the ratios of IL-1&bgr; and IL-6 to IL-10. The wet-weight to dry-weight ratio and the interstitial space were significantly increased only in therapeutic hypercapnia-treated endotoxemic rats (p < .05). The alveolar-septal thickness was significantly increased by 21% in endotoxemic rats (p < .001) and by 33% in therapeutic hypercapnia-treated endotoxemic rats (p < .001). Conclusions: A 24-hr exposure to therapeutic hypercapnia in endotoxin-stimulated, spontaneously breathing rats is associated with a proinflammatory immune response in the lung and anti-inflammatory response in the spleen as well as an increase in certain histologic indices of endotoxin-induced lung injury.

The effects of CO2 on cytokine concentrations in endotoxin-stimulated human whole blood.

Objectives:Hypercapnia is known to modulate inflammation in lungs. However, the effect of hypocapnia and hypercapnia on blood cytokine production during sepsis is not well understood. We hypothesized that CO2 modulates ex vivo inflammatory cytokine production during endotoxin stimulation. To test this hypothesis, we measured the production of pro- and anti-inflammatory cytokines in endotoxin-stimulated human whole blood cultures under hypercapnic, normocapnic, and hypocapnic conditions. Design:Prospective randomized study. Setting:Basic research laboratory. Subjects:Ten male and 10 female volunteers. Interventions:Venous blood samples, taken from volunteers were cultured at 37°C, under hypocapnic (2% CO2), normocapnic (5% CO2), and hypercapnic (7% CO2) conditions, with and without endotoxin stimulation. After 24 hrs of incubation, each cultures supernatant was analyzed for tumor necrosis factor-α, interleukin-1β, interleukin-6, interleukin-10, and interferon-γ concentrations by enzyme-linked immunosorbent assay. Data were analyzed using nonparametric repeated measures of analysis of variance followed by Dunns multiple comparisons test. Analysis of variance with Bonferroni correction was used to compare gender differences in cytokine concentrations. The Pearson test was used to estimate correlation between hydrogen ion and individual cytokine concentrations. Measurements and Main Results:Concentrations of the proinflammatory cytokines tumor necrosis factor-α, interleukin-1β and of the anti-inflammatory cytokine interleukin-10 under hypercapnic condition were significantly decreased (p < 0.05, 0.01, and 0.001, respectively) for both genders when compared with either normocapnic or hypocapnic conditions. Concentrations of tumor necrosis factor-α and interleukin-1β were significantly higher in men. In women, concentrations of interleukin-6 were significantly decreased under hypercapnic condition when compared with hypocapnic condition. An inverse relationship was found between hydrogen ion concentration and concentrations of tumor necrosis factor-α and interleukin-10. Conclusions:Our results are consistent with the hypothesis that CO2 can affect the production of pro- and anti-inflammatory cytokines after ex vivo stimulation with endotoxin.

Physiological Effects of a Novel Immune Stimulator Drug, (1,4)‐α‐d‐Glucan, in Rats

The (1,4)-α-D-glucan (α-D-glucan), derived from medicinal plant, Tinospora cordifolia, activates human lymphocytes with downstream synthesis of the pro- and anti-inflammatory cytokines, in vitro. We investigated physiological and immunological effects of a low and a high dose of α-D-glucan (0.5 and 10 mg/kg), in vivo, testing the hypothesis that intravenous administration of α-D-glucan does not affect haemodynamic, respiratory, haematological, and immune responses in normal rats. Male rats (300-400 g) were anaesthetized, tracheostomized, and catheterized in one femoral artery and vein. The mean arterial blood pressure and heart rate were continuously recorded. The baselines for gas exchange, differential blood cell count, and plasma concentration of TNF-α, IL-1β, IL-4, IL-6, and IFN-γ were determined. Rats were then randomly assigned to controls (n = 7), a low dose (0.5 mg/kg; n = 10), and a high dose (10 mg/kg; n = 7) of α-D-glucan for a six 6 hr study period. Gas exchange, differential cell count, plasma concentration of TNF-α, IL-1β, IL-4, IL-6, and IFN-γ, and mean arterial blood pressure values remained within physiological range. Intravenous administration of 10 mg/kg α-D-glucan created tachycardia, associated with hyperventilation, and significant reductions in the blood haemoglobin and haematocrit concentrations. We suggest that these in vivo effects of α-D-glucan should be considered for future clinical and/or experimental trials.

The use of alteplase for the resolution of an intravesical clot in a neonate receiving extracorporeal membrane oxygenation.

We present a case of the use of alteplase for the lysis of a large urinary bladder clot. A neonate presented with respiratory failure, secondary to a left diaphragmatic hernia necessitating the need for extracorporeal membrane oxygenation (ECMO) support. On day 3 of ECMO support, hematuria was noted, and a subsequent urinary bladder ultrasound revealed a significant urinary bladder clot. Alteplase (0.5–1 mg) was instilled into the urinary bladder via a 10 French Foley catheter (Sherwood Medical, St. Louis, MO). The catheter was clamped for 1 hour, followed by irrigation with normal saline. Multiple doses of alteplase were administered, resulting in complete resolution of the bladder clot. No adverse effects were attributed to the use of the intravesical alteplase. Alteplase seems to be safe and effective for the resolution of bladder clots, thereby potentially avoiding more invasive surgical procedures.

Cardiovascular stability during arteriovenous extracorporeal therapy: a randomized controlled study in lambs with acute lung injury

IntroductionClinical application of arteriovenous (AV) extracorporeal membrane oxygenation (ECMO) requires assessment of cardiovascular ability to respond adequately to the presence of an AV shunt in the face of acute lung injury (ALI). This ability may be age dependent and vary with the experimental model. We studied cardiovascular stability in a lamb model of severe ALI, comparing conventional mechanical ventilation (CMV) with AV-ECMO therapy.MethodsSeventeen lambs were anesthetized, tracheotomized, paralyzed, and ventilated to maintain normocapnia. Femoral and jugular veins, and femoral and carotid arteries were instrumented for the AV-ECMO circuit, systemic and pulmonary artery blood pressure monitoring, gas exchange, and cardiac output determination (thermodilution technique). A severe ALI (arterial oxygen tension/inspired fractional oxygen <200) was induced by lung lavage (repeated three times, each with 5 ml/kg saline) followed by tracheal instillation of 2.5 ml/kg of 0.1 N HCl. Lambs were consecutively assigned to CMV treatment (n = 8) or CMV plus AV-ECMO therapy using up to 15% of the cardiac output for the AV shunt flow during a 6-hour study period (n = 9). The outcome measures were the degree of inotropic and ventilator support needed to maintain hemodynamic stability and normocapnia, respectively.ResultsFive of the nine lambs subjected to AV-ECMO therapy (56%) died before completion of the 6-hour study period, as compared with two out of eight lambs (25%) in the CMV group (P > 0.05; Fishers exact test). Surviving and nonsurviving lambs in the AV-ECMO group, unlike the CMV group, required continuous volume expansion and inotropic support (P < 0.001; Fishers exact test). Lambs in the AV-ECMO group were able to maintain normocapnia with a maximum of 30% reduction in the minute ventilation, as compared with the CMV group (P < 0.05).ConclusionAV-ECMO therapy in lambs subjected to severe ALI requires continuous hemodynamic support to maintain cardiovascular stability and normocapnia, as compared with lambs receiving CMV support.