Danny Lotan

Endotracheal Epinephrine: A Call for Larger Doses

UNLABELLED Endotracheal administration of epinephrine 0.02 mg/kg (twice the IV dose) is recommended when IV access is unavailable during cardiopulmonary resuscitation. The standard IV dose has been considered too small for the endotracheal route by causing a detrimental decrease of arterial blood pressure (BP), presumably mediated by the beta-adrenergic receptor unopposed by alpha adrenergic vasoconstriction. We conducted a prospective, randomized, laboratory comparison of increasing doses of endotracheal epinephrine to ascertain the yet undetermined optimal dose of endotracheal epinephrine that would increase BP. After injecting normal saline (control), saline-diluted epinephrine (0.02, 0.035, 0.1, 0.2, and 0.3 mg/kg) was injected into the endotracheal tube of five anesthetized dogs at least 1 wk apart. Arterial blood samples for blood gases were collected before and at 14 time points up to 60 min after the drug administration. Heart rate and arterial BP were continuously monitored with a polygraph recorder. Only the 0.3 mg/kg dose successfully caused an increase in BP, observed 2 min after administration, and lasting for 10 min. An early decrease in BP was obviated only at a dose equivalent to 10-fold the currently recommended one. IMPLICATIONS We conducted a prospective, randomized, laboratory comparison of increasing doses of endotracheal epinephrine to ascertain the yet undetermined optimal dose of endotracheal epinephrine that would increase arterial blood pressure (BP). A decrease in BP was obviated only at a dose equivalent to 10-fold the currently recommended one. Clinical studies using larger doses of endotracheal epinephrine and their use as first-line therapy in cardiac arrest are warranted.

Is endotracheal adrenaline deleterious because of the beta adrenergic effect

IV adrenaline increases coronary and cerebral perfusion pressures during cardiopulmonary resuscitation. We recently showed that endotracheal adrenaline can decrease blood pressure (BP), a detrimental effect presumably mediated by the &bgr;2-adrenergic receptor unopposed by &agr;-adrenergic vasoconstriction. This prospective, randomized, laboratory comparison of endotracheal adrenaline (0.05 mg/kg diluted with normal saline to 10 mL total volume) with or without nonselective &bgr;-blocker (propranolol) pretreatment was conducted in an attempt to clarify the mechanism of this BP decrease. Five mongrel dogs were given 0.05 mg/kg endotracheal adrenaline (diluted) or 0.05 mg/kg endotracheal adrenaline followed by an IV propranolol (0.1 mg/kg) pretreatment. Each dog served as its own control (10 mL of normal saline administered endotracheally) and received each regimen at least one week apart. Endotracheal adrenaline given after the propranolol pretreatment produced an increase in systolic, diastolic, and mean arterial BPs, from 165/110 mm Hg (mean 128 mm Hg) to 177.5/125 mm Hg (mean 142.5 mm Hg), respectively, as opposed to the hypotensive effect of isolated endotracheal adrenaline (P < 0.03). Thus, endotracheal adrenaline was associated with predominantly &bgr;-adrenergic–mediated effects, causing hypotension via peripheral vasodilatation unopposed by &agr;-adrenergic vasoconstriction. The search for the optimal dose of endotracheal adrenaline should be aimed at achieving the higher &agr;-adrenergic vasoconstrictive threshold.

Should vasopressin replace adrenaline for endotracheal drug administration

ObjectiveArginine vasopressin was established recently as a drug of choice in the treatment of cardiac arrest and in retractable ventricular fibrillation; however, the hemodynamic effect of vasopressin following endotracheal drug administration has not been fully elucidated. We compared the effects of endotracheally administered vasopressin vs. adrenaline on hemodynamic variables in a canine model, and we investigated whether vasopressin produces the same deleterious immediate blood pressure decrease as did endotracheal adrenaline in the canine model. DesignProspective controlled study. SettingAnimal laboratory in Tel-Aviv University, Israel. SubjectsFive adult mongrel dogs weighing 6.5–20 kg. InterventionsDogs were anesthetized; each dog was intubated orally, and both femoral arteries were cannulated for the measurement of arterial pressure and for sampling blood gases. Each dog was studied four times, 1 wk apart, by using the same protocol for injection and anesthesia: endotracheal placebo (10 mL NaCl 0.9%,), endotracheal vasopressin (1 units/kg), endobronchial adrenaline (0.1 mg/kg), and endotracheal adrenaline (0.1 mg/kg). Following placebo, vasopressin, and adrenaline instillation, five forced manual ventilations were delivered with an Ambu bag. Each dog was its own control. Measurements and Main ResultsFollowing placebo or drug administration, heart electrocardiography and arterial pressures were continuously monitored with a polygraph recorder for 1 hr. Endotracheal vasopressin produced an immediate increase of diastolic blood pressure (from 83 ± 10 mm Hg [baseline] to 110 ± 5 mm Hg at 1 min postinjection). This response lasted >1 hr. In contrast, both endotracheal and endobronchial administration of adrenaline produced an early and significant (p < .05) decrease in diastolic and mean blood pressures. The diastolic blood pressure increase from 85 ± 10 mm Hg to 110 ± 10 mm Hg took an ill-afforded 55 secs following endotracheal adrenaline. Diastolic blood pressure was significantly (p < .05) higher following vasopressin compared with adrenaline administration in both routes. ConclusionsVasopressin accomplishes its hemodynamic effect, particularly on diastolic blood pressure, more rapidly, vigorously, and protractedly and to a significant degree compared with both endotracheal and endobronchial adrenaline. Evaluation of the effects of endotracheal vasopressin in a closed chest cardiopulmonary resuscitation model is recommended.

Renal Hypodysplasia Associates with a Wnt4 Variant that Causes Aberrant Canonical Wnt Signaling

Abnormal differentiation of the renal stem/progenitor pool into kidney tissue can lead to renal hypodysplasia (RHD), but the underlying causes of RHD are not well understood. In this multicenter study, we identified 20 Israeli pedigrees with isolated familial, nonsyndromic RHD and screened for mutations in candidate genes involved in kidney development, including PAX2, HNF1B, EYA1, SIX1, SIX2, SALL1, GDNF, WNT4, and WT1. In addition to previously reported RHD-causing genes, we found that two affected brothers were heterozygous for a missense variant in the WNT4 gene. Functional analysis of this variant revealed both antagonistic and agonistic canonical WNT stimuli, dependent on cell type. In HEK293 cells, WNT4 inhibited WNT3A induced canonical activation, and the WNT4 variant significantly enhanced this inhibition of the canonical WNT pathway. In contrast, in primary cultures of human fetal kidney cells, which maintain WNT activation and more closely represent WNT signaling in renal progenitors during nephrogenesis, this mutation caused significant loss of function, resulting in diminished canonical WNT/β-catenin signaling. In conclusion, heterozygous WNT4 variants are likely to play a causative role in renal hypodysplasia.

Circulating leptin and the perioperative neuroendocrinological stress response after pediatric cardiac surgery.

Objective Leptin may be involved in the acute stress response, regulating inflammatory parameters of major importance after cardiopulmonary bypass (CPB) surgery. Critically ill patients demonstrated significant increases in leptin levels in response to stress-related cytokines (tumor necrosis factor, interleukin [IL]-1) and abolishment of the circadian rhythm of leptin secretion. We characterized the pattern of leptin secretion in the acute postoperative period in children undergoing cardiac surgery and compared the changes in leptin levels with concomitantly occurring changes in cortisol levels, IL-8, and clinical parameters. Design Investigative study. Setting University-affiliated tertiary care hospital. Participants and Interventions Twenty-nine consecutive patients, aged 6 days to 15 yrs, operated upon for the correction of congenital heart defects were studied. Surgery in 20 patients (group 1) involved conventional CPB techniques, and 9 (group 2) underwent closed-heart surgery. The time courses of leptin, cortisol, and IL-8 levels were determined. Serial blood samples were collected preoperatively, on termination of CPB, and at six time points postoperatively. Plasma was recovered immediately, aliquoted, and frozen at −70°C until use. Measurements and Main Results The leptin levels in group 1 decreased during CPB to 51% of baseline (p < .001), then gradually increased, reaching 120% of baseline levels at 12–18 hrs postoperatively (p < .001), returning to baseline levels at 24 hrs (p < .01). In patients undergoing closed-heart surgery (group 2), leptin levels displayed a pattern resembling the first group: they decreased during surgery to 71% of baseline levels (p = .002) and showed a tendency to return to baseline thereafter. All group 1 patients’ cortisol levels increased significantly during the first hour of surgery, then decreased, returning to baseline levels at 18–24 hrs postoperatively. There was a significant negative correlation between leptin and cortisol levels (r = −2.8, p < .01). In group 2, cortisol levels increased during and after surgery, peaking 4 hrs postoperatively and decreasing thereafter. IL-8 levels determined in 15 group 1 patients increased significantly during CPB, peaked at the end of surgery, and then decreased but remained slightly elevated even at 48 hrs postoperatively. There was a significant correlation between cortisol and IL-8 levels (r = 2.55, p < .05). Children with leukocytosis, tachycardia, and hypotension had lower leptin levels and less variation over time as opposed to those with an uncomplicated course. Conclusions CPB is associated with acute changes in circulating leptin levels. These changes parallel those in cortisol, demonstrating an inverse relationship between leptin and cortisol. Further studies of the prognostic and therapeutic roles of leptin after CPB should be investigated.

Expression of SDF-1/CXCR4 in injured human kidneys

The chemokine SDF-1α is involved in migration, survival, and development of multiple cells, most notably of hematopoietic stem cells (HSC) expressing its ligand CXCR4. Recently, we have shown engraftment of human HSC in the ischemically injured murine kidney, presumably mediated by SDF-1α. To further investigate a possible role of SDF-1α in the recruitment of CXCR4+ cells in human renal disease of varying etiologies, we immunostained human biopsies of immunoglobulin (Ig)A nephropathy, minimal-change nephrotic syndrome, focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis, chronic pyelonephritis, and acute tubular necrosis (ATN) for SDF-1α, CXCR4, and CD45, a pan-hematopoietic marker. Irrespective of the diagnosis, intense SDF-1α immunoreactivity was localized to distal tubules and collecting ducts, whereas CXCR4 showed intense staining in both distal and proximal tubules. In addition, whereas varying degrees of CD45+ cell infiltrates were observed in all biopsies, we found focal infiltrates of CXCR4+ cells mostly localized to the corticomedullary junction only in ischemic ATN. This correlated with more extensive staining for SDF-1α in these sites. In all investigated renopathologic conditions, CD45+ leukocyte recruitment to the kidney seems not to be driven by SDF-1α/CXCR4 interaction. A contribution of SDF-1α for influx of CXCR4+ cells in the vicinity of arcuate vessels is suggested only in human ATN.

Tracheal epinephrine or norepinephrine preceded by beta blockade in a dog model. Can beta blockade bestow any benefits

Tracheal epinephrine (adrenaline) has been associated with two major deletorious side effects: increased heart rate (HR) and an initial decrease of blood pressure (BP). This prospective randomized animal study compared the haemodynamic responses to tracheally administered epinephrine or norepinephrine (nor adrenaline) alone versus each after pretreatment with propranolol for ameliorating those two untoward effects associated with epinephrine administration. Five anaesthetized mongrel dogs underwent 25 experiments of tracheal epinephrine or norepinephrine (0.02 mg/kg diluted with normal saline to 5 ml total volume) with or without an I/V non-selective beta-blocker (propranolol 0.1 mg/kg) pretreatment, and served as their own controls. Tracheal epinephrine alone produced a rise in both diastolic and mean arterial BP and an increase of HR. Tracheal norepinephrine alone produced the largest increase of diastolic and mean BP but this change was associated with a significant tachycardia (from 37 to 72/m, P<0.001). While both epinephrine or norepinephrine after pretreatment with propranolol produced a significant increase in both diastolic (from 106 to 166 mmHg and from 118 to 169 mmHg, respectively) (P<0.01) and mean BP (from 122 to 183 mmHg and from 133 to 188 mmHg, respectively) (P<0.01), only propranolol-pretreated tracheal epinephrine yielded a significant decrease in HR (from 52 to 33/m, P=0.002). Pretreatment with a beta-blocker protected against the deleterious tachycardia associated with epinephrine or norepinephrine and, by doing so, may improve the myocardial oxygen supply-and-demand balance. At the same time, the pretreatment augmented the relatively mild diastolic BP increase associated with the beta-adrenergic effect of epinephrine.

Renal Function in Patients with Cystic Fibrosis

Renal handling of sodium, potassium, calcium and phosphorus was investigated in 9 patients with cystic fibrosis (CF). Both under baseline conditions and during saline-induced diuresis, urinary excretion rate of sodium (UNaV), potassium, phosphorus and calcium did not differ significantly from control values although the fractional excretion of sodium was significantly higher in patients with CF during saline diuresis. When distally acting diuretics were administered, this difference between CF patients and controls was magnified and in addition, UNaV in CF patients was also significantly higher than in controls. Following saline loading the increment in glomerular filtration rate (GFR) in patients with CF was significantly lower than that of controls. We conclude that patients with CF when subjected to volume expansion demonstrate a lower tubular reabsorptive capacity of sodium as well as a reduced ability to increase their GFR. The defect in sodium reabsorption is probably located in the proximal tubule.

β-Chemokine secretion patterns in relation to clinical course and outcome in children after cardiopulmonary bypass: continuing the search to abrogate systemic inflammatory response

Abstract Background . Surgery involving cardiopulmonary bypass (CPB) is frequently accompanied by a systemic inflammatory response partly triggered by neutrophils and monocyte-macrophages. Certain cytokines that are powerful leukocyte-chemotactic factors have recently been characterized and shown to be important in evoking inflammatory responses: monocyte chemoattractant protein-1 (MCP-1) has monocyte-macrophage chemotactic activity, and regulated-upon-activation normal T-cell expressed and secreted (RANTES) has a potent chemoattractant activity for mononuclear phagocytes. This prospective cohort study investigated possible roles of these chemokines in the inflammatory response to CPB and relationships between the changes in chemokine levels and the clinical course and outcome. Methods . Systemic blood of 16 children undergoing CPB was collected after induction of anesthesia (base line); at 15 minutes after bypass onset; at CPB cessation; and at 1, 2, 4, 8, 12, and 24 hours afterward to measure MCP-1 and RANTES. Results . The significant changes of plasma β chemokine levels following CPB were associated with patient characteristics, operative variables, and postoperative course. Cardiopulmonary bypass of more than 2 hours, longer surgical times, inotropic support, and reoperation were associated with higher MCP-1 levels and lower RANTES levels. Conclusions . Our results suggest a relation between CPB-induced mediators and clinical effects, implying pathogenic roles for chemokines following CPB. These molecules should be considered as possible targets for therapeutic intervention.

Interleukin-8 secretion following cardiopulmonary bypass in children as a marker of early postoperative morbidity.

Background: Interleukin (IL)‐8, an 8 kDa peptide, is the first chemoattractant identified as being specific for neutrophils. Its possible association with early postoperative morbidity following cardiopulmonary bypass (CPB) in infants and children is unknown. This prospective cohort study sought possible roles of IL‐8 in the inflammatory response to CPB and investigated if changes in IL‐8 levels and clinical course and outcome were related.