Role of epigenetic mechanisms in transmitting the effects of neonatal sevoflurane exposure to the next generation of male, but not female, rats.

BACKGROUND: Clinical studies report learning disabilities and attention-deficit/hyperactivity disorders in those exposed to general anaesthesia early in life. Rats, primarily males, exposed to GABAergic anaesthetics as neonates exhibit behavioural abnormalities, exacerbated responses to stress, and reduced expression of hypothalamic K+-2Cl- Cl- exporter (Kcc2). The latter is implicated in development of psychiatric disorders, including male predominant autism spectrum disorders. We tested whether parental early life exposure to sevoflurane, the most frequently used anaesthetic in paediatrics, affects the next generation of unexposed rats. METHODS: Offspring (F1) of unexposed or exposed to sevoflurane on postnatal day 5 Sprague-Dawley rats (F0) were subjected to behavioural and brain gene expression evaluations. RESULTS: Male, but not female, progeny of sevoflurane-exposed parents exhibited abnormalities in behavioural testing and Kcc2 expression. Male F1 rats of both exposed parents exhibited impaired spatial memory and expression of hippocampal and hypothalamic Kcc2. Offspring of only exposed sires had abnormalities in elevated plus maze and prepulse inhibition of startle, but normal spatial memory and impaired expression of hypothalamic, but not hippocampal, Kcc2. In contrast to exposed F0, their progeny exhibited normal corticosterone responses to stress. Bisulphite sequencing revealed increased CpG site methylation in the Kcc2 promoter in F0 sperm and F1 male hippocampus and hypothalamus that was in concordance with the changes in Kcc2 expression in specific F1 groups. CONCLUSIONS: Neonatal exposure to sevoflurane can affect the next generation of males through epigenetic modification of Kcc2 expression, while F1 females are at diminished risk.

[Injuries to blood vessels near the heart caused by central venous catheters]. / Verletzungen herznaher Gefäße durch zentralvenöse Katheter.

Injuries to blood vessels near the heart can quickly become life-threatening and include arterial injuries during central venous puncture, which can lead to hemorrhagic shock. We report 6 patients in whom injury to the subclavian artery and vein led to life-threatening complications. Central venous catheters are associated with a multitude of risks, such as venous thrombosis, air embolism, systemic or local infections, paresthesia, hemothorax, pneumothorax, and cervical hematoma, which are not always immediately discernible. The subclavian catheter is at a somewhat lower risk of catheter-associated sepsis and symptomatic venous thrombosis than approaches via the internal jugular and femoral veins. Indeed, access via the subclavian vein carries a substantial risk of pneumo- and hemothorax. Damage to the subclavian vein or artery can also occur during deliberate and inadvertent punctures and result in life-threatening complications. Therefore, careful consideration of the access route is required in relation to the patient and the clinical situation, to keep the incidence of complications as low as possible. For catheterization of the subclavian vein, puncture of the axillary vein in the infraclavicular fossa is a good alternative, because ultrasound imaging of the target vessel is easier than in the subclavian vein and the puncture can be performed much further from the lung.

Transfusion has no effect on recurrence in hepatitis C after liver transplantation.

BACKGROUND: The literature suggests that blood product transfusions have a negative impact on the survival of liver transplant patients. We investigated the impact of intraoperative blood product usage on the survival of liver transplantation patients being transplanted for hepatitis C-related end-stage liver disease. In addition, we analyzed a potentially more sensitive metric, namely disease recurrence and fibrosis progression, obtained from follow-up liver biopsies. METHODS: We retrospectively studied 194 consecutive patients with hepatitis C virus (HCV) undergoing liver transplantation. To investigate the effect of red blood cell (RBC) or platelet transfusions on post-transplant HCV recurrence, hepatic biopsy data from 4 months and 1 year after transplantation were studied. In addition, survival data were analyzed. RESULTS: There was no effect of intraoperative RBC or platelet transfusion on either 1- or 5-year patient survival following liver transplantation. There was no difference in HCV disease recurrence or progression of hepatic fibrosis at 4 months or 1 year attributable either to RBC or to platelet transfusion. CONCLUSION: This study was not able to confirm an effect on the survival of HCV-infected liver transplant patients related to intraoperative transfusion of RBCs or platelets. In addition, these transfusions had no effect on HCV recurrence or fibrosis progression. This is not to condone a liberal transfusion practice, but rather to reassure that when clinically indicated, transfusion does not have a significant impact on patient survival or disease recurrence in HCV-infected liver transplant patients.

Monitoring technologies in the neonatal intensive care unit: implications for the detection of necrotizing enterocolitis.

Necrotizing enterocolitis is the most common and fulminant gastrointestinal disease affecting neonates. Its pathogenesis is heterogeneous and not clearly understood. Early detection could prevent some of the devastating consequences of this disease, but currently there is no noninvasive method of reliable early-stage detection. Here, we review various noninvasive monitoring technologies that have already been employed or show promise for early detection. Each method may have an important role after its technical difficulties are resolved. These are discussed in detail as they relate to various aspects of the putative pathophysiology of this devastating disease.

Effects of elevating the head of bed on interface pressure in volunteers.

OBJECTIVE: Intensive care unit patients are at particular risk for pressure ulcers and ventilator-associated pneumonia. Current guidelines recommend that mechanically ventilated patients be kept in a semirecumbent position with the head of bed elevated 30 degrees -45 degrees to prevent aspiration and ventilator-associated pneumonia. We tested the effects of elevating the head of bed on the interface pressure between the skin of the sacral area and the bed with healthy volunteers. INTERVENTIONS: Interface pressure profiles of the sacral area were obtained for the 0 degrees , 10 degrees , 20 degrees , 30 degrees , 45 degrees , 60 degrees , and 75 degrees head of bed elevated positions from 15 subjects (14 men, one woman). MEASUREMENTS AND MAIN RESULTS: Peak sacral interface pressures increased with large increases in head of bed elevation. The 30 degrees , 45 degrees , 60 degrees , and 75 degrees head of bed positions all had peak interface pressures that were significantly (p < 0.02) greater than the supine measurement and also were different from all other head of bed positions. Affected areas, defined as areas over which an interface pressure >or=32 mm Hg was obtained, increased with large elevation of the head of bed. The affected areas of the 45 degrees , 60 degrees , and 75 degrees head of bed positions were significantly greater than the supine position and were also significantly different from all other head of bed positions. CONCLUSIONS: Raising the head of bed to 30 degrees or higher on a intensive care unit bed increases the peak interface pressure between the skin at the sacral area and support surface in healthy volunteers. At 45 degrees head of bed elevation or higher, the affected area attributed to a skin-intensive care unit bed interface pressure >or=32 mm Hg increased as well. Further study is needed to determine whether the increased peak interface pressures and affected areas that result from raising the head of bed actually increase the incidence of pressure ulcer formation.

An audible indication of exhalation increases delivered tidal volume during bag valve mask ventilation of a patient simulator.

Self-inflating manual resuscitators (SIMRs) can mislead caregivers because the bag, unlike a Mapleson-type device, reinflates even without patient exhalation. We added a whistle as an audible indicator to the exhalation port of a SIMR. In randomized order, each participant provided two sets of breaths via mask ventilation with a SIMR, one with and one without audible feedback, to a Human Patient Simulator modified to log lung volume changes. The last three breaths in each set were used to compare average tidal volume (Vt) under both conditions. Eighty-seven advanced cardiac life support trainees (54 males, 33 females) with clinical experience averaging 6.4 +/- 9.4 yr were recruited. Average Vt delivered with the standard SIMR was 486 +/- 166 mL and 624 +/- 96 mL with the modified SIMR. Average Vt delivered by a modified SIMR was significantly larger by 40% when it followed standard SIMR use and 19% when using the modified SIMR first. Use of a SIMR with an audible indicator of exhalation significantly (P < 0.001) increased mask ventilation of a patient simulator, suggesting that mask ventilation of a patient with a SIMR may also be increased by objective, real-time feedback of exhaled Vt.

Differential modulation of glutamatergic transmission by 3,5-dibromo-L-phenylalanine.

An increasing body of evidence supports the hypothesis that diminished function of N-methyl-D-aspartate (NMDA) receptors and the associated increase in glutamate release and overstimulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors are critical elements of the pathophysiology of schizophrenia. Here, we describe a halogenated derivative of the aromatic amino acid L-phenylalanine that 1) activates NMDA receptors, 2) depresses presynaptic glutamate release, and 3) blocks AMPA/kainate receptors. The experiments were conducted in rat cerebrocortical cultured neurons by using the patch-clamp technique. 3,5-Dibromo-L-phenylalanine (3,5-DBr-L-Phe) augmented NMDA miniature excitatory postsynaptic currents (mEPSCs) and activated the steady-state current, effects that were eliminated by NMDA receptor antagonists DL-2-amino-5-phosphonopentanoic acid and MK-801 (dizocilpine maleate; 5H-dibenzo[a,d]cyclohepten-5,10-imine). 3,5-DBr-L-Phe was a partial agonist at the glutamate-binding site of NMDA receptors with an EC50 of 331.6 +/- 78.6 microM and with an efficacy of 30.5 +/- 4.7% compared with NMDA. 3,5-DBr-L-Phe depressed both amplitude and frequency of AMPA/kainate mEPSCs. The IC50 of 3,5-DBr-L-Phe to inhibit AMPA/kainate mEPSC frequency was 29.4 +/- 4.3 microM. 3,5-DBr-L-Phe significantly decreased paired pulse depression of AMPA/kainate EPSCs and attenuated current activated by AMPA with higher efficacy at lower concentration of AMPA. 3,5-DBr-L-Phe neither affected GABA miniature inhibitory postsynaptic currents nor elicited action potentials. By enhancing NMDA receptor function, reducing glutamate release and blocking AMPA/kainate receptors 3,5-DBr-L-Phe represents a new type of polyvalent modulator of glutamatergic synaptic transmission with potential therapeutic applications.

Milrinone, not epinephrine, improves left ventricular compliance after cardiopulmonary bypass.

OBJECTIVE: To compare the effects of milrinone versus epinephrine administered after cardiopulmonary bypass (CPB) on left ventricular compliance. DESIGN: Prospective and randomized. SETTING: University-affiliated hospital. PARTICIPANTS: Twenty consenting adult patients. INTERVENTIONS: Patients undergoing aortocoronary bypass surgery were randomized to receive 50 microg/kg of milrinone (group M; n = 10) or 0.03 microg/kg/min of epinephrine (group E; n = 10) shortly after separation from CPB. Left ventricular compliance was assessed by observing changes in left ventricular end-diastolic area (LVEDA) in the short-axis view with transesophageal echocardiography, while maintaining a constant left atrial pressure. Measurements were performed (1) before CPB, (2) after separation from CPB, and (3) after either milrinone or epinephrine. MEASUREMENTS AND MAIN RESULTS: Baseline LVEDA decreased by 20% after CPB in the milrinone group (from 16.6 +/- 3.1 cm2 to 14.3 +/- 2.4 cm2; p < 0.05) and by 22% in the epinephrine group (from 19.4 +/- 4.1 cm2 to 17.2 +/- 3.8 cm2; p < 0.05). LVEDA increased by 15% after milrinone (from 14.3 +/- 2.4 cm2 to 15.6 +/- 2.8 cm2; p < 0.05) but remained unchanged after epinephrine (from 17.2 +/- 3.8 cm2 to 17.1 +/- 4.2 cm2; p = ns). CONCLUSIONS: Left ventricular compliance was decreased after CPB. The administration of milrinone, but not epinephrine, was associated with a partial return to prebypass values. The exact mechanism of action remains to be determined.

Effects of milrinone versus epinephrine on grafted internal mammary artery flow after cardiopulmonary bypass.

OBJECTIVE: To compare changes on grafted internal mammary artery (IMA) flow after cardiopulmonary bypass in response to the administration of milrinone or epinephrine. DESIGN: Prospective and randomized. SETTING: University-affiliated hospital. PARTICIPANTS: Twenty consenting, adult patients undergoing CABG. INTERVENTIONS: Patients were randomized to receive either milrinone, 50 microg/kg, or epinephrine, 0.03 microg/kg/min, immediately after cardiopulmonary bypass. IMA flow was measured with a laser Doppler flow probe before and after the administration of either drug. MEASUREMENTS AND MAIN RESULTS: Baseline grafted IMA flow was similar for both groups (milrinone, 38+/-14 mL/min; epinephrine, 33+/-10 mL/min). In patients who received milrinone, flow increased by 24% to 50+/-17 mL/min, p<0.05; whereas with epinephrine, it remained essentially unchanged (33+/-10 v. 31+/-11 mL/min). CONCLUSIONS: This study confirms that the vasodilatory effect of milrinone on the IMA is also present after its anastomosis, whereas low-dose epinephrine exhibits neither beneficial nor adverse effects. It is suggested that in the absence of excessive vasodilation, milrinone should be considered as a first-line inotrope after coronary artery bypass graft surgery, to achieve an increase in contractility and IMA artery flow.

Growth of Staphylococcus aureus in Diprivan and Intralipid: implications on the pathogenesis of infections.

BACKGROUND: The incidence and severity of infections are increased when Intralipid or Diprivan are administered to patients. Intralipid promotes infection, presumably by inhibiting the reticuloendothelial system, thereby suppressing the host's constitutive immunity, whereas Diprivan supposedly promotes infection by supporting bacterial growth and increasing the inoculating dose. This study considers whether bacterial replication alone in Intralipid and Diprivan adequately explains the increased risk of infection associated with these agents or whether other factors might also be involved. METHODS: Staphylococcus aureus was cultured in 10% Intralipid or Diprivan at clinically relevant conditions or in Intralipid containing 0.005% (w/v) sodium EDTA, a current additive, to measure growth. To determine whether Intralipid affected infection, New Zealand white rabbits were injected intravenously with S. aureus with or without Intralipid. Twenty-four hours later, bacteria in lung, liver, spleen, and kidney tissues were enumerated. RESULTS: S. aureus failed to grow in Diprivan or Intralipid containing 0.005% EDTA. Whereas S. aureus did replicate in plain Intralipid, growth was delayed until the bacteria conditioned the media. Once initiated, growth was slow at clinically relevant temperatures. The administration of Intralipid to rabbits significantly increased the recovery of staphylococci from the kidneys, P < 0.001, relative to the other tissues 24 h after an intravenous inoculation with S. aureus, compared with rabbits receiving S. aureus with no Intralipid. CONCLUSIONS: These results suggest that Diprivan, and possibly Intralipid, represent poor media for the growth of S. aureus and may promote infection through mechanisms other than increased inoculum size.

Spinal anesthesia for nonpulmonary surgery in a lung transplant recipient.

The anesthetic implications for patients requiring anesthesia for surgery after lung transplantation have not been thoroughly studied. The use of spinal anesthesia in patients undergoing lumbar laminectomy has been well described. This case demonstrates the use of spinal anesthesia for lumbar laminectomy in a patient who had previously undergone a bilateral lung transplantation. Spinal anesthesia was used to minimize the risk of respiratory complications such as aspiration, atelectasis, and pneumonia that may be associated with administration of a general anesthetic.

Very limited air elimination capability of the level 1 fluid warmer.

STUDY OBJECTIVE: To determine the volume of air in 1000-ml crystalloid bags before and after connection to an infusion set; and to determine the volume of air that is not eliminated by the air eliminator in the Level 1 fluid warming device (Level 1 Technologies, Inc., Rockland, MA) when air boluses of different volumes enter into the fluid warming set. DESIGN: Prospective analysis and laboratory investigation. SETTING: Operating room (OR) and research laboratory of a university hospital. INTERVENTIONS: Air was aspirated from 200 collapsible, 1000-ml crystalloid bags: 100 before being connected to an infusion set and 100 after being connected to a patient in the OR. A roller pump from a cardiopulmonary bypass machine was connected to a Level 1 D-300 fluid administration set to maintain a continuous flow of normal saline through its air eliminator at a flow that approximated gravity or two thirds maximal flow, which is the rate achieved when fluid is pressurized to 300 mmHg throughout the system. Different volumes of air were administered and the air that passed through the air eliminator was measured. MEASUREMENTS AND MAIN RESULTS: Nonspiked bags contained 56.2 +/- 4 ml (mean +/- SD) of air (range 43-66 ml), and spiked bags contained 61.2 +/- 13 ml of air (range 4-102 ml), a significant difference (p < 0.0001). The amount of air passing through the air eliminator differed significantly at gravity and at two thirds maximal flow with boluses of 5, 10, 20, and 30 ml of air (p < 0.0001), but not with the 60 ml bolus of air. The amount of air passing through the eliminator also differed significantly (p < 0.0001) between boluses of different sizes at each flow rate. At the higher flow rate, even small boluses of air were not reliably eliminated; up to 56% of a 5 ml air bolus passed through the eliminator. CONCLUSION: Air must be rigorously eliminated from all fluid containers because of the limited air elimination capability of the Level 1 air eliminator.

Multilumen central venous catheters in children: relative potential to perforate vessels. An in vitro study.

OBJECTIVE: Because cardiovascular perforation by a central venous catheter (CVC) is a serious complication of catheterization in pediatric patients, we conducted an in vitro study of the relative potential for perforation of a standard material by the tips of multilumen pediatric catheters. Since we could not simulate vessel tissue, we hypothesized that testing catheters on a standard material would show whether catheters varied in tendency to perforate such a material and thus indicate a "relative potential for perforation." METHODS: Each CVC protruding from a support tube was suspended in a water-filled Plexiglas chamber at a 90 degrees incident angle to a polyethylene film, which was made to bulge 6 mm into the CVC tip 120 times per minute by hydropressure. Perforation of the polyetheylene film was documented on a time-based, strip-chart recording of pressure change on the opposite side of the film. We recorded the number of pulsations required for the following catheters to perforate the polyethylene: Arrow flex tip, Cook polyurethane, Viggo hydrocath polyurethane, and Cook silicone CVCs of 4- and 5-Fr size with 2 or 3 lumens (n = 5 catheters of each type, each catheter being tested 5 times). RESULTS: The number of pulsations to perforation ranged from 1 +/- 0.4 SD to > 7000. CONCLUSIONS: This in vitro study of the worst-case condition (90 degrees incident angle between CVC tip and polyethylene film) indicates that pediatric multilumen CVCs vary significantly in their relative potential to perforate a standard material. We suggest that, when central venous catheterization is contemplated in children, in addition to insertion site, catheter length, and depth of insertion, the type of catheter is another variable to consider in order to minimize the chance of cardiovascular perforation by the CVC tip.

Epidural catheter reconnection. Safe and unsafe practice.

BACKGROUND: An in vitro model of epidural catheter contamination was used to determine if disconnected catheters can be safely reconnected. METHODS: Epidural catheters were filled with brain-heart infusion (BHI) broth or preservative-free saline containing 5 micrograms/ml fentanyl. Escherichia coli, Pseudomonas aeruginosa, or Staphylococcus aureus (1.10(5) colony-forming units) was injected into the initial 1.1 +/- 0.24 inch (2.75 +/- 0.60 cm) of the catheters. To study the effect of bacteria settling in a vertically oriented catheter on the advancement of bacteria along the catheter, bacteria were incubated with catheters in the vertical and the horizontal positions. To determine if bacteria are swept further into a catheter when fluid in it is displaced, catheters were inclined 30 degrees and the fluid in them was allowed to drain from the distal end to various extents. Bacteria were incubated with the catheter held horizontally. After incubation, the catheters were serially sectioned, and the resulting segments were eluted with buffered saline-containing gelatin (BSG), which was collected on BHI agar plates for colony counts. This determined if a segment of the catheter remained internally sterile distal to the point of disconnection. Effectiveness of decontaminating the exterior of the catheter was also tested as follows: Catheters (n = 10) were first immersed in BSG containing 1.10(5) S, aureus, immediately immersed in betadine for 2 min, exposed to air for 3 min, cut with a sterile instrument, and reconnected to a sterile screw cap catheter connector. Reconnected catheters were perfused with 10 ml BSG for 1 hr. Collected perfusate (100 microliters) was removed for direct colony count; the remaining perfusate was mixed with an equal volume of BHI and incubated overnight. A 100 microliters aliquot of BHI-BSG mixture was sampled the next day. No bacteria were cultured from either the perfusate or BHI-BSG mixture. RESULTS: Eight hours after contamination, as long as the fluid in the catheter was static, no bacteria were detected more than 13 inches (32.5 cm) from the contaminated end of catheters filled with BHI and no more than 8 inches (20 cm) from the end of those filled with fentanyl solution. This finding was not affected by incubation of the catheter in the vertical position. Fluid displacement less than 8 inches (20 cm) had no effect on dissemination, but when fluid was displaced 13 inches (32.5 cm), bacteria were found at the end of the catheter, 35 inches (87.5 cm) away. No bacteria were recovered from the perfusate of reconnected catheters after the catheters were cleaned with betadine and cut with a sterile instrument. CONCLUSIONS: There may be an area distal to the disconnected end of an epidural catheter where its interior remains sterile for at least 8 hr. Such an area exists only when the fluid in the catheter remains static. Furthermore, the exterior of the catheter can be adequately cleaned to prevent bacteria from entering the catheter when reconnected at that point.