Can ventilation while on cardiopulmonary bypass improve post-operative lung function for patients undergoing cardiac surgery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether ventilation during cardiopulmonary bypass (CPB) improves post-operative lung function. Altogether 187 relevant papers were identified using the below mentioned search, 9 papers represented the best evidence to answer the question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that a wide range of ventilatory strategies, while on cardiopulmonary bypass, have been attempted including CPAP with positive airway pressures of 5-15 cm H(2)O, high frequency low volume ventilation (with 100 breaths per min), inspired oxygen concentrations from 21% to 100% and bilateral extra-corporeal circulation using the lungs to oxygenate the blood while on bypass. While some small and transient benefits for CPAP with 10 cm H(2)O have been demonstrated, no convincing clinical benefits for any of these strategies have been shown and thus ventilation while on cardiopulmonary bypass cannot be supported as a strategy to improve post-operative lung function.     

M protein conserved region antibodies opsonise multiple strains of Streptococcus pyogenes with sequence variations in C-repeats

The development of a group A streptococcal (GAS) vaccine has focused on the M protein, a major virulence factor. Antibodies against the amino terminal domain of the M protein are generally protective but only provide type-specific immunity. J14, a 29-mer peptide sequence which contains a conserved epitope from the C-repeat region of the M protein, offers the possibility of a vaccine which will elicit protective opsonic antibodies against multiple GAS strains. In this study we have shown that antibodies raised against J14 are capable of opsonising 37 GAS isolates representing different emm types derived from a region in which GAS infection is endemic. We also demonstrate that J14 antisera is capable of opsonising GAS isolates containing J14 homologues but not J14-specific sequences, further increasing the strain coverage of this vaccine candidate. Isolates with three C-repeats were opsonised more efficiently than isolates with two repeats. Opsonisation of a strain with only a single C-repeat was dramatically lower than other strains tested. The number of C-repeats present in the M protein of individual isolates therefore appears to be the critical factor in determining bactericidal capacity of J14 antisera. The reduced opsonic capacity of sera against this strain was shown to correlate with a reduced capacity to bind J14 antisera, as demonstrated by immunofluorescence microscopy and FACS analysis. In vivo challenge experiments also confirmed the protective efficacy of immunisation with J14 peptide.     

Can we rely on arterial line sampling in performing activated plasma thromboplastin time after cardiac surgery?

BACKGROUND AND OBJECTIVE: Arterial catheters are routinely used to sample blood for clotting studies in most cardiothoracic intensive care units. The clotting profile in surgical bleeding after cardiac surgery influences further management. Aspiration and discard of a certain amount of blood from the line, prior to sampling, are assumed to clear heparin contamination. We have investigated this assumption through analysis of the clotting profile by simultaneous arterial line and peripheral venous samples. METHODS: The morning following cardiac surgery, simultaneous arterial line and peripheral venous blood samples were taken for activated plasma thromboplastin time (APTT) ratio and international normalized ratio (INR) in 49 randomly selected patients. Also, a thromboelastogram analysis (TEG) (n = 7) was made. A survey of 22 UK cardiothoracic intensive care units was carried out to determine the practice for the withdrawal of blood for clotting studies. RESULTS: The median arterial APTT ratio value was 1.32 +/- 0.52 as compared to the median peripheral APTT ratio value which was 1.1 +/- 0.24 (P < 0.001). INR values were statistically similar by both routes. Heparin contamination was confirmed by TEG which revealed that the R-value for arterial catheter blood samples without heparinase in the cup was higher (406.00 +/- 64.44 s) compared with the value for arterial samples with heparinase in the cup (318.28 +/- 47.26s, P < 0.05). The survey of 22 UK cardiothoracic intensive care units showed that heparinized arterial lines were by far the commonest ports used for blood withdrawal for the measurement of APTT ratio results. CONCLUSIONS: Samples withdrawn from heparinized arterial lines cannot be relied upon for APTT ratio results.     

Prediction of activity energy expenditure using accelerometers in children

PURPOSE: To validate two accelerometer-based activity monitors as measures of children's physical activity using energy expenditure as the criterion measure. METHODS: Actiwatch (AW) and Actical (AC) activity monitors were validated against continuous 4-h measurements of energy expenditure (EE) in a respiratory room calorimeter and 1-h measurements in an exercise laboratory using a portable calorimeter and treadmill in 32 children, ages 7-18 yr. The children performed structured activities including basal metabolic rate (BMR), playing Nintendo, using a computer, cleaning, aerobic exercise, ball toss, treadmill walking, and running. Equations were developed to predict activity energy expenditure (AEE = EE - BMR), and physical activity ratio (PAR = EE/BMR) from a power function of AW or AC, and age, sex, weight, and height. Thresholds were determined to categorize sedentary, light, moderate, and vigorous levels of physical activity. RESULTS: Activity counts accounted for the majority of the variability in AEE and PAR, with small contributions of age, sex, weight, and height. Overall, AW equations accounted for 76-79% and AC equations accounted for 81% of the variability in AEE and PAR. Relatively wide 95% prediction intervals suggest the accelerometers are best applied to groups rather than individuals. Sensitivities were higher for the vigorous threshold (97%) than the other thresholds (86-92%). Specificities were on the order of 66-73%. The positive predictive values for sedentary, light, moderate, and vigorous categories were 80, 66, 69, and 74% for AW, respectively, and 81, 68, 72, 74% for AC, respectively. CONCLUSION: Both accelerometer-based activity monitors provided valid measures of children's AEE and PAR, and can be used to discriminate sedentary, light, moderate, and vigorous levels of physical activity but require further development to accurately predict AEE and PAR of individuals.     

Role of prophylactic scleral buckling in the management of retained intraocular foreign bodies

Purpose: To evaluate the role of prophylactic scleral buckling procedure with pars plana vitrectomy for the removal of retained intraocular foreign bodies (RIOFB) in the prevention of postoperative retinal detachment. Methods: In a prospective, clinical, controlled study, 28 patients with RIOFB without retinal detachment were randomly divided into two groups of 15 (group I) and 13 (group II) patients. All patients underwent a standard three‐port pars plana vitrectomy with foreign body removal. In addition to this standard procedure, patients assigned to group I had a 360° encircling scleral buckle placed at the time of surgery. Group II patients did not have any scleral buckling. All patients were followed up for an average period of 11.8 months. Both groups were comparable with respect to age, sex, duration of injury, nature of injury, and site, size and type of RIOFB. Results: The retinal detachment rate was found to be 6.6% in group I and 30.8% in group II (P = 0.24). Prophylactic scleral buckling reduced the risk of retinal detachment by 24% but this was not found to be statistically significant. Conclusion: Prophylactic scleral buckle placement with pars plana vitreous surgery for RIOFB may reduce the risk of late onset retinal detachment. A larger study would seem warranted.     

Influence of stressors on the rewarding effects of alcohol in Wistar rats: studies with alcohol deprivation and place conditioning

Rationale and objectives Studies on laboratory animals have provided conflicting results regarding the actions of stressors on the rewarding effects of alcohol. In the present study, we first examined the effects of footshock or social defeat, given during deprivation, on the alcohol deprivation effect (ADE). We then tested the effects of stressors on place conditioning to alcohol, another technique used to measure drug reward.Methods Male Wistar rats were trained to drink 10% alcohol in a 24 h access, free-choice design and received intermittent footshock or defeat 5 times during a 2-week alcohol deprivation period, followed by 2 weeks of free access to alcohol. There were three such cycles. In the place conditioning studies, animals received footshock, defeat, or no stress immediately prior to conditioning sessions where they received alcohol (0.6 or 1.0 g/kg, IP) or vehicle injections.Results Alcohol intake of footshock-treated animals was significantly higher than that of controls following the first and second, but not the third period of alcohol deprivation and stress exposure. Defeat caused a smaller increase in alcohol intake that was significant only after the first deprivation and stress cycle. In the place conditioning studies, we found that either stressor blocked the place aversion induced by 1.0 g/kg alcohol.Conclusions These results demonstrate that stressors can modify the rewarding and aversive properties of alcohol, measured using two different paradigms. Footshock and defeat produced transient, but significant increases in the magnitude of ADE, while exposure to either stressor reduced the aversive effects of a high dose of alcohol measured using the place conditioning paradigm.     

Effect of gestational age on cord blood plasma copper,zinc, magnesium and albumin

BACKGROUND: The transport of essential trace elements from mother to fetus varies throughout gestation, and the role of transport proteins in the neonate and the mother may change during pregnancy. Magnesium, often used as tocolytic agent, may reach the fetus and appear in cord blood at higher than normal concentrations. AIMS: To determine cord blood plasma zinc, copper and magnesium concentrations, as well as plasma albumin in premature and full-term newborns, and correlate these values with those of maternal blood plasma at birth. Also, to examine whether cord blood plasma concentration of these elements varies with gestational age. SUBJECTS: The 35 mother-infant pairs included: 11 in the 38-42-week gestational age (GA), 9 in the 34-37-week GA, 11 in the 29-33-week GA group and 4 in the 24-28-week GA. Magnesium for tocolysis was given to five of the mothers in the 29-33-week GA cohort and two of the women giving birth at 24-28-week GA. RESULTS: Trend analysis showed that while cord plasma zinc decreased with GA at birth, the reverse was observed for copper. There were no differences with GA either in maternal plasma zinc or copper. However, maternal ceruloplasmin tended to decrease with GA (P=0.0174). Maternal and cord blood plasma magnesium exhibited a strong correlation (r=0.942, P<0.001), as well as between cord plasma magnesium and zinc (r=0.448, P<0.01). CONCLUSIONS: While the vigorous mother-to-fetus uphill zinc transfer is clear throughout the last trimester, copper remains in cord blood plasma at much lower concentrations than in the mother, suggesting that prematurity may place the newborn infant at a greater risk than the term infant to copper deficiency. This situation, together with a reduced synthesis in the fetus of the transport protein ceruloplasmin, creates another potential challenge in the nutritional support of the premature infant.     

Evaluation of newer diagnostic methods for the detection and differentiation of Entamoeba histolytica in an endemic area

We evaluated the colorimetric polymerase chain reaction (PCR)-based method for the detection and differentiation of Entamoeba spp. and compared the efficacy of E. histolytica-specific antigen detection in faeces with the detection of specific antibodies to E. histolytica-specific antigen in faeces, by enzyme-linked immunosorbent assay. Faecal samples were obtained from patients attending hospital in Chandigarh, India, from March 2001 to February 2002. The PCR-based colorimetric method was found to be the most sensitive (100%) and it could differentiate between pathogenic and non-pathogenic Entamoeba spp. The present study also emphasized that the antigen detection system may prove to be a better diagnostic tool than the antibody detection system in endemic areas.     

Premixed solutions of diamorphine in ropivacaine for epidural anaesthesia: a study on their long-term stability

Background. Local anaesthetics and opioid mixtures are commonlyused to provide anaesthesia or analgesia during the perioperativeperiod. In order to facilitate their preparation and storageit is necessary to establish the stability of such solutions. Methods. In our study, diamorphine was added to ropivacaine0.2% 200-ml polybags to give a concentration of 25 µg ml^–1and to ropivacaine 1% 50-ml syringes to give a concentrationof 45 µg ml^–1. The polybags and syringeswere stored at 40°C, 21°C and 4°C for up to 120days. Samples were taken during this period for measurementof diamorphine and ropivacaine content and pH of the solutions. Results. We found that the storage temperature and the initialconcentration influenced the rate of degradation of diamorphinein both the polybags and the syringes. In the syringes, 10%degradation of diamorphine [T (0.9)] was: 6 days at 40°C,16 days at 21°C and 30 days at 4°C. In the polybags,diamorphine T (0.9) was 6 days at 40°C, 28 days at 21°Cand 70 days at 4°C. Conclusions. It is feasible to manufacture such solutions inpharmacy aseptic units and to store them for up to 1 month forroutine use in epidural infusions. Br J Anaesth 2003; 90: 179–82