FLOW REQUIREMENTS AND REBREATHING DURING MECHANICALLY CONTROLLED VENTILATION IN A T-PIECE (MAPLESON E) SYSTEM

The influence of fresh gas flow (FGF) setting on rebreathingwas investigated in 15 infants and children (weight 3.5–21.8kg) during balanced anaesthesia with mechanically controlledventilation using a T-piece (Mapleson E) system and a Nuffieldventilator 200. Tidal volume (VT), minute volume (VE), maximalinspired (PlCO₂) and end-tidal (PE'_co2) carbon dioxide tensionsand airway pressure were measured. VE, set to produce a PE'_CO2of about 4.5 kPa and measured at a high FGF (minimal rebreathing),was unchanged throughout the study and the regression equationfor VE and weight was: VE (ml min^–1) = 146x kg ³482, r = 0.92. Measurements were then repeated at FGF: VE ratiosreduced to 1.5 and 1.0. To achieve minimal rebreathing (Pl_CO2less than 0.5 kPa), FGF: VE ratios greater than 1.8 (range 1.8–4.9)had to be used. At FGF: VE ratios of 1.5, some alveolar rebreathingoccurred, indicated by increased inspired (P < 0.001) andend-tidal (P < 0.001) carbon dioxide tensions. At FGF: VEratios equal to 1.0, alveolar rebreathing was more pronouncedand hypercapnoea occurred with a PE'_CO2 (mean ± 1 SD)of 5.89±0.53 kPa. At this FGF setting, change in I: Eratio from 1: 2 to 1: 1 did not influence the level of alveolarrebreathing. A minimal FGF (ml min^–1) setting of 1.5 xVE (that is, 1.5 (146 x kg ³ 482), approximated to theexpression (200 x kg ³ 1000) is recommended for controlledventilation to avoid hypercapnoea when using the T-piece systemin children weighing less than 20 kg.     

Acute Myocarditis

ABSTRACT In a prospective study, 57 patients with a preliminary diagnosis of myocarditis were investigated. Twenty-four patients were considered to have an acute myocarditis, 14 had a suspected myocarditis, while in 19 patients myocarditis was excluded. Episodes of frequent supraventricular and/or ventricular extrasystoles during hospital stay were seen in 8/24 cases (33%) with myocarditis and in 1/19 cases (5%) without myocarditis. On follow-up 1 month later, no supraventricular extrasystoles were observed in either group. Echocardiographic signs consistent with left ventricular insufficiency were noted in 7/24 cases (29%) with myocarditis, in 1/14 cases (7%) with suspected myocarditis and in no case without myocarditis. With a “routine” serologic test battery covering influenza viruses A and B, adenovirus, Coxsackie virus group B, ECHO viruses, Chlamydia psittaci, Mycoplasma pneumoniae and hemolytic streptococci group A, a possible etiology could be documented in 9/24 cases (38%) with myocarditis and in 4/19 cases (21%) without myocarditis. Enterovirus-specific IgM was detected with solid-phase reverse immunosorbent test (SPRIST) in 12/23 (48%) cases with myocarditis and in 3/16 cases (19%) without myocarditis. In SPRIST-IgM-positive cases, IgM antibodies were detected in 15/20 (75%) of the sera taken on admission. The overall serological results indicated a recent infection in 16/24 cases (67%) with myocarditis and in 5/19 cases (26%) without myocarditis (p < 0.05).     

LONGITUDINAL COMPARISON OF CARBOHYDRATE-DEFICIENT TRANSFERRIN AND GAMMA-GLUTAMYL TRANSFERASE: COMPLEMENTARY MARKERS OF EXCESSIVE ALCOHOL CONSUMPTION

The utility of carbohydrate-deficient transferrin (CDT) andgamma-glutamyl transferase (GGT) as biochemical markers of excessivealcohol consumption was studied in alcohol-dependent subjects.Serum samples were collected once weekly from 10 male out-patientsundergoing a 6-month alcohol treatment programme. Frequencyof relapse into drinking (defined as any intake of alcoholicbeverage) was assessed by self-reports during patient interviewsthree times per week and by daily determination of the 5-hydroxytryptophollevel in urine. A marked decrease in mean CDT and GGT valueswas observed during the initial month. Only one patient remainedtotally abstinent throughout the observation period, while fourhad sporadic relapses (2–5 days with alcohol consumption).Both CDT and GGT remained below the respective reference limitsin those patients. The other five patients drank more frequently(range 22–57 days) and increased their mean levels ofCDT and GGT after the initial decrease. As determined from thevalues at admission and during the course of the study, CDTappeared to be the most sensitive marker in six out of the 10patients. In one patient, both markers were affected in a parallelway, whereas two of those with frequent relapses responded toalcohol consumption with a marked increase in GGT, but withno or only a slight increase in CDT. One patient did not showany abnormal CDT or GGT values. In 54 female and 60 male serumsamples collected at random from patients during admission atan alcohol detoxification unit, 35% and 58% of the CDT valuesexceeded the reference limits for females and males, respectively.For GGT, 59% of the female and 67% of the male values were abovecut-off. Carbohydrate-deficient transferrin and GGT were notsignificantly correlated. Taken together, the present resultsindicate that measurement of both CDT and GGT will increasethe possibility of identifying excessive alcohol consumption.By following changes in CDT and GGT values during a period ofalcohol withdrawal, the most sensitive individual marker canbe determined. This in turn allows for improved detection ofrelapse into heavy drinking dunng long-term monitoring of out-patients.     

Effects of indomethacin on regional blood flow in conscious rabbits—a microsphere study

In an attempt to reveal the importance of prostaglandins in the control of regional blood flow 20 mg/kg b.wt. indomethacin was given i.v. in conscious resting rabbits. Regional blood flow determinations were made before and 20 min after the injection using the labelled microsphere technique. The blood flow in the stomach wall was reduced by 0.75 ± 0.17 g·min^-1·g^-1 from a level of 1.64 ± 0.24 g·min^-1·g^-1. In jejunum the corresponding figures were 0.44 ± 0.12 and 1.26 ± 0.17 and in the brain 0.29 ± 0.10 and 1.24 ± 0.10. The blood flow in the liver via the hepatic artery increased by 0.20 ± 0.02 g·min^-1·g^-1 from a level of 0.13 ± 0.02 g·min^-1·g^-1. In the retina there was a reduction in blood flow by 2.75 ± 1.03 mg·min^-1 from a starting level of 15.1 ± 2.3 mg·min^-1. In a number of other tissues investigated there were no significant effects of the drug. The results suggest that under resting conditions prostaglandins play a role in the control of blood flow in the gastrointestinal tract, the brain and the retina—tissues which are likely to be rather active under such conditions.     

Specificity of Cell-Mediated Lympholysis for Public and Private H-2 Determinants

The specificity of cell-mediated lympholysis in the mouse was investigated by studying the cross-reactivity of in vitro-generated effector cells against targets carrying H-2 haplotypes different from that of the stimulator. Congenic resistant partners of the C57BL/10 strain carrying ten different, independently derived haplotypes were tested in more than 600 combinations. Strong cytotoxicity was observed when stimulator and target cells shared a private determinant, but considerable cross-killing was also seen in combinations where stimulator and target cells shared only public determinants. Cross-killing is specific and can be blocked only by unlabeled cells of the stimulator or target strain. Although cross-killing does not correlate with the number of stimulating public determinants carried by the target individual determinants 5, 15. 25, and 27 + 28 + 29 are associated with increased cross-killing. Cross-killing can occur both at the K and the D end of H-2 and is not explained by antigens determined by the I region. We conclude that the serologically defined H-2K and H-2D molecules are the primary targets for cytotoxic T lymphocytes but that they may be perceived differently by T and B lymphocytes.     

PULMONARY VENTILATION AND GAS EXCHANGE BEFORE AND AFTER CORRECTION OF CONGENITAL CARDIAC MALFORMATIONS

Sixteen children with congenital cardiac malformations weredivided into cyanotic (n = 9) and acyanotic (n = 7) groups,and pulmonary ventilation and gas exchange were assessed beforesurgery, after sternotomy, just after the completion of cardiopulmonarybypass (CPB), 30 min after CPB and after closure of sternostomybefore transfer to ICU. Most patients in the cyanotic grouphad oligaemic, while all in the acyanotic group had overperfused,lungs before surgery. Total compliance was similar in the twogroups. Alveolar ventilation was higher and the physiologicaldeadspace to tidal volume ratio (Vd/Vt) lower in the acyanoticgroup compared with the cyanotic group (P < 0.05) beforesurgery. In the cyanotic group the preoperative large differencebetween arterial (Pa_CO2) and end-tidal (PE'_CO2) carbon dioxidetension was smaller immediately after CPB and remained so afterclosure of the sternum. In the acyanotic children the smallarterial to end-tidal carbon dioxide difference before CPB hadincreased Just after and 30 min after CPB, and Vo/Vr was significantlyincreased (P < 0.05) just after CPB. After closure of thesternum the arterial to end-tidal carbon dioxide differenceand the Vo/Vr ratio had returned to baseline. The arterial toend-tidal carbon dioxide difference is a good indicator of ventilatoryefficiency after open heart surgery.     

Immune hierarchy among HIV‐1 CD8+ T cell epitopes delivered by dendritic cells depends on MHC‐I binding irrespective of mode of loading and immunization in HLA‐A*0201 mice

Recent human immunodeficiency virus type 1 (HIV‐1) vaccination strategies aim at targeting a broad range of cytotoxic T lymphocyte (CTL) epitopes from different HIV‐1 proteins by immunization with multiple CTL epitopes simultaneously. However, this may establish an immune hierarchical response, where the immune system responds to only a small number of the epitopes administered. To evaluate the feasibility of such vaccine strategies, we used the human leukocyte antigen (HLA)‐A*0201 transgenic (tg) HHD murine in vivo model and immunized with dendritic cells pulsed with seven HIV‐1‐derived HLA‐A*0201 binding CTL epitopes. The seven peptides were simultaneously presented on the same dendritic cell (DC) or on separate DCs before immunization to one or different lymphoid compartments. Data from this study showed that the T‐cell response, as measured by cytolytic activity and γ‐interferon (IFN‐γ)‐producing CD8⁺ T cells, mainly focused on two of seven administered epitopes. The magnitude of individual T‐cell responses induced by immunization with multiple peptides correlated with their individual immunogenicity that depended on major histocompatibility class I binding and was not influenced by mode of loading or mode of immunization. These findings may have implications for the design of vaccines based on DCs when using multiple epitopes simultaneously.