Elevated intrathoracic CO2 pressure during thoracoscopic surgery decreases regional cerebral oxygen saturation in neonates and infants-A pilot study.

BACKGROUND: Intraoperative hypercapnia and acidosis are risk factors during thoracoscopy in neonates and infants. METHODS: In a prospective pilot study, we evaluated the effects of thoracoscopy in neonates and infants on cerebral microcirculation, oxygen saturation, and oxygen consumption. Regional cerebral oxygen saturation and blood flow were measured noninvasively using a new device combining laser Doppler flowmetry and white light spectrometry. Additionally, cerebral fractional tissue oxygen extraction and approximated oxygen consumption were calculated. Fifteen neonates and infants undergoing thoracoscopy were studied using the above-mentioned method. The chest was insufflated with carbon dioxide with a pressure of 2-6 mm Hg. Single lung ventilation was not used. As control group served 15 neonates and infants undergoing abdominal surgery. RESULTS: Data are presented as median and range. The 95% confidence intervals for differences of means (95% CI) are given for the mean difference from baseline values. We observed a correlation between intrathoracic pressure exceeding 4 mm Hg and transient decrease in regional cerebral oxygen saturation of 12.7% (95% CI: 9.7-17.2, P<.001). Peripheral oxygen saturation was normal at the same time. Intraoperative increase in arterial paCO2 (median maximum value: 48.8 mm Hg, range: [36.5-65.4]; 95% CI: -16.0 to -3.0, P=.002) and decrease in arterial pH (median minimum value: 7.3, range: [7.2-7.4]; 95% CI: 0.04-0.12, P=.008) were observed during thoracoscopy with both parameters recovering at the end of the procedure. Periods of regional cerebral oxygen saturation below 20% from baseline were significantly more frequent during thoracoscopy as compared to the control group (median maximum value: 1.3%min/h, range: [0.0-66.2] vs median maximum value: 0.0%min/h, range: [0.0-4.0]; 95% CI: -16.6 to -1.1, P=.028). CONCLUSION: We suggest that thoracoscopic surgery in neonates and infants, although generally safe, may be associated with a decrease in regional cerebral oxygen saturation correlating with the applied intrathoracic pressure. According to our data an inflation pressure >4 mm Hg should be avoided during thoracoscopic surgery.

Susceptibility to infections and adaptive immunity in adults with heart failure.

AIMS: Heart failure (HF) is a systemic inflammatory disorder with infections being an important cause of morbidity and mortality. We asked if HF patients have a higher susceptibility to infections compared with the general population and if a subtle secondary immunodeficiency facilitates infectious complications. METHODS AND RESULTS: In a cohort of 92 patients with HF with reduced ejection fraction, we analysed recirculating lymphocyte subpopulations, serum immunoglobulin levels, and specific antibody titres against pneumococcal antigens. We quantified susceptibility to infections of the respiratory tract with a validated questionnaire and compared it to the general population. Susceptibility to infections of the respiratory tract was comparable in HF patients and the general population. Hypogammaglobulinaemia was present in 16% of HF patients, but anti-pneumococcal titres showed no evidence of specific secondary antibody deficiency. Relative lymphopaenia in our HF cohort was due to B lymphocytopenia with a relative reduction in naive B-cells and expansion of memory B-cells while CD4+ and CD8+ T-lymphocytes as well as NK-cell counts were comparable between HF and healthy donors. The intake of the angiotensin receptor neprilysin (CD10) inhibitor (ARNI) sacubitril/valsartan was associated with increased B-lymphocyte counts, possibly by an increased output of CD10+ transitional B lymphocytes from the bone marrow. CONCLUSION: Despite a reduction of B lymphocytes in HF and mild hypogammaglobulinaemia, patients showed no evidence of secondary immunodeficiency or increased susceptibility to infections. The relevance of B-cell lymphopenia in HF patients and modulation of B-cell counts under ARNI treatment remains to be investigated.