Heart rate increment analysis is not effective for sleep-disordered breathing screening in patients with chronic heart failure

Frequency domain analysis of heart rate variation has been suggested as an effective screening tool for sleep-disordered breathing (SDB) in the general population. The aim of this study was to assess this method in patients with chronic congestive heart failure (CHF). We included prospectively 84 patients with stable CHF, left ventricular ejection fraction (LVEF) <45% and sinus rhythm. The patients underwent polygraphy to measure the apnoea/hypopnoea index (AHI) and simultaneous Holter electrocardiogram monitoring to measure the power spectral density of the very low frequency component of the heart rate increment, expressed as the percentage of total power spectral density [% very low frequency increment (%VLFI)]. %VLFI could be determined in 54 patients (mean age, 52.8 ± 12.3 years; LVEF, 33.5 ± 9.8%). SDB defined as AHI ≥15 h⁻¹ was diagnosed in 57.4% of patients. Percent VLFI was not correlated with AHI ( r  =   0.12). Receiver-operating characteristic curves constructed using various AHI cut-offs (5–30 h⁻¹) failed to identify a %VLFI cut-off associated with SDB. The 2.4% VLFI cut-off recommended for the general population of patients with suspected SDB had low specificity (35%) and low positive and negative predictive values (35% and 54%, respectively). Heart rate increment analysis has several limitations in CHF patients and cannot be recommended as an SDB screening tool in the CHF population.     

Blood Coagulation Factors in Total Body Irradiation

Investigation of the clotting factors in five humans accidentally exposed tototal body irradiation disclosed no deficiencies. There was no evidence of acirculating anticoagulant in any case. Moderate fibrinolysis was seen in twoinstances in the same individual but was not evident in the others. At theeleventh day there was uniformly a moderate increase in the levels of fibrinogen. At the twenty-ninth day there was observed an increase in the levels offactors V and VIII coincidental with thrombocytopenia. This change reverseditself with recovery. A similar increase in the levels of factor VIII and less soof factor V was seen in cases of idiopathic thrombocytopenic purpura andsecondary thrombocytopenia. An increase in level of factor VIII was observedin patients on oral coumarin anticoagulation. It is concluded that the supernormal levels of factors V and VIII are secondary to lowered thrombin levelsin the circulating plasma as a result of the thrombocytopenia and not duedirectly to the effect of irradiation.

Submitted on June 12, 1961 Accepted on September 15, 1961     

Effect of quinolone antibiotics on hepatic growth and protein synthesis following partial hepatectomy in rats

Quinolone antibiotics inhibit eukaryotic as well as prokaryotic cell growth and protein synthesis. To determine whether these properties adversely affect hepatic growth and recovery following surgical resection, five groups of healthy, adult male rats (n = 7–8/group) were treated for 10 days with equal volumes of either ofloxacin (50 mg/kg), fleroxacin (25mg/kg), ciprofloxacin (25 mg/kg), norfloxacin (15mg/kg) or sterile saline (controls) prior to 70% partial hepatectomy (PH) and daily thereafter until death. Restituted liver mass, DNA and protein synthesis rates were determined at 24, 48 and 72 h PH. The results of the study revealed that all parameters of hepatic regeneration were similar in the five study groups at each time interval. To ensure that an effect on hepatic regeneration was not dose-dependent, additional experiments were performed where 1, 10 and 100 mg/kg ciprofloxacin was administered and DNA synthesis was measured 24 h post-PH. Once again, the results were similar to sterile saline-treated controls. These findings suggest that the quinolone antibiotics are unlikely to have an adverse effect on hepatic recovery following surgical resection of the liver and are safe to use in that setting.