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Intraperitoneal injection of oligomycin into the rat (0.5 mg per kg, corresponding to the LD33 dose) reduces the oxygen consumption by about 50%, whereas the arterial pO2 remains normal. The large extent of this decrease points to an involvement of liver and muscle tissue. Triiodothyronine pretreatment (3 doses of 0.075 mg/100 g body weight) is not able to prevent this effect. From the blood metabolites measured glucose, pyruvate and the parameters of lipid metabolism remain unchanged; only lactate is significantly increased, causing compensated metabolic acidosis. Heart rate, systolic blood pressure and electrocardiogram are essentially unchanged. Oliguria, reduced renal excretion of urea and increase of plasma urea also indicate a nephrotoxic action. The results are discussed in comparison with some effects of experimental uremia.

Background Transient diaphragm dysfunction is common during the first week after cardiac surgery; however, the precise incidence, risk factors, and outcomes of persistent diaphragm dysfunction are not well described. Methods In a single-centre prospective cohort study, we included all consecutive patients over 18 yr who underwent elective cardiac surgery. Diaphragm function was evaluated with ultrasound (M-mode) by recording the excursion of both hemidiaphragms at two different time points: preoperatively and after the seventh postoperative day in patients breathing without assistance. Significant diaphragm dysfunction after the seventh day of the index cardiac surgery was defined as a decrease in diaphragm excursion below the lower limit of normal: at rest, < 9 mm for women and < 10 mm for men; after a sniff test, < 16 mm for women and < 18 mm for men. Results Overall, 122 patients were included in the analysis. The median [interquartile range (IQR)] age was 69 [59–74] years and 96/122 (79%) were men. Ten (8%) patients had diaphragm dysfunction after the seventh postoperative day. We did not identify risk factors for persistent diaphragm dysfunction. Persistent diaphragm dysfunction was associated with a longer median [IQR] duration of noninvasive (8 [0–34] vs 0 [0–0] hr; difference in medians, 8 hr; 95% confidence interval [CI], 0 to 22; P < 0.001) and invasive mechanical ventilation (5 [3–257] vs 3[2–4] hr; difference in medians, 2 hr; 95% CI, 0.5 to 41; P = 0.008); a higher reintubation rate (4/10, 40% vs 1/112, 0.9%; relative risk, 45; 95% CI, 7.1 to 278; P < 0.0001), a higher incidence of pneumonia (4/10 [40%] vs 7/112 [6%]; relative risk, 6; 95% CI, 2 to 16; P < 0.001), and longer median [IQR] length of stay in the intensive care unit (8 [5–29] vs 4 [2–6] days; difference in medians, 4 days; 95% CI, 2 to 12; P = 0.002). Conclusion The incidence of persistent diaphragm dysfunction was 8% in patients undergoing elective cardiac surgery and was associated with adverse respiratory outcomes. Study registration ClinicalTrials.gov (NCT04276844); prospectively registered 19 February 2020. Supplementary Information The online version contains supplementary material available at 10.1007/s12630-022-02360-8.

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