Measurement of respiratory function: gas exchange and its clinical applications

Gas exchange is the main function of the lungs. Lungs have a large reserve for gas exchange. Oxygen and carbon dioxide diffuse along their partial pressure gradient across the alveolar–capillary membrane. Alveolar ventilation and pulmonary circulation are closely matched to provide efficient gas exchange in the lungs. Hypoxaemia often results from mismatch in ventilation–perfusion. Gas exchange can be impaired in various disease states. Measurement of the diffusing capacity for carbon monoxide (DLCO) provides estimation of the gas exchange function. A low DLCO indicates an impairment of oxygen transfer across the alveolar–capillary membrane. Based on the lung function tests one can assess the risks of perioperative pulmonary complications. Anaesthesia and surgery adversely affect pulmonary function, many of which adverse effects can be prevented.     

The effects of atorvastatin treatment on the fibrinolytic system in dyslipidemic patients

Statins have pleiotrophic effects related to the pathogenesis of atherosclerosis and thrombogenicity of the vessel wall beyond lipid lowering. The aim of the present study was to examine the effect of atorvastatin treatment on the fibrinolytic system in patients with dyslipidemia. The investigation was carried out on 41 dyslipidemic patients (21 males and 20 females) with a mean age of 53.8 years (range, 30-76). The patients were divided into subgroups according to their cholesterol and triglyceride levels as hypercholesterolemic (n = 26) and mixed-type hyperlipidemic (n = 15) and their risk factors for coronary heart disease including age, sex, hypertension, obesity, smoking, and family history. The patients were started on atorvastatin 10 mg/day, and evaluated within 6-12 weeks to assess the changes in fibrinolytic parameters including global fibrinolytic capacity, plasminogen activator inhibitor type-1 and tissue plasminogen activator, and lipids. After successful lipid-lowering therapy, global fibrinolytic capacity (P = 0.003) and tissue plasminogen activator levels (P = 0.04) were found to be increased and plasminogen activator inhibitor type-1 levels (P = 0.02) decreased in dyslipidemic patients. Global fibrinolytic capacity levels increased (P < 0.001) and plasminogen activator inhibitor type-1 levels decreased (P = 0.01) in patients with hypercholesterolemia (n = 26). However, no significant changes were observed in fibrinolytic parameters in patients with mixed-type hyperlipidemia (n = 15). When the patients were separately evaluated according to risk factors, significant beneficial effects on the fibrinolytic system were observed, especially in patients without obesity and hypertension as well as in older patients and males. These findings suggest that atorvastatin treatment has a beneficial effect on the fibrinolytic system in patients with hypercholesterolemia, but not in patients with mixed-type hyperlipidemia. Further studies are needed to show whether higher doses and longer periods of lipid lowering treatment have beneficial effects in patients with mixed type hyperlipidemia and some risk factors.     

The Effects of Two Different Anaesthesia Techniques on Bispectral Index Values and Awareness During Off-Pump Coronary Artery Bypass Grafting

Objective. The aim of this study was to evaluate Bispectral Index values and awareness during two different anaesthesia regimens (fentanyl-propofol and fentanyl-midazolam) in patients undergoing off-pump CABG surgery. Methods. Fifty patients were included in the study. Patients were premedicated with midazolam and were randomly divided into two groups. Anaesthesia was induced with fentanyl (7–15 μg/kg), with either propofol (2–2.5 mg/kg, Group I) or midazolam (0.1–0.3 mg/kg, Group II) and vecuronium (0.1 mg/kg). Anaesthesia was maintained with fentanyl (15 μg/kg/h) together with either propofol (6 mg/kg/h) or midazolam (0.1 mg/kg/h). Depth of anaesthesia was adjusted according to clinical signs and haemodynamic responses. The level of sedation was monitored with Bispectral index continuously, but these levels were not shown to the attending anaesthetist. Bispectral index values were recorded for nine phases. Twenty-four hours after the operation, the patients were interviewed to determine intraoperative awareness and recall. Results. In all patients, Bispectral index values were found to decrease after induction (in Group I, p = 0.005, in Group II, p = 0.008) with the mean values remaining below 60 for all phases. The differences between the groups were not statistically significant in inter-group comparison. No patients were noted to recall the sounds presented during the operation and the preoperative events. Conclusions. BIS monitoring with clinical signs may be used to assess the adequacy of both types of anaesthesia techniques as well as to detect awareness during off-pump CABG surgery.     

Adrenocortical and hemodynamic predictors of pain perception in men and women

Research has demonstrated that women report more pain than men, and clinical observations suggest that attenuated adrenocortical activity is associated with high pain sensitivity. The extent to which cortisol concentrations and hemodynamics contribute to gender differences in pain sensitivity has not been investigated. Thirty-four women and 31 men performed the hand cold pressor test (CPT). Participants rated their pain every 15 s during a 90-s CPT and a 90-s post-CPT recovery period and reported pain using the McGill Pain Questionnaire (MPQ). Salivary cortisol samples and cardiovascular measures were collected prior to, during, and after the CPT. Women reported greater pain than men during and after the CPT and on the MPQ (Ps<0.01). CPT disrupted the expected diurnal decline in cortisol, as shown by a significant increase in cortisol concentration post-CPT (P<0.01) in men and women. Regression analyses revealed that pre-CPT cortisol concentrations predicted lower pain reports during and after CPT in men only (P<0.01). Systolic blood pressure (BP) and stroke volume correlated negatively with pain reports only in women (Ps<0.05). Controlling for potential confounding variables did not alter these relationships. The negative association between pre-CPT cortisol and pain perception in men and the association between BP and pain in women demonstrate different physiological predictors of pain perception in men and women.     

Caffeic acid phenethyl ester as a protective agent against doxorubicin nephrotoxicity in rats

BACKGROUND: Nephrotoxicity is one of the important side effects of antracycline antibiotics. The aim of this study was to investigate the effects of caffeic acid phenethyl ester (CAPE), an antioxidant agent, against nephrotoxicity induced by doxorubicin (DXR). METHODS: The rats were divided into control, CAPE alone, doxorubicin (20 mg/kg, i.p.) and doxorubicin plus CAPE (10 micromol/kg/day, i.p.) groups. At the end of the 10th day, kidney tissues were removed for light microscopy and analysis. The levels of tissues protein carbonyl content (PC), malondialdehyde (MDA) and nitric oxide (NO) as well as the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and myeloperoxidase (MPO) were determined. Plasma oxidants and antioxidants were also measured. RESULTS: The activities of CAT and GSH-Px were decreased as well as myeloperoxidase, NO, MDA and PC were increased in renal tissue of doxorubicin group compared with the other groups. Plasma GSH-Px activity was higher in doxorubicin plus CAPE group than the others and plasma MDA level was higher in doxorubicin group than the other groups. There were glomerular vacuolization, tubular desquamation, loss of brush border, and adhesion to Bowman's in the light microscopy in the kidneys of doxorubicin group. The tubules and brush border were almost normal and some of the glomerulus was filled with fine vacuoles in CAPE treated rats. CONCLUSION: Doxorubicin caused renal injury and CAPE treatment prevented lipid peroxidation and protein oxidation in renal tissue and partially preserved glomerulus and tubules.