Blood pressure is a cardinal vital sign that gives important information about the cardiovascular function and about hemodynamic trends during anaesthesia, in critical ill patients and during experimental procedures (Rehman and Nelson, 2018). Arterial blood pressure can be evaluated by direct technique (arterial catheter) or indirect technique (Doppler or oscillometry). Direct measurement is gold standard for blood pressure measurement, giving accurate beat-to-beat information and also allow collection of blood samples. However, it is more invasive and requires equipment for monitoring and experience to place the arterial catheter (Araghi et al., 2006; Ward and Langton, 2007; Wingfield and Raffe, 2002). Given its importance in directing care, it is essential to measure blood pressure accurately and consistently.The aim of this article is to present all technique found in literature, with its advantages and disadvantages, with the errors that may occur so that the researchers can have a better knowledge before choosing their technique. For this study we took into consideration articles from literature and speciality books from which we extracted the information reliable for the study. Experimental studies on small laboratory animals, particularly rats are widely used as a model. Three methods are used for recording the blood pressure in rats: tail cuff (indirect technique), intra-arterial catheters (direct technique), and radio telemetry. Each technique has its advantages and disadvantages and each of it may lead to erroneous data if they are improperly performed. The vast ranges of these errors highlight the importance of adhering to appropriate technique when measuring blood pressure.

In a clinical setting, we tested the hypothesis of whether hypercapnia developed during carbon dioxide pneumoperitoneum is associated with changes in blood electrolytes. This prospective study involved ten female cats that underwent elective laparoscopic ovariectomy. Venous blood samples for assessment of electrolytes were collected in the following sequence: T1- before anaesthesia induction, T2 - 10 minutes after anaesthesia induction, T3 - 30 minutes of pneumoperitoneum and T4 - at the end of pneumoperitoneum. Statistical analysis revealed AB disturbances associated with general anaesthesia and pneumoperitoneum, manifested with decreased blood pH, whereas blood PvCO2, PO2 and BE were increased. A constant increase of K+ concentration was recorded in all animals during pneumoperitoneum (P<0.05), whereas iMg registered a significant increase only at T3 (P<0.05). Correlations were recorded between blood pH and Na+, iCa, iMg, as well as between Na+ and Cl¯ at different time points during anaesthesia. No correlations were noted between pH and K+ or PvCO2 and K+. In conclusion, electrolyte imbalance represents a possible complication associated with laparoscopic surgery in healthy cats. However, further studies should investigate the causes involved in K+ concentration elevation.