This study proposes a methodology for the oil and gas businesses to keep their production plant productive with a minimum investment in carrying maintenance, repair, and operating inventory planning. The goal is to assist the exploration and production companies in minimizing the investment in keeping maintenance, repair, and operating (MRO) inventory for improving production plant uptime. The MRO inventory is the most expensive asset and it requires substantial investment. It helps in keeping the oil and gas production plant productive by performing planned and unplanned maintenance activities. A (Q, r) model with a stock-out and backorder cost approach is combined with a continuous inventory review policy for the analysis of class A items of oil and gas production plant MRO inventory. The class A items are identified through popular ABC analysis based on annual dollar volume. The demand for the inventory is modeled through Poisson distribution with consideration of constant lead time. The (Q, r) model in both stock-out cost and backorder cost approaches assigned higher order frequency and lower service level to low annual demand and highly expensive items. The stock-out cost approach shows an 8.88% increase in the average service level and a 56.9% decrease in the company average inventory investment. The backorder cost approach results in a 7.77% increase in average service level and a 57% decrease in average inventory investment in contrast to the company’s existing inventory management system. The results have a direct impact on increasing plant uptime and productivity and reducing company maintenance cost through properly managing maintenance stock. The analysis is carried out on the oil and gas production plant’s MRO inventory data, but it can be applied to other companies’ inventory data as well. All the results reflected in this research are based on the inventory ordering policy of two orders per year. The inventory ordering frequency per year may be other than two orders per year depending on the type of organization.

The aim of this study was to compare the in-hospital outcomes of multiport antegrade cold blood cardioplegia through vein grafts versus conventional antegrade cold blood cardioplegia in patients with left ventricle systolic dysfunction who underwent coronary artery bypass grafting (CABG). This prospective, randomized clinical study was comprised of patients undergoing on-pump CABG at the Ch. Pervaiz Elahi Institute of Cardiology in Multan, Pakistan from November 18, 2018 to December 17, 2019. Patients with multivessel coronary artery disease and left ventricular systolic dysfunction (ejection fraction < 50%) were included. In Group A (N = 73), multiport antegrade cold blood vein graft cardioplegia was given after every distal anastomosis completed for myocardial preservation. In Group B (N = 73), conventional antegrade cold blood cardioplegia was given for myocardial preservation. Spontaneous rhythm (without defibrillation applied) after cross-clamp removal was higher in Group A than in Group B (93.3% vs. 85.2%, p < 0.05). Duration of support, ventilation time, and hospital stay were also significantly lower in Group A than in Group B with p = 0.00001, p = 0.03, and p = 0.002, respectively. Intra-aortic balloon pump insertion (4.1% vs. 23.0%, p = 0.02) and operative mortality (0.5% vs. 4.0%, p = 0.35) were also lower in Group A than in Group B. Postoperative left ventricular ejection fraction (LVEF) increased more in Group A than in Group B, and the postoperative LVEF mean value was 44.68% in Group A versus 41.26% in Group B (p = 0.02). Multiport vein graft blood cardioplegia provides superior myocardial protection in patients with left ventricular systolic dysfunction who underwent CABG. It is also easy to administer, so this technique can be adopted as a routine method for myocardial protection in patients with left ventricular dysfunction planned for on-pump CABG.