Even as a special freight train, Oxygen Express, carrying 51,000 litres of medical oxygen in three tankers arrived in Uttar Pradesh from Bokaro on Saturday, problems continue for patients in home isolation.The state government has made it mandatory for patients in home isolation to produce doctor's prescription before they can buy oxygen cylinders.Lokendra Tripathi, who needs oxygen for his father, 83, and mother, 79, "I need to keep oxygen for an emergency situation and no doctor is ready to give a prescription even though they verbally advise me to keep a cylinder at hand. Both the parents are Covid positive though they are asymptomatic at the moment."Meanwhile, the Oxygen Express has brought some relief to the pandemic-battered state. The supplementary supply will provide a more than a 48-hour buffer for over 1,000 patients with low oxygen saturation, sources said.Indian Medical Association, Lucknow head, Dr. Rama Srivastava, said, "We were told 38,000 litres has arrived in Lucknow. The supplementary supply will be a lifesaver for 800-1,000 patients with critical oxygen saturation levels in Lucknow. A Covid patient with poor oxygen saturation easily consumes 50 litre of jumbo cylinder in 24 hours. More O2 tankers are in queue to reach UP."Bipin Mishra, the additional district magistrate (finance), said: "We expect the supply of O2 delivered to Lucknow will last up to three-four days. The seven O2 plants in city will disburse the life-saving gas to government and private hospitals as well as individuals isolated in their homes after Covid infection."Divisional Commissioner Ranjan Kumar said: "The oxygen supply from Bokaro has been sent to hospitals in Lucknow and Barabanki. Some supplies have been diverted to patients in home isolation."Sanjay Tripathi, divisional railway manager of Northern Railways, Lucknow division, said: "Four empty tankers left for Bokaro on Saturday morning prior arrival of refilled three tankers, including two at Lucknow and one in Varanasi.""Similarly, by evening, at least four more empty tankers were being prepared to dispatch Bokaro."