The numbers of coronavirus patients needing life-or-death care have been doubling every three days, a report by senior doctors has revealed. London is worst affected, but the rest of the UK will soon be hit with a similar surge, the document warns.

The audit of intensive care carried out since the epidemic began shows that patients needing the highest level of help soared from 50 on 9 March to almost 200 on 19 March – and doctors fear this spike could turn into a nationwide surge within a few weeks.

The report, by the Intensive Care National Audit and Research Centre analyses all admissions to critical care units in the UK up until midnight last Thursday. London treated 54% of 196 patients, although the rest of England could start to catch up within seven to 14 days. “Other regions, especially in urban areas, would be wise to see what is happening in London and use lessons from London to assist in their preparation,” one specialist said.

The report also provides the first in-depth profile of those who have needed intensive care. Most (139) were male, 71% of all cases; the median age was 64 although 37% were under 60; only 18 patients had “severe co-morbidities”, such as underlying heart conditions or lung disease; while 63% were overweight, obese or morbidly obese. Two patients had been pregnant within the last six weeks.

In a narrower study of 33 of the patients, it was found 16 died while 17 survived to be discharged to lower-level care. These patients spent an average of three days in intensive care before dying or being transferred, which if replicated could relieve the intense pressure on hospitals.

On Saturday it was announced there were 56 new UK deaths, triggering fears that hospitals could run out of intensive care beds in weeks. Already, London hospitals are struggling to cope as staff are forced to self-isolate. One teaching hospital in the capital has 300 absent staff, the Observer understands.

Simon Walsh, deputy chair of the British Medical Association’s consultants committee, said: “Unless the trajectory is very significantly changed by the government’s measures, then the demands at the peak are going to massively exceed our critical care bed capacity across the UK.”

Northwick Park hospital in north London had to declare a “critical incident” last Thursday because it had too few available staff to intubate its intake of seriously ill coronavirus patients, the Observer understands.

Facebook Twitter Pinterest Northwick Park hospital. Photograph: Anthony Devlin/PA

Larger, urban hospitals have been turning specialist wards into intensive care units to deal with the crisis, but rural hospitals have relatively few ICU beds but a more elderly population, Walsh warned. Models suggest London needs a 130% rise in critical care capacity. “But in rural locations it would have to increase by 600%. You can imagine that’s difficult if not impossible to achieve. Which means patients being transferred to urban centres, which brings new challenges.”

On Saturday it was announced that more beds, ventilators and 20,000 qualified extra staff would be made available from next week – thanks to a deal between NHS England and private hospitals. The extra resources should also help the NHS to deliver other urgent operations and cancer treatments, said an official.

It has also been revealed that taxis are delivering vital personal protective equipment (PPE) amid concerns there is a mask shortage in key regions. In some cases staff are being given out-of-date equipment, some of which has been rebadged as fit for purpose, unions say. Rachel Harrison, of the GMB union, which represents NHS ambulance workers, said moves to take over the PPE delivery by the NHS and the Department of Health were welcome but added that some regions were struggling to get the equipment. “The main issue is that the stuff that is coming through, particularly masks, is out of date,” some by seven years, she added.

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Lisa Anderson, a consultant cardiologist at London’s St George’s hospital, said staff were not getting the equipment they need. She said the government had changed NHS rules and was no longer compliant with World Health Organisation recommendations, which require a full gown and visor. NHS staff only have to wear a simple face mask, short gloves and a pinafore apron. “This is not just about the risk to us and our families. We are travelling home on the tube, on buses,” she told BBC Radio 4. “We are cross-infecting everybody at the moment.”

Susan Hopkins, deputy director of the national infection service at Public Health England, said: “The recommended PPE includes a fluid resistant surgical mask, single-use disposable apron, and gloves and eye protection if required. Higher-level PPE is available.” NHS guidance recommends the same masks as WHO but the UK has long had a “bare below the elbows” policy, which PHE says allows optimum hand hygiene, although full-sleeve gowns are recommended for high-risk procedures.