Two women were in critical condition on life-support machines last night after smoke suffocated them, doctors said. They were unlikely to regain consciousness, the chief of services at the Princess Margaret Hospital intensive care unit, Dr Yan Wing-wah, said. Dr Yan said the two women were displaying no brain reaction and their hearts had stopped while the doctors fought to save their lives. One of the paediatricians treating a two-year-old boy admitted for smoke inhalation said it was imperative the child and other victims be observed over the next 24 hours. Dr Aaron Yu Chak-man said: 'The important thing is to secure the airway. We have to put in ventilation, pump air into the lungs.' It could be hours before symptoms of prolonged smoke inhalation become apparent, he said. Asphyxiation distress was another danger, and doctors had to look out for carbon monoxide poisoning. In effect the smoke burns the airways and carbon monoxide poisoning can be fatal within minutes, bringing about a death 'even more rapid than the effect of burns', Dr Yu said. In a strange twist, one fire victim - Cheung Yee-man, 30 - was reported missing from the hospital.