If this occurs, then modification to existing oropharyngeal suction may be required, such as the use of Suction Assisted Laryngoscopy Airway Decontamination. High levels of oxygen are generally given during CPR. Tracheal intubation has not been found to improve survival rates or neurological outcome in cardiac arrest and in the prehospital environment may worsen it. Endotracheal tube and supraglottic airways appear equally useful. When done by EMS 30 compressions followed by two breaths appear better than continuous chest compressions and breaths being given while compressions are ongoing.For bystanders, CPR which involves only chest compressions results in better outcomes as compared to standard CPR for those who have gone into cardiac arrest due to heart issues. Mouth-to-mouth as a means of providing respirations to the patient has been phased out due to the risk of contracting infectious diseases from the patient. Mechanical chest compressions (as performed by a machine) are no better than chest compressions performed by hand. It is unclear if a few minutes of CPR before defibrillation results in different outcomes than immediate defibrillation. If cardiac arrest occurs after 20 weeks of pregnancy someone should pull or push the uterus to the left during CPR. If a pulse has not returned by four minutes emergency Cesarean section is recommended. Defibrillation
Defibrillation is indicated if an electric-shockable heart rhythm is present. The two shockable rhythms are ventricular fibrillation and pulseless ventricular tachycardia.
High frequency
The high frequency of mutations in the total genome within carcinomas suggests that, often, an early carcinogenic alteration may be a deficiency in DNA repair. For instance, mutation rates substantially increase (sometimes by 100-fold) in cells defective in DNA mismatch repairA deficiency in DNA repair, itself, can allow DNA damages to accumulate, and error-prone translesion synthesis past some of those damages may give rise to mutations. In addition, faulty repair of these accumulated DNA damages may give rise to epigenetic alterations or epimutations. While a mutation or epimutation in a DNA repair gene, itself, would not confer a selective advantage, such a repair defect may be carried along as a passenger in a cell when the cell acquires an additional mutation/epimutation that does provide a proliferative advantage. Such cells, with both proliferative advantages and one or more DNA repair defects (causing a very high mutation rate), likely give rise to the high frequency of total genome mutations seen in carcinomas. DNA repair
In somatic cells, deficiencies in DNA repair sometimes arise by mutations in DNA repair genes, but much more often are due to epigenetic reductions in expression of DNA repair genes. Thus, in a sequence of 113 colorectal carcinomas, only four had somatic missense mutations in the DNA repair gene MGMT, while the majority of these cancers had reduced MGMT protein expression due to methylation of the MGMT promoter region. Diagnosis
Carcinomas can be definitively diagnosed through biopsy, including fine-needle aspiration (FNA), core biopsy, or subtotal removal of single node,.