All are true about Flail chest, except:

Ans is 'd' i.e. Paradoxical movement may not be seen in conscious patients Flail chest is simply when a poion of the bony chest wall loses its continuity from the remainder of the thorax due to multiple fractures. By definition, a flail chest occurs in the presence of two or more fractures in three or more consecutive ribs (either on one side of the chest or either side of the sternum) and causes instability of the chest wall: however, it can also occur after costochondral separation. Flail chest is characterized by paradoxical motion of the chest wall (inward with inspiration and outward with expiration). The chance of having an intrathoracic injury in this situation increases severalfold. The paradoxical motion increases the work of breathing, and the most impoant consequence of flail chest is respiratory failure. Until recently it was believed that ineffective air movement between both lungs caused by paradoxical motion of the chest wall was the main cause of the respiratory distress in patients with flail chest. It is now understood that underlying pulmonary contusion and pain during inspiration are the most impoant components in the pathophysiology of the respiratory failure. Management: Patients without evidence of respiratory distress can be managed with only analgesia. Pain control can be provided by an intercostal nerve block or more adequately by epidural anesthesia. If respiratory distress develops, endotracheal intubation and mechanical ventilation with peak end-expiratory pressure are usually indicated, provided that pain control is adequate. - Sequential aerial blood gas determination may gauge the severity of an injury and is useful to predict which patients will require ventilatory suppo.The ratio of aerial oxygen tension to the fraction of inspired oxygen (Pa02:Fi02 ratio) yields an estimate of the extent of intrapulmonary shunt and may be used as a parameter to determine the need for mechanical ventilation. - Schwaz 7/e p689 writes-"1ntubation is delayed until clear evidence of a need of ventilator suppo develops: a respiratory rate of 40/min, a falling PaCO2 (evidence of excessive work of breathing) or a Pa02 below 60 Corr on inspired 02 fraction of over 0.5" - General Thoracic Surgery By Thomas W. Shields 7/e p894 writes-"Suggested parameters for instituting ventilator suppo are respiratory rate >30 breaths per minute, Pa02 45mm Hg." Open reduction plus internal fixation of sternal or rib fractures is rarely needed.