A method, connector and system for obtaining an indirect measurement of a parameter in a patient with a total liquid ventilation (TLV) system. At least one parameter measurement is obtained of a liquid taken in the TLV system comprising an endotracheal tube having a distal end inserted in a patient's trachea. At least one flow measurement is obtained of a liquid taken in the TLV system. Considering a fluid model of the TLV system, the at least one parameter measurement and the least one flow measurement are processed into the indirect measurement of the parameter in the patient. The indirect measurement may be a temperature or pressure. The temperature can be a lung temperature, a blood temperature or an organ temperature. The pressure may be a tracheal pressure or an alveolar pressure.