Compositions containing a carrier and microbubbles encapsulating one or more gases, preferably oxygen, and methods for making and using the compositions are described herein. The microbubbles contain a lipid envelope. The compositions may be administered to a patient to quickly deliver large amounts of oxygen to the patient's blood supply or directly to a tissue in need of oxygen. The compositions may be administered via injection or as a continuous infusion. The compositions contain a concentrated microbubble suspension, where the suspension contains at least 40 mL oxygen/dL suspension. The microbubbles are preferably less than 20 microns in diameter, more preferably less than 15 microns in diameter. The microbubbles described herein may be administered to a patient in an effective amount to increase in oxygen concentration in the patient's blood, and/or one or more tissues or organs.