Final answer:
Immediate follow-up is needed for the full-thickness burns on the chest and neck, SaO₂ of 89 indicating hypoxemia, and the elevated heart rate of 150/min, which may suggest distress or other physiological responses to critical conditions.
Step-by-step explanation:
The nurse should identify that the findings which require immediate follow-up are the partial- and full-thickness burns to the left upper anterior chest and anterior neck, the SaO₂ of 89, and the heart rate of 150/min. The presence of burns, especially of full-thickness nature and located on critical areas such as the chest and neck, are very serious due to risk of complications like infections and compromised airways. Having an oxygen saturation level (SaO₂) below 90 is indicative of hypoxemia and requires prompt intervention to improve the oxygenation of the tissues. A heart rate of 150/min could suggest a response to pain, distress, hypoxemia, or other complications, also warranting immediate attention. The temperature and blood pressure are less concerning in this context, but should still be monitored closely.