Objective To investigate the impact of permissive low-calorie feeding on nutritional status and prognosis in patients with severe pneumonia in the intensive care unit (ICU).

Methods A total of 100 patients with severe pneumonia in ICU were selected and divided into low-calorie feeding group and adequate feeding group using a random number table method, with 50 patients in each group. The low-calorie feeding group received permissive low-calorie feeding, and the adequate feeding group received adequate feeding, both conducting for a duration of one week. Clinical indicators, nutritional indicators, inflammatory indicators, respiratory function indicators, and intestinal mucosal barrier function indicators were compared between the two groups before treatment and one week after treatment. The incidence of hospital-acquired pneumonia (HAP) and complications (including septic shock, pulmonary edema, bronchiectasis, etc.) were also compared between the two groups.

Results The fever clearance time, mechanical ventilation time, and ICU stay duration were shorter in the low-calorie feeding group compared to the adequate feeding group (P < 0.05). There was no statistically significant difference in 28-day mortality between the two groups (P>0.05). After treatment, there were no statistically significant differences in serum total protein (TP), prealbumin (PA), hemoglobin (HGB), and albumin (ALB) levels between the low-calorie feeding group and the adequate feeding group (P>0.05). The levels of procalcitonin (PCT) and high-sensitivity C-reactive protein (hs-CRP) were lower in the low-calorie feeding group compared to the adequate feeding group (P < 0.05). The oxygenation index, ventilation volume, mean arterial pressure, and central arterial pressure were lower in the low-calorie feeding group compared to the adequate feeding group (P < 0.05). The levels of D-lactic acid and diamine oxidase (DAO) were also lower in the low-calorie feeding group compared to the adequate feeding group (P < 0.05). The incidence of HAP and complications was 4.00% and 10.00% in the low-calorie feeding group and 14.00% and 18.00% in the adequate feeding group, respectively, with no statistically significant differences (P>0.05).

Conclusion Permissive low-calorie feeding has a positive effect on the early recovery of ICU patients with severe pneumonia, which can improve respiratory function and intestinal mucosal barrier function and reduce inflammatory levels.