Prone Positioning of Intubated Patients with an Elevated Body-Mass Index

Hemodynamic changes in the prone position according to fluid loading after anaesthesia induction in patients undergoing lumbar spine surgery: a randomized, assessor-blind, prospective study

INTRODUCTION

A change from the supine to prone position causes hemodynamic alterations. We aimed to evaluate the effect of fluid preloading in the supine position, the subsequent hemodynamic changes in the prone position and postoperative outcomes.

PATIENTS AND METHODS

This prospective, assessor-blind, randomized controlled trial was conducted between March and June 2023. Adults scheduled for elective orthopaedic lumbar surgery under general anaesthesia were enrolled. In total, 80 participants were randomly assigned to fluid maintenance (M) or loading (L) groups. Both groups were administered intravenous fluid at a rate of 2 ml/kg/h until surgical incision; Group L was loaded with an additional 5 ml/kg intravenous fluid for 10 min after anaesthesia induction. The primary outcome was incidence of hypotension before surgical incision. Secondary outcomes included differences in the mean blood pressure (mBP), heart rate, pleth variability index (PVi), stroke volume variation (SVV), pulse pressure variation (PPV), stroke volume index and cardiac index before surgical incision between the two groups. Additionally, postoperative complications until postoperative day 2 and postoperative hospital length of stay were investigated.

RESULTS

Hypotension was prevalent in Group M before surgical incision and could be predicted by a baseline PVi >16. The mBP was significantly higher in Group L immediately after fluid loading. The PVi, SVV and PPV were lower in Group L after fluid loading, with continued differences at 2-3 time points for SVV and PPV. Other outcomes did not differ between the two groups.

CONCLUSION

Fluid loading after inducing general anaesthesia could reduce the occurrence of hypotension until surgical incision in patients scheduled for surgery in the prone position. Additionally, hypotension could be predicted in patients with a baseline PVi >16. Therefore, intravenous fluid loading is strongly recommended in patients with high baseline PVi to prevent hypotension after anaesthesia induction and in the prone position.

TRIAL NUMBER

KCT0008294 (date of registration: 16 March 2023).

Central venous accesses in prone position during the pandemic period: A narrative review

The unprecedented challenges posed by the global COVID-19 pandemic have magnified the significance of managing intensive care patients in prone positions, particularly those requiring mechanical ventilation. Central venous access is crucial for delivering essential therapies to patients, particularly in intensive care settings. However, the shift in patient management during the pandemic, necessitating prone positioning for improved oxygenation, presented unique hurdles in maintaining and establishing central venous access. Before the pandemic, scant literature detailed the insertion of vascular access devices in prone or unconventional positions. Limited case reports and letters highlighted the feasibility of procedures like ultrasound-guided central catheter placement in patients undergoing surgery or with specific clinical needs. During the pandemic, a surge in case reports and series illuminated the complexities faced by clinicians in maintaining vascular access during pronation procedures. These reports delineated critical scenarios, ranging from rapid clinical deterioration necessitating immediate interventions to challenges with vascular access device (VAD) malfunctions or misplacements during prone maneuvers. Patient selection and device types emerged as critical considerations. Various scenarios, including patients transitioning to prone position from non-invasive ventilation and those requiring additional access for therapies like dialysis, posed challenges in device selection and placement. Successful VAD insertion techniques in prone patients encompassed multiple anatomical sites, including the internal jugular, brachial, femoral, and popliteal veins. However, challenges persisted, particularly with respect to anatomical variations and technical complexities in cannulation. Further research, standardized protocols, and randomized studies are needed to refine and validate the proposed strategies in both pandemic and non-pandemic settings.

Effect of prone positioning on gas exchange according to lung morphology in patients with acute respiratory distress syndrome

BACKGROUND

There are limited data on the clinical effects of prone positioning according to lung morphology. We aimed to determine whether the gas exchange response to prone positioning differs according to lung morphology.

METHODS

This retrospective study included adult patients with moderate-to-severe acute respiratory distress syndrome (ARDS). The lung morphology of ARDS was assessed by chest computed tomography scan and classified as "diffuse" or "focal." The primary outcome was change in partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) ratio after the first prone positioning session: first, using the entire cohort, and second, using subgroups of patients with diffuse ARDS matched 2 to 1 with patients with focal ARDS at baseline.

RESULTS

Ninety-five patients were included (focal ARDS group, 23; diffuse ARDS group, 72). Before prone positioning, the focal ARDS group showed worse oxygenation than the diffuse ARDS group (median PaO2/FiO2 ratio, 79.9 mm Hg [interquartile range (IQR)], 67.7-112.6 vs. 104.0 mm Hg [IQR, 77.6-135.7]; P=0.042). During prone positioning, the focal ARDS group showed a greater improvement in the PaO2/FiO2 ratio than the diffuse ARDS group (median, 55.8 mm Hg [IQR, 11.1-109.2] vs. 42.8 mm Hg [IQR, 11.6-83.2]); however, the difference was not significant (P=0.705). Among the PaO2/FiO2-matched cohort, there was no significant difference in change in PaO2/FiO2 ratio after prone positioning between the groups (P=0.904).

CONCLUSIONS

In patients with moderate-to-severe ARDS, changes in PaO2/FiO2 ratio after prone positioning did not differ according to lung morphology. Therefore, prone positioning can be considered as soon as indicated, regardless of ARDS lung morphology.