Massimiliano Guglielmi

Effects of the Beach Chair Position, Positive End-expiratory Pressure, and Pneumoperitoneum on Respiratory Function in Morbidly Obese Patients during Anesthesia and Paralysis

Background:The authors studied the effects of the beach chair (BC) position, 10 cm H2O positive end-expiratory pressure (PEEP), and pneumoperitoneum on respiratory function in morbidly obese patients undergoing laparoscopic gastric banding. Methods:The authors studied 20 patients (body mass index 42 ± 5 kg/m2) during the supine and BC positions, before and after pneumoperitoneum was instituted (13.6 ± 1.2 mmHg). PEEP was applied during each combination of position and pneumoperitoneum. The authors measured elastance (E,rs) of the respiratory system, end-expiratory lung volume (helium technique), and arterial oxygen tension. Pressure–volume curves were also taken (occlusion technique). Patients were paralyzed during total intravenous anesthesia. Tidal volume (10.5 ± 1 ml/kg ideal body weight) and respiratory rate (11 ± 1 breaths/min) were kept constant throughout. Results:In the supine position, respiratory function was abnormal: E,rs was 21.71 ± 5.26 cm H2O/l, and end-expiratory lung volume was 0.46 ± 0.1 l. Both the BC position and PEEP improved E,rs (P < 0.01). End-expiratory lung volume almost doubled (0.83 ± 0.3 and 0.85 ± 0.3 l, BC and PEEP, respectively; P < 0.01 vs. supine zero end-expiratory pressure), with no evidence of lung recruitment (0.04 ± 0.1 l in the supine and 0.07 ± 0.2 in the BC position). PEEP was associated with higher airway pressures than the BC position (22.1 ± 2.01 vs. 13.8 ± 1.8 cm H2O; P < 0.01). Pneumoperitoneum further worsened E,rs (31.59 ± 6.73; P < 0.01) and end-expiratory lung volume (0.35 ± 0.1 l; P < 0.01). Changes of lung volume correlated with changes of oxygenation (linear regression, R2 = 0.524, P < 0.001) so that during pneumoperitoneum, only the combination of the BC position and PEEP improved oxygenation. Conclusions:The BC position and PEEP counteracted the major derangements of respiratory function produced by anesthesia and paralysis. During pneumoperitoneum, only the combination of the two maneuvers improved oxygenation.

Ventricular Dilation Is Associated With Improved Cardiovascular Performance and Survival in Sepsis

OBJECTIVES Myocardial dysfunction in sepsis may be associated with changes in left ventricular (LV) size. The goal of this study was to evaluate the impact of myocardial dysfunction and changes in LV diameter on hemodynamics and survival in a murine model of sepsis. METHODS C57Bl/6 mice (N = 30) were used. Septic mice (n = 24) had cecal ligation and puncture (CLP) followed by fluid and antibiotic resuscitation and control mice (n = 6) received sham ligation. Echocardiography with a 30-mHz probe was performed at baseline and at frequent predefined time points after CLP. Stroke volume (SV), cardiac output (CO), LV internal diameter in diastole (LVIDd), and fractional shortening (FS) were measured. LV dilation was prospectively defined as an increase in LVIDd ≥ 5% from baseline values. Septic animals were classified as dilators or nondilators. RESULTS Among septic animals, 37% were dilators and 63% were nondilators. After CLP, SV and CO decreased early in both groups. With resuscitation, SV and CO improved to a greater extent in dilators than nondilators (for SV, 46.0 ± 8.2 vs 36.1 ± 12.7 μL at 24 h, P = .05; for CO, 20.4 ± 4.8 vs 14.8 ± 6.7 mL/min, P = .04). Survival at 72 h was significantly improved in dilators compared with nondilators (88% vs 40%, P = .01). CONCLUSIONS In a clinically relevant murine model of sepsis, animals with LV dilation had better cardiovascular performance and increased survival. Our results suggest that LV dilation is associated with improved SV and CO, a pattern resulting in greatly improved survival. These studies highlight the importance of diastolic function in septic shock.