Evaluation of Different Positive End-Expiratory Pressures Using Supreme™ Airway Laryngeal Mask during Minor Surgical Procedures in Children.

Background and objectives: The laryngeal mask is the method of choice for airway management in children during minor surgical procedures. There is a paucity of data regarding optimal management of mechanical ventilation in these patients. The Supreme™ airway laryngeal mask offers the option to insert a gastric tube to empty the stomach contents of air and/or gastric juice. The aim of this investigation was to evaluate the impact of positive end-expiratory positive pressure (PEEP) levels on ventilation parameters and gastric air insufflation during general anesthesia in children using pressure-controlled ventilation with laryngeal mask. Materials and Methods: An observational trial was carried out in 67 children aged between 1 and 11 years. PEEP levels of 0, 3 and 5 mbar were tested for 5 min in each patient during surgery and compared with ventilation parameters (dynamic compliance (mL/cmH2O), etCO2 (mmHg), peak pressure (mbar), tidal volume (mL), respiratory rate (per minute), FiO2 and gastric air (mL)) were measured at each PEEP. Air was aspirated from the stomach at the start of the sequence of measurements and at the end. Results: Significant differences were observed for the ventilation parameters: dynamic compliance (PEEP 5 vs. PEEP 3: p < 0.0001, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001), peak pressure (PEEP 5 vs. PEEP 3: p < 0.0001, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001) and tidal volume (PEEP 5 vs. PEEP 3: p = 0.0048, PEEP 5 vs. PEEP 0: p < 0.0001, PEEP 3 vs. PEEP 0: p < 0.0001). All parameters increased significantly with higher PEEP, with the exception of etCO2 (significant decrease) and respiratory rate (no significant difference). We also showed different values for air quantity in the comparisons between the different PEEP levels (PEEP 5: 2.8 ± 3.9 mL, PEEP 3: 1.8 ± 3.0 mL; PEEP 0: 1.6 ± 2.3 mL) with significant differences between PEEP 5 and PEEP 3 (p = 0.0269) and PEEP 5 and PEEP 0 (p = 0.0209). Conclusions: Our data suggest that ventilation with a PEEP of 5 mbar might be more lung protective in children using the Supreme™ airway laryngeal mask, although gastric air insufflation increased with higher PEEP. We recommend the use of a laryngeal mask with the option of inserting a gastric tube to evacuate potential gastric air.

Respiratory and haemodynamic changes during decremental open lung positive end-expiratory pressure titration in patients with acute respiratory distress syndrome.

INTRODUCTION: To investigate haemodynamic and respiratory changes during lung recruitment and decremental positive end-expiratory pressure (PEEP) titration for open lung ventilation in patients with acute respiratory distress syndrome (ARDS) a prospective, clinical trial was performed involving 12 adult patients with ARDS treated in the surgical intensive care unit in a university hospital. METHODS: A software programme (Open Lung Tool) incorporated into a standard ventilator controlled the recruitment (pressure-controlled ventilation with fixed PEEP at 20 cmH2O and increased driving pressures at 20, 25 and 30 cmH2O for two minutes each) and PEEP titration (PEEP lowered by 2 cmH2O every two minutes, with tidal volume set at 6 ml/kg). The open lung PEEP (OL-PEEP) was defined as the PEEP level yielding maximum dynamic respiratory compliance plus 2 cmH2O. Gas exchange, respiratory mechanics and central haemodynamics using the Pulse Contour Cardiac Output Monitor (PiCCO), as well as transoesophageal echocardiography were measured at the following steps: at baseline (T0); during the final recruitment step with PEEP at 20 cmH2O and driving pressure at 30 cmH2O, (T20/30); at OL-PEEP, following another recruitment manoeuvre (TOLP). RESULTS: The ratio of partial pressure of arterial oxygen (PaO2) to fraction of inspired oxygen (FiO2) increased from T0 to TOLP (120 +/- 59 versus 146 +/- 64 mmHg, P < 0.005), as did dynamic respiratory compliance (23 +/- 5 versus 27 +/- 6 ml/cmH2O, P < 0.005). At constant PEEP (14 +/- 3 cmH2O) and tidal volumes, peak inspiratory pressure decreased (32 +/- 3 versus 29 +/- 3 cmH2O, P < 0.005), although partial pressure of arterial carbon dioxide (PaCO2) was unchanged (58 +/- 22 versus 53 +/- 18 mmHg). No significant decrease in mean arterial pressure, stroke volume or cardiac output occurred during the recruitment (T20/30). However, left ventricular end-diastolic area decreased at T20/30 due to a decrease in the left ventricular end-diastolic septal-lateral diameter, while right ventricular end-diastolic area increased. Right ventricular function, estimated by the right ventricular Tei-index, deteriorated during the recruitment manoeuvre, but improved at TOLP. CONCLUSIONS: A standardised open lung strategy increased oxygenation and improved respiratory system compliance. No major haemodynamic compromise was observed, although the increase in right ventricular Tei-index and right ventricular end-diastolic area and the decrease in left ventricular end-diastolic septal-lateral diameter during the recruitment suggested an increased right ventricular stress and strain. Right ventricular function was significantly improved at TOLP compared with T0, although left ventricular function was unchanged, indicating effective lung volume optimisation.

Circadian blood pressure regulation in hospitalized depressed patients and non-depressed comparison subjects.

BACKGROUND: Neuroendocrine dysregulation and disturbed sleep, frequently seen in major depression, may interfere with circadian blood pressure regulation. DESIGN AND METHODS: Using a portable device, 24 h blood pressure profiles were registered in 69 depressed in-patients and 26 hospitalized, non-depressed comparison subjects. The use of antihypertensive medication was considered to be indicative of known arterial hypertension. Mean systolic and diastolic blood pressure levels were compared between the group of depressed patients not taking antihypertensive medication and the healthy comparison subjects, both for the entire 24 h of measurement, and for the daytime and night-time periods. In a subgroup of patients, circadian blood pressure follow-up data were obtained after 5 weeks of antidepressant therapy. RESULTS: Depressed patients not receiving antihypertensive medication (n=52) had higher mean 24 h systolic blood pressure levels than non-depressed comparison subjects (125.5+/-14.7 versus 119.6+/-13.3 mmHg, P<0.05). Subgroup analysis revealed that this difference could be almost exclusively attributed to patients on hypnotic medication; this subgroup also had a high day/night blood pressure change ('dip'). In depressed patients using antihypertensive agents (n=17), circadian blood pressure levels pointed to a suboptimal control of hypertension. In the subgroup with follow-up measurements, circadian blood pressure levels had not changed after 5 weeks of antidepressant therapy. CONCLUSION: Circadian blood pressure monitoring identified a subgroup of depressed patients characterized by higher mean systolic blood pressure levels, the use of hypnotics and a high day/night blood pressure change.