Daniel Verzilli

The Effectiveness of Noninvasive Positive Pressure Ventilation to Enhance Preoxygenation in Morbidly Obese Patients: A Randomized Controlled Study

BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) with pressure support-ventilation and positive end-expiratory pressure are effective in providing oxygenation during intubation in hypoxemic patients. We hypothesized administration of oxygen (O2) using NPPV would more rapidly increase the end-tidal O2 concentration (ETo2) than preoxygenation using spontaneous ventilation (SV) in morbidly obese patients. METHODS: Twenty-eight morbidly obese patients were enrolled in this prospective randomized study. Administration of O2 for 5 min was performed either with SV group or with NPPV (pressure support = 8 cm H2O, positive end-expiratory pressure = 6 cm H2O) (NPPV group). ETo2 was measured using the anesthesia breathing circuit, and is expressed as a fraction of atmospheric concentration. The primary end-point was the number of patients with an ETo2 >95% at the end of O2 administration. Secondary end-points included the time to reach the maximal ETo2 and the ETo2 at the conclusion of O2 administration. RESULTS: A larger proportion of patients achieved a 95% ETo2 at 5 min with NPPV than SV (13/14 vs 7/14, P = 0.01). The time to reach the maximal ETo2 was significantly less in the NPPV than in the SV group (185 ± 46 vs 222 ± 42 s, P = 0.02). The mean ETo2 at the conclusion of O2 administration was larger in the NPPV group than the SV group (96.9 ± 1.3 vs 94.1 ± 2.0%, P < 0.001). A modest, although significant, increase in gastric distension was observed in the NPPV group. No adverse effects were observed in either group. CONCLUSION: Administration of O2 via a facemask with NPPV in the operating room is safe, feasible, and efficient in morbidly obese patients. In this population NPPV provides a more rapid O2 administration, achieving a higher ETo2.

Adaptive support and pressure support ventilation behavior in response to increased ventilatory demand.

Background:Dual-control modes of ventilation adapt the pressure delivery to keep a volume target in response to changes in respiratory mechanics, but they may respond poorly to changes in ventilatory demand. Adaptive support ventilation (ASV), a complex minute volume-targeted pressure-regulated ventilation, was compared to adaptive pressure ventilation (APV), a dual-mode in which the pressure level is adjusted to deliver a preset tidal volume, and to pressure support ventilation (PSV) when facing an increase in ventilatory demand. Methods:A total of 14 intensive care unit patients being weaned off mechanical ventilation were included in this randomized crossover study. The effect of adding a heat-and-moisture exchanger to augment circuit dead space was assessed with a same fixed level of ASV, PSV, and APV. Results:Arterial blood gases, ventilator response, and patient respiratory effort parameters were evaluated at the end of the six periods. Adding dead space significantly increased minute ventilation and Paco 2 values with the three modes. Indexes of respiratory effort (pressure-time index of respiratory muscles and work of breathing) increased with all ventilatory modes after dead-space augmentation. This increase was significantly greater with APV than with PSV or ASV (P < 0.05). The assistance delivered during APV decreased significantly with dead-space from 12.7 ± 2.6 to 6.7 ± 1.4 cm H2O, whereas no change occurred with ASV and PSV. Conclusions:ASV and PSV behaved differently but ended up with similar pressure level facing acute changes in ventilatory demand, by contrast to APV (a simple volume-guaranteed pressure-control mode), in which an increase in ventilatory demand results in a decrease in the pressure support provided by the ventilator.

Positive end-expiratory pressure affects the value of intra-abdominal pressure in acute lung injury/ acute respiratory distress syndrome patients: a pilot study

IntroductionTo examine the effects of positive end-expiratory pressure (PEEP) on intra-abdominal pressure (IAP) in patients with acute lung injury (ALI).MethodsThirty sedated and mechanically ventilated patients with ALI or acute respiratory distress syndrome (ARDS) admitted to a sixteen-bed surgical medical ICU were included. All patients were studied with sequentially increasing PEEP (0, 6 and 12 cmH2O) during a PEEP-trial.ResultsAge was 55 ± 17 years, weight was 70 ± 17 kg, SAPS II was 44 ± 14 and PaO2/FIO2 was 192 ± 53 mmHg. The IAP was 12 ± 5 mmHg at PEEP 0 (zero end-expiratory pressure, ZEEP), 13 ± 5 mmHg at PEEP 6 and 15 ± 6 mmHg at PEEP 12 (P < 0.05 vs ZEEP). In the patients with intra-abdominal hypertension defined as IAP ≥ 12 mmHg (n = 15), IAP significantly increased from 15 ± 3 mmHg at ZEEP to 20 ± 3 mmHg at PEEP 12 (P < 0.01). Whereas in the patients with IAP < 12 mmHg (n = 15), IAP did not significantly change from ZEEP to PEEP 12 (8 ± 2 vs 10 ± 3 mmHg). In the 13 patients in whom cardiac output was measured, increase in PEEP from 0 to 12 cmH2O did not significantly change cardiac output, nor in the 8 out of 15 patients of the high-IAP group. The observed effects were similar in both ALI (n = 17) and ARDS (n = 13) patients.ConclusionsPEEP is a contributing factor that impacts IAP values. It seems necessary to take into account the level of PEEP whilst interpreting IAP values in patients under mechanical ventilation.

Percutaneous thermal ablation of hepatocellular carcinomas located in the hepatic dome using artificial carbon dioxide pneumothorax: retrospective evaluation of safety and efficacy

Abstract Introduction: The targeting of hepatocellular carcinomas (HCC) in the hepatic dome can be challenging during percutaneous thermal ablation (PTA). The aims of this study were (1) to evaluate the safety and efficacy of PTA of HCC in the hepatic dome that cannot be visualized under US, using artificial CO2 pneumothorax and CT-guidance and (2) to compare the results with US-visible HCC located in the liver dome treated under US-guidance. Materials: Over a 32-month period, 56 HCC located in the hepatic dome were extracted from a prospectively maintained database. Twenty-eight cases (US-guidance group) were treated under US-guidance, while the others (n = 28, CT-CO2 group) were treated under CT-guidance using artificial CO2 pneumothorax after lipiodol tagging of the tumor. The primary technical success and complications rates of this technique were retrospectively assessed. Local tumor progression (LTP), intrahepatic distant recurrence (IDR), local recurrence-free survival (LRFS) and overall survival (OS) were also compared between both groups. Results: Primary technical success was 100% in both groups. No major complications occurred. After a median follow-up of 13.8 months (range, 1–33.4 months), LTP occurred in 10.7% (3/28) in CT-CO2 vs. 25% (7/28) in the US-guidance group (p = NS). IDR occurred in 39.3% (11/28) in CT-CO2 vs. 28.6% (8/28) in the US-guidance group (p = NS). Death occurred in 17.9% (5/28) of patients in both groups. LRFS and OS did not significantly differ using Kaplan-Meier survival estimates. Conclusion: CT-guided PTA after artificially induced CO2 pneumothorax is a safe and efficient technique to treat HCC located in the hepatic dome.