Application of PEEP using the i-gel during volume-controlled ventilation in anesthetized, paralyzed patients

Purpose

This prospective, randomized trial was designed to assess whether the i-gel supraglottic airway device is suitable for volume-controlled ventilation while applying positive end-expiratory pressure (PEEP) of 5 cmH₂O under general anesthesia. It was believed that this device might improve arterial oxygenation.

Methods

Forty adult patients (aged 20–60 years) scheduled for elective orthopedic surgery were enrolled in this study. Twenty patients were ventilated without external PEEP [zero positive end-expiratory pressure (ZEEP) group], and the other 20 were ventilated with PEEP 5 cmH₂O (PEEP group) after placing an i-gel device. Volume-controlled ventilation at a tidal volume (TV) of 8 ml/kg of ideal body weight, leak volume, and arterial blood gas analysis were investigated.

Results

The incidences of a significant leak were similar in the ZEEP and PEEP groups (3/20 and 1/20, respectively; P = 0.605), as were leak volumes. No significant PaO₂ difference was observed between the two groups at 1 h after satisfactory i-gel insertion (215 ± 38 vs. 222 ± 54; P = 0.502).

Conclusions

The use of an i-gel during PEEP application at 5 cmH₂O did not increase the incidence of a significant air leak, and a PEEP of 5 cmH₂O failed to improve arterial oxygenation during controlled ventilation in healthy adult patients.     

Argon plasma coagulation is safe and effective for treating smaller gastric lesions with low-grade dysplasia: a comparison with endoscopic submucosal dissection

Background and aims

The best therapeutic modality has not been established for gastric low-grade adenomas or dysplasia (LGD), which can progress to invasive carcinoma despite a low risk. This study aims to investigate the clinical efficacy, safety, and local recurrence after argon plasma coagulation (APC) treatment of gastric LGD compared with endoscopic submucosal dissection (ESD).

Patients and methods

A total of 320 patients with gastric LGD ≤2.0 cm treated with APC or ESD between 2004 and 2011 were retrospectively analyzed. We compared local recurrence rate, complication rate, procedure time, and admission to hospital between APC and ESD groups.

Results

Of the 320 patients, 116 patients were treated with APC and 204 with ESD. During follow-up, local recurrence was more common in the APC group (3.8 %, 4/106) than the ESD group (0.5 %, 1/188; log-rank test P = 0.036). However, all patients with local recurrence (n = 5) were treated by additional APC, and followed up without further recurrences. ESD was complicated by two perforations (1.0 %, 2/204) compared with no perforations in the APC group (0 %, 0/116). Bleeding complications were not different between the APC (1.7 %, 2/116) and ESD (2.0 %, 4/204) groups. Procedure time was shorter in the APC (7.8 ± 5.1 min) than the ESD (53.1 ± 38.1 min) group (P < 0.001). The proportion of hospitalization was less in the APC group (31.0 %, 36/116) than the ESD group (100.0 %, 204/204) (P < 0.001).

Conclusions

APC can be a good treatment option for patients with LGD ≤2.0 cm.     

Proper preparation to reduce endoscopic reexamination due to food residue after distal gastrectomy for gastric cancer

Background

Reducing food residue by proper preparation methods before endoscopy after distal gastrectomy can increase the quality of examination and decrease patient discomfort. We evaluated the risk factors for food residue and proper methods of preparation for endoscopy after distal gastrectomy.

Methods

Follow-up endoscopy with questionnaires was performed on 1,001 patients who underwent distal gastrectomy at Asan Medical Center between December 2010 and July 2011.

Results

Endoscopic examination failed in 94 patients (9.4 %) as a result of large amounts of food residue. Rates of failure were significantly higher in patients who ate a regular diet rather than a soft diet at last dinner before examination (13.9 vs. 6.1 %, p = 0.050), and in those who ate lunch rather than not eating lunch on the day before examination (14.6 vs. 7.7 %, p = 0.020). Multivariate analysis showed that the rate of failed examination was lower in patients who had a history of abdominal surgery (p = 0.011), those who ate a soft (p < 0.001) or liquid (p = 0.003) diet as a last meal rather than a regular diet, those who underwent Billroth I rather than Billroth II reconstruction (p = 0.035), patients with longer fasting time (p = 0.009), and those with a longer gastrectomy-to-endoscopy time interval (p < 0.001).

Conclusions

Patients who undergo follow-up endoscopy after surgery should fast more than 18 h and ingest a soft or liquid diet on the day before examination.     

Effects of rod stiffness and fusion mass on the adjacent segments after floating mono-segmental fusion: a study using finite element analysis

Purpose

The aims of the present study were to compare the biomechanical effects on the adjacent segments after mono-segmental floating fusion with posterior semi-rigid or rigid stabilization, and to evaluate the effect of the amount of fusion mass on the biomechanical differences.

Methods

A detailed, nonlinear L1–S1 finite element model had been developed and validated. Then five models were reconstructed by different fixation techniques on the L3–L4 level: rigid fixation with an interbody spacer (Ti + IS), rigid fixation with a large interbody spacer (Ti + IS_all), semi-rigid fixation with an interbody spacer (PEEK + IS), semi-rigid fixation with a large interbody spacer (PEEK + IS_all), and semi-rigid fixation only (PEEK). Analyses were conducted for the case of erect standing position, flexion, and extension motion.

Results

At L1–L2 and L2–L3, PEEK + IS demonstrated less inter-segmental rotation and nucleus pressure increments from the intact model compared with Ti + IS. The L4–L5 and L5–S1 levels showed slightly higher values with PEEK + IS, but these differences among the instrumented models were not significant. The motion difference based on the fusion mass at the adjacent levels was at most 3 %. All instrumentation cases generated a 55 % higher facet contact force at the lower adjacent level (L4–L5) compared to that of the intact model during 26° extension and the largest increment was detected at the upper adjacent level (L2–L3) in the Ti + IS. Instrumentation with Ti + IS markedly increased the stress in the intervertebral disk at the upper adjacent level, while the stress with PEEK + IS appeared largest at the lower adjacent level.

Conclusions

Posterior instrumentation with semi-rigid rods may lower the incidence of disk and facet degeneration in the upper adjacent segment compared to rigid rods. On the other hand, the possibility of facet degeneration will be similar for all instrumentation devices in the lower adjacent segment in the long-term. The stiffness difference between rigid and semi-rigid rods on the changes in the adjacent motion segments was more crucial than amount of fusion mass.     

Successful treatment of hepatic coma by a new artificial liver device in the pig

In this study, we tested a new artificial liver device using liver pieces in 8-h hemoperfusion of comatous porcine blood and compared two alternative tissue preparations. Acute hepatic coma in the pigs was induced by complete devascularization of the liver. The animals were killed in stage IV coma (15-25 h after the operation), and 1 l blood was perfused over 200 g fresh or DMSO-preserved liver cubes. After the devascularization GOT, GPT, GLDH, AP, LDH, SDH, bilirubin, free fatty acid, and bile acid levels in serum increased progressively. Ammonia concentrations underwent a rapid increase in the first 9 h of coma development from 126.0 +/- 9.9 to 321.9 +/- 62.2 mumol/l. Most of the amino acids in serum were elevated and molar ratio of BCAA/AAA declined from 3.87 +/- 0.79 to 0.92 +/- 0.24. In the course of hemoperfusion ammonia was removed from the perfusate to 71% of the initial values using fresh and to 39% using preserved tissue. Correspondingly, there was an increase in urea concentrations. Amino acid metabolism was ameliorated during the perfusion; Fischer's quotient increased from 0.91 +/- 0.15 to 1.38 +/- 0.14 (fresh liver) and from 0.89 +/- 0.14 to 2.11 +/- 0.44 (preserved liver); neuroexcitatory amino acids Asp and Glu were markedly elevated. Energy charge of the liver cells increased and reached levels exceeding 0.5 in both experimental groups, a balanced energy metabolism was maintained and suggests active metabolization by the liver pieces. In comparison with fresh tissue, preserved liver cubes proved effective. We consider our artificial liver device capable of temporary hepatic support in acute necrosis of the liver and suppose that its efficiency can be potentiated by combining this system with other procedures.