Suturing of the laser resection area is recommended over a depth of 2 cm in an experimental porcine lung model.

BACKGROUND: Lung metastases can be removed by an Nd:YAG laser to save lung parenchyma. At these sites, a coagulated lung surface remains. Airtightness was investigated in relation to the depth of resection on an ex vivo porcine lung model. METHODS: Freshly slaughtered porcine double lung preparations were connected to a ventilator via a tube. Non-anatomical laser resections were performed with an 800 µm laser fiber and the Nd:YAG laser LIMAX® 120 (power: 40 and 60 watts). The following resection depths (each n=12) from the lung surface were examined: 0.5, 1, 1.5 and 2.0 cm. After resection the lungs were submerged under water and ventilated (frequency 10/min, Pinsp =25 mbar, PEEP =5 mbar). Airtightness of resection surfaces was determined by a leakage score, as well as the measurement of the leakage volume (in mL) per respiration (Group 1). Afterwards, the resection areas were coagulated for 5 seconds with a laser power of 60 watts at a distance of approximately 1 cm from the surface. This was followed by a re-evaluation for airtightness (Group 2). Finally, the resection surface was closed by a suture (PDS USP 4-0) and re-tested for airtightness (Group 3). The individual groups were compared for their significance (P<0.05) using a nonparametric test. RESULTS: Up to a resection depth of 1.5 cm, the ventilated resection surfaces were completely airtight regardless of the laser power. From a depth of resection of 1.5 cm, a mean air volume loss of 28.9±5.3 mL/respiratory cycle at 40 watts and of 26.4±5.8 mL at 60 watts was found. Additional surface coagulation did not significantly reduce the leakage rate. In contrast, suturing significantly reduced (P<0.0001) to 7.2±3.7 mL/ventilation (40 watts) and 6.0±3.4 mL/ventilation. At a resection depth of 2 cm, the leakage volume was 42.9±3.3 mL/respiratory cycle (40 watt) and 46.3±6.4 mL/respiratory cycle (60 watt). Additional surface coagulation failed to significantly reduce leakage volume, but suture closure provided airtightness. CONCLUSIONS: In non-ventilated porcine lungs, Nd:YAG laser resection surfaces up to a resection depth of 1.5 cm are airtight after ventilation onset. From a depth of 1.5 cm, closure of resection surfaces by an additional suture is needed. Airtightness of resection surfaces was not increased by additional coagulation.

Transoral parathyroid surgery--a new alternative or nonsense?

PURPOSE: In recent years, several endoscopic techniques have been explored in thyroid and parathyroid surgery, but only few gained acceptance among patients and surgeons. Based on extensive human cadaver and animal studies, we developed a technique for transoral partial parathyroidectomy (TOPP), which was performed for the first time in a patient with primary hyperparathyroidism (pHPT). We now report on results and the acceptance of this new technique 2 years after its implementation. METHODS: A pilot study was initiated to recruit a total of 10 patients with benign sporadic pHPT and a preoperatively localized parathyroid adenoma eligible for initial parathyroidectomy. The study protocol was approved by the ethics committee, and an insurance for unforeseen complications and risks was procured. Data of all patients evaluated and operated were prospectively collected, and follow-up examinations were carried out for 19 months on average, which included clinical examinations; ultrasonography; Ear, Nose, and Throat (ENT) investigations; and blood testing. RESULTS: Between January 2010 and May 2012, 75 patients with pHPT and a preoperative localized parathyroid adenoma were eligible for TOPP. After detailed information about the transoral procedure, only five (7 %) female patients consent to undergo TOPP. In three patients, a parathyroid adenoma could be removed via the transoral access, In two patients, the procedure had to be converted to the conventional technique. Median time until resection of a parathyroid adenoma was 122 min (range, 45-175). One patient had a transient recurrent laryngeal nerve palsy, while one patient suffered from a transient palsy of the right hypoglossal nerve and a slight but persisting dysgeusia. Three patients developed a hematoma of the mouth floor and swallowing problems. In four patients, the visual analog scale (VAS) pain score was high (>7) within the first 2 postoperative days. CONCLUSIONS: Although TOPP is feasible, it is poorly accepted by patients and its complication rate is high. Thus, TOPP is nonsense with currently available devices.

Airtightness of lung parenchyma without a closing suture after atypical resection using the Nd:YAG Laser LIMAX 120.

OBJECTIVES: Lung metastases can be non-anatomically resected with a Nd:YAG Laser. It is recommended that the resected lung surface be sealed by slowly resorbable sutures. However, the lung tissue may be restricted by the sutures once it is re-ventilated. Thus, it was analysed whether the lung parenchyma is airtight after laser resection without suturing the defect. METHODS: The pulmonary artery of unimpaired paracardial lung lobes of freshly slaughtered pigs (mean weight 46 g) was cannulated and rinsed out via a hypotonic saline-heparin solution (5000 IE) until the perfusate was clear of body fluid. The lobular bronchus was connected to an airtight ventilation tube (Fa. VYGON 520 3.5 oral tube) and ventilated pressure-controlled (PEEP + 5 cm H2O, P1 = 20 cm H2O, frequency = 10/min) via a respirator. All lobes were perfused with Ringer solution at 42°C at normothermia and normotonia. In group 1 (n = 8), an atypical peripheral parenchymal resection (average resected surface: 2 × 2 cm(2)) and in group 2 (n = 8), a deep atypical parenchymal resection (average resected surface: 4 × 4 cm(2)) were performed with the Nd:YAG Laser LIMAX 120 (output power at 100 watts). After post-resection ventilation of 15 min, the resection surface was tested for airtightness and burst pressure. RESULTS: All group 1 lobes tested airtight under pressure-controlled ventilation. The mean burst pressure was 34.4 mbar (SD ± 3.2 mbar). Six lobes of group 2 were also completely airtight. The remaining two lobes, however, revealed a serious parenchymal leak (score 3). This was caused by the cross-opening of a segmental bronchus, although the surrounding lung parenchyma was also airtight. The mean burst pressure of these lobes was 31.7 mbar (SD ± 4.08 mbar). There was no significant difference between the two groups (P = 0.12). CONCLUSIONS: Peripheral lung defects after Nd:YAG Laser resection might not be sutured, since the laser-induced vaporization of the lung parenchyma seems to be initially airtight. These experimental data warrant confirmation in a controlled clinical study.

Transoral thyroid and parathyroid surgery--development of a new transoral technique.

BACKGROUND: Transluminal interventions via so-called natural orifices are gaining interest because they allow operative treatment without any skin incision. We previously described a transoral access for (para-)thyroid resection in pigs. To proceed with the first clinical trials, we evaluated the safety of the new technique. METHODS: Transoral hemithyroidectomies were performed on 10 living pigs using a special cervicoscope and conventional laparoscopic instruments. Follow-up examinations were carried out for 14 days and followed by autopsy, which included macroscopic evaluation, microbiologic investigations, and blood testing. In addition, refinement of the new technique was achieved by developing the techniques in 10 human cadavers. Finally, transoral parathyroidectomies were performed in 2 patients with primary hyperparathyroidism and a preoperatively localized parathyroid adenoma. RESULTS: All animal transoral hemithyroidectomies were performed without complications. Postoperatively, oral intake, weight gain, and white blood cell count remained normal. At autopsy, the access route, and operative field showed no signs of infection, and microbiologic swabs remained sterile. Based on these results, a transoral parathyroidectomy was performed successfully in 2 female patients with primary hyperparathyroidism; 1 patient experienced a transient palsy of the right hypoglossal nerve. CONCLUSION: Transoral parathyroid and thyroid operation is feasible; however, additional controlled clinical studies are required to evaluate the safety and success rates of this new technique.

Transoral thyroid and parathyroid surgery.

BACKGROUND: Translumenal endoscopic interventions via so-called natural orifices are gaining increasing interest because they allow surgical treatment without any incision of the skin. Moreover, minimally invasive procedures have found their way into thyroid and parathyroid surgery. Our goal was to develop a new access for thyroid and parathyroid resection via an entirely transoral approach. METHODS: We managed to find an entirely transoral sublingual access to the thyroid region in pigs and human cadavers. Using a modified rigid rectoscope (oraloscope) hemithyroidectomies as well as resection of parathyroid glands were performed via this new approach. Preparation and resection was performed using conventional laparoscopic instruments. In living pigs, integrity of the recurrent laryngeal nerve after resection could be documented by neuromonitoring. An absorbable suture was used to seal the mucosal incision. RESULTS: First, hemithyroidectomy was performed via the transoral access in 10 porcine cadavers, then in 10 living and orally intubated pigs, and finally in five human corpses. In humans, resection of parathyroid glands also was performed. We gained access to the thyroid region by blunt dissection of the layer behind the hyoid bone and the strap muscles of the neck. We did not observe any complication during the insertion, resection, and removal part of the new procedure. CONCLUSIONS: Entirely transoral thyroid and parathyroid surgery via sublingual access seems to be feasible. However, further investigations are needed to evaluate the safety of the new technique, especially potential and clinically relevant contamination of the access route has to be excluded.

Basic life support with four different compression/ventilation ratios in a pig model: the need for ventilation.

BACKGROUND: During cardiac arrest the paramount goal of basic life support (BLS) is the oxygenation of vital organs. Current recommendations are to combine chest compressions with ventilation in a fixed ratio of 30:2; however the optimum compression/ventilation ratio is still debatable. In our study we compared four different compression/ventilation ratios and documented their effects on the return of spontaneous circulation (ROSC), gas exchange, cerebral tissue oxygenation and haemodynamics in a pig model. METHODS: Study was performed on 32 pigs under general anaesthesia with endotracheal intubation. Arterial and central venous lines were inserted. For continuous cerebral tissue oxygenation a Licox PtiO(2) probe was implanted. After 3 min of cardiac arrest (ventricular fibrillation) animals were randomized to a compression/ventilation-ratio 30:2, 100:5, 100:2 or compressions-only. Subsequently 10 min BLS, Advanced Life Support (ALS) was performed (100%O(2), 3 defibrillations, 1mg adrenaline i.v.). Data were analyzed with 2-factorial ANOVA. RESULTS: ROSC was achieved in 4/8 (30:2), 5/8 (100:5), 2/8 (100:2) and 0/8 (compr-only) pigs. During BLS, PaCO(2) increased to 55 mm Hg (30:2), 68 mm Hg (100:5; p=0.0001), 66 mm Hg (100:2; p=0.002) and 72 mm Hg (compr-only; p<0.0001). PaO(2) decreased to 58 mmg (30:2), 40 mm Hg (100:5; p=0.15), 43 mm Hg (100:2; p=0.04) and 26 mm Hg (compr-only; p<0.0001). PtiO(2) baseline values were 12.7, 12.0, 11.1 and 10.0 mm Hg and decreased to 8.1 mm Hg (30:2), 4.1 mm Hg (100:5; p=0.08), 4.3 mm Hg (100:2; p=0.04), and 4.5 mm Hg (compr-only; p=0.69). CONCLUSIONS: During BLS, a compression/ventilation-ratio of 100:5 seems to be equivalent to 30:2, while ratios of 100:2 or compressions-only detoriate peripheral arterial oxygenation and reduce the chance for ROSC.