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The prone position eliminates compression of the lungs by the heart.

The prone position improves gas exchange in many patients with ARDS. Animal studies have indicated that turning prone restores ventilation to dorsal lung regions without markedly compromising ventral regions. To investigate a potential mechanism by which this might occur, the relative volume of lung located directly under the heart was measured in the supine and prone positions in seven patients. Four axial tomographic sections between the carina and the diaphragm were analyzed (Sections 1 through 4). When supine, the percent of the total lung volume located under the heart increased from 7 +/- 4% to 42 +/- 8%, and from 11 +/- 4% to 16 +/- 4% in Sections 1 through 4, in the left and right lungs, respectively. When prone, the percent of left and right lung volume located under the heart was </= 1 and </= 4 %, respectively, in all four sections (p < 0.05 for each section, supine versus prone). Although a large fraction of the lung, particularly on the left, is located directly under the heart in supine patients, and would be subject to the compressive force resulting from heart weight, almost no lung is located under the heart when patients are prone and the compressive force of the heart is directed towards the sternum.

Adult↗

[The effect of intermittent prone position on pulmonary gas exchange in acute lung failure].

In a clinical trial, the influence of repeated intermittent prone position on pulmonary gas exchange was investigated in 6 patients with severe ARDS. Despite various intra- and interindividual differences, oxygenation index (calculated by the paO2:FiO2 ratio) was improved significantly by change from supine to prone position in the first two days of treatment, whereas paCO2 remained unchanged. Later on, a significant improvement of oxygenation could not be verified. In patients with proven or presumed densities of dorsal lung regions, body position changes from supine to prone position in the early phase of treatment may improve arterial oxygenation and may be regarded as a therapeutic principle in conventional ARDS treatment.

Adult↗

Macular hole surgery with internal limiting membrane removal, air tamponade, and 1-day prone positioning.

PURPOSE: The internal limiting membrane (ILM) removal has been combined with macular hole surgery in recent years, which facilitates shortening of the prone-positioning period after surgery. In this study, surgical outcome of macular hole surgery with ILM removal, air tamponade, and 1-day prone positioning was evaluated. METHODS: In a prospective study, 23 patients (23 eyes) underwent vitrectomy for idiopathic macular holes. Macular holes <0.4 disc diameter and without apparent atrophy of retinal pigment epithelium (RPE) were selected for study. After vitrectomy combined with the ILM removal and fluid-air exchange, patients were instructed to keep prone positioning for only 1 day. The initial hole-closure rate, complications and visual outcome were evaluated. RESULTS: Anatomical closure of macular holes was achieved in 21 (91.3%) of the 23 eyes by one operation. The postoperative visual acuity of 0.5 or better and 1.0 were achieved in 19 eyes (82.6%) and 6 eyes (26.1%), respectively. Postoperatively, intraocular pressure was elevated temporarily in 2 eyes (8.7%); retinal break and posterior synechia occurred in 1 eye (4.3%) each. These complications were treated successfully and did not threaten visual acuity. CONCLUSION: Air tamponade with ILM removal followed by 1-day prone positioning was considered to be a useful method for macular holes with small diameter and without apparent atrophy of RPE. This method facilitated early recovery to a normal social life.

Aged↗

[Treatment of postoperative lung failure with prone positioning].

Of forty-three consecutive patients with severe adult respiratory distress syndrome (ARDS) treated in the prone position pulmonary function improved significantly in 39 patients during the first 12 h in prone position. Changes were most pronounced in patients with high QS/QT, as well as in patients in the early stages of ARDS. Twenty-eight patients could be weaned from the ventilator, and 22 patients were able to leave the hospital. These results suggest that prone position has an important role in the overall therapeutic approach to ARDS and should be used as early as possible.

Abdomen↗

Multimedia article. Entirely thoracoscopic pneumonectomy using the prone position: a new technique.

BACKGROUND: Reports on video-assisted pneumonectomy have remained scarce, despite early demonstration of its technical feasibility. A totally videothoracoscopic pneumonectomy was first reported by Conlan and Sandor. The patient in this report was positioned in the full lateral position. In this video, we report a totally videothoracoscopic left-side pneumonectomy with the patient in prone position. METHODS: A 49-year-old man was admitted to our hospital for a bifocal cancer of the left lower lung lobe (LLL) and the cervical esophagus. The preoperative workup included a chest computed tomography (CT) scan showing a 3-cm mass of the laterobasal segment of the LLL, with retrotumoral atelectasis, lymph nodes smaller than 1 cm in diameter at the aortopulmonary window and under the carena, and finally posterolateral adherences between the parietal and the visceral pleura. Flexible bronchoscopy confirmed the presence of a bronchial tumor at the offspring of the apical bronchus of the LLL. Biopsy showed invasive adenocarcinoma, and a CT scan of the neck and head was significant for tumoral infiltration of the cervical esophagus and retropharyngeal space. Gastroscopy showed a stenosis of the cervical esophagus and hypopharynx. Biopsy showed spinocellular epithelioma, but CT scan of the abdomen and bone scintigraphy did not show metastatic disease. A position emission tomography (PET) scan confirmed the findings of the CT scan. Pneumonectomy and esophagectomy by thoracoscopy, laparoscopy, and cervicotomy were proposed. The purpose of this video is to show the details of the thoracoscopic technique with the patient in the prone position. RESULTS: After induction of general anesthesia, a double-lumen endotracheal tube was placed. The patient was subsequently placed and strapped in a prone position. The surgical team was placed to the left of the patient. A 10-mm trocar was placed in the seventh intercostal space on the posterior axillary line, and a 30 degrees angled videoscope was introduced. Three additional 5-mm trocars were placed at the same level in the 5th, 9th, and 11th intercostal spaces on the posterior axillary line. The mediastinal pleura was opened just ventral to the aorta. The first structure identified was the left main bronchus, which was dissected free and transected with a linear stapler (blue load). The aortopulmonary window became immediately visible. Clearance of this window's lymphoglandular tissue showed, bottom to top, the inferior pulmonary vein, the superior pulmonary vein, and the pulmonary artery. These vascular structures were carefully dissected free with the cautery hook and transected with a vascular linear stapler (white load). The lung was freed entirely tend placed in a retrieval bag for later transhiatal extraction during the laparoscopic phase of the esophagectomy. The intraoperative time for the pneumonectomy was 146 min, and intraoperative blood loss was 30 ml. The pathology report confirmed the presence of invasive, poorly differentiated adenocarcinoma. The bronchial section was free of tumor. One intrapulmonary lymphnode (N1) was positive, whereas all 10 N2 and N3 nodes harvested were free of disease. The tumor was thus staged as IIB (pT2N1Mx). The esophagetomy specimen showed fairly wide differentiated keratinizing of the spinocellular epithelioma with invasion of both pyriform sinuses and both sides of the glottis. CONCLUSIONS: First described by Cuschieri et al. in 1992, the prone position for thoracoscopy allows for a more direct approach to the aortopulmonary window under excellent visual and ergonomic circumstances. Dissection of the hilar larger vessels and performance of lymphnode sampling appear more straightforward because with this technique, the lung is kept out of harm's way, thanks to gravity.

Humans↗

A technique for performing ultrasound biomicroscopy in the sitting and prone positions.

To develop a reliable method for performing ultrasound biomicroscopy (UBM) in the sitting and prone positions. The probe suspended from an articulated arm was removed and reattached to the arm upside-down for use in the prone position and horizontally for use in the sitting position. A latex Tono-Pen tip cover was attached to the edge of the eyecup and was placed over the transducer through the small hole on the tip of the Tono-Pen tip cover. UBM was successfully performed in the prone and sitting positions with no loss of image quality. This method can expand the ability of the UBM to examine alterations in anatomic relationships among anterior segment structures between the supine, sitting, and prone positions.

Anterior Eye Segment↗

[Treatment of ureteral calculi in bone coverage using in situ ESWL in prone position].

From January 1988 to February 1992, a total of 26 patients with calculi in the middle third of the ureter underwent primary in situ ESWL in the prone position. All treatments were performed in sedoanalgesia using the Dornier HM 3 lithotriptor. During and after ESWL in the prone position, severe complications did not occur. Of the 26 patients, 10 (38%) were treated by a single application of ESWL. No auxiliary measures were necessary, and they became stone-free within 3 months following treatment. In another 9 patients (35%) auxiliary measures were required for visualization of radiolucent calculi or to relieve a urinary tract obstruction with incipient septicemia. All these auxiliary measures could be performed in sedoanalgesia. In the remaining 7 patients (27%), in whom stone disintegration following ESWL was incomplete, ureteroscopic lithotripsy techniques had to be applied. One of these 7 patients had to undergo an additional open operative procedure. The results of the present study demonstrate that a majority of patients with calculi in the middle portion of the ureter can become stone-free without invasive lithotripsy techniques following ESWL in the prone position, if necessary plus auxiliary measures, in sedoanalgesia. From these results it can be concluded that primary ESWL in the prone position should be considered for patients with calculi in the middle third of the ureter before invasive lithotripsy techniques are applied.

Adult↗

Intraoperative angiography for neurovascular disease in the prone or three-quarter prone position.

BACKGROUND: Intraoperative angiography for neurovascular disease has gained wide acceptance as a useful tool. There are few published cases of intraoperative angiography performed in the prone or three-quarter prone position, and the transradial approach has not previously been described for this situation. METHODS: We retrospectively reviewed our last 177 consecutive cases of intraoperative angiography performed for neurovascular disease. Of these cases, 21 were performed in the prone or three-quarter prone position. Two different approaches were used: (1) a previously described extended femoral sheath approach (13 cases) and (2) a newly described transradial approach (8 cases). RESULTS: All 21 intraoperative angiograms were successfully completed in the prone or three-quarter prone position. This enabled us to make additional surgical adjustments when necessary or to conclude the operation. One complication, a dissection of the brachial artery, occurred during one intraoperative angiographic procedure. CONCLUSIONS: Intraoperative angiography can be performed in the prone or three-quarter prone position with good efficacy and safety. The transfemoral route has the advantage of familiarity but has disadvantages of poor sterility at access site, possible kinking or thrombosis of the sheath, and possible skin injury while resting on the tubing during long procedures. The transradial route has advantages of continuous access to the entry site throughout the surgical procedure and ease of catheterization of vertebral arteries for occipital and suboccipital lesions. However, the transradial route has the disadvantage of working from an unfamiliar approach, especially for spinal arteriovenous malformations.

Adult↗

Quadriplegia in a patient who underwent posterior fossa surgery in the prone position. Case report.

Quadriplegia is a well-known complication of posterior fossa surgery performed while the patient is in the sitting position but is rarely associated with the prone position. A case of an 18-year-old man with a cerebellar medulloblastoma is described. There was no evidence of previous cervical disease. The patient suffered quadriplegia after undergoing surgery in the prone position. Postoperative magnetic resonance imaging demonstrated a long hyperintense C2-T1 lesion on T2-weighted sequences. The authors speculate that, during the prolonged period in which the neck was in hyperflexion, overstretching of the cervical spinal cord and compromise of its blood supply might have caused this devastating complication.

Adolescent↗

[Effect of the prone position on ICG excretion during normotensive or hypotensive isoflurane anesthesia].

We evaluated the effect of prone position on ICG excretion during normotensive and hypotensive isoflurane anesthesia. In supine position, either normotensive or hypotensive anesthesia produced no significant prolongation in ICG excretion. In prone position, however, both normotensive and hypotensive anesthesia caused a significant prolongation in the excretion. The results suggest that prone position decreases the hepatic blood flow or hepatic function during isoflurane anesthesia.

Adult↗

Minimally invasive esophagectomy: thoracoscopic mobilization of the esophagus and mediastinal lymphadenectomy in prone position--experience of 130 patients.

BACKGROUND: To evaluate outcomes after minimally invasive or thoracolaparoscopic esophagectomy (TLE) with thoracoscopic mobilization of the esophagus and mediastinal esophagectomy in prone position. Esophagectomies are being performed increasingly by a minimally invasive route with decreased morbidity and shorter hospital stay compared with conventional esophagectomy. Most series report thoracoscopic mobilization of the esophagus and mediastinal lymphadenectomy in the left lateral position with respiratory complications up to 8% and prolonged operative time, probably because of inadequate stance of the surgeon during the thoracoscopic part. This study shows the potential of the thoracoscopic part of the procedure in prone position to ease these difficulties. STUDY DESIGN: From January 1997 through April 2005, TLE was performed in 130 patients. All patients had histologically proved squamous cell carcinoma of the middle third of the esophagus. Only one (0.77%) patient received neoadjuvant chemotherapy. The thoracoscopic part of the procedure was performed in prone position with excellent ergonomics, translating into less operative time and better respiratory results. We performed a minilaparotomy to retrieve the specimen owing to bulky tumors. Feeding jejunostomy and pyloromyotomy were performed in all patients. RESULTS: There were 102 men and 28 women. Median age was 67.5 years (range 38 to 78 years). There was no conversion to open method. Median ICU stay was 1 day (range 1 to 32 days) and median hospital stay was 8 days (range 4 to 68 days). Perioperative mortality was 1.54% (n = 2). Anastomotic leak rate was 2.31% (n = 3). There was no incidence of tracheal or lung injury and a very low incidence of postoperative pneumonia. At mean followup of 20 months (range 2 to 70 months), stage-specific survival was similar to open and other minimally invasive series. CONCLUSIONS: TLE with thoracoscopic part in prone position is technically feasible, with a low incidence of respiratory complications and less operative time required. It provides comparable outcomes with other techniques of minimally invasive esophagectomy and most open series. In our experience, we observed a low mortality rate (1.54%), hospital stay of 8 days, and low incidence of postoperative pneumonia. It has the potential to replace conventional and other techniques of minimally invasive esophagectomy.

Adult↗

Mechanical ventilation in the prone position: a strategy for acute respiratory failure after cardiac surgery.

Ventilation in the prone position, initially introduced in respiratory therapy to improve the drainage of secretions, has been used in intensive care to improve oxygenation. We report a case of an obese male patient who underwent elective coronary artery bypass grafting and had low PaO2 in the postoperative period. The PaO2 improved whenever the patient was ventilated in the prone position. On each occasion, oxygenation improved without any change in the hemodynamic parameters. The PaO2 increased from 57.8 to 249.7 mmHg on the first occasion, from 48.7 to 194.6 mmHg on the second and 62.5 to 199.7 mmHg on the third at an FIO2 of 1.0. The shunt fraction (Qva/Qt) decreased from 43.6% to 7.2% on the first occasion and from 46.7% to 12.5% on the second. Ventilation in the prone position can be an effective method for improving oxygenation in patients suffering from postoperative acute respiratory failure who are not responding to other ventilatory strategies.

Coronary Artery Bypass↗

Respective and combined effects of prone position and inhaled nitric oxide in patients with acute respiratory distress syndrome.

Inhaled nitric oxide (NO) and prone position (PP) are two of the new therapeutics proposed in the setting of acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the hemodynamic and respiratory effects of NO and prone position in patients with ARDS. Fourteen patients, sedated, paralyzed, and ventilated using volume-control mode, were prospectively investigated. All patients had a radial artery catheter, a pulmonary artery catheter, and a 3-F fiberoptic thermistor catheter advanced via the femoral artery into the descending aorta. The protocol consisted of seven phases: baseline measurements in supine position, SP (T0); SP + NO (T1); baseline 2 in SP (T2); PP without NO (T3); NO + PP (T4); SP + NO (T5); and PP + NO (T6). Inhaled NO (T1) induced an increase in PO2/FI(O2) (from 128 +/- 44 to 180 +/- 75 mm Hg, p < 0.004). Prone position (T3) resulted in an increase in PO2/FI(O2) (193 +/- 83 mm Hg, p < 0.003 versus T0). The association of NO with PP (T4) resulted in a significant improvement in PO2/FI(O2) (261 +/- 98 mm Hg) when compared with T0, T1, and T3. Analysis of variance showed a significant and additive effect of NO and PP on both PO2/FI(O2) (p < 0.000) and shunt fraction (QS/QT) (p < 0.01). Since the association of NO with PP presents additive effects on oxygenation, this association can be proposed for the treatment of ARDS.

Administration, Inhalation↗

Significance of prone positioning in planning treatment for esophageal cancer.

The treatment of esophageal cancer is made difficult by the close proximity of the esophagus to the spinal cord and the requirement to treat the esophageal target volume to doses greater than or equal to 60 Gy while limiting the spinal cord dose to less than or equal to 46 Gy. By placing the patient in the prone position, the esophagus can be displaced away from the spinal cord. We explored the results of this commonly used technique on 16 patients who have undergone simulation in both supine and prone positions. Both AP and lateral orthogonal radiographs were obtained in both positions. The distance between contrast material in the esophagus and spinal cord was noted in at least four transverse planes through the thoracic esophagus on each of the 16 patients. These four transverse planes were located at 3 cm above the carina, at the carina, 3 cm below the carina and 6 cm below the carina. The mean displacement (+/- 1 SD) of the esophagus away from the spinal cord when the patient was in the prone position compared to supine at each of these levels was 1.3 (+/- 0.8) cm, 1.8 (+/- 0.9) cm, 1.8 (+/- 1.0) cm, and 1.9 (+/- 1.1) cm. The range of displacement for all 64 displacement determinations was 0 to 4.2 cm with a mean of 1.7 cm. To evaluate further the consequences of prone positioning on treatment planning and doses received to target volumes and critical structures, we performed 3-dimensional treatment planning with a patient in both prone and supine positions. The requirements were to achieve a tumor volume dose of 60 Gy while keeping the spinal cord dose below 46 Gy. Two types of conventional treatment plans were examined in prone and supine positions. A 6-field plan consisted of delivery of 40 Gy through a large 3-field beam arrangement followed by delivery of 20 Gy through a similar 3-field cone down. An 8-field plan involved the delivery of 30 Gy through AP/PA beams followed by a 3-field beam arrangement to 40 Gy and a subsequent 3-field cone-down for the final 20 Gy. Comparison of dose volume histograms revealed that the 6-field plan spared relatively more heart whereas the 8-field plan spared relatively more lung. Regarding the primary consideration of coverage of target volume with avoidance of spinal cord, prone positioning was superior to supine positioning whether 6- or 8-field arrangements were used.

Esophageal Neoplasms↗

The lateral extracavitary approach to the spine using the three-quarter prone position.

A three-quarter prone position for the lateral extracavitary operative approach to the thoracic and lumbar spine is described. This approach has been used in 40 patients with anterior spinal cord compressive lesions in the thoracic and/or lumbar region. In this patient population, it has allowed a safe ventral decompression of the spinal cord. It also allows placement of spinal instrumentation through the same incision. Both the operating surgeon and the assistant have an excellent view of the operative site, including the dural sac. Patient positioning and the operative approach are described and illustrated.

Brachial Plexus↗

[Prone position and operative posture in neurosurgery].

The most satisfactory method of prone positioning for the posterior approach to the spine and posterior fossa has been influenced by the necessity of providing good operating condition: prone position without abdominal and thoracic compression with a patient's head in the neutral position. Communication between the cava veins and the vertebral venous plexus explain that induce positioning can produce an excessive venous intraoperative bleeding with decreased surgical visibility. Furthermore venous return to the heart decreased resulting in some degree of impaired cardiac output. Hemodynamic disturbances of cerebral or spinal cord bloods flows can occurred.

Cerebrovascular Circulation↗

Cardiac arrest during surgery and ventilation in the prone position: a case report and systematic review.

We present a case report of successful resuscitation following cardiac arrest in a patient undergoing surgery in the prone position. A systematic review of the literature identified 22 further cases. Risk factors for intra-operative cardiac arrest in patients in the prone position include: cardiac abnormalities in patients undergoing major spinal surgery, hypovolaemia, air embolism, wound irrigation with hydrogen peroxide, poor positioning and occluded venous return. Cardiac arrest is also a risk in the increasing number of patients with acute respiratory distress syndrome ventilated in the prone position. Management of prone cardiac arrest may be improved by identification of high-risk patients, careful patient positioning, use of invasive monitoring and placement of self-adhesive defibrillator paddles. Suitable techniques for cardiopulmonary resuscitation including methods for chest compression, defibrillation and the management of air embolism are discussed.

Blood Loss, Surgical↗