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PubMed2006

Effect of prone positioning systems on hemodynamic and cardiac function during lumbar spine surgery: an echocardiographic study.

STUDY DESIGN: Prospective randomized study of patients undergoing spine surgery. OBJECTIVE: To compare changes in hemodynamic and cardiac function after prone positioning using different prone positioners. SUMMARY OF BACKGROUND DATA: Prone positioning decreases blood pressure and cardiac function. Several studies have evaluated changes in cardiac function after prone positioning, and linked them to reduced venous return and ventricular compliance. This study compares different prone positioners using transesophageal echocardiography, and determines their effect on cardiac function and hemodynamics. METHODS: After correction of fluid deficits with the patient under stable anesthesia, hemodynamic and cardiac performance was measured using transesophageal echocardiography. After prone positioning, repeat measurements were performed, and comparisons were made between prone and supine positions. RESULTS: No intergroup differences in demographics, fluid deficit, baseline hemodynamics, or differences from supine to prone position were noted. Cardiac output decreased with the Wilson (Union City, CA) and Siemens AG (Munich, Germany) frames, while cardiac index and stroke volume decreased with the Andrews (Hollywood, CA), Wilson, and Siemens systems. Cardiac preload decreased using the Andrews frame. The Jackson spine table (Hollywood, CA) and bolsters had the least effect on cardiac performance. CONCLUSION: Adequate fluid replacement reduced hypotension and hemodynamic instability after prone positioning. The Jackson spine table and longitudinal bolsters had minimal effects on cardiac function, and should be considered in patients with limited cardiac reserve.

Adult↗

PubMed2006

Arthroscopic visualization of the posterior subtalar joint in the prone position: a cadaver study.

PURPOSE: Subtalar arthroscopy in the prone position is thought to allow broader access to the posterior aspect of the joint than in the standard supine or lateral position. This study is aimed to assess if using the posteromedial (PM) portal in the prone position can increase the working area available through the dorsal and ventral posterolateral (PL) portals commonly used in the standard techniques. TYPE OF STUDY: In vitro cadaver study. METHODS: Six below-knee cadaver specimens were subjected to experimental arthroscopy on the posterior subtalar joint in a simulated prone position. On both the talar and calcaneal surfaces, the working areas (the maximal extent available to a working instrument while preserving surrounding cartilage) for the PL portals and the PM portal were identified. The combined area was compared with the area available from the PL portals alone, to assess the area extended with the PM portal. RESULTS: The talar working areas provided by the PL portals and PM portal were 31% +/- 13% and 26% +/- 8% of the total articular surface, respectively. The combined working area (43% +/- 13%) was greater than the PL working area alone; use of the PM portal increased the working area by a factor of 1.45. The calcaneal working areas from the PL and PM portals were 25% +/- 11% and 20 +/- 7%, respectively. The combined working area (35% +/- 14%) was similarly increased by a factor of 1.46 using the PM portal compared with PL portals alone (P < .05). CONCLUSIONS: In prone subtalar arthroscopy, significant extension of the working area was found by adding the PM portal to the standard PL portals, on both the talar and calcaneal surfaces. CLINICAL RELEVANCE: The PM portal that can be used in the prone position has a potential to increase the arthroscopic working area in the posterior subtalar joint.

Aged↗

PubMed2005

Effect of prone position on regional shunt, aeration, and perfusion in experimental acute lung injury.

RATIONALE: The prone position is used to improve gas exchange in patients with acute respiratory distress syndrome. However, the regional mechanism by which the prone position improves gas exchange in acutely injured lungs is still incompletely defined. METHODS: We used positron emission tomography imaging of [(13)N]nitrogen to assess the regional distribution of pulmonary shunt, aeration, perfusion, and ventilation in seven surfactant-depleted sheep in supine and prone positions. RESULTS: In the supine position, the dorsal lung regions had a high shunt fraction, high perfusion, and poor aeration. The prone position was associated with an increase in lung gas content and with a more uniform distribution of aeration, as the increase in aeration in dorsal lung regions was not offset by loss of aeration in ventral regions. Consequently, the shunt fraction decreased in dorsal regions in the prone position without a concomitant impairment of gas exchange in ventral regions, thus leading to a significant increase in the fraction of pulmonary perfusion participating in gas exchange. In addition, the vertical distribution of specific alveolar ventilation became more uniform in the prone position. A biphasic relation between regional shunt fraction and gas fraction showed low shunt for values of gas fraction higher than a threshold, and a steep linear increase in shunt for lower values of gas fraction. CONCLUSION: In a surfactant-deficient model of lung injury, the prone position improved gas exchange by restoring aeration and decreasing shunt while preserving perfusion in dorsal lung regions, and by making the distribution of ventilation more uniform.

Animals↗

PubMed2005

[Role of prone position mechanical ventilation in patients with acute respiratory distress syndrome originating from pulmonary disease and extra-pulmonary disease].

OBJECTIVE: To assess the effect of mechanical ventilation on prone position for the treatment of acute respiratory distress syndrome (ARDS) originating from pulmonary disease and extra-pulmonary disease. METHODS: From January 2001 to February 2004 in intensive care unit (ICU), 42 patients with ARDS were divided into pulmonary disease group and extra-pulmonary disease group. All the patients were mechanically ventilated on prone position. Arterial blood gases, respiratory rate (RR), fraction of inspired oxygen (FiO(2)), pulmonary compliance (C), tidal volume (V(T)), airway resistance (Raw) were measured before prone position and 2 hours and 4 hours after prone position. Lung-CT was measured in supine position and prone position. RESULTS: When patients were turned to prone position, SaO(2) and RR were decreased markedly in two groups. V(T) was increased in extra-pulmonary disease groups compared with pulmonary disease group at the same time. Oxygen index, hemoglobin oxygen saturation and Raw were increased markedly when patients were turned to prone position, and oxygen index of pulmonary disease group was higher than that of extra-pulmonary disease group at the same time. No change was found in blood pH and partial pressure of carbon dioxide in artery (PaCO(2)), but oxygenation was improved markedly in two groups. The effective rate of improved oxygenation was 65% in pulmonary disease group and 68% in extrapulmonary disease group, but no significant difference was found. Lung CT revealed that when the patients were in prone position, the degree of lung infiltration in the dorsal part of lung decreased while that in the ventral part increased. CONCLUSION: Oxygenation is improved markedly in prone position in two groups. Mechanical ventilation on prone position was an effective method in the treatment of ARDS patients.

Adult↗

PubMed1998

Additive effect of nitric oxide inhalation on the oxygenation benefit of the prone position in the adult respiratory distress syndrome.

BACKGROUND: The response to inhaled nitric oxide and prone positioning was investigated in 47 patients with adult respiratory distress syndrome to test the hypothesis that inhalation of nitric oxide when in the prone position would result in additive improvement in oxygenation. METHODS: The authors prospectively studied patients of both genders who were 15 to 75 yr old and had adult respiratory distress syndrome confirmed by computed tomography (lung injury score, 3.1+/-1). RESULTS: Compared with baseline values in the supine position (T1), inhalation of 10 ppm nitric oxide for 1 h (T2) decreased the mean pulmonary artery pressure from 33+/-9 mmHg to 28+/-6 mmHg (P < 0.05; T2 vs. T1) and increased the ratio of the partial pressure of oxygen in arterial blood (PaO2) to inspired oxygen concentration (FiO2) from 115 (median first quartile [Q1] 97, median third quartile [Q3] 137) to 148 (Q1 132, Q3 196) (P < 0.05; T2 vs. T1). Cessation of nitric oxide brought the values back to baseline (T3). Two hours of prone positioning (T4) significantly increased the PaO2:FiO2 ratio (T4 vs. T3). However, after an additional hour of nitric oxide inhalation in the prone position (T5), a significant decrease of the venous admixture (from 33+/-6% to 25+/-6%; P < 0.05) and an increase of the PaO2:FiO2 ratio (from 165 [Q1 129, Q3 216] to 199 [Q1 178, Q3 316] [P < 0.05; T5 vs. T4]) were observed. CONCLUSIONS: In patients with isolated severe adult respiratory distress syndrome, inhalation of nitric oxide in the prone position significantly improved oxygenation compared with nitric oxide inhalation in the supine position or in the prone position without nitric oxide. The combination of the prone position with nitric oxide inhalation in the treatment of severe adult respiratory distress syndrome should be considered.

Adolescent↗

PubMedDate not supplied

[Prone position in adult respiratory distress syndrome: nursing care].

The use of prone position in patients with Adult Respiratory Distress Syndrome is becoming a more and more habitual therapeutic measure in the units of Intensive Care, for what to have appropriate Nursing protocols will improve our professional performances. This article seeks to modernize knowledge by means of the practical experience and the bibliographical revision about Adult Respiratory Distress Syndrome, of the prone position and its effects on the organism, as well as the prone technique and the Nursing cares of the patients in prone position. It is propounded a detailed technique in steps, to carry out the prone position in a sure way, an itemized revision on the posture of the patient's maintenance in prone position and a Nursing cares protocol for the patients located in this posture.

Humans↗

PubMed2001

Influence of prone position on gastric mucosal-arterial PCO2 gradients.

OBJECTIVE: To evaluate the effects of mechanical ventilation in the prone position on gastric mucosal-arterial PCO2 gradients. DESIGN: Prospective clinical study. SETTING: Intensive care unit in a university clinic. PATIENTS: Twenty-five patients requiring mechanical ventilation. The physician in charge indicated the turning manoeuver for the individual patient. MEASUREMENTS/RESULTS: In addition to routine measurements of global hemodynamics and gas exchange we determined: 1) intragastric pressure; and 2) gastric mucosal-arterial PCO2 difference. After a baseline measurement in the supine position patients were turned to the prone position. After 60', 120', a median of 6.5 h (2-10 h) in the prone position, and again after 60' in the supine position, all measurements were repeated. Global hemodynamics remained unaltered throughout the study. While gastric mucosal-arterial PCO2 gradients did not change significantly during the first 60 min in the prone position, they significantly increased during the following 60 min [median/percentile: baseline: 6 (1 to -3); 60': 7 (15-5); 120': 13 (20-8) mmHg]. The median intragastric pressure was not significantly affected [baseline: 10 (13-5); 60': 12 (16-8); 120': 11 (13-7) mmHg], but 9 of the 11 patients in whom intragastric pressure increased during the first 60 min in the prone position also showed significantly increased PCO2 gradients (P < 0.01). CONCLUSION: Mechanical ventilation in the prone position may be affiliated with increased tonometric gastric mucosal-arterial PCO2 gradients depending on the effect on intraabdominal pressure. Measuring intraabdominal pressure and/or gastric mucosal PCO2 via a nasogastric tube therefore may help to detect adverse effects of this ventilatory strategy.

Analysis of Variance↗

PubMed2003

Response to the prone position in spontaneously breathing patients with hypoxemic respiratory failure.

OBJECTIVES: The prone position is used for intubated patients with adult respiratory distress syndrome (ARDS) and acute lung injury (ALI). The physiological changes associated with the prone position in nonintubated patients may be even more favorable than in intubated patients. We examined the effect of the prone position on arterial blood gases and patient compliance in four awake, nonintubated patients with hypoxemic respiratory failure. DESIGN: We present four consecutive cases of hypoxemic respiratory failure, in which mechanical ventilation was indicated. An attempt was made to avoid assisted ventilation by placing patients in the prone position, while breathing spontaneously. The effect on the clinical condition and the changes in blood gases were registered. RESULTS: We found good patient tolerance. A rapid increase in PaO2 was found, and intubation was avoided in all patients. No significant complications were registered. CONCLUSION: The prone position may prove beneficial in some cases of hypoxemic respiratory failure, even in awake patients, by avoiding mechanical ventilation and ventilator-associated complications.

Adolescent↗

PubMed2002

Induction of anesthesia and insertion of a laryngeal mask airway in the prone position for minor surgery.

UNLABELLED: The use of the prone position for surgery presents potential obstacles to rapid tracking of patients during ambulatory anesthesia. We describe a prospective audit of 73 patients who placed themselves in the prone position; anesthesia was induced in this position and a laryngeal mask airway (LMA) was used to maintain the airway. Additional increments of propofol were given to one patient who had laryngospasm and to nine who required deepening of anesthesia before the LMA could be inserted. Of four cases with LMA malpositioning, the LMA was adjusted easily in three, but in one patient who was edentulous, it was necessary to hold the LMA for the duration of the procedure. Manual ventilation of the lungs via the LMA was required because of arterial oxygen desaturation and hypoventilation in four patients. Blood was noted outside the nostrils in two patients, presumably caused by soft tissue trauma after insertion of the LMA, and bradycardia occurred in five patients. In the postoperative period, hoarseness and sore throat were observed in one and six patients, respectively. With experience and appropriate patient selection, it is possible to induce and maintain anesthesia using a LMA in patients in the prone position for ambulatory surgery. IMPLICATIONS: With experience and appropriate patient selection, it is possible to induce and maintain anesthesia using a laryngeal mask airway in patients in the prone position for ambulatory surgery.

Anesthesia↗

PubMed2002

Prone position in acute respiratory distress syndrome.

In the last few years prone positioning has been used increasingly in the treatment of patients with acute respiratory distress syndrome (ARDS) and this manoeuvre is now considered a simple and safe method to improve oxygenation. However, the physiological mechanisms causing respiratory function improvement as well as the real clinical benefit are not yet fully understood. The aim of this review is to discuss the physiological and clinical effects of prone positioning in patients with ARDS. The main physiological aims of prone positioning are: 1) to improve oxygenation; 2) to improve respiratory mechanics; 3) to homogenise the pleural pressure gradient, the alveolar inflation and the ventilation distribution; 4) to increase lung volume and reduce the amount of atelectatic regions; 5) to facilitate the drainage of secretions; and 6) to reduce ventilator-associated lung injury. According to the available data, the authors conclude that: 1) oxygenation improves in approximately 70-80% of patients with early acute respiratory distress syndrome; 2) the beneficial effects of oxygenation reduce after 1 week of mechanical ventilation; 3) the aetiology of acute respiratory distress syndrome may markedly affect the response to prone positioning; 4) extreme care is necessary when the manoeuvre is performed; 5) pressure sores are frequent and related to the number of pronations; 6) the supports used to prone and during positioning are different and nonstandardised among centres; and 7) intensive care unit and hospital stay and mortality still remain high despite prone positioning.

Acute Disease↗

PubMed1996

Unilateral blindness due to patient positioning during cervical syringomyelia surgery: unilateral blindness after prone position.

During spinal surgery using a horseshoe headrest with the patient in the prone position, the possibility of central retinal artery occlusion (CRAO) increases, and its cause can be attributed primarily to excessive extraocular pressure, a very rare complication. This report describes a case of CRAO, occurring in an adult, after cervical syringomyelia surgery in which a horseshoe headrest was used.

Adult↗

PubMed1999

Intermittent prone positioning in the treatment of severe and moderate posttraumatic lung injury.

OBJECTIVE: Severe posttraumatic lung injury is characterized by impairment of gas exchange and pulmonary densities. The influence of intermittent prone positioning on pulmonary gas exchange and parenchymal densities was investigated prospectively in patients with pulmonary injury after multiple trauma with blunt chest trauma. SETTING: A six-bed trauma intensive care unit in a university hospital. DESIGN: Prospective, descriptive study. PATIENTS: Twenty-two consecutive patients with pulmonary injury after multiple trauma with blunt chest trauma and acute lung injury (n = 11) or severe acute respiratory distress syndrome (ARDS) (n = 11) according to the definitions of the consensus conference on ARDS. INTERVENTIONS: Pulmonary densities were calculated planimetrically from computed tomographic scans of the chest before the first and after the last cycle of prone positioning. Indications for prone positioning were a) mechanical ventilation with FIO2 >0.5 at positive end-expiratory pressure >10 cm H2O for >24 hrs; or b) pulmonary densities in two or more quadrants being constant or increasing within 48 hrs. Arterial blood gas analysis was performed every 2 hrs. Intrapulmonary right-to-left shunt (Qs/Qt) and alveolar-arterial PO2 difference were calculated 2 hrs after the beginning and end of every prone and supine cycle, respectively. Patients were ventilated in the prone position for 8 hrs each day. MEASUREMENTS AND MAIN RESULTS: Every single posture change from the supine to the prone position resulted in a significant average increase in the oxygenation index of 28+/-8 torr (3.7+/-1.1 kPa) (p<.0001). There was a significant improvement in oxygenation (4.3+/-0.8 torr [0.57+/-0.11 kPa]) with time between two consecutive measurements in the prone as well as the supine position (p<.0001). Alveolar-arterial PO2 difference and Qs/Qt showed a significant decrease of 25+/-7 torr (3.3+/-0.9 kPa) and 1.1+/-0.46%, respectively, for every cycle of prone positioning. Statistical analysis revealed no significant alteration of gas exchange within every prone and supine cycle. Total static lung compliance improved significantly over time (p<.001). However, ventilation of patients in the prone position demonstrated a mean decrease in compliance of 2.1+/-0.72 mL/cm H2O. The response to prone positioning was similar in patients with ARDS and acute lung injury and revealed no significant difference. In both groups, the course of the oxygenation index and Qs/Qt over time was almost parallel. Posture changes were continued for 9.0+/-1.1 days. The oxygenation index showed an overall increase of 129+/-20 torr (17.2+/-2.7 kPa) from baseline supine at the end of prone positioning (p<.0001). Pulmonary densities were reduced significantly from 31.1+/-2.5% to 3.8+/-0.81%, Qs/Qt was reduced from 24.9+/-1.5% to 11.7+/-0.32%, and FIO2 was reduced from 0.43+/-0.04 to 0.26+/-0.02 (p<.01). Gas exchange improved in all patients, and no patient died immediately as a result of respiratory failure. CONCLUSION: Repeated prone positioning recruits collapsed lung tissue and improves gas exchange in trauma patients with blunt chest trauma and severe ARDS as well as in trauma patients with acute lung injury.

Adolescent↗

PubMed1998

Effects of the prone position on gas exchange and hemodynamics in severe acute respiratory distress syndrome.

OBJECTIVES: To address the following issues regarding the use of prone position ventilation in patients with severe acute respiratory distress syndrome (ARDS): a) response rate; b) magnitude and duration of improved oxygenation in responders during a 12-hr trial and the consequences of returning to the supine position; c) effects of the prone position on gas exchange and hemodynamics; d) consequences of oxygenation in nonresponders; and e) effects of repeated prone position trials. DESIGN: Prospective, nonrandomized interventional study. SETTING: Medical intensive care unit, university tertiary care center. PATIENTS: Nineteen consecutive, mechanically ventilated patients (age 45+/-20 yrs, mean+/-SD) with ARDS and severe hypoxemia, defined as PaO2/FiO2 of < or = 150 with FiO2 of > or = 0.6 persisting for < or =24 hrs, and a pulmonary artery occlusion pressure of <18 mm Hg. INTERVENTIONS: Patients were turned prone for 2 hrs. Nonresponders were returned supine, but responders were maintained prone for 12 hrs before being returned to the supine position. The procedure was repeated on a daily basis in all patients, until inclusion criteria were no longer met or the patients died. MEASUREMENTS AND MAIN RESULTS: Hemodynamic, blood gas, and gas exchange measurements were performed at the following time points: a) baseline supine; b) after 30 mins prone; and c) after 120 mins prone. Additional measurements for nonresponders were taken after 30 mins supine. For responders, additional measurements were taken after 12 hrs prone and 30 mins supine. Patients were considered responders if an increase in PaO2 of > or = 10 torr (> or =1.3 kPa), or increase in the PaO2/FiO2 ratio of >20 occurred within 120 mins. Eleven (57%) patients responded to the prone position. There was no difference in initial baseline parameters between responders and nonresponders. After 30 mins, the prone position in responders increased PaO2 and decreased calculated venous admixture (Qva/Qt). This improvement was the maximal obtained, and was maintained throughout the 12-hr prone period. After 12 hrs prone, mean FiO2 had been lowered from 0.85+/-0.16 to 0.66+/-0.18 (p < .05). Thirty minutes after the patients were returned supine, PaO2, PaO2/FiO2, and Qva/Qt were not different from 12-hr prone values, and were improved in comparison with baseline supine values. There was no worsening of gas exchange or hemodynamics in nonresponders. After the initial trial, a total of 28 additional episodes of prone position ventilation were performed in nine of the 19 patients. Of the 24 additional episodes in the responders, there was a response in 17 (71%) of 24 episodes. In the four additional episodes in nonresponders, there was a response in only one (25%) of four episodes. Response was accompanied by the same beneficial effects on gas exchange and Qva/Qt and absence of effect on hemodynamics as in the initial trial. There was no worsening in gas exchange or hemodynamics in nonresponder trials. CONCLUSIONS: Based on the data from this study, the prone position can improve oxygenation in severely hypoxemic ARDS patients without deleterious effects on hemodynamics. This beneficial effect does not immediately disappear on return to the supine position. In our patients, an absence of response to this technique was not accompanied by worsening hypoxemia or hemodynamic instability. Repeated daily trials in the prone position should be considered in the management of ARDS patients with severe hypoxemia.

Adolescent↗

PubMed2003

Complications of intermittent prone positioning in pediatric patients receiving extracorporeal membrane oxygenation for respiratory failure.

STUDY OBJECTIVE: To describe the safety and risks of placing pediatric patients in the prone position during extracorporeal membrane oxygenation (ECMO) for the treatment of respiratory failure. DESIGN: Single-center retrospective cohort study. SETTING: Tertiary pediatric ICUs. PATIENTS: All patients admitted to the pediatric ICU who required ECMO for respiratory failure from 1995 to 2000. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Medical records for 93 patients representing 95 ECMO runs for treatment of respiratory failure were reviewed. Of these, 63 patients (66%) received intermittent prone positioning. Demographic data and clinical information were recorded. The median age was 12 months, and the median weight was 9.8 kg. There were 962 position changes. Complications surveyed for included bleeding from appliance insertion sites, appliance dislodgment, unplanned extubation, cutaneous pressure ulceration, corneal abrasion, and extreme hemodynamic instability. These complications were noted as to whether they were present prior to the initiation of prone positioning or whether they developed after prone positioning began. Twenty-four percent of patients had bleeding from cannulation sites prior to prone positioning, and 18% of patients had bleeding begin after prone positioning was initiated. Two patients had chest tubes dislodge after prone positioning began, but neither patient had bleeding occur or required reinsertion of the chest tube. There were no unplanned extubations, appliance displacements, development of cutaneous pressure ulcerations, or corneal abrasions associated with prone-positioning maneuvers. No patient had ECMO support removed secondary to the surveyed complications. Eighty-two percent of children who received prone positioning during ECMO for treatment of respiratory failure survived to hospital discharge. CONCLUSION: We found that prone positioning may be used in pediatric ECMO patients without increasing the risk of complications. A multi-institutional, prospective, randomized, controlled study would better evaluate the efficacy of this practice and whether it is associated with a shorter length of ECMO or shorter post-ECMO ventilation and outcome.

Child↗

PubMed2004

[How to choose the duration of prone-position ventilation in patients with acute respiratory distress syndrome caused by pulmonary or extrapulmonary diseases?].

OBJECTIVE: To determine the different effect of prone-position ventilation (PPV) in patients with acute respiratory distress syndrome (ARDS) resulting from a pulmonary cause (ARDSp) and that from an extrapulmonary cause (ARDSexp) on oxygenation, respiratory mechanics and hemodynamics. To determine an appropriate duration of ventilation in the prone position in the two groups. METHODS: Nine ARDSp patients and seven ARDSexp patients within 3 days of onset of ARDS were included in this study which were classified as two groups. The patients were placed in prone position for 2 h. The effect of different time (pre-PPV, PPV 0.5 h, PPV 2 h) on oxygenation, respiratory mechanics and hemodynamics were observed. Lung computerized tomography (CT) was obtained in both the supine position and 10 min after prone position. RESULTS: Compared with pre-PPV, in ARDSp, partial pressure of oxygen in artery (PaO(2))/inhaled oxygen concentration (FiO(2)) was not increased after 0.5 h, and increased only after 2 h in the prone position (130.6 +/- 36.2 to 165.1 +/- 72.3, P < 0.05). But in ARDSexp, PaO(2)/FiO(2) was significantly increased after 0.5 h and 2 h in the prone position (116.5 +/- 55.0 to 163.2 +/- 46.4 and 182.7 +/- 87.7, P < 0.05). After 0.5 h in the prone position the responding ratio of ARDSexp was higher than ARDSp (7/7 vs 1/9, P = 0.0007). After 2 h, no significant difference of responding ratio was found between the two groups (6/7 vs 6/9, P = 0.392). The changes of the PaO(2) were similar to the PaO(2)/FiO(2). The PaCO(2) and the static respiratory system compliance (Cstrs) did not differ significantly between the prone position and the supine position in the two groups. In ARDSp, the airway resistance was (10.8 +/- 1.4) cm H2O.s(-1).L(-1) in the supine position, and it was significantly decreased after 2 h in the prone position (8.4 +/- 1.8) cm H2O.s(-1).L(-1) (P < 0.05). Chest CT scans of ARDSp and ARDSexp patients showed marked difference. CONCLUSIONS: PPV could be used to improve severe hypoxemia of ARDS. It improved the PaO(2)/FiO(2) ratio rapidly in ARDSexp, but in ARDSp the improvement took a longer time.

Aged↗

PubMed2003

[Hypotension after turning to the prone position].

Hypotension after positioning is sometimes seen especially in patients with cervical spinal lesion operated on under prone position. Patients with spinal lesion and those with brain lesion are compared in the frequency of hypotension after positioning to prone. Sixty-one cases operated on with prone position were studied. Ages ranged from 40 to 82 (mean 61) years and ASA grade was 1 or 2 in each case. Cervical laminoplasty (group C) or craniotomy (group B) are performed in 40 and 21 patients, respectively. Ephedrine was administrated when the systolic blood pressure decreased under 80 mmHg and the frequency of ephedrine use was compared. There were no differences in age and sex distribution between group C and B. The induction doses of propofol and fentanyl in group B were larger than those of group C, but ephedrine use in group C was more frequent than in group B. In T2-weighted image of the cervical cord, high signal intensity areas were depicted in cases with hypotension. The sympathetic flow descends in the medial part in the lateral funiculus. Damage of this pathway would cause autonomic dysfunction in patients with cervical spinal lesion and strict monitoring is necessary during positioning to prone.

Adult↗

PubMed2004

Evaluation of density area in dorsal lung region during prone position using transesophageal echocardiography.

OBJECTIVE: To evaluate the changes of density area in the dorsal lung regions of acute respiratory distress syndrome patients during prone position using transesophageal echocardiography. DESIGN: Retrospective clinical study. SETTING: General intensive care unit in a university hospital. PATIENTS: Ten patients with acute respiratory distress syndrome who underwent prone position therapy. INTERVENTIONS: Density areas in the left dorsal lung region were observed using transesophageal echocardiography before and after patients were in the prone position for 2 hrs. In five patients, a pediatric transesophageal echocardiography probe was left in the esophagus and used for observation during the prone procedure. MEASUREMENTS AND MAIN RESULTS: Changes of density area and PaO2/FiO2 were observed. The density areas decreased after prone position compared with those of preprone position (preprone 11.4 +/- 5.1 cm2, after prone 5.6 +/- 3.5 cm2, mean +/- sd, p <.01, respectively). There was also a significant correlation between the percentage change of density area and PaO2/FiO2 (r =.47, p <.05) after prone position. During prone position, the density area decreased; however, there was no correlation between the percent changes of density area and PaO2/FiO2. CONCLUSION: It was possible to observe the change in density area during prone position using transesophageal echocardiography. The change of density area estimated with transesophageal echocardiography during prone position was useful to estimate the effectiveness of the procedure.

Adult↗

PubMed2005

The effect of prone position on respiratory mechanics during spinal surgery.

OBJECTIVE: To study the effect of prone position on respiratory mechanics during spine surgery. DESIGN: Prospective study. SETTING: Elective spine surgery at a university hospital. PATIENTS: 12 ASA physical I & II with no coexisting cardiorespiratory disease undergoing cervical or lumbar laminectomy under general anesthesia in prone position. MEASUREMENTS: Ten min after induction of general anesthesia and endotracheal intubation, while patients were in supine position, the following measurements were taken using anesthesia delivery unit (Datex Ohmeda type A_Elec, Promma, Sweden): peak airway pressure (Ppeak), peak plataeu pressure (Pplat), peak mean pressure (Pmean) and dynamic lung compliance (DLC). The same measurements were recorded 10 min after placing patients into prone position. At the end of surgery and 5 min after turning the patients supine and before tracheal extubation, the same measurements were again recorded. The results expressed as means +/- sd. One way ANOVA was used for analysis of differences in the data before, during prone position and after turning patients supine at the end of the procedure. For all comparisons p < 0.05 was considered significant. RESULTS: During prone position there was significant reduction in DLC and significant increase in airway pressures. CONCLUSION: We conclude that turning the patients form supine to prone position during anesthesia for spine surgery caused significant decrease of DLC and significant increase of airway pressure.

Aged↗