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PubMed1999

Prone position in spontaneously breathing infants with pneumonia.

This study was designed to evaluate further the effect of prone positioning on oxygen saturation (SpO2) and respiratory mechanics in spontaneously breathing infants with pneumonia. SpO2 and respiratory mechanics were measured in the supine and prone positions in 17 infants. Prone positioning resulted in statistically significant increases in mean (+/- SD) SpO2 (95.52+/-2.87 to 98.00+/-2.40%, p = 0.0002) and respiratory system compliance (5.99+/-2.52 to 7.93+/-4.30 ml/cm H2O, p = 0.02). This suggests that prone positioning is another beneficial supportive measure for spontaneously breathing infants with pneumonia.

Female↗

PubMed2004

[Effects of prone position ventilation on inflammatory factors in blood and bronchial alveolar lavage fluid of acute respiratory distress syndrome dogs caused by pulmonary and extrapulmonary insults].

OBJECTIVE: To observe the changes of inflammatory factors in blood and bronchial alveolar lavage fluid (BALF) of different lung areas of acute respiratory distress syndrome (ARDS) dogs caused by pulmonary and extra-pulmonary causes with low tidal volume and positive end expiratory pressure (PEEP) treatment under prone position ventilation. METHODS: 24 male mongrel dogs were randomly divided into 4 equal groups:ARDSp (ARDS caused by pulmonary causes) experimental group, ARDSp control group, ARDSexp (ARDS caused by extra-pulmonary causes) experimental group, and ARDSexp control group. The ARDSp dogs inspired detergent to cause lung injury, and the ARDSexp dogs were injected with oleic acid through central vein. The results of TNF-alpha, IL-1beta, and IL-6 of blood and BALF in different areas of dog's lung (upper lobe, heart lobe, and diaphragm lobe) and arterial blood gas under lung protective ventilation treatment were measured. RESULTS: After lung injury, the arterial oxygenation index as decreased, and the values of TNF-alpha, IL-1beta, and IL-6 in plasma were obviously getting higher in all groups. The values of inflammatory factors in the BALF from upper lobe and heart lobe of ARDSp dogs were significantly higher than those of the ARDSexp dogs. After receiving low tidal volume and PEEP ventilation under prone position, all dogs were gradually getting ameliorated. CONCLUSION: There are statistically those of the differences in inflammatory factor releasing in different lung areas between the ARDSp dogs and ARDSexp dogs, and low tidal volume and PEEP treatment under prone position ventilation shows good effects both on ARDSexp dogs and ARDSp dogs.

Animals↗

PubMed2001

Prone positioning, systemic hemodynamics, hepatic indocyanine green kinetics, and gastric intramucosal energy balance in patients with acute lung injury.

OBJECTIVE: To investigate the effects of prone positioning on systemic hemodynamics, intra-abdominal pressure (IAP), plasma disappearance rate of indocyanine green (PDR(ICG)), and gastric intramucosal to arterial PCO2 difference (Pi-aCO2). DESIGN AND SETTING: Prospective randomized study in the intensive care unit of a university hospital. PATIENTS: 12 mechanically ventilated, hemodynamically stable patients with acute lung injury. INTERVENTION: Positioning supine and prone for 3 h in random order. MEASUREMENTS: Systemic hemodynamics were determined by transpulmonary double-indicator dilution technique using an integrating fiberoptic monitoring system. The same monitoring system was used to measure PDR(ICG). IAP was measured in the urinary bladder and gastric intramucosal PCO2 was evaluated by automated recirculation gas tonometry. RESULTS: IAP increased from 10 +/-3 in the supine to 13+/-4 mmHg in the prone position. Cardiac index increased from 3.8+/-0.9 (supine) to 4.2+/-0.6 l/m(2) per minute (prone), mean arterial pressure from 75+/-10 (supine) to 81+/-11 mmHg (prone), PaO2/FIO2 from 194+/-66 (supine) to 269+/-68 mmHg (prone), and oxygen delivery from 558+/-122 (supine) to 620+/-74 ml/m(2) per minute (prone). No other parameters, including PDR(ICG) and Pi-aCO2, differed between the two positions. CONCLUSIONS: Prone positioning in mechanically ventilated patients with acute lung injury, despite a small increase in IAP, does not negatively affect the hepatic capacity to eliminate ICG and gastric intramucosal energy balance when systemic blood flow and oxygenation are improved.

APACHE↗

PubMed1988

The prone position in ARDS patients. A clinical study.

The gas exchange and hemodynamics were evaluated before, during, and after a two-hour period of prone position in 13 moderate-severe ARDS patients. Lung computerized tomography was obtained in both the supine and prone positions in two of these patients. Average arterial oxygenation improved after prone positioning (p less than 0.01). A PaO2 improvement of at least 10 mm Hg after 30 minutes of prone position was used as a criterion to discriminate between responders and nonresponders to the postural change. Eight patients met the "responders" group criterion, and in the five nonresponder patients, the PaO2 did not change significantly throughout the study. Computerized tomograms in the prone position showed disappearance of posterobasal densities and appearance of new densities in the anterior regions, in both patients studied. One of these was a responder, the other a nonresponder. A brief test period in prone position is indicated in ARDS patients to identify those who may benefit from this postural treatment. The definite mechanism of the arterial oxygenation improvement observed remains to be clarified.

Adult↗

PubMed2006

Prone positioning precautions in plastic surgery.

Prone positioning carries with it risks associated with neural and vascular compression. Meticulous attention to avoiding compression will protect against the risks associated with improper positioning, particularly for plastic surgeons.

Compartment Syndromes↗

PubMed2004

Prone positioning improves oxygenation without adverse hemodynamic effects during partial liquid ventilation in a canine model of acute lung injury.

BACKGROUND: Partial liquid ventilation (PLV) and prone positioning can improve the arterial oxygenation (PaO2) in acute lung injury (ALI). We evaluated the effect of prolonged prone positioning during partial liquid ventilation (PLV) in a canine model of acute lung injury. METHODS: Six mongrel dogs (weighing 17.4 +/- 0.7 kg each) were anesthetized, intubated and mechanically ventilated. After 1 hour of baseline stabilization, the dogs' lungs were instilled with 40 mL/kg perfluorocarbon (PFC). PLV was first performed in the supine position for 1 hour (S1), then in the prone position for 3 hours with hourly measurements (P1, P2, P3), and finally, PLV was performed with the animal turned back to the supine position for 1 hour (S2). RESULTS: After instillation of the PFC, the PaO2 significantly increased from 992 +/- 32.6 mmHg at baseline to 198.1 +/- 59.2 mmHg at S1 (p = 0.001). When the dogs were turned to the prone position, the PaO2 further increased to 288.3 +/- 80.9 mmHg at P1 (p = 0.008 vs. S1): this increase was maintained for 3 hours, but the PaO2 decreased to 129.4 +/- 62.5 mmHg at S2 (p < 0.001 vs. P3). Similar changes were seen in the shunt fraction. There were no significant differences for the systemic hemodynamic parameters between the prone and supine positions. CONCLUSION: Prolonged prone positioning during PLV in an animal model of ALI appears to improve oxygenation without any hemodynamic compromise.

Animals↗

PubMed2006

Hemodynamic and anesthetic advantages of dexmedetomidine, an alpha 2-agonist, for surgery in prone position.

The alpha2-agonist dexmedetomidine (Dex), a sedative and analgesic, reduces heart rate (HR) and blood pressure, and has been used in the practice of anesthesia. In this study, we aimed to evaluate the effects of Dex on hemodynamic variables, anesthetic sparing effects, and recovery profiles in patients who underwent surgery in prone position. The prone position itself can cause a decrease in the systemic blood pressure. Forty patients who undergo lumbar discectomy were randomly assigned to receive either Dex (a loading dose 1 microg/ kg in 10 minutes followed by an infusion rate of 0.2 microg/ kg/ hr) or saline. In both groups, the anesthesia was induced with fentanyl, thiopental and rocuronium, and maintained with desflurane in 50% N(2)O. Mean arterial blood pressure (MAP), HR, cardiac output (CO), and level of anesthesia were monitored. Recovery times and analgesic requirements were also recorded. As a response to endotracheal intubation, a significant increase in MAP and HR was observed in the control group compared to the Dex group, but no difference in CO. The recovery times were significantly shorter in the Dex group compared to the control group. Anesthetic and analgesic requirements of the Dex group were lower than controls. Thus, the use of Dex caused no detrimental effects on the hemodynamic variables in prone position. In addition, Dex decreased pressure response to intubation, and anesthetic and analgesic requirements, shortened recovery times, and decreased postoperative pain level. Dex may be an alternative to currently used adjunctive anesthetic agents in lumbar discectomy operations.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2004

Prone position improves mechanics and alveolar ventilation in acute respiratory distress syndrome.

OBJECTIVE: We tested the hypothesis that ventilation in the prone position might improve homogenization of tidal ventilation by reducing time-constant inequalities, and thus improving alveolar ventilation. We have recently reported in ARDS patients that these inequalities are responsible for the presence of a "slow compartment," excluded from tidal ventilation at supportive respiratory rate. DESIGN: In 11 ARDS patients treated by ventilation in the prone position because of a major oxygenation impairment (PaO(2)/FIO(2)</=100 mm Hg) we studied mechanical and blood gas changes produced by a low PEEP (6+/-1 cm H(2)O), ventilation in the prone position, and the two combined. RESULTS: Ventilation in the prone position significantly reduced the expiratory time constant from 1.98+/-0.53 s at baseline with ZEEP to 1.53+/-0.34 s, and significantly decreased PaCO(2) from 55+/-11 mm Hg at baseline with ZEEP to 50+/-7 mm Hg. This improvement in alveolar ventilation was accompanied by a significant improvement in respiratory system mechanics, and in arterial oxygenation, the latter being markedly increased by application of a low PEEP (PaO(2)/FIO(2) increasing from 64+/-19 mm Hg in supine position with ZEEP to 137+/-88 mm Hg in prone with a low PEEP). CONCLUSION: In severely hypoxemic patients, prone position was able to improve alveolar ventilation significantly by reducing the expiratory time constant.

Analysis of Variance↗

PubMed2003

Three-dimensional photon dosimetry: a comparison of treatment of the intact breast in the supine and prone position.

PURPOSE: To compare the adequacy of target coverage, dose homogeneity, and volume of normal tissue irradiated in treatment of the intact breast in the supine and prone position. METHODS AND MATERIALS: Fifteen patients with early breast cancer who presented for treatment to the intact breast after excisional biopsy were studied. A specially designed device was used for the prone setup to displace the contralateral breast away from the tangential field borders. Treatment planning computed tomography was performed for each patient in both the supine and prone positions. Dosimetric data were obtained in both positions and isodose distributions were calculated for each patient in both positions. RESULTS: The volume of breast receiving greater than 5% of the prescribed dose was significantly less in the prone position. Medial wedges were either not used or their angles were reduced for all patients in the prone position compared with the supine position. The average volume of lung receiving >10 Gy and >20 Gy was significantly less in the prone positions. The volume of heart irradiated at critical dose levels did not vary consistently in the prone and supine positions. The integral dose delivered to the contralateral breast was not significantly different. CONCLUSION: Treatment of the intact breast in the prone position may result in improved dose homogeneity within the target volume as well as sparing of normal lung compared with treatment in the conventional supine position.

Adult↗

PubMed2000

Efficacy and safety of prone positioning for patients with acute respiratory distress syndrome.

This article presents an overview of a literature review on how prone positioning can alleviate pathophysiological changes in ARDS and improve ventilation and perfusion. Improvement of gas exchange, efficiency of oxygenation and lung function are emphasized. Literature on the pathophysiology of ARDS, and the physiological effects of prone positioning on haemodynamics and lung function is examined. There are both advantages and disadvantages in turning a patient from the supine to the prone position. There are also contraindications in rotating between the supine and prone positions. Nevertheless, by rotating patients with ARDS, it is possible to achieve a significant improvement in A-aDO2, decrease shunting, and therefore improve oxygenation without use of expensive, invasive and experimental procedures. Placing patients with ARDS in the prone position can reduce inspiratory oxygen concentrations and peak inspiratory pressures, which minimizes the chance for barotrauma and the iatrogenic effects of hyperventilation oxygen toxicity.

Blood Gas Analysis↗

PubMed2001

Nursing the ARDS patient in the prone position: the experience of qualified ICU nurses.

The revival of the use of the prone position as a treatment for acute respiratory distress syndrome (ARDS) has been well documented in the medical literature, but there is little information regarding the difficulties of nursing patients in this position. The purpose of this study was to increase the body of knowledge by exploring the experiences of nurses who had cared for a patient in the prone position. A questionnaire was sent to all registered nurses in four large intensive care units (ICUs) to determine the main areas of concern when nursing patients in the prone position. There was a 62% response rate. Following this, a sample of 12 nurses volunteered to participate in three focus group interviews to further explore the issues. The main difficulties experienced related to the manoeuvre, including the timing of the move, the number of personnel and the co-ordination required. Problems experienced in providing nursing care related to pressure areas, suctioning, accidental injuries and management of emergencies. Deficits in knowledge of ARDS and skills in handling communication with relatives were also identified. As a result of this exploration, guidelines have been developed, focusing mainly on the manoeuvre, organizational and nursing issues, to provide guidance in caring for a patient when being nursed in the prone position.

Humans↗

PubMed1991

Hemodynamic effect of the prone position during anesthesia.

We studied 21 patients undergoing lumbar spinal surgery under halothane anesthesia on a convex saddle frame, in order to determine the hemodynamic effect of the prone position. A thermodilution pulmonary arterial catheter was placed in 14 patients (Group PA-1: n = 8; and Group PA-2: n = 6), and an inferior vena caval catheter in the remaining seven patients (Group IVC). Group PA-1 and Group IVC patients were placed in the prone position on a convex saddle frame. In the prone position, the cardiac index (CI) decreased significantly from 3.1 +/- 0.5 to 2.5 +/- 0.3 (l.min-1.m-2, mean +/- s.d., P less than 0.01) without accompanying significant changes in the other hemodynamic variables in Group PA-1. The postural change in Group IVC did not exert a significant effect on the inferior vena caval pressure. Group PA-2 were initially placed in the flat prone position on a flat saddle frame, which produced no significant changes in the hemodynamic variables. Then the convex curvature of the frame was adjusted to the grade appropriate for surgery, which produced a significant reduction in CI (from 2.9 +/- 0.3 to 2.4 +/- 0.4, P less than 0.05). We conclude that the prone position itself may not interfere with the circulatory function. The prone position using a convex saddle frame causes significant reductions in CI, but little change in the other hemodynamic variables.

Anesthesia, Inhalation↗

PubMed1990

Prone positioning in infant gastroesophageal reflux: is elevation of the head worth the trouble?

To determine whether head-elevated prone positioning is better than flat prone positioning for infants with gastroesophageal reflux, we studied 100 babies less than 6 months of age who were being examined for reflux with an intraluminal esophageal pH probe while the babies were in each of the two positions, with the use of a crossover design protocol. During both a 2-hour postprandial period and a fasting period, pH probe measurements in each position included (1) minutes with pH less than 4, (2) number of episodes with pH less than 4, (3) mean duration of such episodes, (4) number of such episodes longer than 5 minutes, and (5) the duration of the longest episode. Significant reductions with head elevation were found for only two of these 10 values: the frequency of reflux episodes postprandially (7.5 +/- 0.7 vs 5.9 +/- 0.5 episodes per 2 hours; p less than 0.05) and the frequency of episodes longer than 5 minutes postprandially (1.4 +/- 0.1 vs 1.2 +/- 0.1 episodes per 2 hours; p less than 0.005). There was no significant reduction in the total duration of postprandial reflux nor in any measure of reflux during the fasting period. The 90 infants in whom an abnormal degree of gastroesophageal reflux was documented had no significant differences between flat prone and head-elevated prone position for any of the 10 pH probe measurements. Head-elevated prone positioning is probably not worth the extra effort required to maintain it.

Esophagus↗

PubMed2001

The effects of prone positioning on intraabdominal pressure and cardiovascular and renal function in patients with acute lung injury.

UNLABELLED: To detect any harmful effects of prone positioning on intraabdominal pressure (IAP) and cardiovascular and renal function, we studied 16 mechanically ventilated patients with acute lung injury randomly in prone and supine positions, without minimizing the restriction of the abdomen. Effective renal blood flow index and glomerular filtration rate index were determined by the paraaminohippurate and inulin clearance techniques. Prone positioning resulted in an increase in IAP from 12 +/- 4 to 14 +/- 5 mm Hg (P < 0.05), PaO(2)/fraction of inspired oxygen from 220 +/- 91 to 267 +/- 82 mm Hg (P < 0.05), cardiac index from 4.1 +/- 1.1 to 4.4 +/- 0.7 L/min (P < 0.05), mean arterial pressure from 77 +/- 10 to 82 +/- 11 mm Hg (P < 0.01), and oxygen delivery index from 600 +/- 156 to 648 +/- 95 mL. min(-)(1). m(-)(2) (P < 0.05). Renal fraction of cardiac output decreased from 19.1% +/- 12.5% to 15.5% +/- 8.8% (P < 0.05), and renal vascular resistance index increased from 11762 +/- 6554 dynes. s. cm(-)(5). m(2) to 15078 +/- 10594 dynes. s. cm(-)(5). m(2) (P < 0.05), whereas effective renal blood flow index, glomerular filtration rate index, filtration fraction, urine volume, fractional sodium excretion, and osmolar and free water clearances remained constant during prone positioning. Prone positioning, when used in patients with acute lung injury, although it is associated with a small increase in IAP, contributes to improved arterial oxygenation and systemic blood flow without affecting renal perfusion and function. Apparently, special support to allow free chest and abdominal movement seems unnecessary when mechanically ventilated, hemodynamically stable patients without abdominal hypertension are proned to improve gas exchange. IMPLICATIONS: Prone positioning is increasingly used to improve gas exchange in patients with acute lung injury. However, during prone positioning an increase in intraabdominal pressure in these critically ill patients may promote dysfunction of other organs. Therefore, we performed a randomized study in mechanically ventilated patients with acute lung injury to investigate the cardiovascular and renal effects of prone positioning.

Abdomen↗

PubMed1993

Factors potentiating the risk of sudden infant death syndrome associated with the prone position.

BACKGROUND: In several studies the sudden infant death syndrome (SIDS) has been significantly associated with sleeping in the prone position. It is not known how the prone position increases the risk of SIDS. METHODS: We analyzed data from a case-control study (58 infants with SIDS and 120 control infants) and a prospective cohort study (22 infants with SIDS and 213 control infants) in Tasmania. Interactions were examined in matched analyses with a multiplicative model of interaction. RESULTS: In the case-control study, SIDS was significantly associated with sleeping in the prone position, as compared with other positions (unadjusted odds ratio, 4.5; 95 percent confidence interval, 2.1 to 9.6). The strength of this association was increased among infants who slept on natural-fiber mattresses (P = 0.05), infants who were swaddled (P = 0.09), infants who slept in heated rooms (P = 0.006), and infants who had had a recent illness (P = 0.02). These variables had no significant effect on infants who did not sleep in the prone position. A history of recent illness was significantly associated with SIDS among infants who slept prone (odds ratio, 5.7; 95 percent confidence interval, 1.8 to 19) but not among infants who slept in other positions (odds ratio, 0.83). In the cohort study, the risk of SIDS was greater among infants who slept prone on natural-fiber mattresses (odds ratio, 6.6; 95 percent confidence interval, 1.3 to 33) than among infants who slept prone on other types of mattresses (odds ratio, 1.8). CONCLUSIONS: When infants sleep prone, the elevated risk of SIDS is increased by each of four factors: the use of natural-fiber mattresses, swaddling, recent illness, and the use of heating in bedrooms.

Bedding and Linens↗

PubMed1999

Combining partial liquid ventilation and prone position in experimental acute lung injury.

BACKGROUND: Partial liquid ventilation (PLV) and prone position can improve arterial oxygen tension (PaO2) in acute lung injury (ALI). The authors evaluated additive effects of these techniques in a saline lung lavage model of ALI. METHODS: ALI was induced in 20 medium-sized pigs (29.2+/-2.5 kg body weight). Gas exchange and hemodynamic parameters were determined in both supine and prone position in all animals. Thereafter, one group was assigned to PLV with two sequential doses of 15 ml/kg of perfluorocarbon (n = 10); the second group was assigned to gaseous ventilation (n = 10). Gas-exchange and hemodynamic parameters were determined at corresponding time points in both groups in prone and supine position. RESULTS: In the PLV group, positioning the animals prone resulted in an increase of PaO2 prior to PLV and during PLV with both doses of perfluorocarbon when compared to ALI. PLV in supine position was only effective if 30 ml/kg of perfluorocarbon was applied. In the gaseous ventilation group, PaO2 increased reproducibly compared with ALI when the animals were turned prone. A significant additive improvement of arterial oxygenation was observed during combined therapy with 30 ml/kg of perfluorocarbon and prone position in the PLV group compared with either therapy alone. CONCLUSIONS: The authors conclude that combining PLV with prone position exerts additive effects on pulmonary gas exchange in a saline lung lavage model of ALI in medium-sized pigs.

Animals↗

PubMedDate not supplied

Usefulness of electron beam tomography in the prone position for detecting atrial thrombi in chronic atrial fibrillation.

OBJECTIVE: We compared the usefulness of electron beam tomography (EBT) in the prone position relative to that in the supine position for detecting atrial thrombi. METHODS: We studied 96 patients with chronic atrial fibrillation, of whom 71 were scanned in the supine position and 25 were scanned in the prone position. Electron beam tomography was performed twice after contrast medium injection to obtain early- and late-phase images. RESULTS: Filling defects were detected in 13 patients in the supine position by EBT. Transesophageal echocardiography (TEE) revealed a thrombus in the region of the filling defect in 9 patients. In 4 patients, filling defects in the left atrial appendage were not confirmed as thrombi by TEE. Filling defects were detected in 4 patients in the prone position, all of which were confirmed as thrombi by TEE. CONCLUSION: Electron beam tomography in the prone position is an effective technique for reducing false-positive results in the detection of atrial thrombi.

Aged↗

PubMed2005

Prone position delays the progression of ventilator-induced lung injury in rats: does lung strain distribution play a role?

OBJECTIVE: To investigate if prone position delays the progression of experimental ventilator-induced lung injury, possibly due to a more homogeneous distribution of strain within lung parenchyma. DESIGN: Prospective, randomized, controlled trial. SETTING: Animal laboratory of a university hospital. SUBJECTS: Thirty-five Sprague Dawley male rats (weight 257 +/- 45 g). INTERVENTIONS: Mechanical ventilation in either supine or prone position and computed tomography scan analysis. MEASUREMENTS: : Animals were ventilated in supine (n = 15) or prone (n = 15) position until a similar ventilator-induced lung injury was reached. To do so, experiments were interrupted when respiratory system elastance was 150% of baseline. Ventilator-induced lung injury was assessed as lung wet-to-dry ratio and histology. Time to reach lung injury was considered as a main outcome measure. In five additional animals, computed tomography scans (GE Light Speed QX/I, thickness 1.25 mm, interval 0.6 mm, 100 MA, 100 Kv) were randomly taken at end-expiration and end-inspiration in both positions, and quantitative analysis was performed. Data are shown as mean +/- sd. MEASUREMENTS AND MAIN RESULTS: Similar ventilator-induced lung injury was reached (respiratory system elastance, wet-to-dry ratio, and histology). The time taken to achieve the target ventilator-induced lung injury was longer with prone position (73 +/- 37 mins vs. 112 +/- 42, supine vs. prone, p = .011). Computed tomography scan analysis performed before lung injury revealed that at end-expiration, the lung was wider in prone position (p = .004) and somewhat shorter (p = .09), despite similar lung volumes (p = .455). Lung density along the vertical axis increased significantly only in supine position (p = .002). Lung strain was greater in supine as opposed to prone position (width strain, 7.8 +/- 1.8% vs. 5.6 +/- 0.9, supine vs. prone, p = .029). CONCLUSIONS: Prone position delays the progression of ventilator-induced lung injury. Computed tomography scan analysis suggests that a more homogeneous distribution of strain may be implicated in the protective role of prone position against ventilator-induced lung injury.

Animals↗