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Severe hypotension and hepatic dysfunction in a patient undergoing scoliosis surgery in the prone position.

Many patients with neuromuscular disorders develop progressive scoliosis and require corrective surgery. We present a patient with hereditary motor and sensory neuropathies who developed severe hypotension during corrective surgery for thoracolumbar scoliosis. The haemodynamic disturbance was probably secondary to thoracic hyperlordosis and the knee-chest position and was aggravated by surgical manipulation. This may be prevented by tailored preoperative evaluation of different patient prone position supports and frames in order to select that which causes least cardiovascular and respiratory disturbance. This patient also developed severely deranged liver function postoperatively and the possible aetiology is discussed.

Adult↗

[Spinal operations performed in prone position: pulmonary gas exchange, hemodynamics, and possible complications].

Invasive and non-invasive studies have been used to study the cardiac and respiratory systems in 93 patients during prolonged prone surgical interventions into the vertebral column. Pronounced hemodynamic changes have been found to be absent at the stage of anesthetic anesthesia and while turning the patient with to the prone position. Gas exchange is determined by the increase in alveolar dead space, PaCO2, and PaO2. The position complications during these interventions are caused by errors while placing the patient on an operating table.

Adolescent↗

Biomechanical simulations of scoliotic spine correction due to prone position and anaesthesia prior to surgical instrumentation.

BACKGROUND: The positioning of patients during scoliosis surgery has been shown to affect the scoliosis curve, yet positioning has not been exploited to help improve surgical outcome from a biomechanics point of view. Biomechanical models have been used to study other aspects of scoliosis. The goal of this study is to simulate the specific influence of the prone operative position and anaesthesia using a finite element model with patient personalized material properties. METHODS: A finite element model of the spine, ribcage and pelvis was created from the 3D standing geometry of two patients. To this model various positions were simulated. Initially the left and right supine pre-operative bending were simulated. Using a Box-Benkin experimental design the material properties of the intervertebral disks were personalized so that the bending simulations best matched the bending X-rays. The prone position was then simulated by applying the appropriate boundary conditions and gravity loads and the 3D geometry was compared to the X-rays taken intra-operatively. Finally an anaesthesia factor was added to the model to relax all the soft tissues. FINDINGS: The behaviour of the model improved for all three positions once the material properties were personalized. By incorporating an anaesthesia factor the results of the prone intra-operative simulation better matched the prone intra-operative X-ray. However, the anaesthesia factor was different for both patients. For the prone position simulation with anaesthesia patient 1 corrected from 62 degrees to 47 degrees and 43 degrees to 31 degrees. Patient 2 corrected from 70 degrees to 55 degrees and 40 degrees to 32 degrees for the thoracic and lumbar curves respectively. INTERPRETATION: Positioning of the patient, as well as anaesthesia, provide significant correction of the spinal deformity even before surgical instrumentation is fixed to the vertebra. The biomechanical effect of positioning should be taken into consideration by surgeons and possibly modify the support cushions accordingly to maximise 3D curve correction. The positioning is an important step that should not be overlooked by when simulating surgical correction and biomechanical models could be used to help determine optimal cushion placement.

Adolescent↗

Prone positioning for the ARDS patient.

Various strategies have been tested in attempts to improve gas exchange in patients with Acute Respiratory Distress Syndrome (ARDS). However, it appears that the simple non-invasive act of prone positioning of the critically ill ARDS patient may improve gas exchange while preventing potential complications of high positive end expiratory pressure (PEEP), volutrauma, and oxygen toxicity.

Critical Care↗

Randomized comparison of sitting and prone positions for stereotactic fine-needle aspiration breast biopsy.

In a prospective randomized study, 103 women had stereotactic biopsies performed either in the prone (n = 51) or sitting (n = 52) position. Questionnaires were administered before and after biopsy, to measure anxiety, pain and subjective experience in all patients. Vasovagal reactions were scored from 0 to 2 according to severity. There was no significant difference between biopsies performed in the sitting or the prone position with regard to overall tolerance. Significantly more patients biopsied in the prone position (15 of 51, 29 per cent) than in the sitting position (seven of 52, 13 per cent) would prefer premedication before a repeat biopsy (P = 0.04). Of the total patient group, three women fainted, one in the prone position and two others in the sitting position. Breast biopsies performed in the prone or sitting position are equally well tolerated. Somatic reactions such as fainting are not a major problem during breast biopsy; however, attention should be focused on patient care, including information given before the procedure.

Anxiety↗

Treatment in the prone position of calculi in the midureter overlying the bony sacrum with extracorporeal shock wave lithotripsy.

Thirty-six patients with radiopaque calculi in the segment of the ureter overlying the sacrum, were treated in the prone position with an unmodified Dornier HM-3 lithotripter. Thirty-one treatments were successful and five failed for a success rate of 86%. Success is defined as the absence of fragments on KUB. The five failures were all removed ureteroscopically. Epidural anesthesia was used for all cases. A post-extracorporeal shock wave lithotripter (post-ESWL) gastrointestinal (GI) bleeding episode, and an upper ureteral extravasation post-ESWL, as well as two patients who could not tolerate the position are discussed.

Adult↗

A case of ventricular fibrillation in the prone position during back stabilisation surgery in a boy with Duchenne's muscular dystrophy.

A 15-year-old boy with Duchenne's muscular dystrophy experienced prolonged cardiac arrest whilst in the prone position for spinal surgery. He was successfully resuscitated without apparent neurological sequelae by internal cardiac massage via a thoracotomy and external and internal direct current cardioversion. Recommendations are suggested for the pre- and peroperative management of such cases.

Adolescent↗

Neck semispinalis capitis muscle size in sitting and prone positions measured by real-time ultrasonography.

OBJECTIVE: To examine the reliability of measurements of semispinalis capitis muscle (SECM) cross-sectional area (CSA) in prone and sitting positions, and to compare the muscle size in these two positions. DESIGN: Semispinalis capitis CSA was measured twice a day on two successive days with a real-time ultrasound apparatus. SUBJECTS: Eighteen males (aged 19-34 years) and 28 females (aged 19-34 years) were studied for the reliability test. Seven males and 12 females were randomly selected to compare SECM size in sitting and prone positions. RESULTS: The intraclass correlation coefficient (ICC) for repeatability measurements was r = 0.98 for the two positions. The correlation of the CSA in sitting and in prone positions was r = 0.93 (p < 0.01). There were no significant differences between CSA, linear dimensions and shape ratio of SECM in the two positions. CONCLUSIONS: In this study SECM ultrasonography appeared to be an accurate method in both positions, and position as such had no significant effects on the SECM cross-sectional size. Such accuracy allows neck muscle evaluation in clinical diagnosis and in follow-up studies during neck rehabilitation programmes.

Adult↗

Do infants have motor responses to sudden surface rotations in prone position?

This study investigated whether sudden rotation of the support surface (platform) triggers motor responses similar to reactions to sudden free fall in infants at very early age (2 to 5 weeks). Ten infants in prone position were exposed to sudden head-down rotation (mimicking the falling phase) and head-up rotation of the platform (mimicking landing phase) of 4 degrees or 6 degrees amplitude and 35 degrees/s velocity while EMGs and kinematics were recorded from the neck, trunk, and right arm. One infant, reassessed at 13 weeks, and one adult were tested for complementary developmental information. Sudden downward acceleration of the platform, induced either during head-down rotation or during the deceleration phase of head-up rotation, indeed mimicked falling and evoked in infants two-peaked EMG responses in the neck, trunk, and arm muscles, lasting in the latter over several hundred milliseconds. The activation pattern showed similarities to the adult and 13-week-old control subjects. The results suggested that the first burst may be ascribed to cutaneous pressure changes at the body and to vestibular signals triggering a startle-like response, whereas the second burst of the pattern in the arm is likely a candidate for an early substrate of the landing response normally seen during later stages of motor development. Head control appeared to be related more to its position with respect to the orientation of the trunk rather than to space in the infants and in the adult and might be due to the experimental paradigm, in which the surface accelerated away from the body and not, as during normal falling, when the body accelerates toward the support surface.

Adolescent↗

Prone positioning of pediatric patients with ARDS results in improvement in oxygenation if maintained > 12 h daily.

OBJECTIVES: To evaluate changes in oxygenation index (OI) in pediatric patients with ARDS during the first 24 h of prone positioning (PP), and to determine whether or not longer periods of PP (> 12 h) result in a more pronounced improvement in oxygenation. DESIGN: A retrospective chart review of patients with ARDS who had been placed in PP for their management. SETTING: Pediatric ICU of a children's hospital. MEASUREMENTS AND MAIN RESULTS: We retrieved the charts of patients with ARDS who had been admitted to our pediatric ICU over a 3-year period and placed in PP for their management. The patients received mechanical ventilation, were sedated and pharmacologically paralyzed, and underwent arterial blood gas analysis, with concomitant documentation of ventilator settings, at a frequency of once every 4 h or more often. We divided the first 24 h of PP into two periods, brief and prolonged. The brief period was defined as duration of PP between 6 h and 10 h, and the prolonged period was between 18 h and 24 h. We compared pre-PP OI values to values after brief periods and prolonged periods of PP. Values of the PaO(2)/fraction of inspired oxygen (P/F) ratio and the mean airway pressure (MAP) were similarly evaluated. We also evaluated the degree of OI fluctuations during 24 h of PP by identifying the time points at which the best OI and the worst OI were observed. Data from a total of 40 pediatric patients with ARDS were evaluated. Twenty-one of the patients were male, and 19 were female; their ages ranged from 1 month to 18 years (mean +/- SD, 6.22 +/- 6.27 years). Thirty-two patients received conventional mechanical ventilation, and 8 patients received high-frequency oscillatory ventilation. Thirty-three patients survived, and 7 patients (21%) died. The mean duration of PP was 67 +/- 64 h (2.8 +/- 2.7 days), the mean number of ventilator days was 32 +/- 32, and the mean interval between endotracheal intubation and placing the patients in PP was 107 +/- 108 h (4.5 +/- 4.5 days). Thirty-seven patients completed 20 h of PP or more. The mean post-PP time points at which OI values were actually evaluated for these patients were 8 +/- 2 h (brief) and 21 +/- 4 h (prolonged), respectively. Overall, the OI decreased from a pre-PP value of 24.8 +/- 13.0 to 16.7 +/- 13.7 after a brief period of PP (p < 0.05 when compared to baseline) and 11.4 +/- 6.3 after prolonged period (p < 0.05 when compared to baseline and brief period values). This improvement in OI followed the improvement seen in the P/F ratio, whereas the MAP remained unchanged. The best mean OI value, with patients in PP, was 11 +/- 9 (p < 0.05 when compared to baseline) that occurred at 16 +/- 6 h, and the worst was 22 +/- 15 (p = not significant when compared to baseline) that occurred at 9 +/- 7 h. CONCLUSIONS: PP of pediatric patients with ARDS for prolonged periods (18 to 24 h) results in a more pronounced and more stable reduction in their OI values than those observed after brief periods (6 to 10 h). This improvement in OI was not associated with changes in MAP during the first 24 h of mechanical ventilation. OI values tend to fluctuate more during the first 12 h of PP then they do during the subsequent 12 h.

Child↗

A method of spontaneously breathing anaesthesia in the prone position without endotracheal intubation.

A method of delivering anaesthetics to spontaneously breathing patients in the prone position was developed. The arterial blood gases of eighteen patients undergoing short-stay surgery and using this technique were analysed. The results showed the influence of premedication on arterial pH and PCO2 levels but they do not differ from accepted values for similar anaesthesia on supine patients. The advantages and disadvantages of this technique are discussed.

Adult↗

Adjunctive therapy to mechanical ventilation: surfactant therapy, liquid ventilation, and prone position.

Acute lung injury and acute respiratory distress syndrome are associated with significant morbidity and mortality in critically ill patients. Although lung protective mechanical ventilation is the only therapy shown to reduce mortality and development of organ failure, several biologic pathways have been identified and provided an opportunity for therapeutic interventions. No pharmacologic or adjunctive treatments are available. Clinical studies demonstrated that prone position results in significant and clinically relevant improvement in oxygenation and ventilation, which persist when patients are returned to supine position; the beneficial response is not limited to patients turned early in disease course. Few complications are associated with prone ventilation. Clinical experience suggests that prone ventilation may protect the lung from potential detrimental effects of mechanical ventilation. Further studies are needed.

Humans↗

Paediatric one lung ventilation in the prone position.

Pulmonary lobectomy in the presence of infected secretions requires isolation of the affected lung to prevent soiling of the healthy lung. In young children this is usually accomplished using a Fogarty embolectomy catheter. We report the successful combination of a Fogarty catheter, a tracheal tube and the prone position, which provided adequate ventilation and oxygenation as well as excellent surgical exposure.

Bronchiectasis↗

Effect of prone positioning on the survival of patients with acute respiratory failure.

BACKGROUND: Although placing patients with acute respiratory failure in a prone (face down) position improves their oxygenation 60 to 70 percent of the time, the effect on survival is not known. METHODS: In a multicenter, randomized trial, we compared conventional treatment (in the supine position) of patients with acute lung injury or the acute respiratory distress syndrome with a predefined strategy of placing patients in a prone position for six or more hours daily for 10 days. We enrolled 304 patients, 152 in each group. RESULTS: The mortality rate was 23.0 percent during the 10-day study period, 49.3 percent at the time of discharge from the intensive care unit, and 60.5 percent at 6 months. The relative risk of death in the prone group as compared with the supine group was 0.84 at the end of the study period (95 percent confidence interval, 0.56 to 1.27), 1.05 at the time of discharge from the intensive care unit (95 percent confidence interval, 0.84 to 1.32), and 1.06 at six months (95 percent confidence interval, 0.88 to 1.28). During the study period the mean (+/-SD) increase in the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen, measured each morning while patients were supine, was greater in the prone than the supine group (63.0+/-66.8 vs. 44.6+/-68.2, P=0.02). The incidence of complications related to positioning (such as pressure sores and accidental extubation) was similar in the two groups. CONCLUSIONS: Although placing patients with acute respiratory failure in a prone position improves their oxygenation, it does not improve survival.

Female↗

[Prone position and severe pneumopathy in a patient with head injuries and intracranial hypertension].

The treatment of hypoxaemia is one of the main goals of intensive care to patients with severe head injury. In the case reported here, the appearance of early pneumonia was accompanied by a severe deterioration of blood gases with worsening of intracranial hypertension. Prone position allowed rapid improvement of blood gases which contributed to the control of intracranial hypertension.

Adult↗