[Tracheobronchial suction as a problem in intensive care. Continuous pO 2 measurements using a polarographic micromethod during various tracheobronchial suction maneuvers].
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OBJECTIVE: Disconnecting the endotracheal tube from the ventilator causes significant loss in lung volume, which is further exacerbated by suctioning. In-line catheter suction systems have putative benefits over open catheter suction by maintaining positive pressure, thereby minimizing hypoxemia and hemodynamic instability. However, there is a theoretical risk of generating large negative airway pressures and auto-cycling of the ventilator with in-line catheter suction systems. We studied the effects on lung volume with both these techniques. DESIGN: Open, randomized, crossover, clinical trial. SETTING: Pediatric critical care unit. PATIENTS: Fourteen paralyzed patients, age 6 days to 13 yrs. INTERVENTIONS: Each patient, acting as his or her own control, was suctioned with an in-line catheter suction system and open catheter suction. Each suction maneuver was standardized. Changes in lung volume were measured by inductance plethysmography. Heart rate, blood pressure, and oxygen saturation were continuously monitored. MEASUREMENTS AND MAIN RESULTS: Total lung volume loss was greater with open catheter suction compared with in-line catheter suction systems (p = .008). The most significant amount of lung volume loss associated with open catheter suction appears to be related to ventilator disconnection, rather than actual suctioning. Patients with decreased pulmonary compliance (< 0.8 mL/cm H2O/kg) demonstrated a greater loss in lung volume, both absolute and relative, as a result of ventilator disconnection (p = .038 and .006, respectively). Patients suctioned with open catheter suction desaturated to a greater extent than patients suctioned with in-line catheter suction (p = .026). There was evidence of ventilator triggering during the actual suction maneuver in all patients during in-line catheter suctions. CONCLUSIONS: The most significant loss in lung volume during suctioning occurs primarily during ventilator disconnection. Hence, open catheter suction results in greater lung volume loss when compared with in-line catheter suction. We suggest that in-line catheter suction is preferable, especially in patients with significant lung disease and who require high positive end-expiratory pressures, to avoid alveolar derecruitment and exacerbating hypoxemia during endotracheal tube suctioning.
UNLABELLED: A new closed tracheo-bronchial suction system was evaluated. With this device the patient need not be disconnected from the ventilator during suctioning, and can thus have a continuous supply of oxygen. The closed suction system is attached to the patient's endotracheal tube and ventilator Y-piece. The catheter, which is enveloped by a plastic sheet, can remain connected to the patient for as long as 24 h (Fig. 1). MATERIALS AND METHODS. In the medical and surgical intensive care unit of Alt/Neuötting General District Hospital, 39 trials on 16 mechanically ventilated patients receiving more than 8 cm H2O positive end-expiratory pressure (PEEP) and/or more than 60% FiO2 were performed. Each subject was suctioned using the open and closed methods. Arterial blood gases were obtained through an indwelling catheter before suctioning and then 1, 5, and 15 min after suctioning. Open suctioning: After 2 min preoxygenation with 100% oxygen the patient was disconnected from the ventilator, the suction catheter was inserted and the subject suctioned for a maximum of 15 s, then manually ventilated four times and reconnected. Closed suctioning: After preoxygenation the patient was suctioned without disconnection by means of the closed suction system. Statistical analysis was done by the two-tailed t-test on individual paired differences or by Student's t-test. P values of less than 0.05 were accepted as significant. RESULTS: Patients were subdivided according to the PEEP level used (less or more than 8 cm H2O) and analysed separately. One minute after suctioning (T1) arterial pO2 was found to increase significantly for the open-system method when PEEP ventilation was < or = 8 cm H2O (Table 1) and for the closed system method when PEEP ventilation was both < or = 8 cm H2O (Table 1) and > 8 cm H2O (Table 2). Five (T5) and 15 (T15) min after suctioning, pO2 dropped significantly compared to baseline values in the open-system method when PEEP was > 8 cm H2O (Table 2). PO2 values 15 min after closed suctioning with PEEP > 8 cm H2O were significantly higher than those after open suctioning (Table 2). After the pO2 differences were formed between baseline and values 1, 5, and 15 min after suctioning, significant differences between open- and closed-system suctioning were found for PEEP > 8 cm H2O at T1, T5, and T15 (Table 2, Fig. 3). DISCUSSION. The increase in pO2 as a positive effect of preoxygenation with 100% oxygen before suctioning was less marked for open-system suctioning with PEEP > 8 cm H2O because FiO2, measured at the ventilator Y-piece, was abruptly reduced after disconnection and simultaneously PEEP was lost. As a consequence, pO2 values fell significantly 5 and 15 min after suctioning in this situation, whereas for all the other conditions pO2 reached baseline as well as slightly higher values. Patients with severe respiratory insufficiency need continuous positive airway pressure to keep unstable alveoli patent. Every maneuver that reduces intra-alveolar pressure may precipitate alveolar collapse. However, in the diseased lung closed alveoli may not re-expand at once when pressure is re-established. Therefore, closed-system suctioning may help to prevent prolonged deterioration of oxygenation in patients with severe respiratory failure.
INTRODUCTION: Endotracheal suctioning of mechanically ventilated, very-low-birthweight infants for removal of respiratory secretions can be associated with morbidity. Routine endotracheal suctioning is inadvisable, but the safe minimum endotracheal suctioning frequency for prevention of airway obstruction has not been determined. HYPOTHESIS: Decreasing suctioning frequency from every 4 hours to every 8 hours (plus as needed) would have no clinically important effect on the primary outcomes (nosocomial bloodstream infection [BSI], ventilator-associated pneumonia [VAP], and bacterial airway colonization) or secondary outcomes (reintubation rates, need for postural drainage, severity of bronchopulmonary dysplasia [BPD], neonatal mortality, duration of mechanical ventilation, and duration of hospitalization). METHODS: We conducted a sequential retrospective study of 90 very-low-birthweight infants who were mechanically ventilated for longer than 7 days and who underwent endotracheal suctioning every 4 hours (plus as needed) and 90 similar infants who underwent endotracheal suctioning every 8 hours (plus as needed). Two-pass endotracheal suctioning used during the study period required predetermined measurement of the suction catheter and prior instillation of saline. RESULTS: The 2 treatment groups were similar in demographic and clinical characteristics, including survival (90% and 85%), age at time of death (28 and 33 d), mean birthweight (926 and 934 g), gestational age (27 and 27 wk), duration of ventilation (29 and 27 d), and duration of stay (55 and 53 d). Regardless of suctioning frequency, airway colonization with Gram-positive cocci occurred in the majority of patients by 2 weeks of life. Forty-three percent of the infants suctioned every 4 hours and 44% of those suctioned every 8 hours became airway colonized with Gram-negative bacilli. No Gram-negative bacilli species was more likely to be associated with either treatment group. VAP was diagnosed in 5 of the infants suctioned every 4 hours and in 9 of the infants suctioned every 8 hours. Nosocomial BSI occurred in 18 of the infants suctioned every 4 hours and in 21 of the infants suctioned every 8 hours. The difference in incidence of VAP and BSI was due to a epidemic that started before the change in suctioning frequency. During hospitalization, approximately one fourth of the patients in each group required postural drainage and were reintubated 11 and 10 times per 100 ventilator days, respectively. A comparable number of infants in each group developed severe BPD and were discharged home on oxygen. Suctionings per patient per ventilator day were 6 for the group suctioned every 4 hours and 4 for the group suctioned every 8 hours (p < 0.01). CONCLUSIONS: A low-frequency suctioning regimen (every 8 hours plus as needed) can be implemented without increasing the incidence of nosocomial BSI, VAP, bacterial airway colonization, frequency of reintubation, need for postural drainage, severity of BPD, neonatal mortality, duration of mechanical ventilation, or duration of hospitalization. Although the minimum suctioning frequency for removal of unwanted respiratory secretions is yet to be established, a substantial reduction in endotracheal suctioning frequency appears to be safe.
The purpose of this multisite study was to determine the effects of endotracheal suctioning on mixed venous oxygen saturation (SvO2) and heart rate in 189 critically ill adults. One-pass, intermittent suction was applied for 10 or fewer seconds, with three prehyperoxygenation and three posthyperoxygenation breaths of 100% oxygen. Subjects at three hospitals (n = 127) underwent suctioning using hyperoxygenation with anesthesia bags and traditional suction catheters (open suction method). Subjects at one hospital (n = 62) underwent suctioning with hyperoxygenation by ventilator and in-line suction catheters (closed suction method). For subjects from all hospital sites combined, the SvO2 decreased from 67% to 64% (p = 0.001), a 4% change from baseline, and returned to baseline within 2 minutes. However, in subjects receiving the open method of suction, SvO2 dropped from 66% to 62% immediately after suctioning and returned to baseline within 4 minutes. In contrast, when the closed suction method was used, SvO2 rose from 67.7% to 67.86% immediately after suctioning, drifting upward to 71% for the next 2 minutes before dropping toward the baseline after 4 minutes. Mean heart rate increased from a baseline of 99 beats/min to 104 beats/min immediately after suctioning (p = 0.001), a 5% change from baseline, and gradually returned to baseline over the next 4 minutes. No significant differences were seen in heart rate between subjects having the open versus closed suction method. In conclusion, the closed suction method showed a higher SvO2 after endotracheal suctioning compared with the open suction method (p = 0.0001). Some form of hyperoxygenation before and after endotracheal suctioning is recommended.
OBJECTIVE: To examine the physiologic consequences and costs associated with two methods of endotracheal suctioning: closed vs. open. DESIGN: A prospective, randomized, controlled study. SETTING: An eight-bed trauma intensive care unit (ICU) in a 460-bed level I trauma center. PATIENTS: The study included 35 trauma/general surgery patients (16 in the open suction group, 19 in the closed suction group) who were treated with a total of 276 suctioning procedures (127 open, 149 closed). MEASUREMENTS AND MAIN RESULTS: Physiologic data collected after hyperoxygenation, immediately after suctioning, and 30 secs after suctioning, were compared with baseline values. Open endotracheal suctioning resulted in significant increases in mean arterial pressure throughout the suctioning procedure. Both methods resulted in increased mean heart rates. However, 30 secs after the procedure, the open-suction method was associated with a significantly higher mean heart rate than was the closed method. Closed suctioning was associated with significantly fewer dysrhythmias. Arterial oxygen saturation and systemic venous oxygen saturation decreased with open suctioning. In contrast, arterial oxygen saturation and systemic venous oxygen saturation increased with the closed suction method. There was no difference between the two methods in the occurrence of nosocomial pneumonia. Open endotracheal suctioning cost $1.88 more per patient per day and required more nursing time. CONCLUSIONS: The closed suction method resulted in significantly fewer physiologic disturbances. Closed suctioning appears to be an effective and cost-efficient method of endotracheal suctioning that is associated with fewer suction-induced complications.
BACKGROUND: Endotracheal suctioning for mechanically ventilated infants is routine practice in neonatal intensive care. However, this practice is associated with serious complications including lobar collapse, pneumothorax, bradycardia and hypoxemia. Increasing the inspired oxygen immediately prior to suction (preoxygenation) has been proposed as an intervention to minimise the risk of complications. OBJECTIVES: To compare the effects of preoxygenation with no preoxygenation for endotracheal suctioning on ventilated newborn infants. To conduct sub group analyses by i) different populations of newborn infants; by gestational age <30 weeks, <34 weeks and <37 weeks and by disease; infants with chronic lung disease compared to those without and; ii) by different techniques of endotracheal suctioning; with or without disconnection from the ventilator, increased mechanical ventilation, use of manual ventilation and chest wall vibrations or percussion. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group was used. This included searches of electronic databases; Oxford Database of Perinatal Trials; Cochrane Controlled Trials Register (Cochrane Library Issue 1 2001); MEDLINE (1966 - April 2001); and CINAHL (1982-2001) using MeSH term infant-newborn and text terms oxygen* and suction*, preoxygenation, pre-oxygenation and premature and also previous reviews including cross references, abstracts in conferences and symposia proceedings, expert informants, journal hand searching in the English language. SELECTION CRITERIA: Random or quasi random controlled trials of mechanically ventilated neonates in which endotracheal suctioning with preoxygenation was compared to suctioning without preoxygenation. DATA COLLECTION AND ANALYSIS: Standard methods of the Cochrane Collaboration and its Neonatal Review Group were used, including independent assessment of trial quality and extraction of data by the authors. Data were analysed using relative risk (RR) for dichotomous outcomes and mean difference (MD) for data measured on a continuous scale with the use of 95% confidence intervals. Meta-analysis was conducted using a fixed effects model. MAIN RESULTS: One cross-over trial involving outcomes for 16 preterm neonates was included in this review. Preoxygenation, prior to an endotracheal suctioning procedure involving two suctions, resulted in a statistically significant reduction in infants with hypoxemia (TcPO2 <40 mmHg) at the end of the first suction (RR 0.18, 95% CI 0.05, 0.69), at the end of the second suction (RR 0.23, 95% CI 0.08, 0.66) and also at 120 seconds after the second suction (RR 0.10, 95% CI 0.01, 0.69). Mean TcPO2 was statistically significantly higher in the preoxygenation group at the end of the first suction (MD 25.00 mmHg, 95%CI 14.20, 35.80), second suction (MD 24.80, 95% CI 14.80, 34.80) and also at 120 seconds after the second suction (MD 29.10, 95% CI 14.96, 43.24). The time taken to return to baseline oxygenation status was shorter than the group not receiving preoxygenation (MD -2.12 minutes, 95% CI -3.82, -0.42). REVIEWER'S CONCLUSIONS: No recommendations for practice can be confidently made from the results of this review. Although preoxygenation was shown to decrease hypoxemia at the time of suctioning, other clinically important short and longer-term outcomes including adverse effects were unable to be assessed. Further studies are needed to adequately assess the effects of this widely practiced procedure.
OBJECTIVE: To determine whether ventilated, low birth weight infants treated with closed versus open tracheal suction in a neonatal intensive care unit (NICU) differ as to airway bacterial colonization, nosocomial pneumonia, bloodstream infection (BSI), incidence and severity of bronchopulmonary dysplasia (BPD), neonatal mortality, frequency of suction, reintubation, and nurse preference. STUDY DESIGN: A total of 175 low birth weight infants (< or = 1250 gm) consecutively born (1997 to 1999), intubated, and ventilated in the delivery room were randomized on admission to the NICU to a closed (Trach Care MAC) or open suction group. Closed multi-use catheters were changed daily; open catheters were changed after every use. Two-pass endotracheal suctioning (both groups) was performed every 8 hours or as needed. Side-port connectors were not used; thus open suction required disconnection from ventilators. Tracheal aspirate cultures were obtained on admission and weekly thereafter. Nosocomial BSI (occurring after 48 hours of life) was documented by positive blood cultures. Radiographs taken before, during, and after tracheal aspirate cultures or BSIs were graded using a semiquantitative system for pneumonia and a modified score for BPD. Nurse preference regarding suction method was recorded. RESULTS: Of the original 175 patients, 10 (5 from each group) died and 32 others (16 form each group) were extubated at or before 7 days of life. The study population comprised 67 patients in the closed group and 66 in the open group who were ventilated longer than 1 week. Groups were not statistically different in terms of demographic and clinical characteristics, such as birth weight (837 vs 876 gm), ventilation (27 vs 26 days), and length of stay (49 vs 40 days). Airway colonization with Gram-positive cocci occurred in the majority of patients by 2 weeks of life, regardless of group. A total of 39% of infants in the closed group and 44% of infants in the open group became airway colonized with Gram-negative bacilli; differences were statistically significant. No Gram-negative bacilli species was more likely to be associated with either suction. Nosocomial pneumonia was diagnosed in five patients from each group. Nosocomial BSIs occurred in six closed suction infants and five open suction infants. A comparable number of infants in each group developed severe BPD and were discharged from the hospital on oxygen. A total of 28% of closed suction patients and 27% of open suction patients died. Infants in the closed versus open group were suctioned on average 4.4 and 4.1 times per day and were reintubated 9.7 and 8.6 times per 100 ventilator days, respectively. A total of 40 of 44 NICU nurses considered closed suction to be easier to use, less time-consuming, and better tolerated by the patient. CONCLUSIONS: Closed suction obviates the physiological disadvantage of ventilator disconnection without increasing the rate of bacterial airway colonization, frequency of endotracheal suction and reintubation, duration of mechanical ventilation, length of hospitalization, incidence of nosocomial pneumonia, nosocomial BSI, severity of BPD, and neonatal mortality. Although slightly more expensive, closed suction is perceived by nursing staff to be easier, less time-consuming, and better tolerated by small premature infants requiring mechanical ventilation for > or = 1 week.
BACKGROUND: Suction drains are routinely used after modified radical mastectomy and are an important factor contributing to increased hospital stay as the patients are often discharged only after their removal. Amongst various factors that influence the amount of postoperative drainage, the negative suction pressure applied to the drain has been reported to be of great significance. While a high negative suction pressure is expected to drain the collection and reduce the dead space promptly, it may also prevent the leaking lymphatics from closing and lead to increased drainage from the wound. Against this background a prospective randomized clinical study was conducted to compare the amount and duration of drainage between a half negative suction and full vacuum suction drainage in patients following modified radical mastectomy. The associated postoperative morbidity was also compared between the two groups. METHODS: 85 FNAC (fine needle aspiration cytology) proven cases of locally advanced breast cancer were randomized. (Using randomly ordered sealed envelops, which were opened immediately before the closure of the wound) in to 50 patients with full vacuum suction (pressure = 700 g/m2) and 35 cases in to half vacuum suction drainage (pressure = 350 g/m2) groups. The two groups were comparable in respect of age, weight, and technique of operation and extent of axillary dissection. Surgery was performed by the same surgical team comprising of five surgeons (two senior and three resident surgeons) using a standardized technique with electrocautery. External compression dressing was provided over the axilla for first 48 hrs and following that patients were encouraged to do active and passive shoulder exercises. The outcomes measured were postoperative morbidity and the length of hospital stay. Statistical methods used: Descriptive studies were performed with SPSS version 10 and group characteristics were compared using student t-test. RESULTS: Half vacuum suction drains were removed earlier than the full suction vacuum suction drains. There was no significant difference in the incidence of seroma formation in the two groups and there was a significant reduction in the total hospital stay in patients with half vacuum suction drainage systems as compared to the full suction drainage group (p < 0.001) without any added morbidity. CONCLUSIONS: Half negative suction drains provide an effective compromise between no suction and full or high suction drainage after modified radical mastectomy by reducing the hospital stay and the post operative morbidity including post operative seromas.
The occurrence of hypoxia during endotracheal tube suctioning and its prevention was examined in 25 hemodynamically stable and non-cyanosed pediatric patients. In each patient 4 suction and treatment protocols were studied: 1. pre- and post-suction arterial blood gases (ABG) with no treatment (control). 2. ABG with pre-suction oxygenation. 3. ABG with presuction hyperinflation. 4. ABG with postsuction hyperinflation. With no presuction treatment the PO2 and saturation fell significantly after suctioning from control level of 116.6 +/- 9.4 mmHg to 93 +/- 9.3 mmHg post-suction and 97.2 +/- 0.4% to 92.8 +/- 1.4% (p less than 0.001) respectively. In 6 patients with low but adequate pre-suction PO2, hypoxic levels (PO2 less than 60 mmHg) were found post-suction. The significant fall in PO2 was completely prevented by pre-suction oxygenation. Post-suction hyperinflation induced a rapid return of the PO2 to control levels. These results suggest that severe hypoxia might occur during endotracheal suctioning and can be prevented by pre-oxygenation. We recommend 1 min oxygenation with FiO2 1.0 prior to suctioning procedures and intermittent hyperinflation with 100% oxygen during repeated endotracheal suction passes to prevent hypoxia, especially in children in respiratory failure who already have low or borderline pre-suction PO2.
BACKGROUND: Suction vacuum pressure (VP) not exceeding 150 torr is recommended during intraoperative blood salvage to minimize hemolysis. When the suction provided by this VP becomes inadequate because of brisk bleeding, an alternative high-VP suction should be used and the blood discarded. This approach often results in the salvage of only a small fraction of the blood shed during surgery complicated by large hemorrhage. STUDY DESIGN AND METHODS: This laboratory study was designed to quantitate the hemolysis caused by various VPs in a suction system commonly used for intraoperative blood salvage. For each experiment, a batch of blood with a hematocrit of 30 to 35 percent was prepared by mixing of outdated units of red cells, fresh-frozen plasma, and saline solution. Aliquots of this blood were suctioned at VPs of 150, 200, 250, and 300 torr, either without (6 experiments) or with (4 experiments) maximal air entrainment. Total hemoglobin, hematocrit, red cell count, plasma-free hemoglobin, and serum potassium were measured in the blood before suction and in each aliquot after suction. RESULTS: Suction of blood mixed with air caused much greater hemolysis than suction of blood alone (p < 0.01 at each VP tested). Raising the VP from 150 to 300 torr increased hemolysis from 0.14 +/- 0.20 percent (mean +/- SD) to 0.32 +/- 0.21 percent (p < 0.05) when blood alone was aspirated and from 1.45 +/- 0.50 percent to 2.85 +/- 0.22 percent (p < 0.05) when blood was suctioned with air. With either type of suction, red cell count, hematocrit, and serum potassium did not change significantly throughout the range of VPs tested. CONCLUSION: Hemolysis was found to depend on the VP applied and, to a much greater extent, on the amount of blood and air mixing. Increasing the VP above the recommended limit of 150 torr was not associated with inordinate hemolysis. Even when a VP as high as 300 torr was used, hemolysis ranged between 0.3 and 3.0 percent, depending on whether air was suctioned with the blood or not. The data support the idea that the lowest VP compatible with a clear surgical field should be used during intraoperative blood salvage and that the suctioning of air should be avoided as much as possible. These data also suggest that, in contrast to current recommendations, suction VP during intraoperative blood salvage can be increased up to 300 torr if required by the rate of bleeding, without causing excessive hemolysis.
INTRODUCTION: We conducted this prospective randomised cross-over study to evaluate the effect of closed system (CS) versus open system (OS) endotracheal suctioning on heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), oxygen saturation (SpO2) and electrocardiogram (ECG) rhythm of patients on mechanical ventilation. MATERIALS AND METHODS: Fourteen adult patients were randomly allocated to receive either CS or OS suctioning in the first instance. For the subsequent suctioning, they were crossed over to the alternate suctioning system. The various cardiorespiratory parameters were recorded at BL1 (baseline 1), S1 (first suction pass), BL2 (baseline 2, i.e. immediately post first suction pass), S2 (second suction pass), T2 (2 minutes post suction) and T5 (5 minutes post suction). RESULTS: Compared to CS, OS suctioning was found to result in higher HR at S1 (P < or = 0.05) and S2 (P < or = 0.05); higher MAP at BL2 (P < or = 0.05); lower SpO2 at BL2 (P < or = 0.01) and S2 (P < or = 0.01). There was no significant difference in RR between the two suctioning systems. OS suctioning was also noted to result in a significantly higher incidence of arrhythmia (P < = or 0.05). CONCLUSION: Our study shows that OS suctioning results in more adverse changes in cardiorespiratory parameters compared to CS suctioning.
Platelet damage and postoperative blood loss are less severe after cardiopulmonary bypass performed with a membrane oxygenator than with a bubble oxygenator. However, this advantage of the membrane oxygenator can be partly negated by the platelet damage caused by cardiotomy suction, which implies the aspiration of air along with suction of blood. In order to reduce platelet damage by cardiotomy suction, we developed an automatic controlled cardiotomy suction system by which the aspiration of air was prevented. We evaluated platelet damage in a group of 28 patients (uncontrolled suction, n = 13; controlled suction, n = 15), and we studied the relationship between increasing volumes of cardiotomy suction and postoperative blood loss in a second group of 80 patients (uncontrolled suction, n = 47; controlled suction, n = 33). All patients underwent a coronary artery bypass operation with a membrane oxygenator. We measured significantly lower beta thromboglobulin concentrations during perfusions of approximately 2 hours and we observed a tendency toward shorter postoperative bleeding times if controlled cardiotomy suction was used. There were no significant differences between uncontrolled and controlled cardiotomy suction in platelet number and adenosine diphosphate-induced platelet aggregation. However, blood loss 18 hours postoperatively was significantly less in the controlled than in the uncontrolled suction group when the total volume of cardiotomy suction exceeded 65 L., which corresponded to perfusion times of over 3 hours. In conclusion, prevention of the aspiration of air along with suction of blood significantly reduced platelet activation and postoperative blood loss, particularly when large volumes of blood were aspirated.
BACKGROUND: Meconium aspiration syndrome (MAS) is a life-threatening respiratory disorder in infants born through meconium-stained amniotic fluid (MSAF). Although anecdotal data concerning the efficacy of intrapartum oropharyngeal and nasopharyngeal suctioning of MSAF are conflicting, the procedure is widely used. We aimed to assess the effectiveness of intrapartum suctioning for the prevention of MAS. METHODS: We designed a randomised controlled trial in 11 hospitals in Argentina and one in the USA. 2514 patients with MSAF of any consistency, gestational age at least 37 weeks, and cephalic presentation were randomly assigned to suctioning of the oropharynx and nasopharynx (including the hypopharynx) before delivery of the shoulders (n=1263), or no suctioning before delivery (n=1251). Postnatal delivery-room management followed Neonatal Resuscitation Program guidelines. The primary outcome was incidence of MAS. Clinicians diagnosing the syndrome and designating other study outcomes were masked to group assignment. An informed consent waiver was used. Analysis was by intention to treat. FINDINGS: 18 infants in the suction group and 15 in the no suction group did not meet entry criteria after random assignment. 87 in the suction group were not suctioned, and 26 in the no suction group were suctioned. No significant difference between treatment groups was seen in the incidence of MAS (52 [4%] suction vs 47 [4%] no suction; relative risk 0.9, 95% CI 0.6-1.3), need for mechanical ventilation for MAS (24 [2%] vs 18 [1%]; 0.8, 0.4-1.4), mortality (9 [1%] vs 4 [0.3%]; 0.4, 0.1-1.5), or in the duration of ventilation, oxygen treatment, and hospital care. INTERPRETATION: Routine intrapartum oropharyngeal and nasopharyngeal suctioning of term-gestation infants born through MSAF does not prevent MAS. Consideration should be given to revision of present recommendations.
OBJECTIVE: Neurologic dysfunction after cardiopulmonary bypass might be due to arterial microembolization. Pericardial suction blood is a possible source of embolic material. Our aim was to determine the capillary-pore flow ability of pericardial suction blood. METHODS: Pericardial suction blood from patients undergoing coronary bypass was collected, and pericardial suction blood and venous blood were sampled at the end of cardiopulmonary bypass and before reinfusion of pericardial suction blood. Pericardial suction blood was (n = 10) or was not (n = 10) prefiltered through a 30-microm cardiotomy screen filter before capillary in vitro analysis. Additionally, in 8 patients the plasma viscosity was measured, and in 5 of these patients, pericardial suction blood capillary deposits were evaluated by using a microscopy-imprint method and fat staining. Capillary flow was tested through 5-microm pore membranes. Tested components were plasma, plasma-eliminated whole-blood resuspension, and leukocyte/plasma-eliminated erythrocyte resuspension. Initial filtration rate and clogging slope expressed the blood-to-capillary interaction. RESULTS: The plasma-flow profile of pericardial suction blood was highly impaired, with a 47% reduction in initial filtration rate (P <.001) and a 142% steeper clogging slope flow deceleration (P <.01). This difference was not due to a change in pericardial suction blood viscosity, such as by free hemoglobin, which corresponded to 5.7% of the erythrocytes. There were no differences in resuspended whole blood or erythrocytes. The cardiotomy filter had no effect. Microscopy suggested the presence of capillary fat deposits in pericardial suction blood that were not seen with venous plasma (P <.05). The pericardial suction blood volume was 458 +/- 42 mL and contained 95.6 +/- 9.3 g/L hemoglobin. CONCLUSIONS: The pericardial suction blood plasma capillary flow function was highly impaired by liquid fat. Pericardial suction blood hemoglobin appears worth recovering after fat removal, despite profound hemolysis.