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Biomedical subjects

Giles J Peek

Publications and source records attributed to Giles J Peek.

17 recordsLinked to original sources
PubMed2006

Strategies for managing Type IV laryngotracheoesophageal clefts at Great Ormond Street Hospital for Children.

OBJECTIVE: To review our strategy for the treatment of patients with Type IV laryngotracheoesophageal cleft-a very rare congenital malformation. METHODS: Retrospective review of nine cases of Type IV laryngotracheoesophageal cleft managed between October 1994 and January 2004 at Great Ormond Street Hospital for Children, London. RESULTS: Three children were not operated upon (Group A) because of serious co-morbidity and parental decision not to opt for repair; they died at the ages of 2, 7 and 14 days, respectively. Six cases were repaired (Group B) at ages ranging from 2 to 53 days, all using an anterior cervico-thoracic approach. Two cases were operated upon using conventional ventilation, three using cardiopulmonary bypass and one using extracorporeal membrane oxygenation. There was no intra-operative mortality. The number of operative and diagnostic procedures varied from 4 to 37. Two operated cases expired at the ages of 11 days and 25 months; both were operated upon using cardiopulmonary bypass and had significant cardiac co-morbidity. Post-operative microlaryngoscopy and bronchoscopy showed dehiscence in the cleft repair ranging from 1mm to 2cm in five cases. This was observed at the distal end in three patients and just below the vocal cords in two cases. Three cases underwent further repair which was successful. The most recent case repaired using extracorporeal membrane oxygenation required less heparin when compared with those done on cardiopulmonary bypass and had the best post-operative result. Two patients were finally decannulated. The total duration of diagnostic and operative procedures ranged from 9 to 26h and 30min. The hospital stay in the operated cases varied from 9 days to 2 years 2 months 3 days, and their ICU stay ranged from 9 days to 10 months 7 days. All four of our patients with clefts which ended above the carina are alive after multiple repairs whereas all five cases with clefts extending all the way to the carina died (repair was attempted in two). CONCLUSION: Early diagnosis and repair are essential for successful treatment of Type IV laryngotracheoesophageal clefts. We believe it is best to repair this defect via an anterior cervico-thoracic approach, with or without a median sternotomy, and extracorporeal membrane oxygenation is now our preferred method of gas exchange during such repair. The longest Type IV clefts extending all the way to the carina have the worst prognosis. The decision to operate or not should be based upon the associated co-morbidity and fully informed parental choice, since treatment entails significant morbidity and mortality.

Esophagus↗
PubMed2006

Improving the quality of reporting randomized controlled trials in cardiothoracic surgery: the way forward.

OBJECTIVE: To evaluate the quality of reporting of randomized controlled trials in cardiothoracic surgery, to identify factors associated with good reporting quality, and to assess the awareness of the Consolidated Standards for Reporting of Trials statement and ascertain the views of authors reporting randomized controlled trials on the difficulties in conducting randomized controlled trials and the possible ways to further improve the reporting quality of randomized controlled trials in cardiothoracic surgery. METHODS: Randomized controlled trials of cardiothoracic surgery published in principal cardiothoracic and 4 general medical journals in 2003 were included. The quality of reporting of randomized controlled trials was assessed by using allocation concealment, the Jadad score, and a Consolidated Standards for Reporting of Trials checklist devised for the purpose. A questionnaire survey of authors reporting randomized controlled trials in principal cardiothoracic journals in 2003 was conducted. RESULTS: The overall reporting quality of the 64 randomized controlled trials included in the analysis was suboptimal as assessed by the 3 methods adopted. Most of the authors (63.5%) were not aware of the Consolidated Standards for Reporting of Trials statement; however, awareness was not associated with reporting quality. More than 65% of the authors responded that conducting randomized controlled trials in surgical specialties was difficult, and the main difficulties were blinding and obtaining a large-enough sample size to detect statistically significant differences. Fifty-four percent of the authors responded that endorsement of the Consolidated Standards for Reporting of Trials statement by the cardiothoracic journals may improve the reporting quality. CONCLUSIONS: The quality of reporting randomized controlled trials in cardiothoracic surgery is suboptimal. Endorsement of the Consolidated Standards for Reporting of Trials statement by the cardiothoracic journals may improve the quality of reporting.

Humans↗
PubMed2005

Partial liquid ventilation.

We describe the technique of partial liquid ventilation and outline its indications. We present our imaging experience with this infrequently used therapy using a wide variety of radiographs from neonatal and adult patients. The radiographic appearance of white lungs, due to the perfluorocarbons used in partial liquid ventilation, may initially be rather perplexing, but can be an advantage in diagnosing certain complications of mechanical ventilation, outlining pathology and demonstrating normal anatomy in an unusual manner.

Adult↗
PubMed2005

Performance of polymethyl pentene oxygenators for neonatal extracorporeal membrane oxygenation: a comparison with silicone membrane oxygenators.

OBJECTIVE: To review the performance of polymethyl pentene versus silicone oxygenators in terms of efficiency in priming and oxygenation, oxygenator resistance, requirements for coagulation proteins and consumption of blood products, for neonatal extracorporeal membrane oxygenation (ECMO) patients. STUDY DESIGN: Forty consecutive neonates were selected retrospectively pre- and post-introduction of the new polymethyl pentene (PMP) oxygenators. They formed two equal groups. After calculation of the sample size, data were collected from ELSO registry forms and patient records. Results were analysed using parametric and non-parametric tests. RESULTS: Neonatal PMP (N-PMP) oxygenators were smaller, faster and easier to prime. They were less efficient than silicone oxygenators, especially in carbon dioxide elimination, and, therefore, required higher sweeps. The preservation of coagulation proteins was significantly better, but there was no reduction in the consumption of blood products, despite having less than half the surface area and significantly lower blood path resistance. CONCLUSION: Small PMP oxygenators (Medos Hilite 800 LT) provide adequate gas exchange and offer technical advantages in terms of more efficient priming, reduced haemodynamic resistance and better control and preservation of coagulation proteins than silicone oxygenators.

Equipment Design↗
PubMed2005

A potential propensity for failure secondary to clot embolism in neonatal ECMO.

OBJECTIVE: To report a single case of oxygenator failure caused by clot embolism originating from the bladder; and to discuss some preventative options. CASE REPORT: A 2.5 kg neonate with a diagnosis of influenza A received veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) for cardiorespiratory support. Halfway through treatment, she underwent an elective circuit change for numerous clots in her circuit. The patient continued to consume vast quantities of platelets and developed a fatal oxygenator failure after 18 days. DISCUSSION: Amongst the factors influencing the outcome in events of a sudden unexpected oxygenator failure are the severity of patient illness, the size of the clot relative to the size of the oxygenator, the availability of a previously primed circuit and the ease and speed of priming a new oxygenator. CONCLUSION: There is a need for improvement in the design of small oxygenators and ECMO circuits. Adjustment of the coagulation parameters and lowering the tolerance towards clots in the circuit by electively changing them may reduce the incidence of sudden unexpected oxygenator failure. However, using a slightly larger Medos oxygenator may gain valuable time needed to arrange an oxygenator/circuit change.

Equipment Design↗
PubMed2004

Experience with mobile inhaled nitric oxide during transport of neonates and children with respiratory insufficiency to an extracorporeal membrane oxygenation center.

OBJECTIVE: To share our experience with the use of inhaled nitric oxide (iNO) during the transport of ventilated neonates and children to an extracorporeal membrane oxygenation (ECMO) center and to discuss the efficacy and safety of iNO use in this situation. DATA SOURCES: Case note review of 55 consecutive patients transported while receiving iNO to Glenfield Hospital, Leicester, UK, for consideration of ECMO. STUDY SELECTION: Retrospective case note review. DATA EXTRACTION: The clinical condition of each patient recorded at arrival of the transport team at the referring hospital, during transport, and at arrival at Glenfield Hospital. Preclinical and postclinical conditions were compared using the paired Student's t-test. DATA SYNTHESIS: Overall data showed a significant improvement in transcutaneous oximetry measurements (Spo(2): 84.8% preclinical, 90.6% postclinical; p = .006) and Pao(2) (59 torr [7.87 kPa] preclinical, 84 torr [11.23 kPa] postclinical; p = .001) during transport in our patient group. Based on limited safety data, no untoward events or toxic metabolites were observed with iNO therapy during transport. CONCLUSIONS: iNO does appear to improve oxygenation during transfer of patients for ECMO in our series. Based on limited safety data, iNO appears safe to use in transport.

Administration, Inhalation↗
PubMed2002

Modular extracorporeal life support for multiorgan failure patients.

Adults receiving respiratory Extracorporeal Membrane Oxygenation (ECMO) have 66% survival. Nonsurvivors develop multisystem organ failure (MSOF). Once hepatic failure develops, death usually follows shortly. Serum bilirubin > 300 micromol/l predicted death with 87.8% sensitivity and 90.3% specificity in 41 adults who received ECMO in our institution during 1998 and 1999. No patients survive with a peak bilirubin > 400 micromol/l. The Molecular Adsorbent Recirculating System (MARS) is a cell-free extracorporeal liver support device; we hypothesized that using MARS in adult respiratory ECMO patients with a bilirubin >300 micromol/l could improve survival in MSOF. The MARS was used in five such patients aged 19-56 who developed liver failure secondary to a respiratory illness. Mean peak bilirubin was 529 micromol/l and the lowest peak bilirubin was 436 micromol/l. Patients received between 1 and 8 MARS treatments, mean reduction in serum bilirubin for each patient ranging between 30 and 162 micromol/l. Two of five patients survived (40%), survivors showing the greatest reduction in serum bilirubin in response to MARS. All patients would have been expected to die according to our previous experience. We believe that MARS may prove a useful therapy for patients with MSOF.

Adult↗
PubMed2002

An in vitro method for comparing biocompatibility of materials for extracorporeal circulation.

UNLABELLED: We measured the response of fresh heparinized human blood to recirculation through circuits made of LVA (Portex Industries, Hythe, Kent, UK), SRT (Rehau UK, Langley, Slough, UK) and Tygon S-65-HL (Norton Performance Plastics, Corby, Northants, UK), as control. Circuit construction: 1/2 in. tubing, heat exchanger (Dideco D-720P), Stockert roller pump, just underoccluded, Cincinnati Sub Zero heater, circuit volume of 500 ml. Flow 3.45 l/min, 37 degrees C. SAMPLES: at 10 min, 1, 2, 4 and 6 h. n=5 in each group; 2/5 SRT experiments were stopped at 45 and 60 min due to overpressurization. RESULTS: Baseline activated clotting time (ACT) of 300 s, increasing in all groups as fibrinogen fell to zero with SRT and LVA. Minimum fibrinogen was 1 g/l for Tygon. Absolute thrombocytopenia occurred (SRT and LVA 60 min and Tygon 240 min). International normalized ratio (INR) in both the SRT and LVA circuits increased, but mean increase for Tygon (0.56) was smaller than the other two materials. Plasma free haemoglobin increased in all three materials; the increase was greater in the LVA circuits compared to the control. C5b9 levels increased equally in all groups. Lactoferrin levels rose equally in all groups to a maximum at 150 min. The neutrophil counts fell, mirroring the lactoferrin. The total white cell counts also fell in all groups; in the LVA circuits, the fall was significantly lower than in the control. Rapid disappearance of platelets and fibrinogen from the blood in the SRT and LVA circuits excludes them both from extracorporeal use. Paradoxically, SRT caused the least complement activation of the three materials. This method can be used to compare biocompatibility.

Adolescent↗
PubMedDate not supplied

Early experience with a polymethyl pentene oxygenator for adult extracorporeal life support.

Silicone oxygenators are the standard devices used for Extracorporeal Life Support (ECLS), but they have some limitations. Microporous polypropylene hollow fiber oxygenators overcome many of these problems but, unfortunately, develop plasma leak. Polymethyl-pentene (PMP) is a novel oxygenator material. We report our initial experience with the Medos Hilite 7000LT, a PMP hollow fiber oxygenator, in six adult respiratory ECLS patients with these characteristics: age, mean 32.2 (+/-13) years; weight, mean 81.2 (+/-17) kg; PaO2/FIO2, mean 62.8 [+/-33] mm Hg; Murray Score, mean 3.4 [+/-0.3]; and sepsis related organ failure assessment score, mean 9.6 [+/-2.3]. One patient was cannulated within 10 hours of multiple trauma and 1 hour after thoracolaparotomy; another patient was cannulated 12 hours after a thoracotomy. All six patients survived. Heparin was infused (7.8-32.5 u/kg/hr) to maintain activated clotting time at 162 to 238 seconds; international normalized ratio was 0.9 to 3.4. Two of the six patients required transfusions of fresh frozen plasma, receiving one and five units, respectively. Fibrinogen was 1.4 to 6 g/dl; no cryoprecipitate was needed. Platelet counts were between 65 and 306, and very little platelet transfusion (mean 2.33; +/-3.03 units per patient) was required to maintain these levels. Two patients did not require any platelet transfusion. Maximum blood flow was 5.3 L/min, sweep was 3 to 10 L/min, and resistance was 11 to 43 Paul Wood Units. There were no oxygenator failures. Mean duration of ECLS was 151.7 hours (+/-75.6). Our initial experience with PMP oxygenators in adults was satisfactory, and platelet consumption and resistance to blood flow seem to be greatly reduced with PMP.

Adult↗
PubMedDate not supplied

Plasma concentrations of midazolam in neonates receiving extracorporeal membrane oxygenation.

Drug disposition is affected during extracorporeal membrane oxygenation (ECMO). This study investigates the dose-concentration relationship of midazolam in neonates requiring ECMO during continuous infusion into the circuit (extracorporeally; n = 10) and intravenously (n = 10). Data on hourly doses and sedation scores were collected for 120 hours. Plasma concentrations were analyzed at times 0, 2, 4, 6, 12, 18, and 24, and every 12 hours thereafter. Both groups were clinically similar. Mean (standard deviation) dose for all patients was 250 (185) microg/kg/h, four times greater than previously reported. Doses administered in the first 24 hours were significantly greater extracorporeally [361 (300)] compared with intravenous [258 (190) microg/kg/h, p < 0.001]. Mean (standard deviation) plasma concentrations in all patients at 24, 48, and 72 hours were 1.4 (0.9), 1.8 (1.2), and 2.6 (1.8) microg/ml, respectively. Satisfactory sedation levels were achieved in all patients. Comparison of the actual observed with predicted (simulated) midazolam concentrations suggested significant attenuation of plasma levels during the first 24 hours of ECMO. However, at 48 hours, observed concentrations exceeded those predicted, suggesting accumulation. We conclude that in the first 24 hours of ECMO, because of an expanded circulating volume and sequestration by the circuit, significantly more midazolam is required to achieve adequate sedation. Subsequently, and because of circuit saturation, maintenance doses should be reduced.

Blood Volume↗
PubMedDate not supplied

Venovenous extracorporeal membrane oxygenation for respiratory failure in inotrope dependent neonates.

It is often stated that venovenous extracorporeal membrane oxygenation (VV ECMO) should not be used in inotrope dependent patients. It is our practice to use VV ECMO in most patients with respiratory failure even though many of these patients are receiving significant doses of inotropes. Our objective was to review the mode of ECMO in relation to precannulation doses of inotropes administered to neonates treated with ECMO for respiratory failure. Forty-three consecutive case notes were reviewed. Data were collected for basic demographic and ECMO parameters. Inotropic doses were converted to a single score for ease of comparison, with one point equivalent to 1 microg/kg/min dopamine. Forty-three neonates were studied; 37(86%) were treated with VV ECMO and 6 (14%) were treated with VA ECMO. Significant pre-ECMO inotropic support (score > 10) was present in 30 (70%) of the 43 cases. Of these patients, 26 were treated via VV ECMO with a survival rate of 84%, while 4 were treated with VA ECMO with a survival of 75%. Inotrope scores fell to nonsignificant levels (< 10) within 24 hours, regardless of ECMO mode. Mean arterial blood pressure remained above precannulation levels in both groups. VV ECMO allows safe treatment of neonatal respiratory failure in the presence of significant inotropic support. We recommend VV ECMO for neonatal respiratory failure in all cases except where double lumen cannulation is impossible or when septic shock is refractory to inotropic support (i.e., mean blood pressure < 35 mm Hg despite inotrope score of > 100).

Blood Pressure↗
PubMedDate not supplied

Poly-methyl pentene oxygenators have improved gas exchange capability and reduced transfusion requirements in adult extracorporeal membrane oxygenation.

The performance of poly-methyl pentene (PMP) oxygenators (Medos Hilite 7000LT) was compared with that of silicone membrane (SM) oxygenators (Medtronic 1-4500-2A) for adult extracorporeal membrane oxygenation (ECMO). Forty consecutive patients were selected retrospectively pre- and post-introduction of PMP oxygenators. They were selected according to the dates they received ECMO and were separated into two equal groups with similar backgrounds. The flow path resistance, gas and heat exchange efficiency, consumption of coagulation factors and platelets, blood transfusion requirements, and incidence of clots for each oxygenator type was assessed. Adult PMP oxygenators showed lower blood path resistance than SM oxygenators. However, lower consumption of blood products in these oxygenators was a direct result of their smaller surface area and heparin coated design, reducing contact activation of coagulation factors. These oxygenators are noticeably smaller, require lower priming volumes, and have better gas exchange capability than SM oxygenators. They showed greater stability and preservation of coagulation factors and platelets compared with SM oxygenators. They also had the advantage of a functioning integrated heat exchanger. Using a single PMP oxygenator in the first instance may be adequate for the majority of patients and would significantly reduce red blood cell consumption during ECMO.

Adult↗
PubMedDate not supplied

Extracorporeal membrane oxygenation for chickenpox pneumonia: a single institution's experience.

The experience of extracorporeal membrane oxygenation (ECMO) use for severe chickenpox pneumonia was reviewed. Case notes of all patients treated with ECMO for this disease between 1992 and 1997 were reviewed. Of 405 patients referred for ECMO during this period, the diagnosis was chickenpox pneumonia in 14 (3.5%); all 14 were treated with ECMO. The median age of patients was 32.5 years (range 5 to 61 years). The median duration of extracorporeal support was 164 hours (range 45 to 652). Ten of 14 patients (71%) required hemofiltration. Overall survival of patients supported with ECMO was 57% (8 of 14). Deaths were caused by sepsis (5 patients, source identified in 4) and multiorgan failure (1 patient). Pneumonia as a complication of chickenpox can rapidly become severe and life threatening. Extracorporeal respiratory support may be helpful in patients refractory to conventional ventilation.

Adult↗