IA Murdoch

Guy's and St Thomas' NHS Foundation Trust, Londinium, England, United Kingdom

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Publications (156)1007.8 Total impact

  • Source
    R. Saxena · S. Steely · A. Durward · I.A. Murdoch · S.M. Tibby

    Full-text · Dataset · Jan 2016
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    ABSTRACT: Purpose: Fluid overload is a risk factor for poor outcome in intensive care; thus volume loading should be tailored towards patients who are likely to increase stroke volume. We aimed to evaluate the paediatric predictive ability (stroke volume increase of at least 15 % after fluid bolus) of novel and established volumetric and dynamic haemodynamic variables, and assess the influence of baseline contractility on response. Methods: We assessed 142 volume loading episodes (10 ml/kg crystalloid) in 100 critically ill ventilated children, median (interquartile) weight 10 (5.6-15) kg. Eight advanced haemodynamic variables were assessed using two commercially available devices. Systemic ventricular contractility was measured as the maximum rate of systolic arterial pressure rise. Results: Overall, predictive ability was poor, with volumetric variables performing better than dynamic (area under receiver operating characteristic curves ranged from 0.53 to 0.67). The best predictor was total end-diastolic volume index; however, this did not increase in a consistent way with volume loading, with change post volume being weakly related to baseline values (r = -0.19, p = 0.02). A multivariable model quantified the importance of contractility in stroke volume response. Children with high baseline contractility (≥75th centile) typically achieved a positive stroke volume response when end-diastolic volume values changed by 10-15 ml/m(2.6), whereas patients with low contractility (≤25th centile) typically required end-diastolic volume increases of 35-40 ml/m(2.6). Conclusions: Current paediatric predictors of volume response perform poorly; prediction may be improved if baseline contractility is taken into account.
    No preview · Article · Sep 2015 · Intensive Care Medicine
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    ABSTRACT: Unplanned extubation (UE) is an important paediatric intensive care unit (PICU) quality indicator. Studies on UE have been modest in size, with accurate UE rate calculation potentially hampered by ventilation episodes recorded in calendar days. We wished to document UE rates, outcomes, associated factors and quantify error when calendar days rather than exact timings are used. We recorded prospectively all UE episodes and potential associated factors in our 20-bed PICU for 12,533 admissions (2000-2013). Ventilation episodes were recorded to the minute, with non-invasive and tracheostomy ventilation excluded. Analysis utilised multilevel mixed-effects Poisson regression, adjusting for multiple ventilation episodes in the same patient. Overall, 243 UEs occurred within 14,141 ventilation episodes (31,564 intubated days), giving a UE rate of 0.77 (95 % CI 0.67-0.87) episodes per 100 intubated days. If calendar ventilation days were used, the yearly UE rate was underestimated by 27-35 %. UE rates decreased with time, by approximately 0.05/100 intubated days each year. Associations with UE incidence rate included patient age, source of admission, disease severity and diagnostic category, with nasal tubes decreasing the risk. Although UE versus planned extubation was associated with a higher re-intubation rate (43 versus 8 %) and longer median PICU stay (4.6 versus 2.6 days, p < 0.001), mortality between the two groups did not differ (3.0 versus 5.1 %, p = 0.18). This study provides contemporaneous UE rates for benchmarking. Recording ventilation in calendar days underestimates UE rate. Several factors associated with UE may serve as a focus of quality improvement.
    No preview · Article · May 2015 · Intensive Care Medicine
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    ABSTRACT: Background: In vast majority of critically ill children needing stabilization, endotracheal intubation will be necessary before arrival of the retrieval team (1). Children make up 9% of patients for rapid sequence induction in the emergency department (2). An audit of all children retrieved to the South Thames Retrieval Service (STRS) showed that 78% of children were intubated by the referring hospital emergency physicians or anaesthetists, and almost 50% were performed in the emergency departments. The incidence of endotracheal tube change by the retrieval team was 17% in 2010, compared to 38% in 2005. Methods: We conducted a telephone survey to look at practice and resource for airway management of children at hospitals covered by STRS for specialist paediatric emergency transport. The paediatric nurses or senior nurses for the emergency departments were invited to take part. Results: All 24 emergency departments in Kent, Surrey, Sussex and London South Thames were contacted, of which 11 had on-site level 3 neonatal intensive care units (ICU) and 3 also had on-site paediatric ICUs. All departments used either our website or local intranet as resource to prepare for paediatric intubation. All departments had a dedicated paediatric equipment trolley, overseen most commonly by emergency department staff (71%) for familiarity and contents, which included laryngeal mask airway at all but one hospital and AirTraq at 6 hospitals (25%). At most hospitals, the duty anaesthetist would be the first person to be called to assist with intubating a child, except for 2 hospitals where the paediatric ICU would be contacted first. The theatre was not located on the same floor as the emergency department at most hospitals (83%). 2 of the 24 paediatric or senior nurses have never attended a paediatric intubation case. Discussion: Endotracheal intubation of critically ill patients, in particular outside of the theatre setting and for children, requires personnel with knowledge and experience. Familiarity of inter- and intra-departmental resource to stabilize sick children, facilitated by the appropriate equipment, is vital to manage a potentially hazardous intervention. Outreach education and simulation training can target on optimizing remote site airway management practice and resource. Ref: (1) JICS 2014 (2) Emerg Med J 2007
    No preview · Conference Paper · Nov 2014
  • S Arenas-Lopez · H Mulla · S Manna · A Durward · I A Murdoch · S M Tibby
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    ABSTRACT: Background: Clonidine is a useful analgesic-sedative agent; however, few data exist regarding its use in infants after congenital heart disease surgery. We thus aimed to assess the absorption and safety of enterally administered clonidine in this setting. Methods: Sixteen infants (median age 6.7 months) received a single nasogastric dose of 3 μg kg(-1) clonidine 2-6 h after surgery. Blood samples were obtained at seven time intervals (up to 480 min). Plasma concentration profiles were obtained, and then pooled with a previous study (137 samples, 30 infants) for estimation of population pharmacokinetic parameters (NONMEM version 7.2). Results: Enteral absorption showed considerable inter-individual variability, with clonidine Cmax ranging from 0.15 to 1.55 ng ml(-1) (median 0.73), and Tmax from 12 to 478 min (median 190). Although therapeutic sedative plasma concentrations were achieved in 94% of patients, only half had attained this by 70 min post-dose. Patients who did not receive inotropes exhibited a positive association between cumulative morphine dose and Tmax (interaction effect P=0.03); this was not seen among those receiving inotropes. The haemodynamic profile was favourable; few patients required fluid boluses, and this bore no relationship to plasma clonidine concentration. Population pharmacokinetic parameter estimation yielded results similar to previous paediatric studies: clearance 13.7 litre h(-1) 70 kg(-1) and Vd 181 litre 70 kg(-1). Conclusions: Early postoperative enteral clonidine produces favourable haemodynamic profiles and therapeutic plasma concentrations in the majority of cardiac surgical infants; however, the time to achieve this can be erratic. Thus, parenteral administration may be preferable if rapid analgo-sedative effects are needed.
    No preview · Article · Jul 2014 · BJA British Journal of Anaesthesia
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    ABSTRACT: Objective Prior to Norwood 1 surgery, neonates with hypoplastic left heart syndrome (HLHS) are at risk of decompensation from systemic underperfusion secondary to pulmonary overcirculation. We examined whether preoperative temporal profiles of physiological and laboratory variables differed between neonates who did and did not decompensate preoperatively. Design Case control study. Setting Paediatric Intensive Care Unit, 2002–2013. Patients Eighty-five neonates with HLHS, matched by birth weight and admission date. Measurements Decompensation was defined as the need for emergency intubation and ventilation due to clinically diagnosed impaired systemic oxygen delivery. The end point was time of decompensation (cases, n=33) or discharge for surgery (controls, n=52). Variable trajectories were modelled non-linearly using generalised estimating equations. Results Decompensation occurred on median (IQR) day 3 (2–4) of life in cases, with surgery occurring on day 4 (3–7) in controls. Oxygen saturation and blood pressure trajectories were identical between groups (p>0.2). Heart and respiratory rates increased with time overall, but significantly faster in cases than controls; by an average of 4.0 bpm/day versus 1.4 bpm/day (p=0.002) and 5.3 respirations/minute/day versus 1.5 respirations/minute/day, respectively, (p=0.003). Although metabolic blood gas components began to decline subtly 24 h before clinical decompensation, they remained in the normal range for much of this period. Conclusions Heart and respiratory rates, and metabolic acid base trajectories show subtle differences prior to decompensation in neonates with HLHS. These findings highlight the importance of evaluating rates of change rather than absolute values of physiological and laboratory variables.
    No preview · Article · Jul 2014 · Archives of Disease in Childhood - Fetal and Neonatal Edition
  • H. Kanthimathinathan · A. Durward · I.A. Murdoch · S. Tibby

    No preview · Article · May 2014 · Pediatric Critical Care Medicine
  • R. Saxena · S. Steely · A. Durward · I.A. Murdoch · S.M. Tibby

    No preview · Article · May 2014 · Pediatric Critical Care Medicine
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    R Saxena · A Durward · I Murdoch · S Tibby

    Full-text · Article · Mar 2013 · Critical Care
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    R Saxena · A Durward · N K Puppala · I A Murdoch · S M Tibby
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    ABSTRACT: Background: Pressure recording analytical method (PRAM) is a novel, arterial pulse contour-based method for measuring cardiac output (CO). Validation studies of PRAM in children are few, and have not assessed both absolute accuracy and ability to track changes in CO across a broad case mix. We aimed to compare CO as measured by PRAM with that using a transpulmonary dilution method in a cohort of critically ill children. Methods: Forty-eight, mechanically ventilated children with a median (inter-quartile) weight of 10.7 (5.5-15) kg with arterial and central venous catheters in situ were studied. CO was measured simultaneously using PRAM and the comparator method, transpulmonary ultrasound dilution (UD). Measurements were repeated before and after therapeutic interventions that were intended to augment CO (e.g. fluid bolus). Results: In total, 210 paired measurements were compared. The mean (sd) CO was 1.9 (1.2) litre min(-1) with UD when compared with 1.92 (0.5) litre min(-1) using PRAM. The mean bias was 0.02 litre min(-1) with wide limits of agreement: ± 2.21 litre min(-1), giving a percentage error of 116%. The concordance between PRAM and UD for measuring changes in CO was also poor, with only 37% of measurements falling within the pre-defined polar plot limits of ±30°. Conclusions: There is an unacceptably poor agreement between UD and PRAM. We do not recommend the use of PRAM for measuring CO in critically ill children with the current algorithm.
    Full-text · Article · Nov 2012 · BJA British Journal of Anaesthesia
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    ABSTRACT: Introduction: Lifting of restrictions on nursing practice and European Working Time Directive to reduce doctors' hours have led to pilot initiative to develop the role of paediatric retrieval nurse practitioners(RNPs) as retrieval team leaders at one UK National Health Service Trust. Objective: We compared the paediatric retrieval practice before and after introduction of nurse-led teams. Methods: A retrospective analysis of the South Thames Retrieval Service(STRS) computerised database for all children who required interhospital transfers for twelve-month periods in 2010 and 2004 was conducted. Data collection for analysis included leadership taskforce, patient demographics, PIM2 scores and procedural interventions. Results: STRS performed 741 interhospital transfers (43.8% RNPs-led, 70% intubated) in 2010, compared with 638 (100% medically-led, 68% intubated) in 2004. Median patient age and PIM2 for ventilated patients were 12months and 5.9 in 2010 respectively, compared with 14months and 5.6 in 2004. Referrals for cardiac, airway/respiratory or sepsis/septic shock disease categories made up 73% retrievals in 2010, compared to 63% in 2004. Procedural interventions with arterial and/or central venous access by local hospitals and STRS teams were similar in both periods. 18% of children intubated by local teams were reintubated by STRS (17% oral-to-nasal route change, 58% for incorrect tube size) in 2010, compared to 38% (73% oral-to-nasal route change) in 2004. Conclusion: Appropriately trained retrieval nurse practitioners can be competent in management and transportation of critically ill children who need advanced airway and vascular interventions. Endotracheal tube change appeared to be more frequent in the historical period with medically-led retrieval teams.
    Full-text · Article · May 2012 · Australian Critical Care
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    S Skellett · A Mayer · A Durward · S Tibby · IA Murdoch

    Full-text · Article · Apr 2012 · Critical Care
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    ABSTRACT: Airway protection with endotracheal intubation can be initiated by referring hospital staff during the golden hour of stabilisation in paediatric interhospital transfers. Objective: We studied endotracheal tube(ETT) intervention events for intensive care transport of critically ill children. Methods: A retrospective analysis of the South Thames Retrieval Service(STRS) computerised database for all children who required advanced airway placement from September2009 to September2010 was conducted. Data collection for analysis included patient demographics, PIM2 scores, advanced airway management and stabilisation times. Results: During the 12-month period, STRS performed 741 interhospital transfers. Median patient age and PIM2 were 12 months and 5.9 for the 520 endotracheally-intubated patients, excluding the 26 children transferred out from our institution. 78% children were intubated by referring hospital teams, of whom 18% required reintubation. STRS stabilisation times were under 60 minutes in fewer than quarter of retrievals (24% without ETT change vs 11% with ETT change), and infrequent when first intubation took place after STRS arrival (7%). Reasons for ETT change were incorrect size resulting in excessive leak and/or ventilation difficulties (51%), ETT malposition and/or cut too short precluding tube securing (25%), oral-to-nasal route change (17%), or too large ETT (7%). There were 3 critical incidents with difficult reintubation, one required laryngeal mask airway use. Conclusion: Almost one in five children required reintubation commonly for poor ETT choice or malposition. Outreach education with feedback to each referring centre anaesthetic teams can be directed towards prompt and correct endotracheal tube securement to facilitate patient stabilisation.
    No preview · Conference Paper · Oct 2011
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    V Sheward · S Tibby · H Bangalore · A Durward · I Murdoch

    Preview · Article · Mar 2011 · Critical Care
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    A Nyman · K Puppala · S Colthurst · S Parsons · S Tibby · I Murdoch · A Durward

    Preview · Article · Mar 2011 · Critical Care
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    ABSTRACT: Cerebral oedema is a potentially devastating complication of diabetic ketoacidosis (DKA). The relationship between osmolar changes, acid-base changes and development of cerebral oedema during therapy is unclear. Retrospective cohort study on 53 children with severe DKA (mean pH at presentation 6.92±0.08). Cerebral oedema was diagnosed using neurological status, response to osmotherapy, and neuroimaging, and classified as: early (occurring ≤1 h after presentation, n=15), late (1-48 h, n=17) or absent (controls, n=21). The temporal profiles for various osmolar and acid-base profiles were examined using a random coefficients fractional polynomial mixed model, adjusted for known risk factors. The three groups could not be differentiated by demographic, osmolar or acid-base variables at presentation. All osmolar and acid-base variables showed non-linear temporal trajectories. Children who developed late onset oedema showed dramatically different temporal profiles for effective osmolality and glucose-corrected serum sodium (both p<0.001). Glucose-corrected sodium provided better qualitative discrimination, in that it typically fell in children who developed late oedema and rose in controls. The maximum between-group difference for both variables approximated the median time of clinical cerebral oedema onset. Blood glucose and acid-base temporal profiles did not differ between the groups. Late onset oedema patients received more fluid in the first 4 h, but this did not influence the osmolar or glucose-corrected sodium trajectories in a predictable fashion. Glucose-corrected serum sodium may prove a useful early warning for the development of cerebral oedema in DKA.
    Preview · Article · Oct 2010 · Archives of Disease in Childhood
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    ABSTRACT: Mediastinal bleeding is common after pediatric cardiopulmonary bypass (CPB) surgery. Thromboelastography (TEG) may predict bleeding and provide insight into likely mechanisms. We aimed to (a) compare perioperative temporal profiles of TEG and laboratory hemostatic variables between patients with significant hemorrhage (BLEED) and those without (CONTROL), (b) investigate the relationship between TEG variables and routine hemostatic variables, and (c) develop a model for prediction of bleeding. TEG and laboratory hemostatic variables were measured prospectively at 8 predefined times for 50 children weighing <20 kg undergoing CPB. Patients who bled demonstrated different TEG profiles than those who did not. This was most apparent after protamine administration and was partly attributable to inadequate heparin reversal, but was also associated with a significantly lower nadir in mean (sd) fibrinogen for the BLEED group compared with CONTROL group: 0.44 (0.18) and 0.71 (0.40) g/L, respectively (P = 0.01). Significant nonlinear relationships were found between the majority of TEG and laboratory hemostatic variables. The strongest relationship was between the maximal amplitude and the platelet-fibrinogen product (logarithmic r(2) = 0.71). Clot strength decreased rapidly when (a) fibrinogen concentration was <1 g/L, (b) platelets were <120 x 10(9)/L, and (c) platelet-fibrinogen product was <100. A 2-variable model including the activated partial thromboplastin time at induction of anesthesia and TEG mean amplitude postprotamine discriminated well for subsequent bleeding (C statistic 0.859). Hypofibrinogenemia and inadequate heparin reversal are 2 important factors contributing to clot strength and perioperative hemorrhage after pediatric CPB. TEG may be a useful tool for predicting and guiding early treatment of mediastinal bleeding in this group.
    No preview · Article · Feb 2010 · Anesthesia and analgesia
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    S Tibby · A Durward · L Ferguson · H Bangalore · I Murdoch

    Preview · Article · Mar 2009 · Critical Care
  • Ellen O'Dell · Shane M Tibby · Andrew Durward · Ian A Murdoch
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    ABSTRACT: Metabolic acidosis is common in septic shock, yet few data exist on its etiological temporal profile during resuscitation; this is partly due to limitations in bedside monitoring tools (base excess, anion gap). Accurate identification of the type of acidosis is vital, as many therapies used in resuscitation can themselves produce metabolic acidosis. Retrospective, cohort study. Multidisciplinary pediatric intensive care unit with 20 beds. A total of 81 children with meningococcal septic shock. None. Acid-base data were collected retrospectively on 81 children with meningococcal septic shock (mortality, 7.4%) for the 48 hrs after presentation to the hospital. Base excess was partitioned using abridged Stewart equations, thereby quantifying the three predominant influences on acid-base balance: sodium chloride, albumin, and unmeasured anions (including lactate). Metabolic acidosis was common at presentation (mean base excess, -9.7 mmol/L) and persisted for 48 hrs. However, the pathophysiology changed dramatically from one of unmeasured anions at admission (mean unmeasured anion base excess, -9.2 mmol/L) to predominant hyperchloremia by 8-12 hrs (mean sodium-chloride base excess, -10.0 mmol/L). Development of hyperchloremic acidosis was associated with the amount of chloride received during intravenous fluid resuscitation (r = .44), with the base excess changing, on average, by -0.4 mmol/L for each millimole per kilogram of chloride administered. Hyperchloremic acidosis resolved faster in patients who 1) manifested larger (more negative) sodium chloride-partitioned base excess, 2) maintained a greater urine output, and 3) received furosemide; and slower in those with high blood concentrations of unmeasured anions (all, p < .05). Hyperchloremic acidosis is common and substantial after resuscitation for meningococcal septic shock. Recognition of this entity may prevent unnecessary and potentially harmful prolonged resuscitation.
    No preview · Article · Oct 2007 · Critical Care Medicine
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    Preview · Article · Mar 2007 · Critical Care

Publication Stats

3k Citations
1,007.80 Total Impact Points

Institutions

  • 2006-2013
    • Guy's and St Thomas' NHS Foundation Trust
      • Paediatric Intensive Care Unit (PICU)
      Londinium, England, United Kingdom
  • 2011
    • London School of Hygiene and Tropical Medicine
      Londinium, England, United Kingdom
  • 2002
    • The Bracton Centre, Oxleas NHS Trust
      Дартфорде, England, United Kingdom