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ICU

Volume Capnography in the Intensive Care Unit: Potential Clinical Applicaitons

Kreit JW.  Ann Am Thorac Soc. 2019 Feb 11. doi: 10.1513/AnnalsATS.201807-502CME. [Epub ahead of print]

 

The abstract is as follows:  It is a good article to read

 

Volume capnography provides a non-invasive, continuous display of the fractional concentration or partial pressure of carbon dioxide versus exhaled volume. Derived measurements and calculations are influenced by changes in both ventilation and perfusion and are therefore useful for assessing both respiratory and cardiovascular function. This article provides an evidence-based review of several potential uses of volume capnography in the ICU: 1) monitoring the effectiveness of ventilation by using end-tidal PCO2 as a surrogate for arterial PCO2; 2) assessing volume-responsiveness; 3) measuring cardiac output; 4) determining prognosis in patients with the acute respiratory distress syndrome; 5) optimizing alveolar recruitment; and 6) excluding pulmonary embolism. Studies performed during the past few decades have clearly shown that volume capnography can provide important prognostic information in patients with ARDS and that end-tidal PCO2 should not be used to estimate or even to monitor the direction of change in the arterial PCO2 in mechanically ventilated ICU patients. Unfortunately, few conclusions can be made from studies evaluating other potential applications. Of these, the most promising are the non-invasive measurement of cardiac output and optimization of alveolar recruitment in patients with ARDS and in mechanically ventilated, morbidly obese patients

Capnography in Pediatric and Neonatal Intensive Care Units

Capnography in Pediatric and Neonatal Intensive Care Units

Despite proven value of continuous capnography waveforms in operating rooms as continuous monitor of ventilation, perfusion, and ventilation perfusion status of the lungs, it has taken considerable time for Intensive Care Units (ICUs) to avail of benefits of capnography.  Capnography is not only a monitor of airway integrity, but also a monitor of cardiac output and ventilation:perfusion status of the lungs.  Appropriate use capnography and pulse oximetry in ICUs can decrease too much reliance on blood gas analysis and decrease expenditure from routine and frequent blood gases. 

In 2011, the Fourth National Audit Project (NAP4) reported high rates of complications in adult intensive care units, including death or brain injury. The project recommended steps to be set in place to manage difficult airways that included routine use of waveform capnography monitoring. More than 80% of UK adult intensive care units have subsequently changed practice. Undetected esophageal intubation has recently been listed as a 'Never Event' in UK practice, with capnography mandated.

Foy et al investigated whether the NAP4 recommendations have been embedded into pediatric and neonatal intensive care units (Paediatric intensive care and neonatal intensive care airway management in the United Kingdom: the PIC-NIC survey. Anaesthesia 2018;73(11):1337-44). 

The authors conducted a telephone survey of senior medical or nursing staff in UK pediatric intensive care units (PICUs) and neonatal intensive care units (NICUs). Response rates were 100% for pediatric intensive care units and 90% for neonatal intensive care units. A difficult airway policy existed in 67% of pediatric intensive care units and in 40% of neonatal intensive care units; a pre-intubation checklist was used in 70% of pediatric intensive care units and in 42% of neonatal intensive care units; a difficult intubation trolley was present in 96% of pediatric intensive care units and in 50% of neonatal intensive care units; a videolaryngoscope was available in 55% of pediatric intensive care units and in 29% of neonatal intensive care units; capnography was 'available' in 100% of pediatric intensive care units and in 46% of neonatal intensive care units, and 'always available' in 100% of pediatric intensive care units and in 18% of neonatal intensive care units. Death or serious harm occurring secondary to complications of airway management in the last 5 years was reported in 19% of pediatric intensive care units and in 26% of neonatal intensive care units. 

The authors conclude that major gaps in optimal airway management provision exist in UK pediatric intensive care units and especially in UK neonatal intensive care units. The authors recommended Wider implementation of waveform capnography is necessary to ensure compliance with the new 'Never Event' and has the potential to improve airway management.

Mactier et al responded to the above publication in the Journal Anaesthesia with their views (http://www.respond2articles.com/ANA/forums/thread/2669.aspx). In essence they agreed that capnography is essential during neonatal and pediatric intubations.  They raised objections to the use of continuous waveform capnography in intensive care units citing limitations of continuous capnography in clinical practice. The authors also cite unfamiliarity of capnography among care providers. Furthermore, the authors state that physiology of new born is very different from that of older children and factors that benefit adults may not apply to children.

Views of author of www.capnography.com  Bhavani Shankar Kodali MD)

Every monitoring device has limitations. Therefore, emphasis has to be on understanding continuous waveform capnography and its limitations, and overcoming the limitations of the system. The advantages of continuous capnography have been well illustrated by Cook et al in their reply as below. 

It is true that physiology of neonate is different from adults. Therefore, it can be argued that since physiology is different in new born and smaller children, continuous capnography should be used to detect deviations early as the margin of safety in newborns and children is decreased, particularly if babies are unhealthy. 

The readers are encouraged to read detailed views on both sides of the coin on this subject. 

Cook et al have responded very eloquently to the queries raised in the above correspondence and can be found at http://www.respond2articles.com/ANA/forums/thread/2669.aspx 

Points to note are: 

" Airway management is challenging in all areas of critical care. In neonatology, challenges include high rates of intubation failure, severe hypoxia and bradycardia being common during intubation and frequent accidental extubations. In 2016, Hatch examined 273 neonatal intubations; first attempt success was 47%, adverse events (which excluded bradycardia and hypoxia) occurred in 39% of cases, and hypoxia (SpO2<60%) and bradycardia (heart rate <60 bpm) occurred in 44% and 24% of cases, respectively [2]. They identified emergency intubation as the most significant risk factor for serious complications at intubation and noted that 62% of cases of emergency intubation on NICU were the result of accidental extubation. The authors went on to perform a quality improvement program, which included a pre-intubation checklist which significantly reduced rates of adverse events, severe hypoxia and bradycardia [3].

As Fawke and Wyllie have identified, capnography is a complex and perhaps vexed topic. Our survey focused only on waveform capnography, so would have underestimated the use of ‘capnometry’ overall and at intubation in particular. Mactier et al. list some of the difficulties of using waveform capnography in the neonatal setting. In our paper, we listed these explicitly and explained that this is an area meriting further research. However, it is notable that many NICUs do use waveform capnography, and both parties agree that it is widely used during transfer of small infants, suggesting it is feasible. There is clearly variation in practices and this merits exploration. The literature suggests waveform capnography is effective and practical in babies as small as ~500g [4]. The UK Resuscitation Council guidelines recommend detection of ‘exhaled carbon dioxide’, but do not specify that this should be colorimetric [5]. In researching this letter, we identified a previous survey from 2013, which reported that 34% of level 3 NICUs did not use capnometry to confirm successful tracheal intubation and 32% only used it if there were difficulties [6]. These results are consistent with our findings.        

Safe airway management extends well beyond the period of intubation and it is highly unlikely that colorimetric capnometry will monitor airway integrity and patency as well as a waveform device would. Using ventilator waveforms to determine precisely what is happening with ventilation is likely to be complicated by airway leak when uncuffed tubes are used. It also involves monitoring something that is at least one step distant from what is happening to the patient’s physiology – waveform capnography on the other hand gives a breath-by-breath indication of that physiology, and is the ideal monitor of airway position and patency. The focus of this discussion is on capnography for airway monitoring, not respiratory monitoring, but waveform capnography provides many other benefits: in this regard Kugelman et al. reported that continuous waveform capnography significantly improved ventilation accuracy and reduced intracranial bleeding complications in ventilated neonates [7].

Mactier et al. refer to a survey abstract presented by Charles et al., which does not state when it was undertaken [8]. This reported ‘routine’ use of capnography (likely capnometry) during intubation in delivery suites in 81-88% of units, but was far less extensive than our survey and had a lower response rate (83%). It may well be that airway management practices in NICUs have changed since our survey, but this survey does not provide robust evidence of that.

There is an inevitable and perhaps unavoidable sense of ‘confrontation’ in letters criticising articles and the resulting responses, but we hope we can all avoid that. We are delighted that the British Association of Perinatal Medicine is conducting a review of airway management in NICUs and would encourage the Association not to restrict the review to the difficult airway but also to consider routine airway management and monitoring. The NAP4 study in adults might serve as an equivalent [9]. Its findings were not welcomed by all anaesthetists, but three years after its publication, 80% of UK adult ICUs had made changes in their practices, closing the safety gap between actual and optimal practice by 60% [10]. There is a significant challenge in determining whether new technology improves safety, and balancing the evidence requires considerable effort. Regarding rare and serious harm events, such as airway-related deaths, the answer rarely lies in randomised controlled trials [11]. We hope the findings of our survey will be of use in the BAPM review and would encourage the specialty to repeat our in-depth survey if they wish to see how practices have changed."

 

 

References

  1. Foy KE, Mew E, Cook TM et al. Paediatric intensive care and neonatal intensive care airway management in the United Kingdom: the PIC-NIC survey. Anaesthesia 2018; 73: 1337-44.
  2. Hatch LD, Grubb PH, Lea AS, et al. Endotracheal intubation in neonates: a prospective study of adverse safety events in 162 infants. Journal of Pediatrics 2016; 168: 62-6.
  3. Hatch LD, Grubb PH, Lea AS et al. Interventions to improve patient safety during intubation in the Neonatal Intensive Care Unit. Pediatrics 2016; 138: e20160069.
  4. Salthe J, Kristiansen SM, Sollid S, Oglaend B, Søreide E. Capnography rapidly confirmed correct endotracheal tube placement during resuscitation of extremely low birthweight babies (< 1000 g). Acta Anaesthesiologica Scandinavica 2006; 50: 1033-6.
  5. Resuscitation council [UK]. Resuscitation and support of transition of babies at birth. https://www.resus.org.uk/resuscitation-guidelines/resuscitation-and-support-of-transition-of-babies-at-birth/ (accessed 21/10/2018).
  6. Whitby T, Lee DJ, Dewhurst C, Paize F. Neonatal airway practices: a telephone survey of all UK level 3 neonatal units. Archives of Disease in Childhood. Fetal Neonatal Edition 2015; 100: F92-3.
  7. Kugelman A, Golan A, Riskin A et al. Impact of continuous capnography in ventilated neonates: a randomized, multicenter study. Journal of Pediatrics 2016; 168: 56-61.
  8. Charles E, Hunt K, Milner A, Greenough A. UK neonatal resuscitation survey. Archives of Disease in Childhood 2018; 103: A203.
  9. Cook TM, Woodall N, Harper J, Benger J. Major complications of airway management in the UK: results of the 4th National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 2 Intensive Care and Emergency Department. British Journal of Anaesthesia 2011; 106: 632-42.
  10. Cook TM, Woodall N, Frerk C. A national survey of the impact of NAP4 on airway management practice in United Kingdom hospitals: closing the safety gap in anaesthesia, intensive care and the emergency department. British Journal of Anaesthesia 2016; 117: 182-90.
  11. Cook TM. Airway complications – strategies for prevention. Anaesthesia 2018; 73: 93-111

Royal College of Anaesthetists - Educational Campaign on Capnography During CPR

Royal College of Anaesthetists - Educational Campaign on Capnography During CPR

No Trace = Wrong Place

 

The Royal College of Anaesthetists (RCoA) and the Difficult Airway Society (DAS) have initiated a campaign 'No Trace = Wrong Place' during CPR.  If there is no capnography waveform during CPR, the endotracheal tube is not in the trachea unless ruled out by other means. This campaign was initiated at the request of UK Coroners to promote awareness of the unrecognized esophageal intubation during CPR.  RCoA and DAS have collaborated to create the video resource Capnography: No Trace = Wrong Place.  Presented by Professor Tim Cook, the video shares the important message that during cardiac arrest, if a capnograhy trace is completely flat, osophageal intubation should be assumed until proven otherwise.  There is also a Power Point presentation by Professor Cook on this subject. 

https://www.rcoa.ac.uk/standards-of-clinical-practice/capnography-no-trace-wrong-place

https://www.youtube.com/watch?v=t97G65bignQ&t=

www.judiciary.uk and search for Mr. Peter Saint and Mrs. Sharon Grierson 

The RCOA and DAS advises to download the Power Point slide for departmental educational purposes. 

Colorimetric devices may not be sensitive enough to measure low concentrations of exhaled carbon dioxide.  Limitations of this device must be understood (https://journals.lww.com/anesthesia-analgesia/pages/articleviewer.aspx?year=2007&issue=03000&article=00054&type=Fulltext).

Continuous waveform capnography is therefore recommended during CPR.

 

Capnography - Sub-Saharan Africa

 

Capnography in Sub-Saharan Africa

A recent study, 'Global Capnography Project (GCAP): implementation of capnography in Malawi - an international anaesthesia quality improvement project’ published in the journal Anaesthesia (https://www.onlinelibrary.wiley.com/doi/10.1111/anae.14426) estimated that 11,000 potentially fatal anaesthetic accidents could be prevented every year by access to a simple breathing monitor, the Capnograph.

The authors R. Jooste, F. Roberts, S. Mindolo, D. Mabedi, S. Chikumbanje, D.K. Whitaker, and E.P. O'Sullivan must be congratulated for having conducted this study.  The findings of such studies are critical for future processes in order to decrease mortality and morbidity during surgery and in intensive care units.

The aim of this study was twofold: to measure the prevalence of capnography in the operating rooms and in intensive care units; and to determine whether its introduction was feasible and could improve the early recognition of critical airway incidents in a low‐income or low-resource country. This is the first project to do this. Forty Capnographs were donated to eight hospitals in Malawi. Thirty‐two anaesthesia providers received a 1‐day capnography training course with pre‐ and post‐course knowledge testing. Providers kept logbooks of capnography use and recorded their responses to abnormal readings. On follow‐up at 6 months, providers completed questionnaires on any significant patient safety incidents identified using capnography. In January 2017, at the commencement of the project, only one operating room had a Capnograph. Overall, 97% and 100% ‘capnography gaps’ were identified in the operating rooms and intensive care units, respectively. The mean (SD) scores of our capnography multiple choice questionnaires improved after training from 15.00 (3.16) to 18.70 (0.99), p = < 0.001. The capnography equipment was appropriately robust and performed well. Six months following implementation, 24 (77%) anesthesia providers reported recognizing 44 esophageal intubations and 28 (90%) believed that capnography had saved lives. This study shows it is feasible to introduce capnography in a low‐income country, resulting in early recognition of critical airway incidents and ultimately helping to save lives. Building on the experience of the first trial of pulse oximetry implementation in low‐income countries in 2007, we believe this is one of the most important projects in anesthesia safety in the last decade. 

One noteworthy point is that during the 6‐month study period, 44 esophageal intubations were reported in Southern Malawi, which has a population of 7.5 million 16, giving a rate of 11.7 esophageal intubations per million population per year. Assuming intubation rates and capnography use in Malawi to be representative of sub-Saharan Africa, with a population of 1022 million 16, we estimate that over 11,000 esophageal intubations could occur per year. These pose a very significant patient safety risk that would most effectively be mitigated by the implementation of capnography. Esophageal intubation, undetected because capnography is not used, is now labelled a ‘Never Event’ in the National Health Service in United Kingdom. 

The introduction of capnography and pulse oximetry have certainly enhanced safety of anesthesia in countries where they are the standards of monitoring during anesthesia.  The findings of this study are not surprising given that the introduction of capnography to low-resource countries enhances patient safety during anesthesia and decreases overall mortality. It is encouraging to note from this study that it is indeed feasible to train clinical care providers and introduce capnography into clinical practice. 

It is hoped that in the future, LIFEBOX will include capnography along with pulse oximetry, and that this combination will enhance patient safety and decrease morbidity and mortality around the world.

 

 

Volume capnography: A narrative review

Volume capnography: A narrative review

Shubhangi Singh, Bhavani Shankar Kodali

Department of Anesthesiology and Critical Care,

Brigham and Women’s Hospital,

Harvard Medical School, Boston, MA, USA

 

Volume capnography is the graph of expired carbon dioxide concentration against the expired volume. It often requires special and bulky equipment to be recorded. It can be used to estimate the dead space with fair amount of precision. Various formulae and equations have been described to estimate the dead space. While the Bohr formula is likely the most accurate for measurement of dead space, the Enghoff ’s equation is likely the most popular and convenient to use. Volume capnography has found uses in both the operating room (OR) and the Intensive Care Unit setting. It can be used to identify the optimal level of positive end-expiratory pressure in patients suffering from the acute respiratory distress syndrome as well as to identify its effect on the ventilation. In the OR, it can be invaluable to monitor ventilation and alveolar recruitment in the obese population. It is also a useful diagnostic adjunct in medical emergencies like pulmonary embolism. In the pediatric population, it finds uses in the monitoring of infants suffering from bronchiolitis. In spite of its multiple and diverse uses, it remains an underutilized technology; the main reasons for this being lack of experience of the providers with volume capnography and the expensive and bulky equipment that is often required. However, volume capnography has a great deal of potential and with further advances in technology, is likely to gain popularity.

For free access to this article: http://www.theiaforum.org/temp/IndianAnaesthForum18233-4065041_111730.pdf