Best Nursing Practices of the Post Moderately Sedated Pediatric Patient: Usage of Capnography – A literature review
Introduction
As more and more pediatric procedures are being performed under sedation, more reports of complications like death, and permanent neurological damage from complications of sedation are being reported. The initial reports came from complications by pediatric dental procedures. These reports forced the American Dental Association, and the American Pediatric Association to issue guidelines on the safe use of pediatric sedation. The most important aspect is to not take sedation lightly. It has been equated to pediatric anesthesia. Elective pediatric sedation procedures have been likened to aviation procedures, where even one adverse event is associated with fatalities. Literature mentions the greatest number of complications occurring in a setting where there were no facilities for resuscitation, and monitoring. Even monitoring procedures need to be modified. Visual examination of the respiratory system and pulse oximetry to monitor desaturation is no longer considered adequate. Current knowledge defines the role of end tidal CO2 monitoring (capnograpy). More and more studies are now attesting to the ‘early warning’ role of Capnography in reducing sedation related adverse events. Following is a literature review of 4 articles that have addressed this particular issue.
Literature review
There is relevant data in literature and more emerging data to confirm the importance of capnography for post sedation in pediatric patients. Now there is definite statistical data, which clearly proves, that the outcome is significantly better in terms of survival and recovery following sedation if monitoring is done, and particularly if end tidal monitor is used.
In the study performed by Lightdale etal, they have done an excellent blinded, randomized, controlled study which has underlined the need for a stricter and more dedicated monitoring of the respiratory recovery during moderate sedation particularly in pediatric group patients, as often routine pulse oximetry and visual monitoring fails to record intermittent hypoxic episodes. This point is also highlighted by Cote (2000) and Levine and Platt (2005). The baseline is that no figure of adverse events during elective patient sedation is acceptable in today’s practice. This point is very valid and is also emphasized by Levine (2005). This has been likened to a flying exercise, where the zone of error is essentially zero, as any mistake here is essentially fatal. Lightdale etal (2006) spare no thought is emphasizing that it is not proper to consider the process of conscious sedation a minor procedure, as the complications can be disastrous. Yildizdas (2006) mention that sedatives are being used more and more in small children than ever before. Thus as, Lightdale (2006) and Cote (2000) point out there is a need to maintain a high level of vigil in this group. Lightdale (2006) suggests the emerging role of microstream capnography as an “early warning system”. This is further attested to by Yildidas (2004). To consider some of these studies in more detail, the objective of the study by Lightdale was whether interventions based on capnography indications of alveolar hypoventilation reduces the incidence of arterial oxygen desaturation in nonintubated children receiving moderate sedation. The study group consisted of 163 patients who were undergoing elective gastrointestinal procedures under moderate sedation. Sedation was performed using oral midazolam (0l.5 management/kg). Depth of sedation was continuously measured using Ramsay score. The Ramsay score has been a general standard to assess sedation as also mentioned by McQuillen (2000). The patients were administered 2 ltr oxygen via a nasal canula, a port to measure expired CO2 was present. During the surgery, sedation was maintained. The methodology consisted of division into 2 study arms, where the ventilatory monitoring was done by trained endoscopy staff. In the study group, microstream monitoring was done by measuring absolute end tidal carbon dioxide monitoring and tracking continuous waveforms (capnograms) by independent observers. Intervention was done if alveolar hypoventilation was present for more than 15 seconds, whereby the nurse would intervene to encourage patient ventilation. The patient oxygen desaturation was defined as pulse oximetry reading of <95% for > 5 seconds. Intervention was done by repositioning patient, capnography indications of alveolar hypoventilation reduces the incidence of arterial oxygen desaturation in nonintubated children receiving moderate sedation. Any adverse event was recorded (such as vomiting, or hypotension and bradycardia. The capnograph was muted, and was visible only to the independent observer. The probes at the nasal orifice recorded CO2 waveforms, and these were monitored at 5 minute intervals for hypoventilation/apnoea. The statistical analysis used was the intention to treat analysis using the SAS software for computing the results. The primary hypothesis was tested by the Fisher’s exact test, and confirmation of the results was done with multiple logistic regression analysis using arterial desaturation as the binary end point, study arm as the independent variable, and various patient characteristics and clinical outcomes as covariates. In the study there were no procedure termination, or adverse events. It was determined that patients in the intervention arm were significantly less likely to have an intraprocedural episode of arterial oxygen desaturation to <95% than those in the control arm. Capnography allowed early detection of arterial oxygen desaturation because of alveolar hypoventilation in the presence of supplemental oxygen. It has been suggested that providing supplemental oxygen during procedural sedation may mask early detection of inadequate ventilation by continuous pulse oximetry. Lightdale etal, point out a few limitation of the study. They state that their results might have been different if some of the latest oximetry instrumentation was some occurrences of capnograms consistent with alveolar hypoventilation may have instead been artifact available, and that some occurrences of capnograms consistent with alveolar hypoventilation may have actually been artifact. The authors conclude by saying that microstream capnography improves the current standard of care for monitoring sedated children by allowing early detection of respiratory compromise, prompting intervention to minimize hypoxemia.
In another study by Cote etal, the authors attempt to create a data base to delineate factors that contribute to adverse sedation events in children undergoing procedures. The authors have used adverse sedation events from the Food and Drug Administration’s adverse drug event reporting system, from the US Pharmacopeia, and from a survey of pediatric specialists. (One hundred and eighteen reports). All outcomes ranging from no adverse reaction to death were noted, and a panel of authors studied the reports to reach a consensus on contributing factors and outcomes. The study highlights the fact that in response to deaths associated with dental procedures, it was the American Academy of Pediatrics (AAP) and the American Academy of Pediatric Dentistry published the first guidelines for caring for children requiring sedation for procedures. They suggested the routine use of pulse oximetry. But even as these guidelines have been in place for a long time, and the pulse oximetry being available for 21 years, adverse effects still occur. Thus it is essential to study the factors which still plague moderate sedation in pediatric patients. A problem Cote (2000) has pointed out is that the data collection faces the major hurdle of inadequate adverse events reporting for the fear of litigation. Levine and Platt (2005) also have said that at times reporting cannot be considered totally accurate for fear of being blamed for human errors. In the study by Cote etal the use of the technique of critical incident analysis of these events has found that human error accounts for most mishaps. The factors which have come out of this study has been, that inadequate medical evaluation, inadequate monitoring during or after the procedure, inadequate skills in problem recognition and timely intervention, and the lack of experience with a particular age patient or with an underlying medical condition are the main causes. In addition the availability of sophisticated monitoring equipment has helped in early warning signs. The authors suggest that it is essential to consider pediatric sedation to be equivalent to pediatric anesthesia, and take appropriate preventive steps. In the study, the study group consisted of 235 FDA adverse drug reports, and118 reports of physician reports. The authors have presented an interesting data in Table B where a list of probable causes is spelled out. Data collected included the year of the incident, age, weight, gender, type of procedure, the venue in which the sedation drug(s) were administered, venue where the adverse sedation event took place, the medical specialty of the individual directing drug administration, the monitoring which was reported as being used, and the underlying medical conditions There is a significant difference in causative factors between hospital and non hospital based events. In the former the major causes are drug-drug interaction, drug overdose, whereas in the latter, inadequate monitoring, inadequate medical evaluation, inadequate resuscitation are more important. Cote has found out that there is 82% incidence of death in the non hospital setting versus 30% in the hospital setting. Permanent neurologic injury is similar in both settings. Interesting is the fact that there were no patients with no harm in the non hospital setting, while 30% of hospital patients escaped with no harm. If pulse oximetry was used, the outcome of adverse events is more favourable, while death was more likely, if pulses oximetry was not used. Statistical analysis was conducted for medical provider, patient demographics, venue, and outcome. The tests included t-test, with chi2 correction. The results obtained reveal the following- there is a 2.5 fold increase in death in non hospital setting. In addition, pulse oximetry and Capnography are the single most important monitoring systems and must be used to prevent and treat complications
Similar findings are echoed in the article by Levine and Platt (2005). In this article the authors define the newer monitoring techniques which are in use during procedural sedation. Agents used in procedural sedation like benzodiazepines, opiates commonly cause respiratory depression, and in children, there is need for close monitoring. Such facts have already been alluded to by Lightdale etal. The authors note that noninvasive monitoring techniques are being applied to patients sedated in the outpatient setting. These devices, the end-tidal carbon dioxide (ETCO2) monitor and the bispectral index (BIS) monitor, aid the emergency physician in the sedation of children, by facilitating efficiency and reducing adverse events. BIS is an index, that has been used by Sinha(2006) in deciding the stage at which Laryngeal mask airway is removed. Though this article does not strictly adhere to the topic, but it does underline the importance of another noninvasive investigation in pediatric monitoring. This may be something future investigations could look at.
As Levine and Platt (2005) explain that in capnometry, the expiratory gases are analysed with infrared spectrography. The waveform pattern of exhaled CO2 is produced by the variations in CO2 concentration throughout the respiratory cycle. Any increase in exhaled CO2 indicated increased arterial increase of CO2. Also loss of this waveform indicated hypoventilation and apnoea. This data is not given by pulse oximetry, thus capnometry gives early detection of sedation induced respiratory depression, thereby enabling a reduction in possible adverse events. The authors suggest that it is important to make the use of Capnography essential in pediatric sedation. The authors quote several studies, which have proved that combined use of opiates and benzodiazepines is associated with significant respiratory depression, and requires monitoring. Other studies have shown the early warning role of Capnography in detecting hypoventilation, even when no such indication was given by pulse oximetry.
Bispectral analysis score monitoring (BIS), is a noninvasive method of evaluating a patient’s level of sedation ( Levine and Platt, Sinha, 2006).Electroencephalograms from probe on the forehead are processed to indicate the level of the patient’s consciousness. Using standard normograms, a numeric scoring system is used. The BIS monitor enables the physician to titrate sedative use to a desired effect prior to adverse sequelae. The BIS score offers a reliable and objective measurement of the level of sedation and may replace subjective sedation scales that rely on verbal and physical response. In various studies it has been shown that patients whose medications were titrated based on the BIS score received lower mean doses of medications, had shorter recovery times, and were more likely to be in the optimum sedation range. The authors conclude that incorporation of Capnography, and BIS score may allow an early recognition of hypoventilation and reduce the incidence of complications.
In the study by McQuillen and Steele (2000), this is an excellent article that tries to focus on the relative changes in end-tidal CO2 when using different sedation techniques and drugs. Apart from its role in monitoring of sedation, they authors have tried its role in the emergency setting. The authors note of the recent attempt by the American Society of Anesthesiologists (1) (ASA) and the American Academy of Pediatrics (2) (AAP) in an attempt to minimize the risks associated with sedation/analgesia by publishing guidelines. To recall, Cote etal have also mentioned the wonderful role of AAP in bringing out the importance of monitored moderate sedation, and taking positive steps to decrease complications. The AAP guidelines encourage the use of a precordial stethoscope or capnograph for deeply sedated patients, while the ASA guidelines stress the importance of monitoring ventilatory function by observation of respiratory activity or auscultation of breath sounds. As in the earlier studies, the authors also confirm the fact that the waveform is the most immediate indicator of hypoventilation and changes in the waveform are rapidly followed by changes in the ETCO2 level.
McQuillen and Steele studied 106 children with mean age of 6.8 years requiring intravenous sedation. These children were diagnosed with various problems. according to the authors, “Side stream, nasal cannula end-tidal CO2 tracings were recorded on a Capnogard® ETCO2 Monitor (Model 1265) via the Analog Output Module (Novametrix Medical Systems, Wallingford, CT)”. In this study, the primary outcome variable was the difference between peak ETCO2 before and during sedation. The statistical analysis used 95% confidence limits and mean to summarize the changes in ETCO2 using a paired t-test. McQuillen and Steele attempt to quantify the roles of different sedatives in producing hypoventilation and subsequent rise in ETCO2. The maximum increase of ETCO2 was when midazolam was combined with opiate, and the next greatest increase was with midazolam alone. 2 patients in the study had transient desaturation, which was recognized early, and treated by stimulation. The authors note that side stream sampling of end-tidal CO2 via a nasal cannula is a feasible and practical way to follow trends in ventilation during pediatric sedation/analgesia. On the role of pulse oximetry, the authors emphasize that because the relationship between the partial pressure of oxygen in arterial blood (PaO2) and the SaO2 is not linear, large changes in oxygenation can go unnoticed before they are reflected by changes in pulse oximetry. . a decline in PaO2 from 100 to 40 mm Hg results in only 3% of SO2 (Yildizdas, 2004) .On the other hand, the high solubility of CO2 across lung tissue membranes, however, results in a nearly linear correspondence between the alveolar partial pressure of carbon dioxide (PACO2), the arterial partial pressure of carbon dioxide (PaCO2) and, in healthy children, and the end-tidal carbon dioxide level (ETCO2). The authors conclude thus by saying that Capnography can be useful in sedation, as well as in high risk situations like cardiac surgery, trauma surgeries. The authors underline the need for greater research on this topic.
Reference:
1 Lightdale etal . Microstream Capnography Improves Patient Monitoring During Moderate Sedation: A Randomized, Controlled Trial.. PEDIATRICS Vol. 117 No. 6 June 2006, pp. e1170-e1178
2 Cote CJ etal. Adverse Sedation Events in Pediatrics: A Critical Incident Analysis of Contributing Factors. PEDIATRICS Vol. 105 No. 4 April 2000, pp. 805-814
3 Levine DA, Platt SL. Novel monitoring techniques for use with procedural sedation. Current Opinion in Pediatrics. Vol 17(3) June 2005. 351-354.
4 McQuillen KK, Steele DW. Capnography during sedation/analgesia in the pediatric emergency department. Pediatric Emergency Care. Vol 16(6), Dec 2000, 401-404.
5 Yıldızdas¸D, Hacer Yapıcıogˇlu, Yılmaz HL , The Value of Capnography During Sedation or Sedation/Analgesia in Pediatric Minor Procedures. Pediatric Emergency Care _ Volume 20, Number 3, March 2004
6 Sinha A, Sood, J. Safe removal of LMA in children – at what BIS? Paediatric Anesthesia. Volume 16(11), November 2006, p 1144–1147