Detecting Post-Operative Respiratory Depression in Children
Condition: Respiratory Depression
MeSH terms: Respiratory Insufficiency; Depression; Depressive Disorder
Study type: Interventional

Summary: 
      Background: Due to the lingering effects of general anesthesia and the administration of
      medications for pain after surgery, children in the recovery room are at risk for breathing
      problems. While there are less data specific to children, in general 25% of patients in the
      recovery room experience complications from anesthesia. The most common complications involve
      the patient's airway and their ability to breath adequately. Currently, checks of oxygenation
      with a pulse oximetry monitor and of respiration through nursing assessments are used to
      detect breathing problems. However, these are believed not to be adequate for reliably
      recognizing significant respiratory depression until other dangerous events develop such as
      the cessation of breathing, severe drops in oxygen levels, or cardiac arrest. Capnography is
      a monitoring device that measures the amount of carbon dioxide being exhaled and assesses the
      adequacy of respiration. A small plastic cannula sits at the base of the nose and on the lip
      to continuously monitor the patient's breathing. Most children tolerate this device well and
      staff consider it easy to use. While capnography is routinely used in the operating room to
      monitor breathing, it is not used during post-operative care when patients are still at risk
      of breathing problems.

      Objectives: To determine if capnography can detect problems with breathing faster and more
      often than traditional monitors. To determine if the addition of capnography to routine
      monitoring will decrease the numbers of additional adverse events that occur in children
      undergoing post-operative care by allowing nurses to intervene in care faster and more
      frequently.

      Methods: In the first phase of this study, the investigators will apply the capnography
      monitor to children in the recover room and determine how often they experience breathing
      difficulties measured by this device. In the second phase, the investigators will educate
      staff on the use of capnography and what values are considered abnormal. Children will again
      have the capnography cannula placed on them as they enter the recovery room. They will then
      be divided into two groups - in one group the nurses in the recovery room will have access to
      the capnography monitor for their patients, whereas in the other group the nurses will not be
      able to see the readout from the monitor. The investigators will determine if children have
      fewer breathing problems and less additional adverse events when nurses use capnography in
      addition to the routine monitors already in place in the recovery room as compared to when
      nurses use standard monitoring alone.

      Potential Impact: If capnography can detect breathing problems prior to being identified by
      current monitoring devices, staff may be able to intervene more quickly and before more
      serious events occur in the children receiving post-operative care. This can reduce adverse
      events, improve patient safety, and avert harm in children. The adoption of this device for
      routine monitoring of post-operative care has the potential to save lives.
    

Detailed description: 
      Study Site: Children will be enrolled in the post-anesthesia care unit (PACU) at Yale-New
      Haven Children's Hospital, where capnography is not currently utilized. The pediatric PACU is
      a 12-bed monitored unit and a 4-bed perioperative area where patients receive one-on-one
      nursing care. Generally, between 20-30 patients are cared for in the PACU each day with a
      typical length of stay of approximately 2 hours.

      Specific Aim 1b: To determine whether the addition of capnography will lead to a decrease in
      the frequency of oxygen desaturations as measured by pulse oximetry and respiratory
      depression in children recovering from general anesthesia.

      Study Design and Setting: The investigators will conduct a randomized controlled trial in the
      Yale-New Haven Children's PACU.

      The identical population, inclusion and exclusion criteria and recruitment procedures will
      apply. A random number list will again be generated to guide recruitment. Investigators will
      be blinded to group designation prior to consent and enrollment.

      Study Intervention and Data Collection: Prior to the onset of this study, PACU nursing staff
      will receive focused training on the application and interpretation of capnography. Proper
      positioning of the nasal-oral cannula will be demonstrated. Capnography waveforms will be
      reviewed including normal respiratory patterns and end-tidal CO2 (ETCO2) levels that would
      indicate hypoventilation, apnea or obstruction. Staff will be instructed that they can
      provide interventions when ETCO2 values greater than 50mmHg or less than 30mmHg are obtained
      without a concomitant increase in respiratory rate. Simple noninvasive interventions may
      include reposition of the head, instructing the patient to take several deep breaths,
      physical stimulation, or placing a shoulder roll under the patient. Invasive interventions
      may include administration of reversal medications, bag-valve mask assisted ventilation, the
      insertion of an oral or nasal airway and endotracheal intubation. Patients who develop oxygen
      saturations less than 93% may receive an increased amount of supplemental oxygen at the
      discretion of the treating staff.

      Patients will undergo routine care and monitoring while in the PACU. As part of this study, a
      duo-port nasal-oral cannula for ETCO2 monitoring will be placed in the nostrils and over the
      lip of the patient prior to transfer from the operating room to the PACU (Filterline Smart
      CapnoLine Plus) and attached to the portable capnography monitor (Capnostream 20 Bedside
      Capnography Monitor by Oridion). Subjects will be randomized into 2 groups: those in whom the
      responsible nurse and physician are blinded to the capnography monitor (controls), and those
      in whom the capnography monitor is viewed by treating staff during the recovery period
      (cases). The investigators control group represents the current standard of care for PACU
      monitoring. Stratified block randomization will take place. Patients will be stratified by
      type of surgery: otolaryngology (ENT) or non-ENT. The randomization sequence will be placed
      in sequentially numbered opaque envelopes for each stratum. Although each patient and his/her
      family will consent to the study prior to surgery, they will not be officially enrolled until
      the patient demonstrates that he/she can tolerate the nasal-oral cannula upon arrival to the
      PACU. Thus, when an enrolled subject arrives to the PACU and is successfully tolerating the
      nasal-oral cannula the study envelope containing their group designation will be opened by
      the research assistant (RA) or principal investigator (PI) for this study and data collection
      will commence. All staff will be blinded to group designation until this time.

      For the case subjects, alarm settings will be programmed on the monitor to alert the provider
      to ETCO2 levels below 30mmHg and above 50mmHg. The monitor will be positioned where it can be
      easily viewed by both the treating staff and the RA/PI for this study. For control subjects,
      the portable capnography monitor will be positioned by the PI or RA and out of the line of
      sight of other treating staff. The alarm function will be turned off so as not to alert staff
      to abnormal readings on the monitor. Since the investigators are not mandating that staff
      intervene for abnormal ETCO2 values, the RA or PI will be the only participant to view the
      capnography monitor in the control group and will not inform the treating staff of any
      abnormal values under 2 minutes in length. The Yale Human Investigations committee was
      consulted regarding the ethics of withholding information from the control arm of this study
      and approves this decision. Instances where the PI or RA had to notify staff of events will
      be recorded on the data form.

      Methodology: For the purposes of this randomized controlled trial, heart rate, respiratory
      rate, and oxygen saturation will be routinely monitored and recorded on a data sheet every 30
      seconds while the patient is in the PACU by the PI or RA who will not otherwise be involved
      in patient care. ETCO2 values are recorded by the capnography monitor every 30 seconds and
      waveforms are continuously captured. These data will be downloaded from the capnography
      monitor at the time of discharge for each patient. Adverse respiratory events as well as
      nurse and physician interventions related to airway and ventilatory management will be
      documented by the PI/RA. These were described previously. Additional pain or sedative
      medications may be administered by nursing staff and will be recorded during this study.
      Patient disposition and total length of stay in the PACU will be recorded.

      The investigators primary outcome will be frequency of The investigators previously defined
      respiratory events that occur with and without the use of capnography.

      Sample size calculations: While the investigators will refine their sample size based on
      event rates found in the first cohort of this proposal, the investigators plan to enroll at
      least 200 children in this pilot study in order to detect a 30% reduction in adverse event
      rates.

      Statistical Analysis: Variable distributions will first be examined with descriptive
      statistics, including box-plots and histograms. Any missing data due to artifact or equipment
      malfunction will be explored for each group. The investigators will describe the two groups
      of patients, those with blinded capnography readings vs. those without, in terms of their
      age, gender, ethnicity, type of condition for which sedation was required, and physician
      performing procedure. The investigators will use Student's t-test for continuous variables
      and chi-square/Fisher's exact test for categorical variables. Statistically significant (p <
      0.05) or clinically meaningful differences (10%) between two randomized groups will be added
      to the multivariate analysis of the primary outcome. Groups will then be analyzed by strata -
      patients receiving ENT procedures and those receiving other non-ENT procedures.

      The primary outcomes, airway or respiratory adverse events, will be summarized by group in
      terms of the number and percent of patients in each group who experience these outcomes.
      Generalized estimating equation (GEE) approach will be used to model the probability of an
      outcome (two separate models for each outcome of interest) with the randomization group
      (blinded vs. not to capnography readings) as the main independent predictor. The
      investigators will adjust the model with other important predictors, especially the ones that
      were different between the two groups. Odds ratios (OR) and surrounding confidence intervals
      will be reported for each predictor. The investigators can use the adjusted OR for the group
      variable to calculate relative risk (RR).37 Significance will be established with a
      two-tailed alpha=0.05. The investigators will use this data to obtain funding for a larger,
      randomized trial which will also include cost-effectiveness analyses.
    

Intervention name(s): Capnography
Intervention type(s): Device
Intervention description(s): Capnostream 20 Portable Capnography Monitor with Internal Printer by Oridion
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention