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Melissa Knauert, MD, PhD

Assistant Professor of Medicine (Pulmonary)

Contact Information

Melissa Knauert, MD, PhD

Office Location

Mailing Address

  • Pulmonary, Critical Care & Sleep Medicine

    PO Box 208057

    New Haven, CT 06520-8057

    United States

Knauert Lab
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Research Summary

Dr. Knauert investigates sleep deprivation and circadian disruption in critically ill patients. In collaboration with the many members of the medical ICU care team, she has implemented an overnight sleep promotion protocol aimed at providing patients with an opportunity to sleep while admitted to the medical ICU. She is currently studying the influence of circadian light patterns on circadian alignment in medical ICU patients.

Extensive Research Description

Dr. Knauert investigates sleep deprivation and circadian disruption in critically ill patients. Sleep deprivation and circadian disruption are likely key factors in the development of ICU delirium. Furthermore, sleep and circadian abnormalities are implicated in broader perturbations of normal physiology including abnormalities of cardiovascular, immune, endocrine and metabolic systems. Over the long-term, this patient-oriented research will improve outcomes in the ICU by investigating questions and developing interventions at the intersection of sleep, circadian biology, and critical illness.

Past and current projects include:

  • A feasibility study of ambulatory polysomnography in the medical ICU (MICU) examining sleep architecture. This work demonstrated the feasibility of portable polysomnography in a MICU setting, alterations in normal sleep architecture, and a high percentage of daytime sleep in MICU patients. (Funding R21 NR011066)
  • A randomized controlled trial of a nocturnal clustered care intervention in the MICU (“Naptime”). Monitoring of sound levels during the Naptime Study revealed a large burden of low frequency sound which had not been previously reported. During Naptime (midnight to 4:00 AM), the intervention arm had 32% fewer room entries, and fewer minutes per hour of in-room activity. Naptime almost doubled the length of time between room entrances from 26 to 46 minutes. The intervention arm also had lower average and peak sound levels during the intervention period. (Funding P20 NR014126)
  • An observational cohort study examining the overlap between delirium, electroencephalographic atypia and atypical sleep as defined by sleep montage electroencephalography. Patients without K-complexes or without sleep spindles had more severe encephalopathy and higher odds of death. The odds ratio (OR) for patients without K-complexes was 18.8 (p=0.046). The odds ratio for patients without sleep spindles was 6.3 (p=0.036). We concluded that loss of stage N2 features is common and associated with more severe encephalopathy and higher odds of death. The absence of either Stage N2 feature, K complexes or sleep spindles, may have important prognostic value. (Pepper Scholar, Funding P30 AG021342)
  • An observational cohort study examining circadian rhythms in ICU using continuous heart rate monitoring. Analysis is in progress. (YCCI Scholar, Funding KL2 TR000140)
  • An observational cohort study examining the influence of light on circadian rhythms in the ICU. This study will also examine the influence or circadian rhythm abnormalities on the duration of ICU delirium. (K23 HL138229)
  • A randomized controlled trial of daytime bright light examining the impact of daytime bright light on circadian alignment and duration of delirium. (AASM Strategic Research Award)

Coauthors

Research Interests

Critical Care; Delirium; Noise; Respiration; Sleep; Sleep Deprivation; Sleep Wake Disorders; Pulmonary Medicine; Critical Illness

Selected Publications

  • Pilot Observational Study to Detect Diurnal Variation and Misalignment in Heart Rate Among Critically Ill Patients.Knauert MP, Murphy TE, Doyle MM, Pisani MA, Redeker NS, Yaggi HK. Pilot Observational Study to Detect Diurnal Variation and Misalignment in Heart Rate Among Critically Ill Patients. Frontiers In Neurology 2020, 11: 637 PubMed ID: 32760341, PMCID: PMC7373742, DOI: 10.3389/fneur.2020.00637.
  • Pilot study: an intensive care unit sleep promotion protocol.Knauert MP, Pisani M, Redeker N, Murphy T, Araujo K, Jeon S, Yaggi H. Pilot study: an intensive care unit sleep promotion protocol. BMJ Open Respiratory Research 2019, 6: e000411 PubMed ID: 31258916, PMCID: PMC6561389, DOI: 10.1136/bmjresp-2019-000411.
  • Circadian Biology and Its Importance to Intensive Care Unit Care and Outcomes.Gao CA, Knauert MP. Circadian Biology and Its Importance to Intensive Care Unit Care and Outcomes. Seminars In Respiratory And Critical Care Medicine 2019, 40: 629-637 PubMed ID: 31826263, DOI: 10.1055/s-0039-1698394.
  • Association of intensive care unit delirium with sleep disturbance and functional disability after critical illness: an observational cohort study.Altman MT, Knauert MP, Murphy TE, Ahasic AM, Chauhan Z, Pisani MA. Association of intensive care unit delirium with sleep disturbance and functional disability after critical illness: an observational cohort study. Annals Of Intensive Care 2018, 8: 63 PubMed ID: 29740704, PMCID: PMC5940933, DOI: 10.1186/s13613-018-0408-4.
  • Non-circadian signals in the intensive care unit: Point prevalence morning, noon and night.Altman MT, Pulaski C, Mburu F, Pisani MA, Knauert MP. Non-circadian signals in the intensive care unit: Point prevalence morning, noon and night. Heart & Lung : The Journal Of Critical Care 2018, 47: 610-615 PubMed ID: 30143362, PMCID: PMC6234066, DOI: 10.1016/j.hrtlng.2018.07.011.
  • Association between death and loss of stage N2 sleep features among critically Ill patients with delirium.Knauert MP, Gilmore EJ, Murphy TE, Yaggi HK, Van Ness PH, Han L, Hirsch LJ, Pisani MA. Association between death and loss of stage N2 sleep features among critically Ill patients with delirium. Journal Of Critical Care 2018, 48: 124-129 PubMed ID: 30179762, PMCID: PMC6226351, DOI: 10.1016/j.jcrc.2018.08.028.
  • Creating Naptime: An Overnight, Nonpharmacologic Intensive Care Unit Sleep Promotion Protocol.Knauert MP, Redeker NS, Yaggi HK, Bennick M, Pisani MA. Creating Naptime: An Overnight, Nonpharmacologic Intensive Care Unit Sleep Promotion Protocol. Journal Of Patient Experience 2018, 5: 180-187 PubMed ID: 30214923, PMCID: PMC6134539, DOI: 10.1177/2374373517747242.
  • Factors Influencing Patients' Sleep in the Intensive Care Unit: Perceptions of Patients and Clinical Staff.Ding Q, Redeker NS, Pisani MA, Yaggi HK, Knauert MP. Factors Influencing Patients' Sleep in the Intensive Care Unit: Perceptions of Patients and Clinical Staff. American Journal Of Critical Care : An Official Publication, American Association Of Critical-Care Nurses 2017, 26: 278-286 PubMed ID: 28668912, PMCID: PMC5559223, DOI: 10.4037/ajcc2017333.
  • Sleep Disturbance after Hospitalization and Critical Illness: A Systematic Review.Altman MT, Knauert MP, Pisani MA. Sleep Disturbance after Hospitalization and Critical Illness: A Systematic Review. Annals Of The American Thoracic Society 2017, 14: 1457-1468 PubMed ID: 28644698, PMCID: PMC5711402, DOI: 10.1513/AnnalsATS.201702-148SR.
  • Perceptions and Practices Regarding Sleep in the Intensive Care Unit. A Survey of 1,223 Critical Care Providers.Kamdar BB, Knauert MP, Jones SF, Parsons EC, Parthasarathy S, Pisani MA. Perceptions and Practices Regarding Sleep in the Intensive Care Unit. A Survey of 1,223 Critical Care Providers. Annals Of The American Thoracic Society 2016, 13: 1370-7 PubMed ID: 27104770, PMCID: PMC5021080, DOI: 10.1513/AnnalsATS.201601-087OC.
  • Reply: Sleep in the Intensive Care Unit Is a Priority.Knauert MP, Kamdar BB. Reply: Sleep in the Intensive Care Unit Is a Priority. Annals Of The American Thoracic Society 2016, 13: 1868-1869 PubMed ID: 27726437, PMCID: PMC5122496, DOI: 10.1513/AnnalsATS.201607-578LE.
  • Comparing average levels and peak occurrence of overnight sound in the medical intensive care unit on A-weighted and C-weighted decibel scales.Knauert M, Jeon S, Murphy TE, Yaggi HK, Pisani MA, Redeker NS. Comparing average levels and peak occurrence of overnight sound in the medical intensive care unit on A-weighted and C-weighted decibel scales. Journal Of Critical Care 2016, 36: 1-7 PubMed ID: 27546739, PMCID: PMC5097003, DOI: 10.1016/j.jcrc.2016.06.005.
  • Sleep Loss and Circadian Rhythm Disruption in the Intensive Care Unit.Knauert MP, Haspel JA, Pisani MA. Sleep Loss and Circadian Rhythm Disruption in the Intensive Care Unit. Clinics In Chest Medicine 2015, 36: 419-29 PubMed ID: 26304279, DOI: 10.1016/j.ccm.2015.05.008.
  • Feasibility study of unattended polysomnography in medical intensive care unit patients.Knauert MP, Yaggi HK, Redeker NS, Murphy TE, Araujo KL, Pisani MA. Feasibility study of unattended polysomnography in medical intensive care unit patients. Heart & Lung : The Journal Of Critical Care 2014, 43: 445-52 PubMed ID: 25023504, PMCID: PMC4150840, DOI: 10.1016/j.hrtlng.2014.06.049.
  • Sleep and sleep disordered breathing in hospitalized patients.Knauert MP, Malik V, Kamdar BB. Sleep and sleep disordered breathing in hospitalized patients. Seminars In Respiratory And Critical Care Medicine 2014, 35: 582-92 PubMed ID: 25353103, DOI: 10.1055/s-0034-1390080.
  • A Clinic Blueprint for Post-Coronavirus Disease 2019 RECOVERY: Learning From the Past, Looking to the Future.Lutchmansingh DD, Knauert MP, Antin-Ozerkis DE, Chupp G, Cohn L, Dela Cruz CS, Ferrante LE, Herzog EL, Koff J, Rochester CL, Ryu C, Singh I, Tickoo M, Winks V, Gulati M, Possick JD. A Clinic Blueprint for Post-Coronavirus Disease 2019 RECOVERY: Learning From the Past, Looking to the Future. Chest 2021, 159: 949-958 PubMed ID: 33159907, PMCID: PMC7641526, DOI: 10.1016/j.chest.2020.10.067.
  • Light Levels in ICU Patient Rooms: Dimming of Daytime Light in Occupied Rooms.Lusczek ER, Knauert MP. Light Levels in ICU Patient Rooms: Dimming of Daytime Light in Occupied Rooms. Journal Of Patient Experience 2021, 8: 23743735211033104 PubMed ID: 34368424, PMCID: PMC8312159, DOI: 10.1177/23743735211033104.
  • A SAS macro for modelling periodic data using cosinor analysis.Doyle MM, Murphy TE, Pisani MA, Yaggi HK, Jeon S, Redeker NS, Knauert MP. A SAS macro for modelling periodic data using cosinor analysis. Computer Methods And Programs In Biomedicine 2021, 209: 106292 PubMed ID: 34380075, PMCID: PMC8435001, DOI: 10.1016/j.cmpb.2021.106292.

Clinical Trials

ConditionsStudy Title
Immune System; Men's Health; Women's HealthEffects of circadian regulation and sleep on immune responses
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