Editorial The importance of temporal structure can be explained by the following two sequences: A = {1232123212321} and B = {1111222222333} [5, 7]. Both have the same variability, measured by the range and standard deviation, but completely different structures. Sequence A defines a triangular wave whereas sequence B is a step function. With advanced technology to capture beat-to-beat BP values and computational methods, the temporal dynamics of the BP waveform could be analyzed easily. BP complexity similar to frailty reflects the physiologic reserve and adaptive responsiveness of the system to stress. Recent evidence reports a significantly lower BP complexity in patients with adverse outcomes [5]. Furthermore, BP complexity indices were found to correlate with standard risk prediction scores [8]. Hence, frailty and complexity could possibly be a surrogate of an individual’s physiological reserve. Recent evidence suggests autonomic dysfunction could possibly be the underlying mechanism behind frailty and perioperative complications [4]. Being mainly regulated by the autonomic nervous system, blood pressure (BP) variability is significantly affected by autonomic dysfunction. The relationship between BP variability (beat to beat change) independent of the individual BP numbers on perioperative adverse outcomes has gained increased interest recently [5, 6]. Various methods were used to study BP variability. However, these methods do not describe the temporal dynamics of the BP waveform. Substantial stressor like surgery in frail patients could result in a disproportionate change from independent to dependent, mobile to immobile, stable posture to frequent falls, or lucid to delirious state. Emerging evidence demonstrates increased perioperative complications associated with frailty and incorporating frailty assessment has shown to improve prognostication of existing risk stratification tools [3]. The two widely accepted models of frailty include a phenotypic construct and a deficit accumulation model. However, there is no clear consensus regarding a standard method to assess frailty. The 2010 National Confidential Enquiry into Patient Outcome and Death from the UK found that frailty was not included in the risk assessment of elderly patients. They recommended to include frailty in perioperative risk assessment [9]. Despite recommendations from major organizations (American Chemical Society, Anesthetic Groups, and Association of Anaesthetists of Great Britain and Ireland), frailty is rarely used in routine perioperative care. Multiple methods are used to assess frailty. Their limitations such as time consumption need for specialized training or evaluation and difficulty with emergency surgeries has An increasing number of elderly patients presenting for surgery has profound implications for perioperative medicine. Around half of the surgeries, in the United States were done among elderly patients [1]. Unique physiological changes result in multisystem decline and increase their vulnerability for complications. Frailty expresses this phenomenon and has been considered as a state of decreased physiological reserve and resistance to stressors. Although more common with age, frailty is a distinct concept of biological rather than chronological age [2]. Moreover, the underlying mechanisms of frailty are different from aging. Hence, frailty could explain the observed variations in clinical outcomes that cannot be explained by chronological age alone. Evaluation of geriatric physiological reserve – Keeping an ear to the ground Guest Editorial Journal of Anaesthesia and Critical Care Case Reports 2019 Jan-April;5(1):3-5 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non- Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non- commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2019 by Journal of Anaesthesia and Critical Care Case Reports| Available on www.jaccr.com | Journal of Anaesthesia and Critical Care Case Reports Volume 5 Issue 1 Jan-April 2019 Page 3-5 3 | | | | | 1 Center for Anesthesia Research Excellence, Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. E-mail: bsubrama@bidmc.harvard.edu Ellison C. “Jeep” Pierce Associate Professor of Anaesthesia, Harvard Medical School, Director, Center for Anesthesia Research Excellence, Beth Israel Deaconess Medical Center, Boston, MA, USA. Address of Correspondence Dr. Balachundhar Subramaniam, Valluvan Rangasamy¹, Balachundhar Subramaniam¹ Dr. Valluvan Rangasamy Dr. Balachundhar Subramaniam