The presence of a trained and experienced anesthesiologist is the main determinant
of patient safety during anesthesia. Monitoring is defined as observation of a patient
by a physician and analysis of the quality of sedation or anesthesia over a time period.
Administration of anesthesia requires continual assessment of the physiological state
of the patient as well as the adequacy of anesthesia. Although monitoring of the patient
using monitors supplements clinical observation, the former is by no means a substitute
for the latter. Monitoring and recording may be performed using either automated computerized
methods or manual measurement. Automated computerized methods have the advantage of
saving the recorded information and observing trends over time. Association of Anaesthetist
of Great Britan and Ireland standards of monitoring include the following [1]:
1. The presence of a qualified anesthetist,
2. Monitoring the patient’s oxygenation, ventilation, circulation, and temperature
a) Ventilation: Assessed by measuring end-tidal carbon dioxide and inspired anesthetic
gases.
b) Oxygenation: Assessed by measuring peripheral oxygen saturation and inspired anesthetic
gases.
c) Temperature: Core temperature monitoring (e.g., tympanic membrane, distal esophagus,
nasopharynx, etc.) is used to monitor intraoperative hypothermia, prevent over-heating,
and facilitate detection of malignant hyperthermia.
d) Circulation: Assessed by measuring heart rate and non-invasive blood pressure every
five minutes, and through electrocardiogram analysis.
Minimum basic standard monitoring during general anesthesia includes pulse oximetry,
electrocardiogram, monitoring of non-invasive blood pressure, end-tidal carbon dioxide,
and airway pressure. The use of a nerve stimulator is indicated whenever a muscle
relaxant is used. During regional anesthesia and sedation procedures, appropriate
monitoring should be performed using pulse oximetry, measurement of non-invasive blood
pressure, and electrocardiography, at a minimum [1]. In principle, monitoring of physiological
variables provides information and feedback on the body’s response to therapeutic
interventions or changing clinical conditions. This allows fine-tuning of patient
management to achieve optimal outcomes and minimization of complications.
Clinical observation and assessment by a vigilant anesthetist are essential for safe
patient care during anesthesia. Appropriate clinical observations include the color
of the mucosa, sweating, lacrimation, movement of the patient, response to a surgical
stimulus, excursions of the chest wall, and movements of reservoir bag/bellows etc.
A simple palpation of the radial/carotid pulse can indicate the volume status of the
patient. Other clinical monitoring parameters include measurement of urine output,
blood loss, and auscultation of heart sounds and breath sounds. Standard monitoring
requires that measurements be performed every 5 minutes. Changes in clinical signs
often precede abnormalities detected by monitoring equipment. For example, just after
induction, or after administering local anesthetic during a subarachnoid block, hypotension
is anticipated. While monitors may not pick it up immediately, clinical assessment
and palpation of the pulse can detect hypotension earlier. Similarly, if breathing
circuit get disconnected, it can be detected by direct observation even before saturation
falls on monitor. Most of the alarm signs are seen on the monitor only after an event
occurs in the surgical field (e.g., tachycardia on the monitor, after blood loss);
this indicates that assessing the surgical field should also be a component of anesthetic
monitoring.
Till date, technological advances are unable to alert us about displaced intravenous
lines, urinary catheters, breathing circuits, or surgical drains. To ensure comprehensive
monitoring of the patient at regular intervals, we suggest a closed-loop monitoring
method. The principles of closed-loop monitoring can be used in regional anesthesia,
general anesthesia, monitored anesthesia care, and the intensive care unit. Closed-loop
monitoring includes closed-loop visual inspection of the patient, anesthesia machine,
standard monitors, and surgical field at regular intervals in a predetermined sequence
so that none of the parameters are missed. The main sequence is as follows: Patient
(clinical assessment, pulse, airway, chest movements, intravenous lines, rate and
amount of fluid infusion, urine output, surgical field, blood loss, suction drains,
etc.) → Monitor → Anesthesia workstation (including vaporizers, ventilators, etc.),
→ Operating table and patient record sheet → and back to Patient (Fig. 1). Simultaneously,
it needs to be ensured that alarm limits are set at an appropriate level so that the
changes can be detected early. Collection of all data on a data sheet is not a huge
task, but it is an indispensable part of monitoring the patient, as it provides information
on the entire duration of the surgery and can also be used later as part of the medical
records. The closed-loop monitoring approach will not only prevent adverse incidents
or accidents but will also help in improving the safe provision of anesthesia and
reducing anesthesia-related morbidity/mortality.