Research Article: Unexpectedly prolonged fasting and its consequences on elderly patients undergoing spinal anesthetics. A prospective observational study1

Date Published: March 18, 2019

Publisher: Sociedade Brasileira para o Desenvolvimento da Pesquisa em
Cirurgia

Author(s): Oguzhan Yeniay, Zeki Tuncel Tekgul, Onur Okur, Noyan Koroglu.

http://doi.org/10.1590/s0102-865020190030000009

Abstract

To measure the preoperative fasting durations with respect to time of the day
and its effect on vital parameters and electrocardiogram in elderly patients
undergoing surgery under spinal anesthesia.

This study investigated 211 patients older than 60 years undergoing elective
surgery under spinal anesthesia. Patients scheduled for surgery in morning
hours (AM) and afternoon hours (PM) were compared. Patients fasting hours
and repeated measurements of mean arterial pressure (MAP), heart rate (HR),
peripheral oxygen saturation (Sp02) and the type and number of ischemic
electrocardiogram (ECG) signs were recorded and compared [preoperative,
zeroth, 2nd,5th,15th,30th minutes following spinal anesthesia(SA)].

Mean fasting durations were 12±2.8 and 9.5±2.1 hours in AM group and 15.5±3.4
12.7±4.4 hours in PM group for foods and liquids respectively. ECG changes
were significantly more frequent in PM group and body temperatures were
significantly higher in AM group patients.

Our study has shown that fasting times in our population is far longer than
recommended and fasting prolonged>15 hours is related to a transiently
increased cardiac stress and mild hypothermia.

Partial Text

Halting oral intake in the night before surgery has long been a part of routine
preoperative preparation to avoid a possible aspiration of gastric content in lungs.
Unconciousness and supression of protective airway reflexes associated with
anesthesia and sedation may result in regurgitation and vomiting of gastric content
when gastric pressure exceeds lower eosephageal pressure which in turn causes
aspiration of gastric content into lungs1.

This prospective observational study was conducted following approval of the
hospital’s human research ethics board and in accordance with Helsinki declaration.
This study was registered prospectively to “ClinicalTrials.gov” protocol registry
system.

Mean age of the patients in the study was 72.5±7.8 and 130 (61.6%) of the patients
were male. Mean BMI of the patients were 28.0±4.0. One hundred and thirty-five
(62.5%) of the patients had comorbidities with most frequent comorbidity being
hypertension. There were no statistically significant differences between groups for
age, gender, BMI, ASA class score, comorbidities, operation type, amounts of fluids
infused, spinal anesthetic amounts and sensory block levels (p>0.05) (Table 1).

One of the most important preoperative preparations aimed at reducing the risk of
pulmonary aspiration of gastric contents, preoperative fasting, is the restriction
of oral fluid and food intake for a certain time. ASA preoperative guidelines
suggest that a six hours of oral food restriction following a light meal and a two
hours of fluid restriction following a clear fluid is safe for patients undergoing
surgery1. Longer fasting periods were proposed to be the cause of various deleterious
effects such as distress, fatigue, restlessness, dehydration, electrolyte imbalances
and hypoglycemia3,8,9. In addition, hunger stimulates gastric acid secretion, both increasing
gastric volume and decreasing gastric pH, thus, increasing the risk of pulmonary
aspiration of gastric contents10. Fluid losses continue to occur during the fasting period via urine
production and in the form of insensible fluid loss resulting hypovolemia4,10. Hypovolemia decreases tissue perfusion resulting in perioperative organ
damage.

Shorter preoperative fasting periods are proven to be safe by various studies.
Nevertheless, a significant number of centers continue to practice longer,
traditional overnight fasting. This is not only unobliging; but also harmful to
patients. Our study has shown that fasting times in our population is far longer
than recommended and fasting prolonged more than 15 hours is related to a
transiently increased cardiac stress and mild hypothermia. Yet, bringing the valid
guidelines in effect might prove difficult and costly in busy tertiary centers, such
as our hospital. Forming perioperative nutrition teams to overwatch patients’
nutritional status, especially in high risk populations, such as geriatrics, could
improve the quality of healthcare.

 

Source:

http://doi.org/10.1590/s0102-865020190030000009

 

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