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Determination of Safe Apnoea Period in Relation to Haemoglobin Concentration at Komfo Anokye Teaching Hospital

The induced cessation of ventilation or suspension of external breathing is a common occurrence in anaesthetic practice. During the period of induced apnoea, there is no movement of the muscles of inhalation and lung volumes initially remain unchanged. Maintaining haemoglobin saturation during airway management is critical to guarantee the safety of patients. However, there has been little quantitative study of apnoea especially on the rate of change in oxygen saturation in relation to haemoglobin concentration in the apnoeic period of induction of anaesthesia. The study sought to determine the safe apnoea period in relation to haemoglobin concentration. The study showed that patients with low haemoglobin concentration took less time to reach 100% oxygen saturation, while those with high haemoglobin concentration took more time to reach 100% oxygen saturation during pre-oxygenation. The study found that the average safe apnoea period for patients in relation to haemoglobin concentrations to desaturation (from 100% 92%) following the administration of suxamethonium was 7.0 9.9 g/dl was 3:15.07 minutes, 10.0 12.9 g/dl was 3:43.05 minutes and 13.0 16 g/dl was 4:23.04 minutes. And the overall safe apnoea time for the patients was 3:27.02 minutes. All the patients who attained 100% oxygen saturation without inhaling 100% oxygen were living in mountainous areas. The mean induction period (6:52.26 ms) of the patients was higher than the mean safe apnoea period (3:27.02 ms). The study recommends that anaemia should be corrected before induction of anaesthesia and people living at high altitude should be advised to occasionally move down to areas of low altitude to improve tissue oxygenation. Subject Areas Anaesthesiology, Pain Management How to cite this paper: George, T., Acquaye, J., Agbenyega, T. and Sallah, L. (2021) Determination of Safe Apnoea Period in Relation to Haemoglobin Concentration at Komfo Anokye Teaching Hospital. Open Access Library Journal, 8: e7930. https://doi.org/10.4236/oalib.1107930 Received: September 6, 2021 Accepted: October 15, 2021 Published: October 18, 2021 Copyright © 2021 by author(s) and Open Access Library Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access


Introduction
The induced cessation of ventilation or suspension of external breathing is a common occurrence in anaesthetic practice. According to Wills and Sirian (2009) [1], safe apnoea period is the duration of time following cessation of breathing or ventilation until critical arterial desaturation occurs (SaO 2 88% to 90%). Patients undergoing general anaesthesia go through a period of apnoea during laryngoscopy and tracheal intubation, which makes it necessary to ensure safe apnoea period [2].

Health report for 2000-2002 by American Society of Anaesthesiologist Task
Force in United Kingdom on Confidential Enquiry into Maternal and Child health associated three out of seven maternal anaesthetic deaths to apnoea as a result of failed endotracheal intubation [3] [4]. A further study in the Netherland for more than two years revealed that 10% out of 87,000 clients' death associated with anaesthesia was as a result of improper management of apnoea [5]. In addition, most studies in apnoea took place in the settings of advanced and emerging countries with highly sophisticated medical technology. However, there has been little quantitative understanding of apnoea, on the rate of change in oxygen saturation in relation to haemoglobin concentration in the apnoeic period of induction of anaesthesia due to its clinical research limitations, hence the need to study that during suxamethonium apnoea at Komfo Anokye Teaching Hospital.

Materials and Method
It's an observational research design with independent variables of haemoglobin concentration and administration of induction agent, whereas the dependent variable was oxygen saturation. The population of the study comprised all surgery patients admitted to department of Surgery at Komfo Anokye Teaching Hospital from 1 st April to 31 st July 2016.
A sample size of Ninety-four was used, Kirkwood and Sterne (2003) [6], this ensured statistical representation of the sample size in relation to the study population. Purposive sampling was used to sample patients from the population, aimed at obtaining clients eligible for the study. The data were processed using Microsoft Excel 2010 Professional Edition.
Descriptive statistics such as means, standard deviation as well as inferential statistics such as correlation and one-way analysis of variance were used to analyse data collected. An error margin of 0.05 was used for all inferential analyses.

Results
A little over half (52.1%) of the patients were females, while 47.9% were males.
Patients presented for surgery based on the classification of American Society of Anaesthesiology (ASA), with 55.3% being emergency and 44.7% being elective.     Table 3 shows BMI data on sample size with 68% (normal), 27.7% (overweight) and 4.3% (obese).
Below 25 kg/m 2 -Normal BMI 25 -29.9 kg/m 2 -Overweight 30 and plus kg/m 2 -Obese Table 4 represents mean oxygen saturation of 97% in relation to different haemoglobin concentration groupings of patient's breathing room air during anaesthetic assessment. And those with haemoglobin concentration of 7.0 -9.9 none attained 100% saturation. Table 5 shows no statistical significance since significant value of 0.974 was more than acceptable margin of error 0.05. Imply that there were similar oxygen saturations with room air across the three haemoglobin concentrations.   As shown in Table 9, there is statistical significant association among the different haemoglobin concentration levels in relation to the rate of increase in oxygen saturation during pre-oxygenation.      (Table 11).
The results of a one-way analysis of variance with post hoc test showing statistical significance of the observed differences in the rate of oxygen desaturation in relation to haemoglobin concentration following the administration of suxamethonium as significant value of 0.001 is within an acceptable error margin of 0.05 (Table 12).      (Table 13).
Data (Table 14) showing normal vital signs of sampled patients who attained 100% oxygen saturation without inhaling 100% oxygen being similar to those who did not attained 100% oxygen saturation.

Discussion
The results show that preoperative anaemia was prevalent in the majority (66%) of the patients. This result is in agreement with the finding of Baron et al., (2014) [7] that preoperative anaemia had a high prevalence in both adult men and women (31.1% and 26.5%, respectively).
From the study, the majority (55.3%) of patients were operated under emergency circumstances. This is likely to affect extensive preoperative assessment for effective airway management as described by Lane et al., (2005) [8].
The study found that patients with low haemoglobin concentration took less time to achieve 100% oxygen saturation, while those with high haemoglobin concentration took more time to reach 100% oxygen saturation during pre-oxygenation.
This disagrees with the assertion of Davis et al. (2008) [9] that patients with high haemoglobin concentration reach oxygen saturation faster than those with low Open Access Library Journal haemoglobin concentration. However, Baillard et al., (2006) [10] posited that high haemoglobin count could occur when the body requires an increased oxygen-carrying capacity, especially for patients who smoke and those living at higher altitude. The average time taken for patients to de-saturate from 100% oxygen to 92% in relation to haemoglobin concentrations with suxamethonium apnoea were 7.0 -9.9 g/dl was 3:15.07 minutes, 10.0 -12.9 g/dl was 3:43.05 minutes and 13.0 -16 g/dl was 4:23.04 minutes, with overall the mean safe apnoea period of the sampled patients being 3:27.02 minutes. These were lower than the six to eight minutes suggested by Nielsen et al., (2008) [11] as the normal time for desaturation. This could be attributed to the fact that anaesthesia reduces the functional residual capacity of patients, as well as increase oxygen consumption from suxamethonium fasciculation, which causes faster rate of desaturation following the administration of suxamethonium according to Weingart (2012) [2]. This also disagrees with Oddo et al., (2006) [12] that the importance of haemoglobin is not in the storage of oxygen but in its effective transport from the lungs to the tissues.
None of the sampled patients with haemoglobin concentration level 7.0 -9.9 attained 100% oxygen saturation compared to those with 10.0 -12.9 and 13.0 -16 when breathing room air during anaesthetic assessment and before induction of anaesthesia which according to Davis et al., (2008) [9] indicates anaemic hypoxia.
All the patients who attained 100% oxygen saturation without inhaling 100% oxygen had the majority (80%) of such patients with haemoglobin concentration of 13 -16 g/dl and 20% had haemoglobin concentration of 10 -12.9 g/dl and were living in mountainous areas and within the active working age group (30 -45 years) with respiratory rate of 14 cpm.
This was in agreement with the assertion of Palkovits et al., (2014) [13] that people living at high altitudes have low arterial partial pressure of oxygen, low partial pressure of carbon dioxide resulting slight increase in arterial pH and for that matter increases their haemoglobin affinity to oxygen which makes them attain 100% saturation without releasing oxygen. However, this result disagrees with the assertion of McCahon and Hardman (2007) [14] that people of high altitude lack oxygen because of the negative relationship between oxygen saturation in air and altitude.
From the study, the mean induction period of the patients was 6:52.26 ms which was higher than the mean safe apnoea period (3:27.02). Per the argument of Davis et al., (2008) [9], the implication is that the patients were generally at risk. This is because such patients have to be re-oxygenated in the process to guarantee their safety in the physiological processes before surgery.

Conclusions
The study found a positive relationship between haemoglobin concentration levels and time taken by patients to reach 100% oxygen saturation during pre-Open Access Library Journal oxygenation.
The time for oxygen desaturation among the patients was directly or positively related to the level of haemoglobin concentration.
All the patients who attained 100% oxygen saturation without inhaling 100% oxygen were living in mountainous areas.
The study concludes that haemoglobin concentration plays a critical role in the induction and apnoea period.

Limitation of the Study
Since the study was conducted in human, the critical desaturation point of 88% -90% was set at 92%.
Another limitation of the study was difficulty of the researcher to obtain the background information about some of the patients because of pain.

Recommendations
The following recommendations were made to ensure safe apnoea period in patients in relation to haemoglobin concentration.
1) Anaemia must be corrected before induction of general anaesthesia in order to ensure safe apnoea period.
2) Awake anaemic hypoxia patients compensate better than during induction of anaesthesia and for that matter induction period for anaemic patient, when necessary must be done with accurate speed.
3) The study also recommend all intubators to use the apnoeic oxygenation technique for all critically ill patient during laryngoscopy and intubation 4) The study recommends that the Ghana Health Service should deploy an online database application system to store the medical and surgical records of people in the country. 5) Educational programmes to educate the public on nutrition to enable people consume balance diet that would help maintain adequate haemoglobin concentration in their bodies.

Suggestion for Further Study
The study suggests that further studies should be conducted into causes or reasons why patients who lived in mountainous areas attained 100% oxygen without inhaling 100% oxygen.
In such a study, the selection of patients should be based on altitude of place of stay. Regression and factor analyses could be used to determine the factors which account for the attainment of 100% oxygen without inhaling 100% oxygen.